WO 2006/104601 PCT/US2006/006006
FLUID-ELASTOMERIC DAMPER ASSEMBLY INCLUDING
INTERNAL PUMPING MECHANISM
FIELD OF THE INVENTION
The present invention relates generally to a damper assembly used to control
movement/vibration in a mechanical system or the like. More specifically, the present
invention relates to a fluid-elastomeric damper assembly including an internal
pumping mechanism. More specifically the fluid-elastomeric damper assembly
controls movement/vibration in a rotary-wing aircraft.
BACKGROUND OF THE INVENTION
Dampers are coupled to one or more moving/vibrating structures. These
moving/vibrating structures may include, for example, the flex-beam and the pitch
case of the rotor of a rotary-wing aircraft or the like. The damper produces a damping
force resisting the movement/vibration of the one or more moving/vibrating
structures.
Advantageously, the damper is capable of accommodating
movement/vibration in a plurality of directions. This is not always possible, for
example, in the control of movement/vibration in the lead-lag direction of the rotor of
a rotary-wing aircraft or the like.
Thus, what is needed is a damper assembly that accommodates movement and
provides beneficial damping of the accommodated movements and vibrations. There
is a need for a robust and reliable damper that is economically producible and allows
for the creation of relatively higher damping forces and accommodates relatively
greater movement/vibration of the one or more moving/vibrating structures than is
possible with conventional damper assemblies. Although the assemblies,
mechanisms, and methods of the present invention are described herein below in
conjunction with the flex-beam and the pitch case of the rotor of a rotary-wing aircraft
or the like, the assemblies, mechanisms, and methods of the present invention may be
used in conjunction with any mechanical system or the like including one or more
moving/vibrating structures that it is desirable to damp.
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BRIEF SUMMARY OF THE INVENTION
In various embodiments of the present invention, a fluid-elastomeric damper
assembly includes at least a first elastomer seal, such as a rubber seal or the like,
disposed at a first end of the fluid-elastomeric damper assembly and a second
elastomer seal, such as a rubber seal or the like, disposed at a second end of the fluid-
elastomeric damper assembly. The first elastomer seal is fixedly attached or
otherwise coupled to a first moving/vibrating structure, such as a flex-beam of the
rotor of a rotary-wing aircraft or the like, and the second elastomer seal is fixedly
attached or otherwise coupled to a second moving/vibrating structure, such as a pitch
case of the rotor of a rotary-wing aircraft or the like. The first elastomer seal and the
second elastomer seal are both bonded, fixedly attached, or otherwise coupled to a
housing structure including, for example, a first housing member and a second
housing member. Together, the first elastomer seal, the second elastomer seal, and
the housing structure are operable for containing a fluid, such as hydraulic fluid or the
like. An internal pumping mechanism including one or more piston structures and a
piston structure housing is also disposed within the housing structure. The internal
pumping mechanism is grounded to or integrally formed with the first
moving/vibrating structure and moves in relation to the housing structure and the
second moving/vibrating structure to which the housing structure is grounded. The
internal pumping mechanism is configured such that, when the internal pumping
mechanism moves with respect to the housing structure and the second
moving/vibrating structure, the fluid surrounding and disposed within the internal
pumping mechanism is pumped from a first chamber disposed within each of the one
or more piston structures to a second chamber disposed within each of the one or
more piston structures through a restriction, i.e., an orifice. Optionally, the relative
size of the restriction is controlled by an adjustable pressure relief device and/or a
temperature-compensating device. Advantageously, the first elastomer seal, the
second elastomer seal, and the housing structure provide a fluid-elastomeric chamber
operable for containing the fluid and in which the internal pumping mechanism may
be submerged. This fluid-elastomeric chamber is flexible and allows the internal
pumping mechanism to damp movement/vibration in a primary direction with a
relatively high damping force. Additionally, movement/vibration in a plurality of
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other directions are accommodated by the internal pumping mechanism by design,
without damping force.
In one embodiment of the present invention, a fiuid-elastomeric damper
assembly includes a housing structure, a first elastomer seal coupled to the housing
structure, and a second elastomer seal coupled to the housing structure. The housing
structure, the first elastomer seal, and the second elastomer seal define a fluid-
elastomeric chamber operable for containing a fluid. The fiuid-elastomeric damper
assembly also includes an internal pumping mechanism disposed within the fiuid-
elastomeric chamber.
In another embodiment of the present invention, a fluid-clastomeric damper
assembly operable for damping relative motion between a first structure and a second
structure includes a housing structure coupled the first structure, a first elastomer seal
coupled to the housing structure, wherein the first elastomer seal is also coupled to the
second structure, and a second elastomer seal coupled to the housing structure.
Again, the housing structure, the first elastomer seal, and the second elastomer seal
define a fiuid-elastomeric chamber operable for containing a fluid. The fiuid-
elastomeric damper assembly also includes an internal pumping mechanism disposed
within the fiuid-elastomeric chamber, wherein the internal pumping mechanism is
coupled to the second elastomer seal.
In a further embodiment of the present invention, a fiuid-elastomeric damper
assembly operable for damping relative motion between a first structure and a second
structure includes a housing structure grounded to the first structure and a plurality of
elastomer seals coupled to the housing structure, wherein the housing structure and
the plurality of elastomer seals define a fiuid-elastomeric chamber operable for
containing a fluid. The fiuid-elastomeric damper assembly also includes one or more
piston structures disposed within the housing structure and the fiuid-elastomeric
chamber, wherein the one or more piston structures are grounded to the first structure
and driven by the second structure, and wherein the one or more piston structures
each include a first substantially fluid-filled chamber and a second substantially-fluid-
filled chamber in communication via an orifice, the first substantially fluid-filled
chamber and the second substantially fluid-filled chamber also in communication with
the fiuid-elastomeric chamber. The housing structure is operable for pumping the
fluid through the orifice.
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111 a still further embodiment of the present invention, a method for damping
relative motion between a first structure and a second structure includes grounding a
housing structure to the first structure, coupling a plurality of elastomer seals to the
housing structure, wherein the housing structure and the plurality of elastomer seals
define a fluid-elastomeric chamber, and disposing a fluid within the fluid-elastomeric
chamber. The method also includes disposing one or more piston structures within
the housing structure and the fluid-elastomeric chamber and grounding the one or
more piston structures to the first structure, wherein the one or more piston structures
each include a first substantially fluid-filled chamber and a second substantially-fluid-
filled chamber in communication via an orifice, the first substantially fluid-filled
chamber and the second substantially fluid-filled chamber also in communication with
the fluid-elastomeric chamber. Again, the housing structure is operable for pushing
the fluid through the orifice. The method further comprising driving the one or more
piston structures with the second structure.
The invention includes a fluid-elastomeric damper assembly operable for
damping a relative motion between a first structure and a second structure. The fluid-
elastomeric damper assembly includes elastomeric seals coupled to a fluid-
elastomeric chamber housing to define a fluid-elastomeric chamber operable for
containing a damper fluid. The fluid-elastomeric damper assembly includes an
internal pumping mechanism with at least one fluid moving piston disposed within the
fluid-elastomeric chamber. Preferably the internal pumping mechanism is grounded to
the first structure and driven by the second structure. The internal pumping
mechanism at least one piston forces the damper fluid through at least one pumping
piston restriction orifice between a first fluid variable volume chamber and a second
fluid variable volume chamber. The first fluid variable volume chamber includes a
first fluid backfiller, the first fluid backfiller providing fluid communication of the
damper fluid from the fluid-elastomeric chamber into the first fluid chamber and
inhibiting a flow of the fluid from the first fluid chamber into the fluid-elastomeric
chamber. The second fluid chamber includes a second fluid backfiller, the second
fluid backfiller providing fluid communication of the fluid from the fluid-elastomeric
chamber into the second fluid chamber and inhibiting a flow of the fluid from the
second fluid chamber into the fluid-elastomeric chamber. The relative motion
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between the first structure and the second structure is operable for pumping the fluid
through the at least one restriction orifice.
The invention includes a method for damping a relative motion between a first
structure and a second structure. The method includes grounding a housing to the first
structure; coupling a plurality of elastomeric seals to the housing, wherein the housing
and the plurality of elastomeric seals provide a fluid-elastomeric chamber for
containing a damper fluid. The method includes disposing a damper fluid within the
fluid-elastomeric chamber. The method includes disposing an internal fluid pump
with at least one fluid moving piston within the fluid-elastomeric chamber, with the
internal fluid pump comprising a first fluid variable volume chamber and a second
fluid variable volume chamber in communication via at least one orifice. The first
fluid chamber includes a first fluid backfiller and the second fluid chamber including
a second fluid backfiller. The first fluid chamber and the second fluid chamber are in
communication with the fluid-elastomeric chamber wherein the relative motion
between the first structure and the second structure drives the at least one fluid
moving piston to pump the fluid through the at least one orifice with the first fluid
backfiller providing fluid communication of the fluid from the fluid-elastomeric
chamber into the first fluid chamber and inhibiting a flow of the fluid from the first
fluid chamber into the fluid-elastomeric chamber and the second fluid backfiller
providing fluid communication of the fluid from the fluid-elastomeric chamber into
the second fluid chamber and inhibiting a flow of the fluid from the second fluid
chamber into the fluid-elastomeric chamber .
The invention includes a method of making a fluid-elastomeric damper
assembly for damping a relative motion between a first structure and a second
structure. The method includes coupling a plurality of elastomeric seals to a housing,
wherein the housing and the plurality of elastomeric seals provide a fluid-elastomeric
chamber for containing a damper fluid. The method includes disposing an internal
fluid pump with at least one fluid moving piston within the fluid-elastomeric chamber
wherein the internal fluid pump comprises a first fluid variable volume chamber and a
second fluid variable volume chamber in communication via at least one orifice, and
the first fluid filled chamber including a first fluid backfiller and the second fluid
filled chamber including a second fluid backfiller. The method includes disposing a
damper fluid within the fluid-elastomeric chamber, with the first fluid chamber and
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the second fluid chamber in communication with the fluid-elastomeric chamber,
wherein the relative motion between the first structure and the second structure drives
the at least one fluid moving piston to pump the fluid through the at least one orifice
with the first fluid backfiller providing fluid communication of the fluid from the
fluid-elastomeric chamber into the first fluid chamber and inhibiting a flow of the
fluid from the first fluid chamber into the fluid-elastomeric chamber and the second
fluid backfiller providing fluid communication of the fluid from the fluid-elastomeric
chamber into the second fluid chamber and inhibiting a flow of the fluid from the
second fluid chamber into the fluid-elastomeric chamber.
The invention includes a method for damping relative motion between a first
structure and a second structure. The method includes providing a housing structure.
The method includes coupling a plurality of elastomer seals to the housing structure,
wherein the housing structure and the plurality of elastomer seals define a fluid-
elastomeric chamber. The method includes disposing a piston within the housing
structure and the fluid-elastomeric chamber, wherein the piston comprises a first
variable volume chamber and a second variable volume chamber in communication
via an orifice, the first fluid-filled chamber and the second fluid-filled chamber also in
communication with the fluid-elastomeric chamber. The method includes disposing a
damper fluid within the fluid-elastomeric chamber, wherein the relative motion
between the first structure and the second structure is operable for driving the piston
and pumping the fluid through the orifice, with the fluid outside the piston and
contained in the fluid-elastomeric chamber having an operational ambient fluid
pressure PA, and the fluid inside the piston having an operational dynamic fluid
pressure PD when pumped by the piston with PD ≥ 1.01 PA.
It is to be understood that both the foregoing general description and the
following detailed description are exemplary of the invention, and are intended to
provide an overview or framework for understanding the nature and character of the
invention as it is claimed. The accompanying drawings are included to provide a
further understanding of the invention, and are incorporated in and constitute a part of
this specification. The drawings illustrate various embodiments of the invention, and
together with the description serve to explain the principals and operation of the
invention.
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BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a cross-sectional side (cord-wise) view of one embodiment of the
fluid-elastomeric damper assembly of the present invention, highlighting an internal
pumping device disposed with a fluid-elastomeric chamber of the fluid-elastomeric
damper assembly (the top portion of Figure 1 illustrating the internal pumping device,
the bottom portion of Figure 1 illustrating the fluid-elastomeric chamber);
Figure 2 is a perspective view of the fluid-elastomeric damper assembly of
Figure 1, again highlighting the internal pumping device disposed with the fluid-
elastomeric chamber of the fluid-elastomeric damper assembly (the top portion of
Figure 2 illustrating the internal pumping device, the bottom portion of Figure 2
illustrating the fluid-elastomeric chamber);
Figure 3A-B are exploded perspective views of the fluid-elastomeric damper
assembly of Figures 1 and 2, again highlighting the internal pumping device disposed
with the fluid-elastomeric chamber of the fluid-elastomeric damper assembly;
Figure 4 is a side (cord-wise) view of the fluid-elastomeric damper assembly
of Figures 1-3;
Figure 5 is a cross-sectional front (beam-wise) view of the fluid-elastomeric
damper assembly of Figures 1-4 (the top portion of Figure 5 illustrating the internal
pumping device, the bottom portion of Figure 5 illustrating the fluid-elastomeric
chamber);
Figure 6 is another cross-sectional side (cord-wise) view of the fluid-
elastomeric damper assembly of Figures 1-5 (the top portion of Figure 6 illustrating
the internal pumping device, the bottom portion of Figure 6 illustrating the fluid-
elastomeric chamber);
Figure 7A-D are cross-sectional top views of the fluid-elastomeric damper
assembly of Figures 1-6, again highlighting the internal pumping device disposed
with the fluid-elastomeric chamber of the fluid-elastomeric damper assembly;
Figure 8 is another perspective view of the fluid-elastomeric damper assembly
of Figures 1-7;
Figure 9 is a top view of the fluid-elastomeric damper assembly of Figures 1-
8; and
Figure 10 is a front (beam-wise) view of the fluid-elastomeric damper
assembly of Figures 1-9.
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Figure 11A-B are cutaway perspective views of the fluid-elastomeric damper
assembly highlighting the internal pumping device and the fluid backfillers.
Figure 12 shows a fluid backfiller spring plate valve embodiment.
DETAILED DESCRIPTION OF THE INVENTION
Additional features and advantages of the invention will be set forth in the
detailed description which follows, and in part will be readily apparent to those skilled
in the art from that description or recognized by practicing the invention as described
herein, including the detailed description which follows, the claims, as well as the
appended drawings.
Reference will now be made in detail to the present preferred embodiments of
the invention, examples of which are illustrated in the accompanying Drawings. The
invention includes a fiuid-elastomeric damper assembly with a reciprocating piston
structure grounded to a first structure and driven by a second structure with the piston
structure submerged in a fluid and having a first fluid filled chamber and a second
fluid filled chamber which communicate via a pump restriction orifice through which
the piston forces the fluid through. The invention includes fluid-elastomeric damper
assembly 10 which includes a first elastomer seal 12, such as a rubber seal or the like,
disposed at a first end 14 of the fluid-elastomeric damper assembly 10 and a second
elastomer seal 16, such as a rubber seal or the like, disposed at a second end 18 of the
fluid-elastomeric damper assembly 10. The first elastomer seal 12 and the second
elastomer seal 16 are fixedly attached or otherwise coupled to a first moving/vibrating
structure 20, such as a flex-beam of the rotor of a rotary-wing aircraft or the like, and
the first elastomer seal 12 and the second elastomer seal 16 are fixedly attached or
otherwise coupled to a second moving/vibrating structure 22, such as a pitch case of
the rotor of a rotary-wing aircraft or the like. The first elastomer seal 12 and the
second elastomer seal 16 are both bonded, fixedly attached, or otherwise coupled to a
housing structure 24 including, for example, a first housing member 26, a second
housing member 28, and a third housing member 70. The first elastomer seal 12 and
the second elastomer seal 16 are also both bonded, fixedly attached, or otherwise
coupled to a substantially circular base plate 64. Together, the first elastomer seal 12,
the second elastomer seal 16, the housing structure 24, and the substantially circular
base plate 64 are operable for containing a damper fluid. An internal pumping
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mechanism 30 is also disposed within the housing structure 24. The internal pumping
mechanism 30 is grounded to the first moving/vibrating structure 20 and moves in
relation to the housing structure 24 and the second moving/vibrating structure 22 to
which the housing structure 24 is grounded. The internal pumping mechanism 30 is
configured such that, when the internal pumping mechanism 30 moves with respect to
the housing structure 24 and the second/moving vibrating structure 22, the fluid
surrounding and disposed within the internal pumping mechanism 30 is pumped from
at least a first variable volume chamber 32 disposed within the internal pumping
mechanism 30 to at least a second variable volume chamber 34 disposed within the
internal pumping mechanism 30 through a restriction, i.e., an orifice 86 (Figure 3).
Optionally, the relative size of the restriction is controlled by an adjustable pressure
relief device 36 and/or a temperature-compensating device 38 (both described in
greater detail herein below). It should be noted that Figure 1 illustrates an upper
fluid-elastomeric damper assembly 10 (top portion of Figure 1) including an internal
pumping mechanism 30 and a lower fluid-elastomeric damper assembly 10 (bottom
portion of Figure 1) without an internal pumping mechanism 30. The lower-fluid-
elastomeric damper 10 assembly may, optionally, include an internal pumping
mechanism 30.
Advantageously, the first elastomer seal 12, the second elastomer seal 16, the
housing structure 24, and the substantially circular base plate 64 provide a fluid-
elastomeric chamber 40 operable for containing the fluid and in which the internal
pumping mechanism 30 may be submerged. This fluid-elastomeric chamber 40 is
flexible and allows the internal pumping mechanism 30 to damp movement/vibration
in a primary direction with a relatively high damping force. Movement/vibration in a
plurality of other directions are also accommodated by design, due to the coupling
features of the internal pumping mechanism 30. It should be noted that two (2) fluid-
elastomeric damper assemblies 10 are illustrated and used in combination such as in
Figure 1 (and in other drawings described herein below) in order to damp lead-lag
movement/vibration in the rotor of a rotary-wing aircraft or the like. Figure 1
illustrates an upper fluid-elastomeric damper assembly 10 (top portion of Figure 1)
including an internal pumping mechanism 30 and a lower fluid-elastomeric damper
assembly 10 (bottom portion of Figure 1) without an internal pumping mechanism 30.
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The lower-fluid-elastomeric damper 10 assembly preferably includes an internal
pumping mechanism 30.
Referring to Figures 2 and 3A-B, the first elastomer seal 12 disposed at the
first end 14 of the fluid-elastomeric damper assembly 10 and the second elastomer
seal 16 disposed at the second end 18 of the fluid-elastomeric damper assembly 10
may, optionally, include a plurality of metal or substantially rigid laminates (shims)
50 (Figure 3A-B) or the like disposed within a rubber seal 52 (Figure 3A-B) or the
like. This configuration provides both the first elastomer seal 12 and the second
elastomer seal 16 with strength/rigidity and flexibility/pliability. Both the first
elastomer seal 12 and the second elastomer seal 16 may have a substantially
cylindrical or conical shape, although other suitable shapes may be utilized. In an
exemplary embodiment of the present invention, the diameter of the second elastomer
seal 16 is between about one-third (1/3) and about three-quarters (3/4) the diameter of
the first elastomer seal 12. Other shapes and sizes may, however, be used as
necessary.
The first elastomer seal 12 is fixedly attached or otherwise coupled to the first
moving/vibrating structure 20, such as a flex-beam of the rotor of a rotary-wing
aircraft or the like, via a first attachment mechanism 60. Likewise, the first elastomer
seal 12 and the second elastomer seal 16 (Figure 5) are fixedly attached or otherwise
coupled to the second moving/vibrating structure 22, such as a pitch case of the rotor
of a rotary-wing aircraft or the like, via a second attachment mechanism 62. The first
attachment mechanism 60 may include, for example, the substantially circular base
plate 64 bonded, fixedly attached, or otherwise coupled to the first elastomer seal 12
and the second elastomer seal 16. The base plate 64 is fixedly attached or otherwise
coupled to one or more spanning members 66 that are, in turn, fixedly attached or
otherwise coupled to a compliant member 68 (Figure 5) associated with the first
moving/vibrating structure 20. The base plate 64, the one or more spanning members
66, and the compliant member 68 may be made of, for example, a metal or any other
substantially rigid material. Optionally, the base plate 64, the one or more spanning
members 66, and/or the compliant member 68 may be integrally formed. Although an
exemplary first attachment mechanism 60 has been described herein, any other first
attachment mechanism 60 operable for fixedly attached or otherwise coupling the first
elastomer seal 12 and the base plate 64 to the first moving/vibrating structure 20 may
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be used. As is described in greater detail herein below, the second attachment
mechanism 62 fixedly attached or otherwise coupled to the second moving/vibrating
structure 22 may, optionally, be integrally formed/coincident with the housing
structure 24 (Figure 1). Optionally, the fluid-elastomeric damper assembly 10 of the
present invention further includes a gas charge/discharge valve 63 operable for
introducing damping fluid and/or a gas, such as nitrogen or the like, into and/or
removing damping fluid and/or a gas from the fluid-elastomeric chamber 40.
The first elastomer seal 12 and the second elastomer seal 16 are both bonded,
fixedly attached, or otherwise coupled to the housing structure 24, which may be
made of, for example, a metal or any other substantially rigid material. In an
exemplary embodiment of the present invention, the housing structure 24 includes a
first housing member 26 and a second housing member 28. The first housing member
26 may be a substantially cup-shaped structure. Accordingly, the second housing
member 28 may be a substantially disc-shaped structure. Optionally, the housing
structure 24 may also include a third, substantially disc-shaped housing member 70
that, together with the first housing member 26 and the second housing member 28,
serves as the second attachment mechanism 62, fixedly attaching or otherwise
coupling the first elastomer seal 12 and the second elastomer seal 16 to the second
moving/vibrating structure 22. The first housing member 26, the second housing
member 28, and the third housing member 70 may be bolted or otherwise attached
together, or they may be integrally formed. Together, the first elastomer seal 12, the
second elastomer seal 16, and the housing structure 24 are operable for containing the
damper fluid 72 in the fluid-elastomeric chamber 40. The fluid-elastomeric chamber
40 partially formed by the first elastomer seal 12, the second elastomer seal 16, and
the housing structure 24 may, optionally, have a plurality of circular diameters
substantially conforming to the shape of the internal pumping mechanism 30 disposed
therein.
The internal pumping mechanism 30 disposed within the housing structure 24
is grounded to the first moving/vibrating structure 20 and moves in relation to the
housing structure 24, which is grounded to the second moving/vibrating structure 22.
The internal pumping mechanism 30 includes one or more piston structures 80
disposed within a piston structure housing 82. Preferably, the one or more piston
structures 80 include one or more substantially cylindrical, hollow structures.
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Preferably, the one or more piston structure housings 82 are free to move along one or
more axially-extending structures 84, such as hollow and/or solid rods or the like,
integrally formed with the piston assembly. Preferably the piston structure housing
82 is grounded to the first moving/vibrating structure 20 by a stem piece that may be
integrally formed with the base plate 64 or, optionally, may include a plurality of
components. The piston structure housing 82 may be constructed in multiple sections
to allow grounding of the piston structure housing 82 to the stem piece of the base
plate 64. The one or more piston structures include a first chamber 32 and a second
chamber 34 separated by the piston assembly, with the first chamber 32 and the
second chamber 34 in fluid communication through a pumping piston restriction, i.e.,
an orifice 86. The piston assembly extends through the piston structure housing 82 to
the housing structure 24, to which it is grounded. A plurality of relatively small holes
88 are disposed within the walls of the one or more piston structure housings 82,
allowing trapped gas and a limited flow of the fluid 72 between the fluid-elastomeric
chamber 40 and the internal pumping mechanism 30. Additionally, clearance
between the piston structure housing 82 and the piston assembly allow a limited flow
of fluid between the fluid-elastomeric chamber 40 and the internal pumping
mechanism 30. The pumping piston restriction orifices 86 represents the path of
least resistance for the fluid 72 within the fluid-elastomeric chamber 40 with the
orifices 86 sized relatively large compared to the small holes 88. The internal
pumping mechanism 30 is configured such that, when the one or more piston structure
housing 82 move with respect to the housing structure 24 and the second/moving
vibrating structure 22, the fluid 72 surrounding and disposed within the one or more
piston structures is pumped from the first chamber 32 to the second chamber 34 by
the movement of piston structures 80 with the fluid 72 pumped back and forth
between the first and second chambers through the orifice 86. As shown in Figures 1-
3, the relative linear motion between the first moving structure 20 and the second
moving structure 22 drives the linear reciprocating motion of the internal pumping
mechanism 30, and forces the flow of fluid 72 through the orifice 86 between the first
chamber 32 and the second chamber 34. This fluid restriction 86 creates fluid
damping forces. As shown the pumping piston restriction orifice 86 can be in the
plate piston 80.
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The invention includes a fluid-elastomeric damper assembly 10 operable for
damping a relative motion between a first structure 22 and a second structure 20, the
fluid-elastomeric damper assembly 10 comprising: a plurality of elastomer seals 12,
16 coupled to the housing 24 of the first structure 22, wherein the first structure
housing 24 and the plurality of elastomer seals define a fluid-elastomeric chamber 40
operable for containing a fluid 72; an internal pumping mechanism 30 with at least
one fluid moving piston 80 disposed within the first structure housing 24 and the
fluid-elastomeric chamber 40, wherein the internal pumping mechanism 30 is
grounded to the first structure and driven by the second structure, and wherein the at
least one piston 80 forces said fluid 72 through at least one orifice 86 between a first
substantially fluid-filled chamber 32 and a second substantially-fluid-filled chamber
34 which are in fluid communication with the fluid-elastomeric chamber 40; and
wherein said relative motion between said first structure 22 and said second structure
20 is operable for pumping the fluid 72 through said at least one orifice 86. In a
preferred embodiment the at least one fluid moving piston 80 is a linearly
reciprocating piston structure that pumps said fluid with a linear motion.
The invention includes a method for damping a relative motion between a first
structure 22 and a second structure 20. The method comprises grounding a housing 24
to the first structure 22; coupling a plurality of elastomeric seals 12,16 to the housing,
wherein the housing 24 and the plurality of elastomeric seals 12,16 provide a fluid-
elastomeric chamber 40 for containing a fluid 72; disposing a fluid 72 within the
fluid-elastomeric chamber 40; disposing an internal fluid pump 30 with at least one
fluid moving piston 80 within the housing and the fluid-elastomeric chamber and
grounding the internal fluid pump 30 to the first structure, wherein the internal fluid
pump 30 comprises a first substantially fluid-filled chamber 32 and a second
substantially fluid-filled chamber 34 in communication via at least one orifice 86, said
first substantially fluid-filled chamber 32 and said second substantially fluid-filled
chamber 34 in communication with the fluid-elastomeric chamber 40; wherein said
relative motion between said first structure 22 and said second structure 20 drives said
at least one fluid moving piston 80 to pump said fluid 72 through said at least one
orifice 86. In a preferred embodiment the at least one fluid moving piston 80 is a
linearly reciprocating piston and pumps said fluid 72 through said at least one orifice
86 with a linear motion.
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The invention includes a method of making a rotary-wing aircraft fiuid-
elastomeric damper assembly 10 for damping a relative motion between a first rotary-
wing aircraft structure 22 and a second rotary-wing aircraft structure 20 in a rotary-
wing aircraft. The method includes coupling a plurality of elastomeric seals 12, 16 to
a housing 24, wherein the housing 24 and the plurality of elastomeric seals 12, 16
provide a fluid-elastomeric chamber 40 for containing a fluid 72; disposing an internal
fluid pump 30 with at least one fluid moving piston 80 within the housing 24 and the
fluid-elastomeric chamber 40 and grounding the internal fluid pump 30 to the first
structure, disposing a fluid 72 within the fluid-elastomeric chamber 40 wherein the
internal fluid pump 30 comprises a first substantially fluid-filled chamber 32 and a
second substantially fluid-filled chamber 34 in communication via at least one orifice
86, said first substantially fluid-filled chamber 32 and said second substantially fluid-
filled chamber 34 in communication with the fluid-elastomeric chamber 40; wherein
said relative motion between said first structure 22 and said second structure 20 drives
said at least one fluid moving piston 80 to pump said fluid 72 through said at least one
orifice 86. In a preferred embodiment said at least one fluid moving piston 80 is a
linearly reciprocating piston that pumps said fluid 72 through said at least one orifice
86 with a linear motion.
Thus, the first elastomer seal 12, the second elastomer seal 16, the housing
structure 24, and the base plate 64 provide a fluid-elastomeric chamber 40 operable
for containing the fluid 72 and in which the internal pumping mechanism 30 may be
submerged. This fluid-elastomeric chamber 40 is flexible and allows the internal
pumping mechanism 30 to damp movement/vibration in a primary direction with a
relatively high damping force.
Referring to Figure 7A, as described above, an adjustable pressure relief
device 36 and/or a temperature-compensating device 38 may be disposed within the
one or more hollow axially extending structures 84 (i.e., the piston assembly) that
carry the one or more piston structures 80. The adjustable pressure relief device 36
includes a spring-loaded member 90 (Figure 3) that partially protrudes into the orifice
86 (Figure 3), selectively blocking a portion thereof and restricting the flow of fluid
there through. The spring-loaded member 90 of the adjustable pressure relief device
36 is displaced in the presence of relatively high fluid pressure. The amount of force
required to displace the spring-loaded member 90 of the adjustable pressure relief
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device 36 may be adjusted via an adjustment mechanism 92 (Figure 3) disposed
within the housing structure 24. Additionally, the spring-side of the hollow structure
communicates with the fluid-elastomeric chamber 40 via one or more holes 93
(Figure 3) disposed within and through the walls of the hollow portion of the piston
assembly 84. These communication holes 93 allow a pressure differential to occur
between the relatively high dynamic pressure at the orifice 86 and the steady ambient
pressure of the fluid-elastomeric chamber 40, actuating the adjustable pressure relief
device 36. The temperature-compensating device 38 includes a temperature-sensitive
member 94 (Figure 3) that partially protrudes into the orifice 86, selectively blocking
a portion thereof and restricting the flow of fluid therethrough. Preferably, the
temperature sensitive member has a predetermined thermal expansion coefficient such
that the degree of flow restriction may be varied for a given change in temperature.
The pressure relief device 36 and the temperature-compensating device 38 work
together to provide a predetermined degree of damping. The grounding of the piston
assembly to the housing structure 24 is accomplished by means of one or more
retaining structures. The one or more retaining structures may be solid and/or hollow
and allow for the adjustment of the internal mechanisms of the fluid-elastomeric
damper assembly 10. Preferably, the one or more retaining structures form an integral
seal with the piston assembly and the housing structure 24. The one or more retaining
structures may allow access to either or both, if multiple retaining structures disposed
adjacent to the appropriate mechanisms are used, the adjustable pressure relief device
36 and/or the temperature-compensating device 38.
Figures 8, 9, and 10 provide several other views of the fluid-elastomeric
damper assembly of the present invention, for use in conjunction with a typical flex-
beam helicopter rotor assembly.
Preferably the fluid-elastomeric damper assembly 10 provides beneficial
damping of a relative motion between a first structure 20 and a second structure 22.
The fluid-elastomeric damper assembly 10 preferably comprises the elastomer seals
12,16 coupled to the fluid-elastomeric chamber housing 24, with the fluid-elastomeric
chamber housing 24 and the elastomer seals 12,16 providing the fluid-elastomeric
chamber 40 operable for containing damper fluid 72. The fluid-elastomeric damper
assembly 10 internal pumping mechanism 30 with at least one fluid moving piston 80
disposed within the fluid-elastomeric chamber 40 preferably includes the first
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substantially fluid-filled variable volume chamber 32 and the second substantially
fluid filled variable volume chamber 34 with the internal pumping mechanism driven
by the relative motion wherein the piston 80 forces the fluid 72 through the pumping
piston restriction orifice 86 between the first fluid variable volume chamber 32 and
the second fluid variable volume chamber 34. The first fluid chamber 32 includes a
first fluid backfiller 500, the first fluid backfiller 500 providing fluid communication
of the fluid 72 from the fluid-elastomeric chamber 40 into the first fluid chamber 32
and inhibiting a flow of the fluid 72 from the first fluid chamber 32 into the fluid-
elastomeric chamber 40. The second fluid chamber 34 includes a second fluid
backfiller 500, the second fluid backfiller 500 providing fluid communication of the
fluid 72 from the fluid-elastomeric chamber 40 into the second fluid chamber 34 and
inhibiting a flow of the fluid 72 from the second fluid chamber 34 into the fluid-
elastomeric chamber 40. The relative motion between the first structure 20 and the
second structure 22 pumps the fluid 72 through the at least one restriction orifice 86.
The fluid-elastomeric damper assembly internal pumping mechanism 30 preferably
includes a second fluid moving piston 80, with the second fluid moving piston 80
forcing the fluid 72 through a second pumping piston restriction orifice 86 between a
third substantially fluid-filled variable volume chamber 32 and a fourth substantially-
fluid-filled variable volume chamber 34 with the third fluid variable volume chamber
32 including a third fluid backfiller 500, the third fluid backfiller 500 providing fluid
communication of the fluid 72 from the fluid-elastomeric chamber 40 into the third
fluid chamber 32 and inhibiting a flow of the fluid 72 from the third fluid chamber 32
into the fluid-elastomeric chamber 40. The fourth fluid variable volume chamber 34
includes a fourth fluid backfiller 500, the fourth fluid backfiller 500 providing fluid
communication of the fluid 72 from the fluid-elastomeric chamber 40 into the fourth
fluid chamber 34 and inhibiting a flow of the fluid 72 from the fourth fluid chamber
34 into the fluid-elastomeric chamber 40. The relative motion between the first
structure 20 and the second structure 22 is operable for pumping the fluid 72 through
the second restriction orifice 86.
The fluid-elastomeric damper assembly backfiller 500 is comprised of a valve
501. The backfiller valve 501 is relatively closed and restricts fluid flow in the
direction from the fluid variable volume chamber 32, 34 back into the surrounding
fluid-elastomeric chamber 40 and relatively open with relatively low restriction of
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fluid flow in the opposite direction from the surrounding fluid-elastomeric chamber
40 into the fluid variable volume chamber when the volume of its variable volume
chamber is increasing. Preferably the variable volume chamber backfiller 500 is
comprised of a flow blocker spring plate 504, with the spring plate 504 allowing fluid
flow into the fluid variable volume chamber 32, 34 when the volume of the variable
volume chamber is increasing and the spring plate 504 closing and blocking fluid
flow from the variable volume back into the fluid-elastomeric chamber 40 when the
volume of the variable volume chamber is decreasing. As shown in Figure 7 A when
the piston housing 82 of the internal fluid pumper 30 is moving to the left relative to
the surrounding housing 24 and the fluid-elastomeric chamber 40 the first backfiller
500 opens and allows an inflow of fluid 72 into the first variable volume fluid
chamber 32 when the volume of the first fluid chamber 32 is increasing at a high rate
of change. The volume of the second variable volume fluid chamber 34 is decreasing
from this internal fluid pumper 30 piston housing 82 moving to the left relative to the
surrounding housing 24, with the fluid in the second fluid chamber 34 pumped
through the orifice 86 into the first variable volume fluid chamber 32 with the second
backfiller valve 501 closed. As shown in Figure 7B when the internal pumper piston
housing 82 moves to the right relative to the fluid-elastomeric chamber 40 and the
surrounding housing 24, the first fluid chamber 32 first backfiller spring plate flapper
valve 501 in the left side of the pumper piston housing 82 closes because the first
fluid chamber 32 on this side is compressed against the piston 80 with the fluid forced
through the orifice 86 in the piston. This causes an increase in pressure in this left side
first variable volume fluid chamber 32 that seats the backfiller spring plate flapper
valve 501 against the inside of the internal piston pumper housing closing the fluid
communication opening 503. The fluid in the right side second variable volume fluid
chamber 34 is uncompressed causing a decrease in pressure (to something less than
the steady ambient pressure of the outside fluid-elastomeric chamber 40) which cause
the backfill flapper valve 501 to unseat and open which allows fluid 72 from the
outside fluid-elastomeric chamber 40 to backfill into this right side lower pressure
second fluid chamber 34.
Preferably the first fluid chamber 32 is comprised of a first chamber housing
wall 502 with the first chamber housing wall 502 segregating the first fluid chamber
32 from the fluid-elastomeric chamber 40. As shown in Figure 7C the first fluid
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chamber housing wall 502 separates the fluid 72 inside the first fluid chamber 32 from
the fluid 72 out in the fluid-elastomeric chamber 40, with the fluid chamber housing
wall 502 having a fluid communication opening 503. In Figure 7C no relative
movement is shown, and the backfill flapper valves 501 are not shown to clearly
illustrate the chamber housing walls 502 of the variable volume fluid chambers and
the fluid backfiller communication openings 503 in the walls 502. Figure 7D
illustrates no relative movement as shown in Figure 7C, but with the backfill flapper
valves 501 blocking the fluid communication openings 503 in the walls 502.
Preferably the fluid backfiller 500 is comprised of a flow blocker backfill spring plate
504, with the spring plate 504 adjacent the fluid communication opening 503 in the
chamber housing wall 502 of its variable volume fluid chamber. Preferably the
backfill flapper valve spring plate restricts flow in one direction and provides low
restriction of fluid 72 in the opposite direction, with the spring plate 504 covering the
wall opening 503 and obstructing, blocking, and plugging the flow of fluid 72 from
inside its fluid chamber through the opening 503 in chamber wall 502 out into the
fluid-elastomeric chamber 40. Preferably the spring plate backfiller 500 is pressure
activated, with a fluid pressure drop in the variable volume fluid chamber the spring
plate 504 deflects to an open position allowing an in flow of fluid 72 back into the
increasing volume variable volume chamber from the fluid-elastomeric chamber 40
driven by the increasing volume pressure drop, such as a high amplitude displacement
of the piston 80, the pressure drop from a first direction relative movement of the
piston housing 82 relative to the housing 40 and orifice 86 along axially-extending
piston structure rod 84 inside fluid-elastomeric chamber 40 opens the opening 503
and fluid 72 flows into the variable volume chamber so when the piston stroke
pumping direction is reversed to the opposite direction with the volume of the
variable volume chamber decreasing the variable volume chamber will be full of fluid
72, the opening 503 will be closed by the backfiller plate 504 and the fluid 72 will
then be forced through the restriction orifice 86, with the fluid flow through the
pumping piston restriction orifice 86 dissipating the unwanted kinetic energy of the
relative motion between the first structure 20 and the second structure 22. Preferably
the backfiller plate 504 of the second fluid chamber 34 opens fluid flow, into the
second fluid chamber when the volume of the second fluid chamber 34 is increasing
and the volume of the first fluid chamber 32 is decreasing with the backfiller plate
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WO 2006/104601 PCT/US2006/006006
504 of the first fluid chamber 32 closed with the backfiller plate blocking fluid 72
from flowing through first fluid chamber wall opening 503 while the fluid 72 is forced
from the second chamber 34 through the restriction orifice 86 into the first chamber
32.
Preferably the internal pumping mechanism fluid pump 30 includes a second
fluid moving piston 80 with a piston housing 82 forming a third substantially fluid-
filled chamber 32 and a fourth substantially-fluid-filled chamber 34 which are in fluid
communication with the fluid-elastomeric chamber 40. The second fluid moving
piston 80 forces the fluid 72 through a second pumping piston restriction orifice 86
between the third fluid chamber 32 and the fourth fluid chamber 34. The third
variable volume chamber 32 includes a third fluid backfiller 500 providing fluid
communication of the fluid 72 from the fluid-elastomeric chamber 40 into the third
fluid chamber 32 and inhibiting a flow of the fluid 72 from the third fluid chamber 32
back into the fluid-elastomeric chamber 40. The fourth fluid chamber 34 includes a
fourth fluid backfiller 500 providing fluid communication of the fluid 72 from the
fluid-elastomeric chamber 40 into the fourth fluid chamber 34 and inhibiting a flow of
the fluid 72 from the fourth fluid chamber 34 back into the fluid-elastomeric chamber
40 wherein the relative motion between the first structure 20 and the second structure
22 is operable for pumping the fluid through the second restriction orifice 86.
Preferably the damper assembly first fluid chamber housing wall 502
segregates the first fluid chamber 32 from the fluid-elastomeric chamber 40 by
separating and segregating fluid 72 inside the first fluid chamber from the fluid out in
the surrounding fluid-elastomeric chamber 40 with the first fluid backfiller 500
comprised of a valve 501 which provides liquid flow control through opening 503 in
wall 502. The first chamber housing wall 502 defines the fluid communication
opening 503 with the first fluid backfiller valve proximate the first chamber housing
wall fluid communication opening 503. The second chamber housing wall 502 of the
second fluid chamber 34 is preferably distal from the first chamber housing wall 502
of first chamber 32. The second chamber housing wall 502 segregates the second fluid
chamber 34 from the surrounding outside fluid-elastomeric chamber 40, with the
second chamber housing wall 502 defining a second fluid communication opening
503 and the second fluid backfiller 500 is comprised of a second valve 501 proximate
this second chamber housing wall second fluid communication opening 503, wherein
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a relative motion of the internal pumping mechanism piston opens the first valve 501
and closes the second valve 501 with pumping of the internal pumping mechanism 30
in a first direction with the first fluid chamber 32 variable volume increasing and the
second fluid chamber 34 variable volume decreasing. The third chamber housing
wall 502 defines the fluid communication opening 503 with the third fluid backfiller
valve 501 proximate the third chamber housing wall fluid communication opening
503. The fourth chamber housing wall 502 of the fourth fluid chamber 34 is
preferably distal from the third chamber housing wall 502 of third chamber 32. The
fourth chamber housing wall 502 segregates the fourth fluid chamber 34 from the
surrounding outside fluid-elastomeric chamber 40, with the fourth chamber housing
wall 502 defining a fourth fluid communication opening 503 and the fourth fluid
backfiller 500 is comprised of a fourth valve 501 proximate this fourth chamber
housing wall fourth fluid communication opening 503, wherein a relative motion of
the internal pumping mechanism piston opens the third valve 501 and closes the
fourth valve 501 with pumping of the internal pumping mechanism 30 in a first
direction with the third fluid chamber 32 variable volume increasing and the fourth
fluid chamber 34 variable volume decreasing. Preferably the motion of the first
structure 20 relative to the second structure 22 pumps the internal pumping
mechanism 30 with the first and third backfiller valves 501 opening to provide fluid
flow in from the surrounding outside fluid-elastomeric chamber 40 while the second
and fourth backfiller valves 501 close to inhibit fluid flow from the second and fourth
chambers into the surrounding outside fluid-elastomeric chamber 40.
Preferably in operation of the fluid elastomeric damper assembly 10 with the
damper internal fluid pump driven by the relative motion between the first structure
20 and the second structure 22 the damper fluid 72 outside the at least one fluid
moving piston 80 and contained in the fluid-elastomeric chamber 40 has an
operational ambient fluid pressure PA. The operational ambient fluid pressure PA is
the pressure of fluid 72 outside the internal fluid pump but inside the damper fluid-
elastomeric chamber 40 while the damper 10 is operating. The fluid 72 inside the at
least one fluid moving piston variable volume chamber 32,34 in which the variable
volume is being decreased by the relative motion has an operational dynamic fluid
pressure PD when pumped by the at least one fluid moving piston with PD ≥ 1.01 PA.
Preferably the relative motion compresses the variable volume chamber and decreases
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WO 2006/104601 PCT/US2006/006006
the fluid volume at a high rate of change therein that provides for the increase in
pressure of the fluid 72 to the operational dynamic fluid pressure PD with the
backfiller valve 501 closed and the fluid forced through the restriction orifice 86 into
the opposing variable volume chamber in which the variable volume is increasing.
In operation the relative motion preferably drives the internal pumping mechanism 30
with the damper fluid pressurized in the variable volume chamber with PD-PA≥1PSI.
In embodiments of the fluid elastomeric damper assembly PD ≥ 1.05PA, preferably
PD > 1.06PA, and more preferably PD ≥ 1.07PA. In embodiments of the fluid
elastomeric damper assembly PD-PA≥10PSI, preferably PD-PA≥100PSI, more
preferably PD-PA≥500PSI. In embodiments of the fluid elastomeric damper
assembly 10 preferably PD ≥500PSI, such as about 873PSI, and about 1000PSI. In
embodiments of the fluid elastomeric damper assembly 10 preferably PA≤100PSI,
more preferably PA≤50PSI, such as about 15PSI.
The fluid elastomeric damper assembly 10 preferably operates with a broad
range of fluid viscosities. Preferably the provided damper fluid 72 has a viscosity less
than 5,000 centistokes, preferably a damper fluid with a viscosity in the range from 30
to 5000 centistokes. Preferably the damper fluid 72 has a viscosity less than 1,500
centistokes, preferably a viscosity in the range of 40 to 1200 centistokes, and more
preferably 50 to 1000 centistokes. The backfiller damper assembly 10 preferably can
utilize a broad range of viscosities, from relatively low at about 30 centistokes to
relatively high at about 5000 centistokes.
Figure 3A is an exploded perspective view of the fluid-elastomeric damper
assembly 10 highlighting the internal pumping device 30 and the backfillers 500 of
the first and second variable volume fluid chambers 32 and 34. Figure 3B shows a
similar view without the spring plate valves 504 inorder to highlight the fluid
communication openings 503 in the variable volume fluid chamber walls 502.
Similarly Figure 11A-B highlight the backfillers 500 with the spring plate valve 504
covering the fluid communication openings 503 in the fluid chamber walls 502.
Figure 12 shows an embodiment of a spring plate 504 which is utilized as a flow
blocker flapper valve 501 to control the flow fluid through the fluid communication
openings 503 in the chamber walls 502. Spring plate 504 is preferably made from a
flexible sheet material such as stainless steel sheet metal with the spring plate flapper
tongue 505 sized to cover and block the opening 503.
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The invention includes a method for damping a relative motion between a first
structure and a second structure. Preferably the method provides a beneficial means to
damp a relative motion between a first structure 20 and a second structure 22. The
method preferably includes providing a structure housing 24, with the structure
housing 24 providing for a structural grounding to one of the structures 20,22. The
method preferably includes coupling a plurality of elastomeric seals 12,16 to the
housing 24, wherein the housing 24 and the plurality of elastomeric seals 12,16
provide a fiuid-elastomeric chamber 40 for containing a damper fluid 72. The method
includes providing and disposing a damper fluid 72 within the fluid-elastomeric
chamber 40. The method includes disposing an internal fluid pump 30, preferably
with at least one fluid moving piston 80 enclosed in a piston housing 82, within the
fluid-elastomeric chamber 40. The internal fluid pump 30 preferably comprises a first
substantially fluid-filled variable volume chamber 32 and a second substantially fluid-
filled variable volume chamber 34 in communication via at least one orifice 86. The
first fluid chamber 32 preferably includes a first fluid backfiller 500 and the second
fluid chamber 34 includes a second fluid backfiller 500.Preferably the first fluid
chamber 32 and the second fluid chamber 34 are in communication with the fluid-
elastomeric chamber 40, wherein the relative motion between the first structure 20
and the second structure 22 drives the at least one fluid moving piston 80 to pump the
fluid 72 through the at least one orifice 86 with the first fluid backfiller 500 providing
fluid communication of the fluid 72 from the fluid-elastomeric chamber 40 into the
first fluid chamber 32 and inhibiting a flow of the fluid 72 from the first fluid chamber
32 back into the fluid-elastomeric chamber 40 and the second fluid backfiller 500
providing fluid communication of the fluid 72 from the fluid-elastomeric chamber 40
into the second fluid chamber 34 and inhibiting a flow of the fluid 72 from the second
fluid chamber 34 back into the fluid-elastomeric chamber 40 .
The relative motion between the first structure and the second structure pumps
the fluid 72 in the internal pumping mechanism 30 in a first direction with the first
fluid chamber 32 variable volume increasing and the second fluid chamber 34
variable volume decreasing, and then pumping in a second opposite direction with the
second fluid chamber 34 variable volume increasing and the first fluid chamber 32
variable volume decreasing. Preferably the first fluid backfiller 500 includes a first
valve 501, and the second fluid backfiller 500 includes a second valve 501, wherein a
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relative movement of the piston 80 and the piston housing 82 opens the first valve 501
and closes the second valve 501.
Providing the internal pumping mechanism 30 preferably includes providing a
second fluid moving piston 80, with the second fluid moving piston 80 forcing the
fluid 72 through a second pumping piston restriction orifice 86 between a third
substantially fluid-filled variable volume chamber 32 and a fourth substantially-fluid-
filled variable volume chamber 34 which are in fluid communication with the fluid-
elastomeric chamber 40. The third fluid variable volume chamber 32 preferably
includes a third fluid backfiller 500, the third fluid backfiller 500 providing fluid
communication of the fluid 72 from the fluid-elastomeric chamber 40 into the third
fluid chamber 32 and inhibiting a flow of the fluid 72 from the third fluid chamber 32
into the fluid-elastomeric chamber 40. The fourth fluid variable volume chamber 34
preferably includes a fourth fluid backfiller 500, the fourth fluid backfiller 500
providing fluid communication of the fluid 72 from the fluid-elastomeric chamber 40
into the fourth fluid chamber 34 and inhibiting a flow of the fluid 72 from the fourth
fluid chamber 34 into the fluid-elastomeric chamber 40. The relative motion between
the first structure 20 and the second structure 22 pumps the fluid 72 through the
second restriction orifice 86.
Providing the damper fluid 72 preferably includes providing a damper fluid
with a viscosity less than 5,000 centistokes, preferably in the range from 30 to 5,000
centistokes. Preferably the damper fluid 72 has a viscosity less than 1,500
centistokes, preferably a viscosity in the range of 40 to 1200 centistokes, and more
preferably 50 to 1000 centistokes.
Preferably in damping the relative motion between the first structure 20 and
the second structure 22 the fluid 72 outside the internal pumping mechanism 30 and
contained in the fluid-elastomeric chamber 40 has an operational ambient fluid
pressure PA and the fluid 72 inside the internal pumping mechanism variable volume
chamber which has the decreasing volume has an operational dynamic fluid pressure
PD when pumped by the at least one fluid moving piston 80 with PD > 1.01PA.
Preferably in operation the relative motion compresses the variable volume chamber
and decreases the fluid volume at a high rate of change therein that provides for the
increase in pressure of the fluid 72 to the operational dynamic fluid pressure PD with
the backfiller valve 501 closed and the fluid forced through the restriction orifice 86
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into the opposing variable volume chamber in which the variable volume is
increasing. Preferably the relative motion drives the internal fluid pump 30 with the
damper fluid 72 pressurized in the variable volume chamber with PD-PA≥1PSI. In
embodiments preferably PD ≥ 1.05PA, preferably PD ≥ 1.06PA, and more preferably
PD ≥ 1.07PA. In embodiments preferably PD-PA≥1 OPSI, preferably PD-PA≥1 OOPSI, •
more preferably PD-PA≥500PSI. In embodiments preferably PD ≥500PSI, such as
about 873PSI, and about 1000PSI. In embodiments preferably PA≤1 OOPSI, more
preferably PA≤50PSI, such as about 15PSI.
The invention preferably includes a method of making a rotary-wing aircraft
fluid-elastomeric damper assembly 10 for damping a relative motion between a first
structure 20 and a second structure 22 in a rotary-wing aircraft. The method includes
coupling the elastomeric seals 12,16 to the housing 24, wherein the housing 24 and
the elastomeric seals 12,16 provide the fluid-elastomeric chamber 40 for containing
the damper fluid 72. The method includes disposing the internal fluid pump 30 with
the first fluid variable volume chamber 32 and the second fluid variable volume
chamber 34 within the fluid-elastomeric chamber 40. The method includes disposing
the damper fluid 72 within the fluid-elastomeric chamber 40 wherein the internal fluid
pump first variable volume chamber 32 and the second fluid variable volume chamber
34 are substantially filled with the fluid. The substantially fluid filled variable volume
chambers are in communication via the at least one orifice 86, with the first fluid
chamber 32 including the first fluid backfiller 500 and the second fluid chamber 34
including the second fluid backfiller 500.The first fluid chamber 32 and the second
fluid chamber 34 are in communication with the fluid-elastomeric chamber 40,
wherein the relative motion between the first structure 20 and the second structure 22
drives the fluid moving piston 80 of the pump 30 to pump the fluid 72 through the
orifice 86 with the first fluid backfiller 500 providing fluid communication of the
fluid 72 from the fluid-elastomeric chamber 40 into the first fluid chamber 32 and
inhibiting a flow of the fluid 72 from the first fluid chamber 32 back into the fluid-
elastomeric chamber 40 and the second fluid backfiller 500 providing fluid
communication of the fluid 72 from the fluid-elastomeric chamber 40 into the second
fluid chamber 34 and inhibiting a flow of the fluid 72 from the second fluid chamber
34 into the fluid-elastomeric chamber 40. Providing the internal fluid pump 30
preferably includes providing the second fluid moving piston 80, with the second
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fluid moving piston 80 forcing the fluid 72 through the second pumping piston
restriction orifice 86 between the third substantially fluid-filled variable volume
chamber 32 and the fourth substantially-fluid-filled variable volume chamber 34
which are in fluid communication with the fluid-elastomeric chamber 40. The third
fluid variable volume chamber 32 preferably includes the third fluid backfiller 500,
the third fluid backfiller 500 providing fluid communication of the fluid 72 from the
fluid-elastomeric chamber 40 into the third fluid chamber 32 and inhibiting the flow
of the fluid 72 from the third fluid chamber 32 into the fluid-elastomeric chamber 40.
The fourth fluid variable volume chamber 34 preferably includes the fourth fluid
backfiller 500, the fourth fluid backfiller 500 providing fluid communication of the
fluid 72 from the fluid-elastomeric chamber 40 into the fourth fluid chamber 34 and
inhibiting the flow of the fluid 72 from the fourth fluid chamber 34 into the fluid-
elastomeric chamber 40. The relative motion between the first structure 20 and the
second structure 22 pumps the fluid 72 through the second restriction orifice 86.
Preferably the provided damper fluid 72 has a viscosity less than 5,000 centistokes,
preferably a viscosity in the range from 30 to 5000 centistokes. Preferably the
damper fluid 72 has a viscosity less than 1,500 centistokes, preferably a viscosity in
the range of 40 to 1200 centistokes, and more preferably 50 to 1000 centistokes. The
backfiller damper assembly utilizes a broad range of viscosities, from relatively low at
about 30 centistokes to relatively high at about 5000 centistokes. Preferably the
damper fluid 72 outside the internal fluid pump 30 and contained in the fluid-
elastomeric chamber 40 has an operational ambient fluid pressure PA. The operational
ambient fluid pressure PA is the pressure of fluid 72 outside the internal fluid pump
but inside the damper fluid-elastomeric chamber 40 while the damper 10 is operating.
The fluid 72 inside the variable volume chamber 32,34 in which the variable volume
is being decreased by the relative motion has an operational dynamic fluid pressure
PD when pumped by the at least one fluid moving piston with PD ≥ 1.01 PA.
Preferably the relative motion compresses the variable volume chamber and decreases
the fluid volume at a high rate of change therein that provides for the increase in
pressure of the fluid 72 to the operational dynamic fluid pressure PD with the
backfiller valve 501 closed and the fluid forced through the restriction orifice 86 into
the opposing variable volume chamber in which the variable volume is increasing.
In operation the relative motion preferably drives the internal pumping mechanism 30

WO 2006/104601 PCT/US2006/006006
with the damper fluid pressurized in the variable volume chamber with PD-PA≥1PSI.
In embodiments of the fluid elastomeric damper assembly PD ≥ 1.05PA, preferably
PD ≥ 1.06PA, and more preferably PD ≥ 1.07PA. In embodiments of the fluid
elastomeric damper assembly PD-PA≥10PSI, preferably PD-PA≥1 OOPSI, more
preferably PD-PA≥500PSI. In embodiments of the fluid elastomeric damper
assembly preferably PD≥500PSI, such as about 873PSI, and about 1000PSI. In
embodiments of the fluid elastomeric damper assembly preferably PA≤1 00PSI, more
preferably PA≤50PSI, such as about 15PSI.
The invention preferably includes a method for damping relative motion
between a first structure 20 and a second structure 22. The method includes providing
the housing 24. The method includes grounding the housing structure 24 to one of the
structures. The method includes coupling the elastomer seals 12,16 to the housing
structure 24, wherein the housing structure 24 and the elastomer seals define the fluid-
elastomeric chamber 40. The method includes providing and disposing the damper
fluid 72 within the fiuid-elastomeric chamber 40. The method includes providing and
disposing a internal piston pump 30 within the housing structure 24 and the fluid-
elastomeric chamber 40, wherein the piston pump 30 comprises the first substantially
fluid-filled variable volume chamber 32 and the second substantially fluid-filled
variable volume chamber 34 in communication via the orifice 86, with the first fluid-
filled chamber 32 and the second fluid-filled chamber 34 also in communication with
the fluid-elastomeric chamber 40. The piston pump 30 preferably is comprised of a
piston 80 enclosed by a piston housing 82. The relative motion between the first
structure 20 and the second structure 22 drives the piston pump 30 and pumps the
fluid 72 through the orifice 86, with the fluid 72 outside the piston pump 30 and
contained in the fluid-elastomeric chamber 40 having an operational ambient fluid
pressure PA, and the fluid 72 inside the piston pump 30 having an operational
dynamic fluid pressure PD when pumped by the piston pump with PD ≥ 1.01 PA. In
operation the relative motion preferably drives the internal pump 30 with the damper
fluid 72 pressurized in the variable volume chamber in which the volume is being
reduced with PD-PA≥1PSI. In embodiments the internal pump 30 is driven by the
relative motion with the operational dynamic fluid pressure PD ≥ 1.05PA, preferably
PD ≥ 1.06PA, and more preferably PD ≥ 1.07PA. In embodiments the internal pump
30 is driven by the relative motion with PD-PA≥10PSI, preferably PD-PA≥1 OOPSI,
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more preferably PD-PA≥500PSI. In embodiments the internal pump 30 is driven by
the relative motion with the operational dynamic fluid pressure PD ≥500PSI, such as
about 873PSI, and about 1000PSI. In embodiments PA<100PSI, more preferably
PA<50PSI, such as about 15PSI. Preferably the first substantially fluid-filled chamber
32 includes the first fluid backfiller 500 and the second substantially fluid-filled
chamber 34 includes the second fluid backfiller 500, wherein the relative motion
between the first structure and the second structure drives the fluid 72 through the
orifice 86 with the first fluid backfiller 500 providing fluid communication of the
fluid 72 from the fluid-elastomeric chamber 40 into the first fluid chamber 32 and
inhibiting a flow of the fluid 72 from the first fluid chamber 32 into the fluid-
elastomeric chamber 40 and the second fluid backfiller 500 providing fluid
communication of the fluid 72 from the fluid-elastomeric chamber 40 into the second
fluid chamber 34 and inhibiting a flow of the fluid 72 from the second fluid chamber
34 into the fluid-elastomeric chamber 40. Preferably the relative motion compresses
the variable volume chamber and decreases the fluid volume at a high rate of change
therein that provides for the increase in pressure of the fluid 72 to the operational
dynamic fluid pressure PD, preferably with the backfiller valve 501 closed and the
fluid forced through the restriction orifice 86 into the opposing variable volume
chamber in which the variable volume is increasing.
It is apparent that there has been provided, in accordance with the assemblies,
mechanisms, and methods of the present invention, a fluid-elastomeric damper
assembly including an internal pumping mechanism. Although the assemblies,
mechanisms, and methods of the present invention have been described with reference
to preferred embodiments and examples thereof, other embodiments and examples
may perform similar functions and/or achieve similar results. All such equivalent
embodiments and examples are within the spirit and scope of the present invention
and are intended to be covered by the following claims.
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CLAIMS
What is claimed is:
1. A fluid-elastomeric damper assembly operable for damping a relative motion
between a first structure and a second structure, the fluid-elastomeric damper
assembly comprising: a plurality of elastomer seals coupled to a fluid-elastomeric
chamber housing, wherein the fluid-elastomeric chamber housing and the plurality of
elastomer seals define a fluid-elastomeric chamber containing a fluid; an internal
pumping mechanism with at least one fluid moving piston disposed within the fluid-
elastomeric chamber, wherein the internal pumping mechanism is grounded to the
first structure and driven by the second structure, and wherein the at least one piston
forces said fluid through at least one restriction orifice between a first fluid chamber
and a second fluid chamber; said first fluid chamber including a first fluid backfiller,
said first fluid backfiller providing fluid communication of said fluid from said fluid-
elastomeric chamber into said first fluid chamber and inhibiting a flow of said fluid
from said first fluid chamber into said fluid-elastomeric chamber, said second fluid
chamber including a second fluid backfiller, said second fluid backfiller providing
fluid communication of said fluid from said fluid-elastomeric chamber into said
second fluid chamber and inhibiting a flow of said fluid from said second fluid
chamber into said fluid-elastomeric chamber and wherein said relative motion
between said first structure and said second structure is operable for pumping the fluid
through said at least one restriction orifice.
2. The fluid-elastomeric damper assembly of claim 1, wherein said internal
pumping mechanism includes a second fluid moving piston, with said second fluid
moving piston forcing said fluid through a second restriction orifice between a third
fluid chamber and a fourth fluid chamber; said third fluid chamber including a third
fluid backfiller, said third fluid backfiller providing fluid communication of said fluid
from said fluid-elastomeric chamber into said third fluid chamber and inhibiting a
flow of said fluid from said third fluid chamber into said fluid-elastomeric chamber,
said fourth fluid chamber including a fourth fluid backfiller, said fourth fluid
backfiller providing fluid communication of said fluid from said fluid-elastomeric
chamber into said fourth fluid chamber and inhibiting a flow of said fluid from said
fourth fluid chamber into said fluid-elastomeric chamber and wherein said relative
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motion between said first structure and said second structure is operable for pumping
the fluid through said second restriction orifice.
3. The fluid-elastomeric damper assembly of claim 1, wherein said first fluid
backfiller is comprised of a spring plate.
4. The fluid-elastomeric damper assembly of claim 1, wherein said first fluid
chamber is comprised of a first chamber housing wall, said first chamber housing wall
segregating said first fluid chamber from said fluid-elastomeric chamber, and said
first fluid backfiller is comprised of a plate, said plate adjacent a fluid communication
opening in said first chamber housing wall.
5. The fluid-elastomeric damper assembly of claim 1, wherein said fluid has a
viscosity less than 5,000 centistokes.
6. The fluid-elastomeric damper assembly of claim 1, said first fluid chamber
comprised of a first chamber housing wall, said first chamber housing wall
segregating said first fluid chamber from said fluid-elastomeric chamber, said first
chamber housing wall defining a fluid communication opening and said first fluid
backfiller including a first flow blocker proximate said first chamber housing wall
fluid communication opening, said second fluid chamber comprised of a second
chamber housing wall, said second chamber housing wall segregating said second
fluid chamber from said fluid-elastomeric chamber, said second chamber housing
wall defining a second fluid communication opening and said second fluid backfiller
is comprised of a second flow blocker proximate said second chamber housing wall
second fluid communication opening, wherein a relative motion of said piston moves
said first flow blocker away from said first chamber wall fluid communication
opening and blocks said second chamber wall fluid communication opening with said
second flow blocker.
7. The fluid-elastomeric damper assembly of claim 2, said internal pumping
mechanism includes a second fluid moving piston, with said second fluid moving
piston forcing said fluid through a second restriction orifice between a third fluid
chamber and a fourth fluid chamber; said third fluid chamber including a third fluid
backfiller, said third fluid backfiller providing fluid communication of said fluid from
said fluid-elastomeric chamber into said third fluid chamber and inhibiting a flow of
said fluid from said third fluid chamber into said fluid-elastomeric chamber, said
fourth fluid chamber including a fourth fluid backfiller, said fourth fluid backfiller
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providing fluid communication of said fluid from said fluid-elastomeric chamber into
said fourth fluid chamber and inhibiting a flow of said fluid from said fourth fluid
chamber into said fluid-elastomeric chamber and wherein said relative motion
between said first structure and said second structure is operable for pumping the fluid
through said second restriction orifice.
8. The fluid-elastomeric damper assembly of claim 1, wherein said first fluid
backfiller is comprised of a valve.
9. The fluid-elastomeric damper assembly of claim 1, wherein said first fluid
chamber is comprised of a first chamber housing wall, said first chamber housing wall
segregating said first fluid chamber from said fluid-elastomeric chamber, and said
first fluid backfiller is comprised of a valve.
10. The fluid-elastomeric damper assembly of claim 1, said first fluid chamber
comprised of a first chamber housing wall, said first chamber housing wall
segregating said first fluid chamber from said fluid-elastomeric chamber, said first
chamber housing wall defining a fluid communication opening and said first fluid
backfiller including a first valve proximate said first chamber housing wall fluid
communication opening,
said second fluid chamber comprised of a second chamber housing wall, said second
chamber housing wall segregating said second fluid chamber from said fluid-
elastomeric chamber, said second chamber housing wall defining a second fluid
communication opening and said second fluid backfiller is comprised of a second
valve proximate said second chamber housing wall second fluid communication
opening, wherein a relative motion of said piston opens said first valve and closes said
second valve.
11. The fluid-elastomeric damper assembly of claim 7, wherein said third fluid
backfiller includes a third valve and said fourth fluid backfiller includes a fourth
valve.
12. The fluid-elastomeric damper assembly of claim 1, wherein said fluid outside
said at least one fluid moving piston and contained in said fluid-elastomeric chamber
has an operational ambient fluid pressure PA, and said fluid inside said at least one
fluid moving piston has an operational dynamic fluid pressure PD when pumped by
said at least one fluid moving piston with PD ≥ 1.01PA.
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13. A method for damping a relative motion between a first structure and a second
structure, the method comprising: providing a housing; coupling a plurality of
elastomeric seals to the housing, wherein the housing and the plurality of elastomeric
seals provide a fluid-elastomeric chamber for containing a fluid; disposing a fluid
within the fluid-elastomeric chamber; disposing an internal fluid pump with at least
one fluid moving piston within the fluid-elastomeric chamber, the internal fluid pump
comprising a first fluid chamber and a second fluid chamber in communication via at
least one orifice, said first fluid chamber including a first fluid backfiller and said
second fluid chamber including a second fluid backfiller, said first fluid chamber and
said second fluid chamber in communication with the fluid-elastomeric chamber,
wherein said relative motion between said first structure and said second structure
drives said at least one fluid moving piston to pump said fluid through said at least
one orifice with said first fluid backfiller providing fluid communication of said fluid
from said fluid-elastomeric chamber into said first fluid chamber and inhibiting a flow
of said fluid from said first fluid chamber into said fluid-elastomeric chamber and said
second fluid backfiller providing fluid communication of said fluid from said fluid-
elastomeric chamber into said second fluid chamber and inhibiting a flow of said fluid
from said second fluid chamber into said fluid-elastomeric chamber .
14. A method as claimed in claim 13, wherein said internal pumping mechanism
includes a second fluid moving piston, with said second fluid moving piston forcing
said fluid through a second restriction orifice between a third fluid chamber and a
fourth fluid chamber; said third fluid chamber including a third fluid backfiller, said
third fluid backfiller providing fluid communication of said fluid from said fluid-
elastomeric chamber into said third fluid chamber and inhibiting a flow of said fluid
from said third fluid chamber into said fluid-elastomeric chamber, said fourth fluid
chamber including a fourth fluid backfiller, said fourth fluid backfiller providing fluid
communication of said fluid from said fluid-elastomeric chamber into said fourth
fluid chamber and inhibiting a flow of said fluid from said fourth fluid chamber into
said fluid-elastomeric chamber and said relative motion between said first structure
and said second structure is operable for pumping the fluid through said second
restriction orifice.
15. A method as claimed in claim 13 said first fluid backfiller including a first
valve,
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said second fluid backfiller including a second valve, wherein a movement of said
piston opens said first valve and closes said second valve.
16. A method as claimed in claim 13 wherein disposing a fluid within the fluid-
elastomeric chamber includes providing a damper fluid with a viscosity in the range
from 30 to 5,000 centistokes.
17. A method as claimed in claim 14 said first fluid backfiller including a first
valve,
said second fluid backfiller including a second valve, said third fluid backfiller
including a third valve, said fourth fluid backfiller including a fourth valve wherein a
movement of said at least one piston opens said first valve and closes said second
valve, and a movement of said second piston opens said third valve and closes said
fourth valve.
18. A method as claimed in claim 13, wherein said fluid outside said at least one
fluid moving piston and contained in said fluid-elastomeric chamber has an
operational ambient fluid pressure PA, and said fluid inside said internal fluid pump
has an operational dynamic fluid pressure PD when pumped by said at least one fluid
moving piston with PD > 1.01PA.
19. A method of making a fluid-elastomeric damper assembly for damping a
relative motion between a first structure and a second structure, the method
comprising: coupling a plurality of elastomeric seals to a housing, wherein the
housing and the plurality of elastomeric seals provide a fluid-elastomeric chamber for
containing a damper fluid; disposing an internal fluid pump with at least one fluid
moving piston within the fluid-elastomeric chamber, disposing a damper fluid within
the fluid-elastomeric chamber wherein the internal fluid pump comprises a first fluid
chamber and a second fluid chamber in communication via at least one orifice, said
first fluid chamber including a first fluid backfiller and said second fluid chamber
including a second fluid backfiller, said first fluid chamber and said second fluid
chamber in communication with the fluid-elastomeric chamber, wherein said relative
motion between said first structure and said second structure drives said at least one
fluid moving piston to pump said fluid through said at least one orifice with said first
fluid backfiller providing fluid communication of said fluid from said fluid-
elastomeric chamber into said first fluid chamber and inhibiting a flow of said fluid
from said first fluid chamber into said fluid-elastomeric chamber and said second
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fluid backfiller providing fluid communication of said fluid from said fluid-
elastomeric chamber into said second fluid chamber and inhibiting a flow of said fluid
from said second fluid chamber into said fluid-elastomeric chamber.
20. A method as claimed in claim 19, wherein said internal pumping mechanism
includes a second fluid moving piston, with said second fluid moving piston forcing
said fluid through a second restriction orifice between a third fluid chamber and a
fourth fluid chamber; said third fluid chamber including a third fluid backfiller, said
third fluid backfiller providing fluid communication of said fluid from said fluid-
elastomeric chamber into said third fluid chamber and inhibiting a flow of said fluid
from said third fluid chamber into said fluid-elastomeric chamber, said fourth fluid
chamber including a fourth fluid backfiller, said fourth fluid backfiller providing fluid
communication of said fluid from said fluid-elastomeric chamber into said fourth
fluid chamber and inhibiting a flow of said fluid from said fourth fluid chamber into
said fluid-elastomeric chamber and said relative motion between said first structure
and said second structure is operable for pumping the fluid through said second
restriction orifice .
21. A method as claimed in claim 19 said first fluid backfiller including a first
valve,
said second fluid backfiller including a second valve, wherein a relative motion of
said piston in a first direction with the first fluid chamber volume increasing and the
second fluid chamber volume decreasing opens said first valve and closes said second
valve.
22. A method as claimed in claim 19 wherein disposing a fluid within the fluid-
elastomeric chamber includes providing a damper fluid with a viscosity in the range
from 30 to 5,000 centistokes.
23. A method as claimed in claim 20 said first fluid backfiller including a first
valve,
said second fluid backfiller including a second valve, said third fluid backfiller
including a third valve, said fourth fluid backfiller including a fourth valve wherein a
relative motion of said at least one piston opens said first valve and closes said second
valve, and a relative motion of said second piston opens said third valve and closes
said fourth valve.
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34
24. A method as claimed in claim 19, wherein said fluid outside said at least one
fluid moving piston and contained in said fluid-elastomeric chamber has an
operational fluid pressure PA, and said fluid inside said at least one fluid moving
piston has an operational dynamic fluid pressure PD when pumped by said at least
one fluid moving piston with PD ≥ 1.01 PA.
25. A method for damping relative motion between a first structure and a second
structure, the method comprising: providing a housing structure, coupling a plurality
of elastomer seals to the housing structure, wherein the housing structure and the
plurality of elastomer seals define a fluid-elastomeric chamber, disposing a damper
fluid within the fluid-elastomeric chamber, disposing a piston pump within the fluid-
elastomeric chamber, wherein the piston pump comprises a first fluid-filled variable
volume chamber and a second fluid-filled variable volume chamber in communication
via an orifice, the first fluid-filled chamber and the second fluid-filled chamber also in
communication with the fluid-elastomeric chamber, wherein the relative motion
between the first structure and the second structure is operable for driving the piston
pump and pumping the fluid through the orifice, with the fluid outside said piston
pump and contained in said fluid-elastomeric chamber having an operational ambient
fluid pressure PA, and said fluid inside said piston pump having an operational
dynamic fluid pressure PD when pumped by said piston pump with PD ≥ 1.01 PA.

A fluid-elastomeric damper assembly (10) operable for damping relative motion
between a first structure (20) and a second structure (22) including a housing structure
(24) grounded to the first structure (20) and a plurality of elastomer seals (12,16)
coupled to the housing structure, the housing structure and the plurality of elastomer
seals defining a fluid-elastomeric chamber (40) operable for containing a fluid. The
fluid-elastomeric damper assembly also including one or more piston structures (80)
disposed within the housing structure and the fluid-elastomeric chamber, the one or
more piston structures grounded to the first structure and driven by the second
structure, and the one or more piston structures each including a first fluid chamber
and a second fluid chamber in communication via an orifice, the first substantially fluid-
filled chamber and the second substantially fluid filled chamber also in communication
with the fluid-elastomeric chamber through a fluid backfiller (500). The relative motion
is operable for plumping the fluid (72) through the orifice (86). The fluid-elastomeric
damper assembly preferably controls movement/vibration in the lead-lag direction of
the rotor of a rotary-wing aircraft.