U.S. patent application number 14/436713 was filed with the patent office on 2016-01-28 for damper assembly.
The applicant listed for this patent is RENOLD PLC.. Invention is credited to Michael Charles Christmas, Torquil Edmund Pyper.
Application Number | 20160025175 14/436713 |
Document ID | / |
Family ID | 49484383 |
Filed Date | 2016-01-28 |
United States Patent
Application |
20160025175 |
Kind Code |
A1 |
Christmas; Michael Charles ;
et al. |
January 28, 2016 |
DAMPER ASSEMBLY
Abstract
A damper assembly has a chain, a first mounting element and a
second mounting element. The chain has a longitudinal axis and
comprising a plurality of links pivotally interconnected by
transverse articulation elements. It has a straight configuration
in which the links are substantially aligned in a linear direction,
and has at least one resilient member configured to force adjacent
links of the chain to articulate out of the straight configuration.
The first and second mounting elements are each attached to the
chain and are movable relative to one another between a first
position and a second position, and are arranged to urge the chain
towards the straight configuration when they are moved towards the
second position.
Inventors: |
Christmas; Michael Charles;
(Cheshire, GB) ; Pyper; Torquil Edmund;
(Oxfordshire, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
RENOLD PLC. |
Greater Manchester |
|
GB |
|
|
Family ID: |
49484383 |
Appl. No.: |
14/436713 |
Filed: |
October 18, 2013 |
PCT Filed: |
October 18, 2013 |
PCT NO: |
PCT/GB2013/052731 |
371 Date: |
April 17, 2015 |
Current U.S.
Class: |
267/217 |
Current CPC
Class: |
F16G 13/18 20130101;
B66C 1/125 20130101; F16F 7/00 20130101; A01K 1/064 20130101; F16F
9/3207 20130101; F16F 9/14 20130101; F16G 13/06 20130101; F16F 9/54
20130101; B21L 11/02 20130101 |
International
Class: |
F16F 9/32 20060101
F16F009/32; F16F 9/54 20060101 F16F009/54; F16F 9/14 20060101
F16F009/14 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 19, 2012 |
GB |
1218800.9 |
Oct 26, 2012 |
GB |
1219281.1 |
Dec 20, 2012 |
GB |
1223073.6 |
Jan 15, 2013 |
GB |
1300689.5 |
Mar 8, 2013 |
GB |
1304231.2 |
Mar 28, 2013 |
GB |
1305756.7 |
Claims
1-20. (canceled)
21. A damper assembly comprising: a chain having a longitudinal
axis and comprising a plurality of links pivotally interconnected
by transverse articulation elements, the chain having a straight
configuration in which the links are substantially aligned in a
linear direction and at least one resilient member configured to
force adjacent links of the chain to articulate out of the straight
configuration, and a first mounting element and a second mounting
element each attached to the chain, the mounting elements being
movable relative to one another between a first position and a
second position and being arranged to urge the chain towards the
straight configuration when they are moved towards the second
position.
22. A damper assembly according to claim 21 wherein the resilient
member is a flexible elongate resilient member threaded along at
least part of the length of the chain.
23. A damper assembly according to claim 21 wherein the chain is
located within a reservoir that is arranged to contain damping
fluid.
24. A damper assembly according to claim 21 wherein the first
mounting element comprises a mounting element cavity and the second
mounting element comprises a piston, the piston being slidably
received within the cavity; optionally wherein the piston defines a
piston cavity therein.
25. A damper assembly according to claim 21 wherein the first
mounting element comprises a mounting element cavity and the second
mounting element comprises a piston, the piston being slidably
received within the cavity, wherein the piston defines a piston
cavity therein and the chain is at least partially received within
the piston cavity; optionally wherein one portion of the chain is
attached to the piston, and another portion of the chain is
attached to the first mounting element via a protrusion projecting
through an aperture in the piston.
26. A damper assembly according to claim 24 wherein the mounting
element cavity and the piston co-operatively form a piston pump
mechanism arranged to displace a damping fluid; optionally wherein
the piston pump mechanism is arranged to displace damping fluid
into the piston cavity.
27. A damper assembly according to claim 21 wherein the damper
assembly further comprises a housing unit with a housing unit
cavity, the first mounting element being slidably received within
the housing unit cavity.
28. A damper assembly according to claim 27 wherein the first
mounting element comprises a mounting element cavity and the second
mounting element comprises a piston, the piston being slidably
received within the cavity and the mounting element cavity and the
piston co-operatively form a piston pump mechanism arranged to
displace a damping fluid and the piston pump mechanism is arranged
to displace damping fluid into the housing unit cavity.
29. A damper assembly according to claim 21 comprising two
counterposed second mounting elements
30. A damper assembly according to claim 29, wherein the first
mounting element comprises a mounting element cavity and the second
mounting element comprises a piston, the piston being slidably
received within the cavity, and wherein each of the second mounting
elements comprises a piston, both pistons being received within the
mounting element cavity.
31. A damper assembly according to claim 21 wherein the chain
comprises one or more extensions configured to increase the
resistance to motion of the chain due to drag.
32. A damper assembly according to claim 31 wherein the extensions
are configured to co-operatively define one or more voids between
neighbouring extensions, the shape of each of said voids being
variable according to the configuration of the chain.
33. A damper assembly according to claim 31 wherein at least some
of the extensions are shaped to maintain a predetermined clearance
with neighbouring extensions when the chain articulates out of the
straight configuration.
34. A damper assembly according to claim 21 comprising a plurality
of said chains comprised within a chain assembly, wherein: each of
the plurality of chains runs between a first connection bracket and
a second connection bracket of the chain assembly; the first and
second connection brackets are movable between a first position and
a second position and are arranged to urge each of the chains
towards the straight configuration when they are moved towards the
second position; the first and second mounting elements of the
damper assembly are arranged to urge each chain towards the
straight configuration by urging the first and second connection
brackets towards their second position.
35. A damper assembly according to claim 34 wherein each of said
chains defines an articulation plane within which the links can
pivot, and the plurality of chains are positioned whereby their
respective articulation planes are substantially parallel.
36. A damper assembly according to claim 34 wherein each of said
chains defines an articulation plane within which the links can
pivot, and at least two of said chains are positioned whereby their
respective articulation planes are non-parallel.
37. A damper assembly according to claim 34 wherein the chain
assembly further comprises a damper sub-assembly configured to damp
movement of the first and second connection brackets relative to
one another; optionally wherein the damper sub-assembly comprises
an elongate piston extending between the first and second
connection brackets, and at least one of the first and second
connection brackets defines a fluid cavity within which the piston
is slidably received, relative movement of the first and second
connection brackets causing the piston to slide within the fluid
cavity.
38. A damper assembly according to claim 37 wherein the damper
sub-assembly comprises a deformable bladder which defines a fluid
cavity therein, relative movement of the first and second
connection brackets causing the bladder to change shape, thereby
changing the shape of the fluid cavity.
39. A damper assembly according to claim 34 wherein the chain
assembly further comprises a resiliently deformable element
configured to be deformed by relative movement of the first and
second connection brackets.
40. A damper assembly according to claim 34 wherein the chain
assembly further comprises an alignment structure positioned to
prevent at least two of the chains from contacting each other.
Description
[0001] The present invention relates to a damper assembly of the
kind that may be used, for example, in automotive suspension
systems.
[0002] Conventional damper assemblies for automotive suspension
utilise a coil spring connected in parallel with a cylinder and
piston. When the damper assembly is disturbed by the application of
a load, the spring is deformed and the piston moves within the
cylinder. The deformed spring provides a restorative force, urging
the damper back to its default position, and movement of the piston
displaces fluid within the cylinder, dissipating energy and
bringing about a damping effect. In such damper assemblies, failure
of the coil spring can lead to the damper assembly failing
catastrophically under load. This, in turn, can cause damage to
other components, for instance in the case of a vehicle suspension
system the vehicle chassis or bodywork may impact the ground.
[0003] It is one object of the present invention to provide an
improved or alternative damper assembly.
[0004] According to a first aspect of the present invention there
is provided a damper assembly comprising: a chain having a
longitudinal axis and comprising a plurality of links pivotally
interconnected by transverse articulation elements, the chain
having a straight configuration in which the links are
substantially aligned in a linear direction and at least one
resilient member configured to force adjacent links of the chain to
articulate out of the straight configuration, and a first mounting
element and a second mounting element each attached to the chain,
the mounting elements being movable relative to one another between
a first position and a second position and being arranged to urge
the chain towards the straight configuration when they are moved
towards the second position.
[0005] One advantage of the present invention is that it can allow
the portion of the damper assembly which provides the restorative
force, and the portion which brings about the damping effect, to be
at least partially independent of one another. This can be
advantageous in providing a degree of redundancy. For instance, if
the resilient member were weaker than the chain, then any failure
of the former would not be catastrophic since load applied to the
damper assembly could still be carried by the chain. A second
advantage arises in that the components of the damper assembly
moving over each other (and/or being deformed) can provide inherent
damping capabilities as outlined below. In contrast, a conventional
coil spring offers very little inherent damping. Further, the
extent of inherent damping may be selectively varied by virtue of
the configuration and geometry of the chain and resilient member,
and/or the use of lubricant and/or damping fluid (or lack
thereof).
[0006] The chain may be a roller-bush chain. Where the chain is a
roller bush chain, the resilient member may bear against one or
more of the rollers. One or more rollers may be attached to or
integral with the resilient member.
[0007] The resilient member may be connected to one of the mounting
elements. For example, it may be attached to the first or second
mounting element at one end. Alternatively, the resilient member
may be attached to the chain. For instance, it may be attached at
one end of the chain and/or resilient member, at both ends of the
chain and/or resilient member, or at an intermediate location along
the length of the chain and/or resilient member.
[0008] When the chain is subjected to a tensile load (i.e. is urged
towards the straight configuration) by the mounting elements, the
links tend towards the straight configuration but are resisted by
the resilient member, which may deflect as a consequence. The
resilient member is arranged such that when the tensile load is
removed it returns to its original shape.
[0009] The resilient member applies a reactive force to the chain
when the chain is subjected to a tensile load, by virtue of it
being deflected and its resilience. The tensile load forces the
chain links to move towards the straight configuration but the
reactive force of the resilient member acts on the chain (and
preferably on individual chain links) so as to resist such
movement.
[0010] The resilient member thus acts in a manner analogous to a
spring. The reactive force may act in the manner of a spring
constant in that it may change in proportion to the tensile load
applied. It may change in a linear or non-linear relationship. The
magnitude of the reactive force may be dependent on a combination
of the configuration and geometry of the resilient member and the
mechanism of the chain elements. In one embodiment the resilient
member acts like a constant-force spring such that the force it
exerts over its range of motion is a constant.
[0011] The resilient member may provide a degree of damping by
virtue of movement of the links relative to the resilient member,
the friction between the two providing sufficient energy losses to
achieve effective damping. Alternatively or in addition, damping
may be designed into the chain by virtue of the resilient member
comprising a suitable elastomeric material that absorbs some of the
energy (such as an elastomeric polymer). The member may wholly
comprise such a material or may be made in part from such material.
For example, the resilient member may comprise a core material and
an elastomeric polymer coating, such as, for example, nitrile
rubber or other synthetic rubber copolymer. The core material may
be any suitable material that has sufficient stiffness such as a
metal. One example is steel and preferably a spring steel. Instead
or in addition, the chain may have rollers made from a suitable
elastomeric damping material such as a polymeric damping material.
The material may be injection mouldable. The size and/or thickness
of the rollers may vary along the length of the chain in order to
provide different damping characteristics along the chain.
Alternatively or in addition, the material of the rollers may vary
along the length of the chain.
[0012] The chain may be disposed between guide members for guiding
movement of the chain.
[0013] The chain may be substantially enclosed within the damper
assembly. For example, it may be contained in a space provided in
one of the mounting elements or in a space co-operatively provided
by more than one of the mounting elements. Alternatively, the chain
may be only partially enclosed or may be in an exposed
position.
[0014] The resilient member may be a resilient elongate flexible
member threaded along at least part of the length of the chain. One
advantage of such an arrangement is that if the resilient member
breaks, in some embodiments it can be retained in position by the
chain, at least for a period of time, allowing any intact portions
of the resilient member to continue to offer a restorative force
(albeit at a reduced effectiveness). Instead, the resilient member
may take the form of a resilient elongate flexible loop held within
the chain, or may take the form of an elastomeric block held within
the chain. Alternatively, it may take any other suitable form and
be in any other suitable position, for instance it may be a
resilient elongate flexible which is not threaded along at least
part of the length of the chain.
[0015] Alternatively, the resilient member may take the form of a
resilient elongate flexible member, but not be threaded between the
chain links. In either case, it may be deflected into an undulating
form as the chain links articulate towards the straight
configuration, and tend towards the straight, linear configuration
(but may be prevented from being perfectly straight by virtue of
the chain links).
[0016] The damper assembly may have a plurality of resilient
members disposed in a side-by-side relationship. This may be
advantageous in that the resilient members moving against one
another may increase energy dissipation, thereby improving the
damping capability of the assembly.
[0017] The chain may be located within a reservoir that is arranged
to contain damping fluid. The reservoir may contain damping fluid.
Damping fluid is any fluid (liquid or gas) which exhibits
sufficient viscosity to be useful in dissipating kinetic energy
applied to it, such as natural or synthetic oil or grease, or
water. The damping fluid may be manufactured from viscous synthetic
oil, and/or have a viscosity in the region of 30,000-70,000 cSt and
preferably around 50,000 cSt. The reservoir may be partially of
completely filled with damping fluid. Alternatively, the damper
assembly may have no such reservoir. In this case no damping fluid
may be present in contact with the chain, or one or more moving
parts of the chain may be coated with damping fluid. The moving
parts may be one or more selected from the group comprising the
links, rollers, pins, bushes or the resilient member. The presence
of damping fluid in contact with the chain, whether it is in a
reservoir or as a coating on parts of the chain itself, may
increase the damper constant of the assembly. The damping fluid may
also function as a lubricant, and/or have the effect of reducing
the noise of the chain in use.
[0018] In one embodiment of the invention, the first mounting
element comprises a mounting element cavity and the second mounting
element comprises a piston, the piston being slidably received
within the cavity. The mounting element cavity and the piston may
be of complementary shape. Each may be cylindrical (of circular or
ovoid cross-section), prismatic, or of any other suitable shape.
One or more sealing members may be interposed between the piston
and the mounting element cavity. The mounting element cavity and
the piston may define a common longitudinal axis along which they
are movable relative to one another. The longitudinal axis of the
chain (when it is in the straight configuration) may or may not be
in line with or parallel to the common longitudinal axis of the
mounting element cavity and piston.
[0019] In the above embodiment, the piston may define a piston
cavity therein. The piston cavity may be fully enclosed,
substantially fully enclosed or only partially enclosed, by the
piston or by the piston and other components. It may be cylindrical
(of circular or ovoid cross-section), prismatic, or of any other
suitable shape. Alternatively, the piston may be solid.
[0020] In an embodiment where the piston defines a piston cavity,
the chain is at least partially received within the piston cavity.
Where the chain is only partially received within the piston cavity
it may be partially exposed, or may be partially received within
another component (for example the mounting element cavity).
Alternatively, the chain may be in a fully exposed position, and/or
may be fully or partially received in a different component of the
damper assembly (such as the mounting element cavity).
[0021] In the above embodiment one portion of the chain may be
attached to the piston, and another portion of the chain attached
to the first mounting element via a protrusion projecting through
an aperture in the piston. Where the mounting element cavity and
the piston define a common longitudinal axis along which they are
movable relative to one another, the protrusion may project
substantially radially through the aperture in the piston, and/or
the aperture may be in the form of an elongate slot substantially
parallel with the common longitudinal axis of the mounting element
cavity and piston. The protrusion may be a pin extending through an
aperture in a chain link.
[0022] Alternatively, in the above embodiment the damper assembly
may further comprise a plug slidably received within the piston
cavity, one portion of the chain being attached to the piston and
another portion of the chain being attached to the plug. The plug
may be of complementary shape to the piston cavity. It may be
cylindrical, prismatic, or of any other suitable shape. There may
be one or more sealing members interposed between the plug and the
piston cavity.
[0023] Where the first mounting element comprises a mounting
element cavity and the second mounting element comprises a piston
slidably received within the mounting element cavity, the mounting
element cavity and the piston may co-operatively form a piston pump
mechanism arranged to displace a damping fluid. The damper assembly
may contain damping fluid arranged to be displaced by the piston
pump mechanism. In embodiments where the chain is located within a
reservoir of damping fluid, the damping fluid in the reservoir and
damping fluid displaced by the piston pump may or may not be of the
same composition. Where the fluid is of the same composition, the
fluid in the reservoir may or may not be displaced by the piston
pump.
[0024] Where the damper assembly includes a piston cavity, the
piston pump mechanism may be arranged to displace damping fluid
into the piston cavity.
[0025] The damper assembly may further comprise a housing unit with
a housing unit cavity, the first mounting element being slidably
received within the housing unit cavity.
[0026] Where a damper assembly has a housing unit and a piston pump
mechanism, the piston pump mechanism may be arranged to displace
damping fluid into the housing unit cavity.
[0027] In one embodiment, the damper assembly comprises two
counterposed second mounting elements. The two counterposed second
mounting elements may or may not be substantially identical to one
another and/or substantially mirror images of each other.
[0028] Where the first mounting element comprises a mounting
element cavity and the second mounting element comprises a piston,
in the above embodiment each of the second mounting elements may
comprise a piston, both pistons being received within the mounting
element cavity. Alternatively, the damper assembly may comprise
more than one mounting element cavity and the pistons may be
received within different mounting element cavities.
[0029] In the above embodiment, the chain may be attached to the
first mounting element at a first location along its longitudinal
axis, and attached to each of the second mounting elements at
locations along its longitudinal axis that are on opposite sides of
the first location. The first location may or may not be
substantially equidistant from the points at which the second
mounting elements are attached. Alternatively, the damper assembly
may have separate chains attached to each of the second mounting
elements.
[0030] In the above embodiment, the two counterposed second
mounting elements may be connected such that their relative
movement is restricted. The second mounting elements may be
substantially prevented from moving relative to one another.
Alternatively, each of the second mounting elements may be free to
move independently of the other.
[0031] In a damper assembly according to the first aspect of the
invention the chain may comprise one or more extensions configured
to increase the resistance to motion of the chain due to drag. The
extensions may induce drag in air, or in a damping fluid
surrounding the chain. The extensions may be in the form of plates,
which may each be attached to a link of the chain and be positioned
substantially orthogonally to it. Alternatively, they may take any
other suitable shape (for instance they may take the form of
elongate members or arrays thereof), may be attached in any other
suitable way and/or may be in any other suitable orientation.
[0032] The extensions may be configured to co-operatively define
one or more voids between neighbouring extensions, the shape of
each of said voids being variable according to the configuration of
the chain.
[0033] At least some of the extensions may be shaped to maintain a
predetermined clearance with neighbouring extensions when the chain
articulates out of the straight configuration. For instance, some
extensions may be provided with a convex shape configured to
maintain a particular clearance with neighbouring extensions of a
flat shape. As another example, all the extensions may have convex
surfaces which are shaped to maintain a predetermined clearance
with the convex surfaces of adjacent extensions. By utilising this
latter arrangement, the volume of each void can be maintained at a
substantially constant level when the chain articulates out of the
straight configuration.
[0034] The damper assembly may comprise a plurality of said chains
comprised within a chain assembly, wherein: [0035] each of the
plurality of chains runs between a first connection bracket and a
second connection bracket of the chain assembly; [0036] the first
and second connection brackets are movable between a first position
and a second position and are arranged to urge each of the chains
towards the straight configuration when they are moved towards the
second position; [0037] the first and second mounting elements of
the damper assembly are arranged to urge each chain towards the
straight configuration by urging the first and second connection
brackets towards their second position.
[0038] The first and second mounting elements of the damper
assembly may be attached to the second and first connection
brackets respectively, or vice versa.
[0039] Each chain may be attached to the first and second
connection brackets. First and second ends of each chain may be
attached to the first and second connection brackets
respectively.
[0040] Each of the plurality of chains may be different, or one or
more of the plurality may be substantially identical to one
another. For instance, if one of the chains comprises one or more
of the features described above, each of the other chains may or
may not also comprise those features. Two or more of the chains may
be positioned substantially parallel to one another when the first
and second connection brackets are in the second position. Each of
said plurality of chains may define an articulation plane within
which the links can pivot, and the plurality of chains may be
positioned whereby their respective articulation planes are
substantially parallel.
[0041] All of the plurality of the chains may be so positioned. For
the avoidance of doubt, reference to planes being parallel is
intended to include their being coplanar.
[0042] Alternatively, and at least two of said chains may be
positioned whereby their respective articulation planes are
non-parallel.
[0043] All of the plurality of chains may be positioned such that
none are parallel to each other.
[0044] The chain assembly may further comprise a damper
sub-assembly configured to damp movement of the first and second
connection brackets relative to one another.
[0045] The damper sub-assembly may be configured to damp movement
of the connection brackets towards the first position and/or
towards the second position. The damper sub-assembly may take any
suitable form. For instance, it may be a dashpot, a piston pump, an
electromagnetic damper, an elastomeric component which dissipates
energy through hysteresis.
[0046] The damper sub-assembly may comprise an elongate piston
extending between the first and second connection brackets, and at
least one of the first and second connection brackets defines a
fluid cavity within which the piston is slidably received, relative
movement of the first and second connection brackets causing the
piston to slide within the fluid cavity.
[0047] Both the first and second connection brackets may define
fluid cavities within which the piston is slidably received.
[0048] The damper sub-assembly may comprise a deformable bladder
which defines a fluid cavity therein, relative movement of the
first and second connection brackets causing the bladder to change
shape, thereby changing the shape of the fluid cavity.
[0049] The change of shape of the fluid cavity in the bladder may
be a change in geometric shape (for instance a change in aspect
ratio) and/or a change in volume.
[0050] The chain assembly may comprise a duct in fluid
communication with the fluid cavity or cavities.
[0051] The duct may run through one or both of the connection
brackets, or may be positioned in any other suitable location. For
instance, where the chain assembly comprises a piston the duct may
run through the piston.
[0052] The chain assembly may further comprise a resiliently
deformable element configured to be deformed by relative movement
of the first and second connection brackets.
[0053] The resiliently deformable element may be an elastomeric
component such as a tube, sheet or block, or it may be a spring
such as a coil spring, leaf spring or Belleville washer.
Alternatively, it may take any other suitable form.
[0054] The resiliently deformable element is configured to be
deformed by movement of the first and second connection brackets
towards the first position.
[0055] Alternatively or in addition, the resiliently deformable
element may be configured to be deformed by movement of the first
and second connection brackets towards the second position.
[0056] The chain assembly may further comprise an alignment
structure positioned to prevent at least two of the chains from
contacting each other.
[0057] The alignment structure may be positioned to prevent all the
plurality of chains from contacting each other.
[0058] Specific embodiments of the present invention will now be
described, by way of example only, with reference to the
accompanying drawings in which:
[0059] FIG. 1 is a perspective view of a chain of a damper assembly
according to a first embodiment of the invention;
[0060] FIGS. 2a-2c are cross-sectional side views of the chain of
FIG. 1 in different configurations;
[0061] FIGS. 3a-3c are cross-sectional side views of a damper
assembly according to a first embodiment of the invention, in
different configurations;
[0062] FIG. 4 is a cross-sectional side view of a modification of
the damper assembly of the first embodiment;
[0063] FIG. 5 is a cross-sectional side view of a further
modification of the damper assembly of the first embodiment;
[0064] FIG. 6 is a cross-sectional side view of a damper assembly
according to a second embodiment of the invention;
[0065] FIG. 7 is a cross-sectional side view of a damper assembly
according to a third embodiment of the invention;
[0066] FIG. 8 is a side view of a modification of the third
embodiment of the invention, shown in partial cross-section;
[0067] FIGS. 9a and 9b are side and perspective views respectively
of a damper assembly according to a fourth embodiment of the
invention, shown in partial cross-section;
[0068] FIG. 10 is a perspective view of a chain suitable for use in
the invention;
[0069] FIGS. 11a-11c are side views of the chain of FIG. 10;
[0070] FIG. 12 is a side view of another chain suitable for use in
the invention;
[0071] FIG. 13 is a side view of a further chain suitable for use
in the invention;
[0072] FIG. 14 is a cross-sectional side view of another
modification of the first embodiment of the invention;
[0073] FIG. 15 is a cross-sectional side view of a further
modification of the first embodiment of the invention;
[0074] FIG. 16 is a cross-sectional side view of an additional
modification of the first embodiment of the invention;
[0075] FIG. 17 is a schematic side-view of a damper assembly
according to a fifth embodiment of the invention;
[0076] FIG. 18 is a perspective view of a first embodiment of a
chain assembly for use as part of a damper assembly according to
any of the preceding embodiments;
[0077] FIG. 19 is a side view of the chain assembly of FIG. 18;
[0078] FIG. 20 is a front view of the chain assembly of FIG.
18;
[0079] FIG. 21 is a perspective view of a modification of the chain
assembly of FIG. 18;
[0080] FIG. 22 is a perspective cutaway view of a second embodiment
of a chain assembly for use as part of a damper assembly according
to any of the preceding embodiments;
[0081] FIG. 23 is a perspective cutaway view of a modification of
the chain assembly of FIG. 22;
[0082] FIG. 24 is a perspective cutaway view of a modification of
the chain assembly of FIG. 23; and
[0083] FIG. 25 is a perspective cutaway view of a modification of
the chain assembly of FIG. 24.
[0084] Referring now to FIG. 1 of the drawings, a chain 1 of a
damper of a first embodiment of the invention is a roller bush
chain, although it is to be understood other chain types may be
used. The roller bush chain 1 comprises a plurality of inner link
assemblies 2 that are interconnected along the length of the chain
by outer link plates 4 such that the inner link assemblies can
articulate relative to each other.
[0085] Each inner link assembly 2 comprises a pair of opposed
spaced inner link plates 6 connected together by a pair of bushes 8
(most of which are hidden in FIG. 1) extending perpendicularly to
the plates 6. Each of the inner link plates 6 has a pair of spaced
apertures 10 in which the ends of the pair of bushes 8 are
received. Each of the opposed inner link plates 6 is mounted in a
friction or interference fit on the ends of the bushes 8 in a fixed
relationship and a rotatable cylindrical roller 12 is supported on
each bush 8 between the inner link plates 6.
[0086] The outer link plates 4 are of similar configuration to the
inner link plates 6 but with smaller apertures 14 and are arranged
to connect together adjacent inner link assemblies 2. A given outer
link plate 4 overlaps with adjacent inner link assemblies 2 such
that each of its apertures 14 is aligned with a corresponding
aperture 10 in the inner link assembly 2 and is connected to the
inner link assemblies 2 by pins 16 that pass through the aligned
apertures 10, 14 and are received in the bushes 8. The apertures 10
in the inner link assemblies 2 are sized such that the assemblies
are free to rotate on the pins 16 but the outer link plates 4 are
fixed to the pins 16. More specifically, the apertures 14 in the
outer link plates 4 are sized such that the edge of the plate
around them is an interference or friction fit with the pins
16.
[0087] The chain 1 further comprises a resilient member which in
this embodiment is in the form of an elongate flexible member 20
that is threaded through the inner link assemblies 2, along the
length of the chain, in a sinuous formation. The elongate flexible
member 20 is made of any suitable resilient material that is
elastically deformable in a direction substantially perpendicular
to its longitudinal axis in the manner shown in FIG. 2. It is able
to move relative to the chain 1, although in order to prevent the
elongate flexible member 20 working free of engagement with the
chain it may be loosely connected to the chain at each end, or
otherwise retained as outlined below.
[0088] In this arrangement the elongate flexible member 20 is
threaded through the chain 1 such that it alternately passes over
and under successive rollers 12 of the chain (in other embodiments
however, it may be arranged to miss one or more rollers, for
instance it may pass over and under successive pairs of rollers).
This can be seen most clearly in FIGS. 2a-2c in which the member is
shown in solid line for clarity. The resilient member 20 is
designed such that in the undeformed state it tends towards a
straight (linear) configuration (without undulations along its
length), as shown in FIG. 2a. As a result the chain links 2, 4 are
forced to articulate on the pins 16 and the chain 1 adopts a
zig-zag configuration, i.e. a non-straight configuration, in which
the link assemblies 2 are disposed at an angle to the outer link
plates 4. Thus the inner link assemblies 2 on each side of a pin 14
(which defines an articulation axis) are forced to move in opposite
directions resulting in contraction of the chain length compared to
when it is in a straight configuration.
[0089] The arrangement allows the chain 1 to behave in the manner
of a spring in that a load applied to the chain in a direction that
tends to straighten the chain, such that the link plates 4, 6 are
moved towards a straight configuration, is resisted by the elongate
flexible member 20. As the load increases the chain 1 is forced
towards the straight configuration and the undulating form of the
flexible member 20 increases, thereby offering greater resistance
to the load. This is shown in FIG. 2b. The resistance operates in
the manner of a spring force i.e. the force the member exerts on
the chain links is proportional to its deflection. When the load
has reached a magnitude such that the chain is pulled to the
straight configuration, as shown in FIG. 2c, the flexible member 20
will not deflect any further and the load is carried entirely
through the chain links, thus providing a hard stop. A graph of
load plotted against deflection would show a curve that is
initially steep but which flattens out. In some embodiments the
resilient member may be compressed by the chain links in a
direction transverse to its length such that its thickness is
reduced.
[0090] The resilient elongate flexible member 20 may be made from
any suitable flexible material such as for example, a polymer,
steel, a synthetic or natural fibrous material, or a composite
material. It is resilient such that it springs back to its original
linear form once the load is removed. The chain 1 is thus designed
such that elongate flexible member 20 has sufficient stiffness to
force the chain links 2, 4 to articulate and to resist
straightening of the chain links. The member may be rectangular or
any other shape that would conveniently pass along the length of
the chain in the manner described above. The member may be a
unitary, continuous piece or it may be discontinuous i.e. it may
comprise a plurality of pieces placed at different locations along
the length of the chain. In the latter instance the pieces may be
disposed at selected strategic locations so as to provide a
variable stiffness characteristic along the chain length.
[0091] This chain 1 may have inherent damping capabilities owing to
losses in energy that occur as a result of the elongate flexible
element 20 sliding over the rollers 12 as the chain flexes. The
damping characteristics could be improved if the resilient elongate
flexible member 20 is manufactured wholly or partly from a suitable
polymeric damping material. In one example the entire member 20 is
made from a polymeric damping material having suitable
characteristics to provide the required damping whilst also having
the capacity to carry the load applied to the chain. One example is
an injection mouldable polymer such as, for example, a
thermoplastic polyester elastomer. A commercially available product
of this kind is available from Dupont under the trade mark
Hytel.RTM.. As an alternative, the resilient elongate flexible
member 20 may comprise a core of suitable material such as spring
steel (for example) to which a suitable elastomeric polymer coating
is applied (e.g. a nitrile rubber or other synthetic rubber
copolymer).
[0092] A damper assembly according to a first embodiment of the
invention is shown in FIGS. 3A-3C. The damper assembly of the first
embodiment has a chain 1 as described above, a first mounting
element 22 and a second mounting element 24. The first mounting
element 22 and the second mounting element 24 are movable relative
to one another between a first position, as shown in FIG. 3a, to a
second position, as shown in FIG. 3c. FIG. 3b shows the mounting
elements 22, 24 in an intermediate position.
[0093] In this embodiment the first mounting element takes is in
the shape of an elongate cylindrical cup of substantially uniform
wall thickness, in other words it is in the shape of a
substantially uniform cylindrical tube with one closed end and one
open end. The internal space within the first mounting element 22
forms a mounting element cavity 28. The second mounting element 24
takes the form of a piston 26, which is slidably received within
the mounting element cavity 28. The piston of this embodiment is in
the shape of a closed-ended cylindrical tube of substantially
constant cross section. The internal space within the piston 26
defines a piston cavity 30. The chain 1 is received fully within
the piston cavity 30, which forms a reservoir which contains
damping fluid and holds it in contact with the chain.
[0094] The chain 1 is connected at one end to the piston 26 by a
protrusion 32 in the form of a cylindrical peg which is received
within a bush 8 of the chain (which allows the adjacent link to
pivot about the protrusion). The chain 1 is connected at the other
end to the first mounting element 22 via another protrusion 34,
also in the form of a cylindrical peg received within a bush 8. The
peg 34 projects from the surface of the mounting element cavity 28,
through an aperture 36 in the piston. In this embodiment the
aperture is in the form of a slot which is parallel to the common
axis of the piston 26 and cavity 28 (that is to say the axis about
which the piston and cavity are movable relative to one
another).
[0095] The damper assembly of the first embodiment is arranged to
damp compressive forces (in the vertical direction from the
perspective of FIG. 3). With no such force applied, the behaviour
of the chain is dominated by the action of the resilient elongate
flexible member 20. The chain therefore adopts the zig-zag
configuration discussed above, due to the links 2, 4 being forced
to articulate around the pins 16 by the resilient elongate flexible
member 20. In such a configuration the axial length of the chain
decreases. This urges the protrusions 32, 34 towards each other,
biasing the mounting elements 22, 24 to the first position (shown
in FIG. 3A).
[0096] When a compressive force is applied, the first and second
mounting elements 22, 24 are forced towards the second position
(shown in FIG. 3C), against the bias of the chain 1 that is
provided by the resilient elongate flexible member 20. As the
mounting elements 22, 24 move towards the second position, the
piston 26 moves further inside the mounting element cavity 28,
taking with it projection 32, and the slot 36 travels across the
projection 34. Since projection 34 is fixed to the first mounting
element 22 and projection 32 moves with the piston 26, this
movement results in the projections 32, 34 being moved further
apart, stretching the chain 1 and moving it towards the straight
configuration (forcing the resilient elongate flexible member to
deform and undulate). In this embodiment when the mounting elements
22, 24 are in the second position the chain is in the straight
configuration. In other embodiments however, when the mounting
elements are in the second position the chain may not reach the
straight configuration (for instance it may only reach the
configuration shown in FIG. 3b, i.e. a partially-straight
configuration).
[0097] As outlined above as the extension of the chain increases,
the resistive force generated by the resilient elongate flexible
member 20 also increases. If the compressive force is relatively
low, therefore, the mounting elements 22, 24 will only move part
way to the second position and the chain will reach a configuration
nearer to the straight configuration but not fully straight, as
shown in FIG. 3b.
[0098] If the compressive force is relatively large, however, the
biasing force from the chain 1 will be insufficient to counteract
it. The mounting elements 22, 24 will therefore move to the second
position and (in this embodiment) the chain will reach the straight
configuration. The chain reaching the straight configuration will
provide the `hard stop` discussed above.
[0099] Movement of the mounting elements 22, 24 between the first
and second positions undergoes a damping action by virtue of energy
being dissipated by friction between the rollers 12 and the
resilient elongate flexible member 20 (as well as hysteresis in
embodiments where the resilient elongate flexible member and/or the
rollers are elastomeric). Further damping is provided by the energy
dissipated by displacement of the damping fluid as the chain 1
articulates towards/away from the straight configuration. When such
a damping fluid is present between surfaces that would otherwise
come into contact with one another, it requires a significant
amount of energy to move those surfaces relative to each other.
Further, in embodiments such as the first embodiment where the
chain is in a reservoir of damping fluid, movement of the chain
links acts to `stir` the damping fluid, dissipating further energy.
The amount of force required and therefore the amount of the
damping effect can be controlled by suitable selection of the
components of the damping fluid, e.g. the oil components of a
grease. The higher the molecular weight of the oil the greater the
internal shear resistance of the grease. The damping fluid may also
have the effect of reducing the noise of the chain in use, e.g. by
acting as a lubricant. A grease which may be suitable for use as a
damping fluid is commercially available from Nye Lubricants Inc. of
Fairhaven, Mass., USA. It is thought that a such a damping grease
having a base kinematic viscosity (at 25.degree. C.) of around
50,000 cSt (0.05 m.sup.2/s) would be appropriate for most
applications.
[0100] FIG. 4 shows a modification of the first embodiment in which
the piston 26 is formed from two piston portions 40, 42, and the
damper assembly has sealing members 44 interposed between the
piston 26 and the mounting element 22. In this embodiment the
sealing members 44 are disposed in annular grooves in the piston
26. The sealing members 44 prevent leakage of damping fluid from
the piston cavity 30 (though a minimal amount may escape into the
annular clearance between the piston 26 and the first mounting
element 22), or leakage of air into the piston cavity 30. They also
seal the mounting element cavity 28, creating a gas pocket 45 in
the portion of the mounting element cavity which is not occupied by
the piston 26. In this modification the second mounting element 24
(in this case the piston 26) is received entirely within the first
mounting element 22 and compressive force is applied to it through
an aperture 46 in the first mounting element, as denoted by arrow
48. The piston portions 40, 42 are not mechanically joined
together, but are prevented from separating by the enclosed damping
fluid. The damping fluid is incompressible therefore without the
introduction of air (which is prevented by the sealing members 44)
the piston portions 40, 42 can only be separated by a force large
enough to produce a vacuum in the piston cavity 30. Further, when
the damper assembly is under load the two piston portions 40, 42
are held together by the virtue of the compressive force (arrow 48)
urging piston portion 42 towards piston portion 40, and the
resistive force from the chain urging piston portion 40 towards
piston portion 42 (through protrusion 32).
[0101] The piston 26 being made from multiple sections may simplify
the manufacturing and/or assembly processes of the damper assembly,
and as outlined above the sealing members 44 assist in the
prevention of leaks. Further, the provision of the gas pocket 45
provides the damper assembly with additional resistance to
compression, as movement of the piston 26 further into the mounting
element cavity 28 compresses the gas in the gas pocket 45, which in
turn provides a restorative force acting to push the piston
outwards again. The extent of this restorative force can be
controlled by suitable selection of the volume of the gas pocket
45, and the pressure of the gas contained therein for a given
displacement of the piston 26 (for example the gas pocket could be
filled with pressurised gas during construction of the assembly).
Though the gas pocket of this damper assembly is located in the
mounting element cavity, other embodiments may have one or more gas
pockets for the same purpose in the same or in any other suitable
locations.
[0102] A further modification of the first embodiment is shown in
FIG. 5. As well as a piston 26, the second mounting element 24 has
an outer casing member 50 which is concentric with the piston 26
and defines an annular clearance therewith, the clearance receiving
the first mounting element 22. Also, in this modification the
mounting elements 22, 24 are arranged so that the slot 36 remains
sealed by the surface of the mounting element cavity 28, preventing
leakage of damping fluid from the piston cavity 30 (such an
arrangement would preferably have one or more sealing members
positioned around the slot 36, though these are not shown in the
diagram). The piston 26 and mounting element cavity 28 function as
a piston pump. As a compressive load forces the piston 26 further
into the mounting element cavity 28, the piston displaces damping
fluid contained in the mounting element cavity 28. The damping
fluid is forced out of the cavity 28 through an aperture 52 in the
first mounting element 22, and into an auxiliary receptacle (not
shown). When the compressive load is removed and the piston
partially withdraws from the cavity under action of the chain 1,
the displaced fluid is sucked back from the auxiliary receptacle
(not shown) into the mounting element cavity 28 through the
aperture 52. This pumping of damping fluid can increase the damping
capabilities of the device.
[0103] FIG. 6 shows a second embodiment of the invention. Like the
first embodiment, the second embodiment has a chain 1 of the type
described previously, and first and second mounting elements 22, 24
which are movable from a first position to a second position
relative to one another. FIG. 6 shows the mounting elements 22, 24
in an intermediate position between the first and second
positions.
[0104] As in the first embodiment, the second mounting element 24
takes the form of a piston 26, which is slidably received within a
mounting element cavity 28 defined by the first mounting element
22. Unlike the first embodiment, the piston of the second
embodiment is solid (i.e. does not define a cavity). It also has a
projection 58 which protrudes from the mounting element cavity 28.
In this embodiment the chain is fully enclosed within the damper
assembly by virtue of it being positioned within the mounting
element cavity 28. The mounting element cavity 28 in this
embodiment acts as the reservoir for damping fluid.
[0105] The damper assembly of the second embodiment has a housing
unit 54 with a housing unit cavity 55. The first mounting element
22 is slidably received within the housing unit cavity 55. It will
be noted that the housing unit 54 is similar in appearance to the
first mounting element of the first embodiment, and the first
mounting element 22 of the second embodiment is similar in
appearance to the piston of the first embodiment. The first
mounting 22 element has an aperture 53, which provides fluid
communication between the mounting element cavity 28 and the piston
cavity housing unit cavity 55.
[0106] As with the first embodiment, the chain 1 is connected at
one end to the piston 26 by a protrusion 32, and the other end of
the chain is connected to the first mounting element 22 by a
protrusion 34. Again, both protrusions take the form of cylindrical
pegs received within a bush 8 of the chain.
[0107] In the second embodiment, moving the mounting elements 22,
24 to the first position requires the piston 26 to be moved
outwards within the mounting element cavity 28, away from the first
mounting element 22. This can be achieved e.g. by applying a
tensile force between the piston 26 and the housing unit 54, or by
applying a compressive force between the first mounting element 22
and the housing unit. If a tensile force is applied between the
piston 26 and the housing unit 54 (e.g. if the piston is pulled
downwards from the perspective of FIG. 6, with the housing unit
held stationary), the piston moves away from the housing unit,
sliding within the mounting element cavity 28. This decreases the
pressure in the mounting element cavity 28, which decreases the
pressure in the housing unit cavity 55, which in turn sucks the
first mounting element 22 further into the housing unit 54. If on
the other hand a compressive force is applied between the first
mounting element 22 and the housing unit 54 (e.g. if the first
mounting element 22 is pushed upwards from the perspective of FIG.
6, with the housing unit 54 held stationary), the first mounting
element moves towards the housing unit 54, sliding within the
housing unit cavity 55. This increases the pressure in the housing
unit cavity 55, which increases the pressure in the mounting unit
cavity 28, which in turn forces the piston 26 outwards along the
mounting element cavity. In either case, first and second mounting
units 22, 24 are forced to move in opposite directions, i.e. away
from each other. This moves the protrusions 32, 34 away from each
other, stretching the chain 1 towards the straight configuration.
The stretched chain urges the mounting elements 22, 24 to the first
position, as described previously.
[0108] The second embodiment provides damping as described above,
with energy being dissipated by friction between the rollers 12 and
the resilient elongate flexible member 20 (and potentially by
hysteresis as outlined previously), and by displacement of the
damping fluid by the chain 1 as it articulates towards/away from
the straight configuration. Further energy is dissipated by the
piston 26 and mounting element cavity 28 functioning as a piston
pump, in this case displacing damping fluid between the mounting
element cavity 28 and the housing unit cavity 55.
[0109] In the second embodiment both the first mounting element 22
and the piston 26 (via the projection 58) both protrude from the
housing unit cavity 55. They are therefore both accessible for the
application of force, allowing the damper to work either in tension
(e.g. by moving the piston 26 relative to the housing unit 54) or
in compression (e.g. by moving the first mounting element 22
relative to the first housing unit). In other embodiments however,
the piston 26 or the first mounting element 22 may be flush with or
recessed within the mouth of the housing unit cavity 55 so that the
damper functions only in tension or compression. For instance, the
piston may not be provided with a projection.
[0110] It is to be understood that the relationship between
movement of the piston 26 and movement of the first mounting
element 22 is linked by the sizes of the mounting element cavity 28
and the housing unit cavity 55. For instance, the stroke length of
the assembly (i.e. the total displacement which can be accommodated
before reaching the `hard stop`) when compressive load is applied
between the first mounting element 22 and the housing unit 54 could
be decreased by narrowing the mounting element cavity 28. By doing
so, the amount of damping fluid displaced from the housing unit
cavity 55 by moving the first mounting element 22 a particular
amount would constitute a larger proportion of the total volume of
the mounting element cavity 28. The piston 26 would therefore have
to move further within the mounting element cavity to accommodate
this fluid, which would stretch the chain to a greater extent and
mean that it reached the straight configuration sooner.
[0111] FIG. 7 shows a third embodiment of the invention. Like the
first and second embodiments, the third embodiment has a first
mounting element 22 with a mounting element cavity 28, and a chain
1 of the type described above. In this embodiment it is the
mounting element cavity 28 which acts as a reservoir that contains
damping fluid and within which the chain 1 is received.
[0112] The damper assembly of the third embodiment has two
identical counterposed second mounting elements 24a, 24b, either
one of which can be moved to a second position with respect to the
first mounting element 22. Each second mounting element 24a, 24b
comprises a piston 26a, 26b. Both pistons 26a, 26b are slidably
received within the mounting element cavity 28. The chain 1 is
attached at one end to piston 26a by protrusion 60a, and at the
other end to piston 26b by protrusion 60b. The chain is also
attached to the first mounting element 22 via a protrusion 62 that
projects from the surface of the mounting element cavity 28. The
point along the longitudinal axis of the chain 1 at which the first
mounting element 22 is attached is between the points at which the
second mounting elements 24a, 24b are attached. In other words, the
points along the longitudinal axis of the chain at which the second
mounting elements 24 are attached are on opposite sides of the
point at which the first mounting element 22 is attached.
[0113] The damper assembly of the third embodiment can function in
tension or compression, with force being applied between the first
mounting element 22 and one of the second mounting elements 24a,
24b. For example, if compressive force was applied between the
first mounting element 22 and the second mounting element 24b, the
piston 26b would move upwards (from the perspective of FIG. 7)
relative to the first mounting element, moving deeper into the
mounting element cavity 28. This moves the protrusion 60b and the
protrusion 62 closer together, causing the portion of chain between
them to contract (i.e. to move further from the straight
configuration). Since the portion of the mounting element cavity 28
between the two pistons 26a, 26b is filled with (incompressible)
damping fluid, as the piston 26b moves deeper into the mounting
element cavity 28 the counterposed piston 26a is forced outwards
(i.e. upwards from the perspective of FIG. 7) by the damping fluid.
This moves the first mounting element 22 and the other second
mounting element 24a (i.e. the second mounting element which is not
being acted on by the compressive force) to the second position,
increasing the distance between the protrusion 62 and the
protrusion 60a, stretching the portion of chain between them (i.e.
urging it towards the straight configuration).
[0114] If, on the other hand, a tensile force was applied between
the first mounting element 22 and the second mounting element 24b,
the piston 26b would move downwards (from the perspective of FIG.
7) relative to the first mounting element 22, moving outwards
within the mounting element cavity 28. This moves the first
mounting element 22 and the second mounting element 24b (i.e. the
first mounting element being acted on by the tensile force) to the
first position. This in turn moves the protrusion 60b and the
protrusion 62 further apart, causing the portion of chain between
them to be stretched (i.e. to move towards the straight
configuration). Since the portion of the mounting element cavity 28
between the two pistons 26a, 26b is filled with (incompressible)
damping fluid, as the piston 26b moves outwards within the mounting
element cavity 28 the counterposed piston 26a is sucked deeper into
the cavity (i.e. downwards from the perspective of FIG. 7). This
decreases the distance between the protrusion 62 and the protrusion
60a, contracting the portion of chain between them (i.e. urging it
further from the straight configuration).
[0115] In any event, when a force is applied to the damper assembly
one of the second mounting elements 24a, 24b is moved to the first
position relative to the first mounting element 22, which leads to
one portion of the chain being stretched (i.e. moved towards the
straight configuration) and another being contracted (i.e. moved
away from the straight configuration). The stretched portion of
chain provides a biasing force which urges the first mounting
element 22 and second mounting element (the one which was moved
towards the second position relative to the first mounting element
by the applied force) towards the first position again. As the
entire chain articulates (be it towards or away from the straight
configuration), dissipating energy through friction and
displacement of damping fluid, the whole chain contributes to the
damping effect of the assembly.
[0116] In the third embodiment the movement of the counterposed
second mounting elements 24a, 24b is restricted by the damping
fluid, which (due to its incompressible nature) prevents any change
in volume of the space in the mounting element cavity 28 between
the two pistons 26a, 26b. FIG. 8 shows a variation of the third
embodiment in which the two second mounting elements 24a, 24b are
physically joined by a connecting body 64. In this embodiment the
connecting body 64 is integral to both the counterposed second
mounting elements 24a, 24b, though in other embodiments it may be a
separate component to one or both of them. The connecting body 64
and the second mounting elements 24a, 24b co-operatively define the
reservoir of connecting fluid in which the chain 1 is positioned.
This arrangement functions in the same fashion as the third
embodiment, except that while in the third embodiment the second
mounting elements 24a, 24b can be moved apart relative to one
another by exerting a force large enough to induce a vacuum in the
reservoir, in this arrangement the second mounting elements can
only be moved relative to one another by exerting a force of
sufficient magnitude to physically deform the connecting body
64.
[0117] As outlined above, part of the damping capabilities of the
above embodiments result from motion of the chain dissipating
energy by displacing damping fluid. FIGS. 9a and 9b show a fourth
embodiment of the invention. This embodiment is identical to the
second embodiment except that the piston 26 is recessed within the
mounting element cavity 28 rather than having a projection
protruding from it, and the chain 1 has a plurality of extensions
66. The extensions 66 are arranged to project from the chain 1 to
increase the resistance to motion of the chain that is offered by
the damping fluid. In other words, they increase the volume of
damping fluid which is displaced by articulation of the chain 1,
increasing the aerodynamic drag of the chain as it moves. This
increased drag increases the extent to which the damping effect of
the assembly is proportional to the acceleration it experiences
(i.e. magnitude of the force applied), which is particularly
desirable in vehicle suspension systems. In this embodiment each
outer link plate 4 has one extension 66, which is in the form of a
substantially flat plate projecting orthogonally from the outer
link plate to which it is attached and is connected to the outer
link plate by a flange 67.
[0118] FIG. 10 shows a chain 1 for use in the invention which also
has extensions 66. In this arrangement the chain 1 is formed from
two lengths 1a, 1b of roller bush chain (each with its own
resilient elongate flexible member 20a, 20b) connected together in
parallel. The two lengths 1a, 1b are joined together via common
outer link plates 68, arranged alternately with standard roller
bush chain outer link plates 4. The extensions 66 are arranged such
that they co-operatively define a plurality of voids 70 along the
length of the chain. In this embodiment the voids 70 are formed by
virtue of the extensions 66 being arranged two different
orientations (horizontal or vertical from the perspective of FIG.
10). As shown in more detail in FIGS. 11a-11c, as the chain 1
articulates out of the straight configuration (which is shown in
FIG. 11a) the voids 70 change in shape and volume. The same is true
when the chain articulates towards the straight configuration. This
further increases the extent to which damping fluid is displaced
(and therefore the damping capabilities of a damper assembly in
which such a chain is mounted).
[0119] A development of the above chain is shown in FIG. 12. In
this arrangement each of the extensions 66 is shaped to maintain
minimal clearance between it and the neighbouring extensions 66
with which it defines a void 70 as the chain articulates. The
extensions have either a flat interface surface 71 or a convex
interface surface 72. In both cases the extensions have a flat rear
surface 73. The flat and convex interface surfaces 71, 72 are
shaped and positioned such that as the chain 1 articulates to or
from the straight orientation, the edges 74 of the flat interface
surfaces 71 sweep across the convex interface surfaces 72,
maintaining a substantially constant clearance. As a minimal
clearance is maintained between the extensions 66 which form each
void 70, as the chain articulates little damping fluid can pass
between adjacent extensions (i.e. little damping fluid can move
into or out of the voids in the plane shown in FIG. 12). The fluid
must therefore take a more convoluted route to and from the voids
70, which further increases the energy dissipation (and thus
damping) offered by the system.
[0120] FIG. 13 shows a further development of this chain (with the
extensions not shown). While in the chains described above the
resilient elongate flexible member is threaded along the chain, in
this arrangement the chain has a plurality of resilient flexible
loop members 76 housed within the chain 1 which act to urge it away
from the straight configuration. In a further arrangement these
loop-shaped resilient elongate flexible members may be replaced by
elastomeric blocks.
[0121] It will be appreciated that in embodiments with a resilient
elongate flexible member threaded along at least part of the length
of the chain, in use the resilient elongate flexible member may
move along the longitudinal axis of the chain under the influence
of repeated contact with the moving rollers (or other components of
the chain). It may therefore be preferable to include retaining
means for restricting movement of the resilient member along the
chain. FIG. 14 shows a modification of the damper assembly of the
first embodiment, in which the resilient elongate flexible member
20 is attached at one end 77 to one of the mounting elements 22,
24. In this case, it is attached to the piston 26 of the second
mounting element 24, due to it being joined to the surface of the
piston cavity 30.
[0122] FIG. 15 shows a further modification of the first embodiment
in which the resilient elongate flexible member 20 of the chain 1
is restrained in its axial movement relative to the chain. In this
arrangement the resilient elongate flexible member has a hooked
portion 78 at each end. The hooked portions 78 are configured to
hook onto respective rollers 12 of the chain 1 to restrict axial
movement of the resilient elongate flexible member 20 along the
chain 1. In this arrangement the hooked end portions 78 are spaced
apart just enough for the chain 1 to reach the straight
configuration. In other arrangements however, they may be spaced
more closely together (for example so as to prevent the chain
reaching the straight configuration) or may be spaced further apart
(for example to provide a degree of leeway or to allow for less
stringent manufacturing tolerances).
[0123] It will be appreciated that in embodiments where the
resilient member protrudes from one or both ends of the chain, the
extent to which it protrudes will be dependent on the configuration
of the chain. In some situations it may be preferable to include
one or more retainer lugs. FIG. 16 shows a further modification of
the first embodiment which includes a pair of retainer lugs 84a,
84b, each mounted to a surface of the piston cavity 30. Each
retainer lug 84a, 84b has an aperture 86a, 86b within which a
respective end 77a, 77b of the resilient member 20 is received.
Each aperture 86a, 86b terminates in a base 88a, 88b.
[0124] As the chain articulates, the ends 77a, 77b of the resilient
member 20 move within the apertures 86a, 86b (but the retainer lugs
84a, 84b are of sufficient length that the ends of the resilient
member are not completely withdrawn from the apertures at any
point). The retainer lugs 84a, 84b therefore restrain the lateral
movement of the ends 77a, 77b of the resilient member 20. Further,
the bases 88a, 88b are positioned to restrain the axial movement of
the resilient member 20, preventing it from working free of the
chain and/or being damaged or damaging other components.
[0125] While in this arrangement the retainer lugs 84a, 84b are
both fixed to the piston 26, in other arrangements they may be
arranged differently. For instance, the lower (from the perspective
of FIG. 16) retainer lug 84b may be fixed relative to the
projection 34, so that each retainer lug is in a constant axial
position relative to its respective end of the chain.
[0126] Though the above embodiments all describe damper assemblies
which can work in compression, as these are particularly suitable
for use as shock absorbers in vehicle suspension systems, in other
applications a damper assembly according to the invention may be
designed to work solely in tension. A schematic diagram of one such
arrangement, a fifth embodiment of the invention, is shown in FIG.
17. The fifth embodiment has a first mounting element 22 with a
mounting element cavity 28, and a second mounting element 24 with a
piston 26 slidably received within the mounting element cavity. The
piston 26 of the fifth embodiment has a plurality of apertures 80.
The chain 1 (which is shown as a spring in the schematic diagram of
FIG. 16, but may be a chain of any of the embodiments above or may
be any other suitable chain) is located within the mounting element
cavity 28, which functions as a reservoir for damping fluid. The
chain 1 is attached at one end to the mounting element cavity 28 of
first mounting element 22, and attached at the other end to the
piston 26 of the second mounting element 24.
[0127] When a tensile force is applied to the damper assembly
between the first and second mounting elements 22, 24 (e.g. if the
second mounting element 24 is moved downwards from the perspective
of FIG. 17 with the first mounting element 22 held stationary), the
mounting elements 22, 24 move to the second position. The piston 26
slides outwards within the mounting element cavity 28 and stretches
the chain 1 towards the straight configuration. The stretched chain
provides a restorative force to bias the mounting elements 22, 24
back towards the first position and its articulation provides
damping, as outlined above. In addition, as the piston 26 moves,
the damping fluid within the mounting element cavity 28 in the path
of the piston is displaced and forced through the piston through
the apertures 80. This increased displacement of damping fluid may
increase the damping capabilities of the assembly. To increase the
displacement of damping fluid yet further, the chain 1 may be
positioned adjacent one or more baffle members (not shown) arranged
to restrict entry of damping fluid into the voids, and/or exit of
damping fluid therefrom, from a particular direction.
[0128] In damper assemblies for some applications, the required
resistance to extension may be beyond what can practically be
achieved with a single chain. In such circumstances a chain
assembly may be utilised. FIGS. 18-20 show a first embodiment of a
chain assembly for use as part of a damper assembly according to
any of the preceding embodiments.
[0129] The chain assembly 112 has six chains 114 each of which is
attached at one end to a first connection bracket 116 and at the
other end to a second connection bracket 118. In the chain assembly
112 shown in FIG. 18 each chain 114 is substantially the same as
the chain shown in FIG. 1, but wherein the resilient flexible
elongate member 120 of each chain 114 passes underneath two
successive pins 122 (and rollers 124) before passing between
adjacent pins to the opposite side where it passes over the next
two successive pins 112 (and rollers 124).
[0130] The chains 114 are arranged in two rows of three, with an
alignment structure 128 positioned between the rows. The alignment
structure 128 is loosely received within recesses 130 in the
connection brackets 116, 118, so that it is able to move to a
certain extent within them (see FIG. 19). The alignment structure
128 being positioned between the two rows of chains 114 acts to
prevent any of the chains from coming into contact with each other,
which could significantly increase wear and reduce service life of
the assembly 112. In this arrangement the chains 114 are positioned
such that they run substantially parallel to one another when in
the straight configuration. However, in other arrangements this may
not be the case.
[0131] Each chain 114 of the chain assembly 112 is a roller bush
chain, as described previously. As such, each chain 114 defines an
articulation plane within which its links can articulate about
their respective pins 122. The articulation plane of each chain 114
is substantially perpendicular to its pins 122. In this
arrangement, the chains 114 are positioned so that their
articulation planes are parallel. As such, the entire chain
assembly 112 can articulate within a plane that is parallel to the
articulation planes of the chains 114, in a manner akin to a single
chain. The articulation of the chain assembly 112 is limited,
however, by the alignment structure 128. The loose fit of the
alignment structure 128 in the recesses 130 permits movement to a
certain extent, beyond which the alignment structure will brace
against the walls of the recesses 30 and prevent any further
articulation.
[0132] The chains 114 are connected to the connection brackets 116,
118 by rivets 126, about which the adjacent link plates (i.e. the
distal link plates of the chains 114) can rotate. Each connection
bracket 116, 118 also has a rivet 127 which may provide a mounting
point for attaching that connection bracket to a first or second
mounting element (not shown) of a damper assembly.
[0133] In this arrangement the first and second connection brackets
116, 118 are substantially identical. One of the connection
brackets 116, 118 is attached to the first mounting element of the
damper assembly and the other connection bracket 116, 118 is
attached to the second mounting element, such that movement of the
mounting elements towards the second position moves the connection
brackets 116, 118 towards a second position (described in more
detail below), which urges each chain 114 towards the straight
configuration. Since the mounting elements are attached to the
connection brackets 116, 118 and the connection brackets 116, 118
are attached to the first and second ends of the chains 114, the
mounting elements are attached to the first and second ends of
chains 114 via the connection brackets 116, 118.
[0134] For example, where the chain assembly is part of the damper
assembly according to the first embodiment (see FIGS. 3A-3C), the
first connection bracket 116 of the chain assembly 112 may be
attached to the second mounting element (24 in FIGS. 3A-3C) by
positioning the chain assembly such that the protrusion (32 in
FIGS. 3A-3C) is accommodated in the first connection bracket 116 in
place of the rivet 127. Similarly, the second connection bracket
118 of the chain assembly 112 may be attached to the first mounting
element (22 in FIGS. 3A-3C) by positioning the chain assembly such
that the protrusion (34 in FIGS. 3A-3C) is accommodated in the
second connection bracket 118 in place of the rivet 127.
[0135] FIGS. 18-20 show the chain assembly 112 with the connection
brackets 116, 118 in a first position. As stated above, movement of
the mounting elements towards the second position moves the
connection brackets 116, 118 directly apart from one another
towards a second position. This movement of the connection brackets
116, 118 towards the second position urges each chain 114 towards
the straight configuration. As described previously, the chains 114
resist being stretched towards the straight configuration. They
therefore act to urge the connection brackets 116, 118 (and
therefore the mounting elements) back towards the first position
when moved therefrom. Since moving the connection brackets 116, 118
towards the second position stretches six chains 114 in parallel,
the resistance to extension provided by the chain assembly 112 is
six times that of a single chain 114. Other arrangements may have
any number of chains 114 (i.e. two or more chains), allowing the
resistance to extension to be tailored to a specific
application.
[0136] The chain assembly 112 may comprise a plurality of the
chains described in relation to the damper assemblies of the above
embodiments. The chains may be identical, or may differ (for
instance one of the chains may be of the form described in relation
to one of the embodiments, and another may be of the form described
in relation to a different embodiment).
[0137] The chain assembly 112 may be used as part of any of the
damper assemblies of the above described embodiments.
[0138] FIG. 21 shows a modification of the arrangement of FIGS.
18-20. In this arrangement, the chains 14 are of reduced length,
each having only three pairs 132 of link plates (as opposed to five
in the above arrangement). In addition, though in the arrangement
of FIGS. 18-20 the resilient elongate flexible member 120 of each
chain 114 is positioned so that it urges the central portion of
that chain outwards, in this arrangement it is positioned to urge
the central portion of the chain inwards. As such, the overall size
of the chain assembly 112 is reduced, allowing it to be used in
smaller spaces.
[0139] FIG. 22 shows a second embodiment of the chain assembly.
Again, it has a first connection bracket 116 and a second
connection bracket 118 connected by a plurality of chains 114 and
movable between said first position (as shown in FIG. 22) and said
second position. In this case however, there are three chains 114
(two of which are visible in FIG. 22), and each chain is positioned
so that its articulation plane is non-parallel to the articulation
planes of each of the other chains. More particularly, the chains
114 are positioned substantially circumferentially around the
longitudinal axis of the assembly 112, and are evenly spaced so
that each chain 114 is positioned with its articulation plane at an
angle of 60 degrees with the articulation planes of the other two
chains. At least two of the chains 114 (in this case all of the
chains) being arranged with non-parallel articulation planes may
provide the chain assembly 112 with increased torsional and/or
lateral rigidity in comparison with arrangements where all the
chains 114 are positioned so that their articulation planes are
parallel. In other words, the chain assembly of this embodiment has
increased resistance to torsional forces applied (for instance
between the connection brackets 116, 118) about its longitudinal
axis in comparison to the embodiment of FIGS. 18-20. In addition,
because the articulation planes of the chains 114 are non-parallel
the chain assembly of this embodiment has increased resistance to
bending along its longitudinal axis.
[0140] The chain assembly 112 of this arrangement also comprises a
damper sub-assembly 134 which provides additional damping to that
supplied by the chains (as described previously). The damper
sub-assembly 134 comprises a piston 136 comprised within the first
connection bracket 116, which is slidably received in a fluid
cavity 138 provided in the second connection bracket 118. Sealing
elements may be provided between the piston 136 and fluid cavity
138, though these are not shown in FIG. 22. As the connection
brackets 116, 118 move between the first and second positions, the
piston slides within the fluid cavity 138, changing the volume
thereof. The piston 136 of the first connection bracket 116 being
received within the fluid cavity 138 of the second connection
bracket 118 also provides additional structural support to the
chain assembly 112.
[0141] In this arrangement the fluid cavity 138 is connected to a
duct 140a in the first connection bracket 116 (the duct in this
case running through the piston 136) and connected to a duct 140b
in the second connection bracket 118. In this arrangement the fluid
cavity 138 is filled with damping fluid in the form of grease, and
the ducts 140a, 140b are each connected to a bulk source of this
grease (such as a reservoir provided by a damper assembly, in which
case the entire chain assembly may be positioned within the
reservoir and the ducts may simply be left open). The piston 136
and fluid cavity 138 cooperatively form a piston pump mechanism.
Movement of the piston 136 deeper into the fluid cavity 138 (i.e.
when the connection brackets 116, 118 move towards the first
position) forces grease out of the cavity 138 and into the bulk
source through one or both of the ducts 140a, 140b. Similarly, the
piston being moved outwards from within the fluid cavity 138 (i.e.
when the connection brackets 116, 118 move towards the second
position) sucks grease into the cavity 138 through one or both of
the ducts 140a, 140b. In other arrangements, the fluid cavity 138
may enclose a sealed volume of gas, allowing the piston 136 and
fluid cavity 140 to function as an air damper.
[0142] The arrangement of FIG. 22 also differs from that of FIGS.
18-20 in that the connection brackets 116, 118 have threaded ports
142 rather than rivets (127 in FIGS. 18-20) for attaching the first
and second connection brackets 116, 118 to the first and second
mounting elements 22, 24 respectively of the damper assembly.
Alternatively the first and second brackets 116, 118 may be
attached to the second and first mounting elements 22, 24
respectively.
[0143] FIG. 23 shows a modification of the chain assembly of FIG.
22. In this case the piston 136 is not part of either connection
bracket 116, 118, but is slidably received in fluid cavities 138a,
138b in each of them. As in the arrangement of FIG. 22 each
connection bracket 116, 118 has a duct 140a, 140b connected to its
fluid cavity 138a, 138b, but in this case the ducts 140a, 140b are
positioned radially rather than longitudinally. In addition, the
piston 136 contains a further duct 140c which connects the two
fluid cavities 138a, 138b.
[0144] The piston 136 and each of the fluid cavities 138a, 138b
co-operatively form piston pump mechanisms as described above.
Moving the connection brackets 116, 118 towards the second position
pulls the piston 136 outwards from within one or both of the fluid
cavities 138a, 138b, sucking grease into the or each cavity through
its associated duct 140a, 140b (and potentially from one fluid
cavity to the other through the duct 140c in the piston 136).
Similarly, moving the connection brackets 116, 118 towards the
first position pushes the piston 136 deeper into one or both of the
fluid cavities 138a, 138b, forcing grease out of the or each cavity
through its associated duct 140a, 140b (and potentially from one
fluid cavity to the other through the duct 140c in the piston
136).
[0145] The arrangement of FIG. 23 also comprises chains 114 of
increased length. The chain assembly 112 therefore comprises an
alignment structure 128 to prevent the chains 114 touching as
described previously. In this case, the alignment structure 128
takes the form of an enlarged section of the piston 136, providing
a section of large enough radius to space apart the middle portions
of the chains 114 and prevent them touching.
[0146] FIG. 24 shows a modification of the arrangement of FIG. 23.
In this case, the piston 136 of the damper sub-assembly 134 is not
provided with an alignment structure (128 in FIG. 23) since the
chains 114 will not touch each other due to their being relatively
short and due to the resilient elongate flexible member 120 being
positioned to urge the middle portions of the chains 114 outwards
(i.e. away from each other). In this arrangement, a resiliently
deformable element in the form of a coil spring 144 is positioned
around the piston, between the first and second connection brackets
116, 118 and attached thereto. The spring 144 is at its natural
length when the connection brackets 116, 118 are in the first
position, therefore moving the connection brackets apart (i.e.
towards the second position) stretches the spring and causes it to
urge them back together (towards the first position). Similarly,
moving the connection brackets 116, 118 closer together (beyond the
first position) compresses the spring and causes it to urge them
apart (towards the first position). The spring 144 therefore works
with the chains 114 in providing additional resistance to extension
of the chain assembly 114, and also allows the assembly 112 to
resist compressive loads.
[0147] In other arrangements, the spring 144 may only act in
tension to supplement the restorative force from the chains 114, or
may only act in compression so as to allow the assembly 112 to
react to compressive loads (in which case the spring may simply be
held between the connection brackets 116, 188, rather than being
attached thereto). Further, though in this arrangement no alignment
structure is needed, in other arrangements this may be included as
well. For instance, the spring 140 may be of diameter sufficient to
allow it to function as an alignment structure as described in
relation to FIG. 23.
[0148] FIG. 25 shows a modification of the chain assembly of FIG.
24. In this spring assembly 112 the damper sub-assembly 134 takes
the form of a deformable bladder 146 which defines a bifurcated
fluid cavity 138 therein. The bladder 146 is attached to each
connection bracket 116, 118 so that relative movement of the
connection brackets changes the shape of the bladder, which in turn
changes the shape of the fluid cavity 138. For example, moving the
connection brackets 116, 118 towards the second position stretches
the bladder axially (vertically from the perspective of FIG.
25).
[0149] In this case, the bladder 146 is shaped so that deforming it
not only changes the shape of the fluid cavity 138, but also
changes the volume of the fluid cavity. The bladder can therefore
function as a pump for damping fluid such as grease, as outlined in
relation to FIG. 22. For instance, moving the connection brackets
116, 118 together deforms the bladder 146 and reduces the volume of
the fluid cavity 138, forcing grease out of the cavity through one
or both of the ducts 140a, 140b, and moving them apart increases
the volume of the fluid cavity, sucking grease back into it. The
bladder may instead pump another fluid such as a gas, however due
to gas being of lower viscosity than grease the damping effect may
be reduced.
[0150] The chain assembly 112 of FIG. 25 may instead provide
damping by displacing fluid by changing the shape of the fluid
cavity 138, without the volume of the cavity necessarily changing.
For instance, the cavity 138 may be filled with grease and sealed
(for instance by inserting plugs into the ducts 140a, 140b).
Deformation of the bladder 146 (and thus of the cavity 138) would
dissipate energy by forcing the grease within the cavity 134 to
move within the cavity to conform to its new shape. As another
example, the fluid cavity 138 may be a sealed pocket of gas such as
air, allowing it to function as an air damper.
[0151] As an additional point, it is to be noted that if the
bladder 146 is made of a resiliently deformable material, and/or if
the fluid cavity comprises a sealed volume of compressible fluid
(i.e. gas), the bladder may also constitute a resiliently
deformable element as described in relation to FIG. 24.
[0152] It will be appreciated that numerous modifications to the
above described designs may be made without departing from the
scope of the invention as defined in the appended claims. For
example, in embodiments with a resilient elongate flexible member
that is threaded along at least part of the length of the chain,
the particular manner in which it is threaded may vary depending on
the application. Moreover, for any of the embodiments covered by
the claims the rollers (where present) may be made from a polymeric
damping material to improve the damping performance of the chain.
The material may be injection mouldable for ease of manufacture. In
one embodiment the material may be Nylon 6 but many other options
would be readily appreciated by the skilled person. The size and/or
thickness of the rollers may vary along the length of the chain in
order to provide different damping characteristics along the chain.
Alternatively, the material of the rollers may vary along the
length of the chain to achieve the same effect.
[0153] It is to be appreciated that the invention may utilise
different forms of chain such as a chain without rollers or bushes,
or a chain comprising link plate and pins only such as a leaf chain
(e.g. a fork lift truck chain) or a Galle chain. In some instances
where there are multiple strands of link plates arranged in
parallel along the width of the chain, selected link plates may be
removed from the chain to accommodate a resilient elongate flexible
member. Moreover, the inner link assembly may take any suitable
form including moulded from a plastics material.
[0154] While in the described embodiments the first mounting
element, second mounting element(s), mounting element cavity,
housing unit, housing unit cavity, piston(s) and piston cavity are
all cylindrical in shape, in other embodiments one or more of them
may be any other suitable shape. For instance one or more of them
may be oval, triangular, square, hexagonal or octagonal in
cross-section.
[0155] In some embodiments of the invention it may be advantageous
to provide one or more abutment surfaces to restrict relative
motion between two components. Such abutment surfaces may restrict
the relative motion between any two of a/the first mounting
element, second mounting element, piston, housing unit, or two or
more portions of one of said components. It may be particularly
advantageous to provide the damper assembly of the second
embodiment of the invention with abutment surfaces so as to prevent
the piston from being entirely withdrawn from the mounting element
cavity.
[0156] For the avoidance of doubt, reference above to the `ends` of
the chain being attached to components of the damper assembly
should not be construed as limiting. Arrangements in which the
chain is a continuous loop that is attached to the mounting
elements at two points, and arrangements in which a length of chain
is attached to the mounting elements at locations other than its
ends, are intended to fall within the scope of the invention.
Similarly, though the chain is defined as having a `straight`
configuration, it is to be appreciated that in practice the links
of a chain may be incapable of reaching substantial alignment (such
as if the force from the resilient member is sufficient that the
chain would deform or snap under load before reaching the straight
configuration).
[0157] Although in the above damper assemblies with two
counterposed second mounting elements the relative motion of the
second mounting elements is substantially prevented, in some
applications it may be preferable for them to be partially or
entirely free to move independently. For instance, it may be
preferable in some situations to change the damping fluid between
the pistons of the third embodiment from a grease to a gas. This
would provide a degree of autonomy of the second mounting elements
but still restrict their motion up to a point. Alternatively, the
damping fluid may be replaced by a (vented) space. The two second
mounting elements would then be entirely independent and the damper
assembly would function as a pair simple tension dampers.
Furthermore, though FIGS. 6 and 7 show damper assemblies where a
single chain is connected to the first mounting element and to both
the second mounting elements, in other embodiments one piece of
chain may be attached to the first mounting element and one of the
second mounting elements, and separate piece of chain may be
attached to the first mounting element and the other of the second
mounting elements.
[0158] For the avoidance of doubt, although in the described
embodiments of chain assemblies the connection brackets are moved
towards the second position by moving them directly apart, in other
embodiments they may be movable towards the second position in any
other suitable fashion. For instance, they may be moved towards the
second position by rotation, pivoting, and/or movement towards
and/or tangentially relative to one another, instead or in addition
to movement away from one another.
[0159] The described and illustrated embodiments are to be
considered as illustrative and not restrictive in character, it
being understood that only the preferred embodiments have been
shown and described and that all changes and modifications that
come within the scope of the inventions as defined in the claims
are desired to be protected. Optional and/or preferred features as
set out herein may be used either individually or in combination
with each other where appropriate and particularly in the
combinations as set out in the accompanying claims. It should be
understood that while the use of words such as "preferable",
"preferably", "preferred" or "more preferred" in the description
suggest that a feature so described may be desirable, it may
nevertheless not be necessary and embodiments lacking such a
feature may be contemplated as within the scope of the invention as
defined in the appended claims. In relation to the claims, it is
intended that when words such as "a," "an," "at least one," or "at
least one portion" are used to preface a feature there is no
intention to limit the claim to only one such feature unless
specifically stated to the contrary in the claim. When the language
"at least a portion" and/or "a portion" is used the item can
include a portion and/or the entire item unless specifically stated
to the contrary.
* * * * *