Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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CONTROLLABLE VEHICLE SUSPENSION SYSTEM
WITH MAGNETO-RHEOLOGICAL FLUID DEVICE
Cross Reference
This application claims the benefit of, and incorporates by reference,
United States Patent Application Number 11/742,911 filed May 1, 2007, and
United States Provisional Patent Application Number 60/984212 filed
October 31, 2007.
Field of the Invention
The invention relates to the field of suspension systems for controlling
motion. The invention relates to the field of controllable systems for
controlling motion and providing support. The invention relates to the field
of
controllable vehicle systems for controlling vehicle motions. More
particularly,
the invention relates to vehicle cab suspensions with controllable magneto-
rheological fluid device having beneficial motion control.
Background of the Invention
Magneto-rheological fluid devices such as magneto-rheological fluid
dampers and struts are useful in controlling or damping motion in suspension
systems such as vehicle suspension systems. A typical magneto-rheological
fluid damper includes a damper body with a sliding piston rod received
therein. The damper body includes a reservoir that is filled with magneto-
rheological fluid, i.e., non-colloidal suspension of micron-sized magnetizable
particles. One or more seals are used to retain the magneto-rheological fluid
within the reservoir as the piston rod reciprocates within the damper body.
The damping characteristics are controlled by applying a magnetic field to the
magneto-rheological fluid. A magneto-rheological fluid strut combines a
magneto-rheological fluid damper function with the ability to support loads.
There is a need for controllable magneto-rheological fluid devices for
supporting a load while providing motion control and vibration isolation.
There
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is a need for vehicle cab magneto-rheological fluid devices for isolating
vibrations and cab motions. There is a need for controllable magneto-
rheological fluid devices which accurately and economically control and
minimize vibrations. There is a need for an economically feasible method of
making motion control magneto-rheological fluid devices and vehicle
suspension systems. There is a need for a robust suspension system and
magneto-rheological fluid devices for isolating troublesome vibrations and
controlling vehicle motions. There is a need for an economic suspension
system providing beneficial controlled motion and vibration isolation.
Summary of the Invention
In one aspect, a controllable suspension system for controlling the
relative motion between a first body and a second body includes at least one
strut. The at least one strut includes a magneto-rheological fluid damper
which comprises: a damper body; a piston rod guide disposed within the
damper body, the piston rod guide having a passage therein for receiving a
piston rod; a piston rod bearing assembly disposed in the piston rod guide to
engage with and support reciprocal motion of the piston rod; at least a first
piston rod seal and at least a second piston rod seal arranged to seal
between the piston rod guide and the piston rod; a fluid chamber defined
between the piston rod guide and the piston rod; and a piston rod guide gas
charged accumulator arranged between the piston rod and the damper body.
In another aspect, a controllable suspension system for controlling the
relative motion between a first body and a second body comprises: a damper
body; a spring longitudinally aligned with the damper body; a piston rod guide
disposed within the damper body, the piston rod guide having a passage
therein for receiving a piston rod; a piston rod bearing assembly disposed in
the piston rod guide to engage with and support reciprocal motion of the
piston rod; at least a first piston rod seal and at least a second piston rod
seal
arranged to seal between the piston rod guide and the piston rod; a fluid
chamber defined between the piston rod guide and the piston rod; and a
piston rod guide gas charged accumulator arranged between the piston rod
and the damper body.
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In another aspect, a controllable suspension system for controlling the
relative motion between a first body and a second body includes at least one
strut. The at least one strut includes a magneto-rheological fluid damper
which comprises: a damper body; a piston rod guide disposed within the
damper body, the piston rod guide having a passage therein for receiving a
piston rod; a piston rod bearing assembly disposed in the piston rod guide to
engage with and support reciprocal motion of the piston rod; at least a first
piston rod seal and at least a second piston rod seal arranged to seal
between the piston rod guide and the piston rod; a fluid chamber defined
between the piston rod guide and the piston rod; means for filtering fluid
entering the fluid chamber; and a piston rod guide gas charged accumulator
arranged between the piston rod and the damper body.
In another aspect, a method of making a controllable suspension
system for controlling the relative motion between a first body and a second
body comprises: providing a damper body having a reservoir for containing
the magneto-rheological fluid; providing a piston rod; providing a piston rod
guide disposed within the damper body, the piston rod guide having a
passage therein for receiving the piston rod; providing a piston rod assembly
coupled to the piston rod guide and arranged to engage and support
reciprocal motion of the piston rod; providing at least a first piston rod
seal
and at least a piston rod seal arranged to seal between the piston rod guide
and the piston rod; providing a fluid chamber defined between the piston rod
guide and the piston rod; providing a piston rod guide filter arranged in a
communication path between the fluid chamber and the reservoir to filter
particulates out of fluid entering the fluid chamber; and providing an
accumulator arranged between the piston rod guide and the damper body.
In another aspect, a controllable suspension system for controlling the
relative motion between a first body and a second body includes at least one
magneto-rheological fluid damper. The at least one magneto-rheological fluid
damper comprises: a damper body; a piston rod guide disposed within the
damper body, the piston rod guide having a passage therein for receiving a
piston rod; a piston rod bearing assembly disposed in the piston rod guide to
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engage with and support reciprocal motion of the piston rod; at least a first
piston rod seal and at least a second piston rod seal arranged to seal
between the piston rod guide and the piston rod; and a piston rod guide gas
charged accumulator arranged between the piston rod and the damper body.
The magneto-rheological fluid damper includes a reservoir for a magneto-
rheological fluid provided within the damper body and a piston rod guide
filter
arranged in a communication path between the fluid chamber and the
reservoir to filter particulates out of the magneto-rheological fluid entering
the
fluid chamber from the reservoir.
In another aspect, a vehicle suspension system for controlling the
relative motion between a first body and a second body comprises: a damper
body; a spring longitudinally aligned with the damper body; a piston rod guide
disposed within the damper body, the piston rod guide having a passage
therein for receiving a piston rod; a piston rod bearing assembly disposed in
the piston rod guide to engage with and support reciprocal motion of the
piston rod; at least a first piston rod seal and at least a second piston rod
seal
arranged to seal between the piston rod guide and the piston rod; a fluid
chamber defined between the piston rod guide and the piston rod; a piston
rod guide gas charged accumulator, said piston rod guide gas charged
accumulator arranged between the piston rod and the damper body; and a
piston rod guide filter.
In another aspect, a method of controlling motion between a first body
and a second body comprises: providing a magneto-rheological damper fluid
comprised of a plurality of magnetic particulates in a carrier fluid;
providing a
damper body having a reservoir for containing the magneto-rheological fluid;
providing a piston rod; providing a piston rod guide disposed within the
damper body, the piston rod guide having a passage therein for receiving the
piston rod; providing a piston rod assembly coupled to the piston rod guide
and arranged to engage and support reciprocal motion of the piston rod;
providing at an outer piston rod seal arranged to seal against the piston rod;
providing a piston rod guide accumulator arranged between the piston rod
and the damper body; and inhibiting the magnetic particulates from the
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magneto-rheological fluid in the reservoir from reaching the outer piston rod
seal.
Brief Description of the Drawinas
The accompanying drawings, described below, illustrate typical
embodiments of the invention and are not to be considered limiting of the
scope of the invention, for the invention may admit to other equally effective
embodiments. The figures are not necessarily to scale, and certain features
and certain view of the figures may be shown exaggerated in scale or in
schematic in the interest of clarity and conciseness.
FIG. 1 is a side view of a vehicle with a controllable suspension system
including magneto-rheological fluid struts.
FIG. 2A is a side view of a tractor with a controllable suspension
system including magneto-rheological fluid struts.
FIG. 2B is an end view of the tractor shown in FIG. 2A.
FIG. 3 is a diagram of a controllable suspension system including
magneto-rheological fluid struts.
FIG. 4A is a side view of a magneto-rheological fluid strut including a
magneto-rheological fluid damper.
FIG. 4B is an enlarged view of a portion of the magneto-rheological
fluid strut shown in FIG. 4A.
FIG. 4C is another side view of the magneto-rheological fluid strut
shown in FIG. 4A.
FIG. 4D is an end view of the magneto-rheological fluid strut shown in
FIG. 4A.
FIG. 5 is a perspective view of a magneto-rheological fluid strut.
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FIG. 6A is a side view of the magneto-rheological fluid strut shown in
FIG. 5.
FIG. 6B is another side view of the magneto-rheological fluid strut
shown in FIG. 5.
FIG. 6C is an end view of the magneto-rheological fluid strut shown in
FIG. 5.
FIG. 6D is an end view of the magneto-rheological fluid strut shown in
FIG. 5.
FIG. 6E is a side view of the magneto-rheological fluid strut shown in
FIG. 5.
FIG. 6F is a cross-section of the magneto-rheological fluid strut shown
in FIG. 6E.
FIG. 6G illustrates the relationship between piston rod bearing seal
interface, bearing gap, piston head fluid flow interface, piston gap, and
stroke
length for the magneto-rheological fluid strut shown in FIG. 6F.
FIG. 6H is an enlarged view of a portion of the cross-section shown in
FIG. 6G.
FIG. 61 is an enlarged view of a portion of a magneto-rheological fluid
damper depicted in FIG. 6G, depicting an upper piston rod bearing assembly.
FIG. 6J is a perspective view of a head portion of the magneto-
rheological fluid strut of FIG. 6G.
FIG. 6K is a perspective view of an end portion of the magneto-
rheological fluid damper in the magneto-rheological fluid strut of FIG. 6G.
FIG. 6L is a perspective view of an electromagnetic coil included in the
piston head of the magneto-rheological fluid damper of FIG. 6G.
FIG. 6M is a cross-section of the electromagnetic coil shown in FIG.
6L.
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FIG. 6N is a perspective view of two overmolded EM coils.
FIG. 7A is an enlarged view of a piston head portion of the magneto-
rheological fluid damper shown in FIG. 6G.
FIG. 7B is a perspective view of an overmolded EM coil.
FIGS. 7C through 7N are end, side, and cross-sectional views of
portions or components of an overmolded EM coil.
FIG. 8 shows an arrangement of magneto-rheological fluid struts in a
suspension system.
FIG. 9 is a cross-section of an EM coil.
FIG. 10 is a cross-section of a magneto-rheological fluid strut.
FIG. 11 is a perspective view of a magneto-rheological fluid damper.
FIGS. 12 and 13 depict vertical cross-section views of the magneto-
rheological fluid damper of FIG. 11.
FIGS. 14-16 depict a partial cross-section of the magneto-rheological
fluid damper of FIG. 11.
FIG. 17 is a schematic illustration of a vehicle with a suspension
system including magneto-rheological fluid dampers.
Detailed Description
The invention will now be described in detail with reference to a few
preferred embodiments, as illustrated in the accompanying drawings. In
describing the preferred embodiments, numerous specific details are set forth
in order to provide a thorough understanding of the invention. However, it
will
be apparent to one skilled in the art that the invention may be practiced
without some or all of these specific details. In other instances, well-known
features and/or process steps have not been described in detail so as not to
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unnecessarily obscure the invention. In addition, like or identical reference
numerals are used to identify common or similar elements.
In an embodiment the invention includes a controllable suspension
system for controlling the relative motion between a first body and a second
body. Referring to FIGS. 1-10, and particularly to FIGS. 1-3, a controllable
suspension system 20 controls the relative motion between a first body 22
and a second body 24. In preferred embodiments the controllable suspension
system 20 is a vehicle controllable suspension system 20, most preferably as
shown in FIGS. 1-3 a cab suspension controllable suspension system 20, with
the suspension system controlling motion between the vehicle cab body 22
and the vehicle frame body 24. In alternative embodiments the controllable
suspension system 20 is a non-vehicle suspension system, preferably a
stationary suspension system.
The controllable suspension system 20 includes at least one magneto-
rheological fluid strut (30 in FIGS. 1-6N). Referring to FIG. 3, the
controllable
suspension system strut 30 includes a single-ended magneto-rheological fluid
damper 32, preferably a cantilevered single-ended magneto-rheological fluid
damper. As more clearly shown in FIG. 6F, the magneto-rheological fluid
damper 32 includes a longitudinal damper tubular housing 34 having a
longitudinally extending axis 36. The longitudinal damper tubular housing 34
has an inner wall 38 for containing a magneto-rheological fluid 40 within the
tubular housing 34. Preferably the longitudinal damper tubular housing 34 is
comprised of a magnetic metal material, preferably a magnetic low carbon
steel as compared with a nonmagnetic metal material such as stainless steel.
Preferably the magneto-rheological fluid 40 is a magneto-rheological damper
fluid with the fluid containing iron particles wherein the rheology of the
damper
fluid changes from a free flowing liquid to a flow resistant semi-solid with
controllable yield strength when exposed to a magnetic field, such as the
LORD MR fluids available from LORD Corporation, Cary, N.C.
Referring to FIG. 6G, the magneto-rheological fluid damper 32 includes
a cantilevered damper piston 42, the damper piston 42 including a piston
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head 44 movable within the damper tubular housing 34 along a longitudinal
length of the tubular housing axis 36. The damper piston head 44 provides a
first upper variable volume magnetorheological fluid chamber 46 and a
second lower variable volume magnetorheological fluid chamber 48. The
damper piston head 44 has a fluid flow gap 50 between the first upper
variable volume magnetorheological fluid chamber 46 and the second lower
variable volume magnetorheological fluid chamber 48 with a piston head fluid
flow interface length HL, with the fluid flow gap 50 between the piston head
44
and inner wall surface 38 of the tubular housing 34 with a piston gap Pgap
between the OD of the piston head 44 and the ID of the inner wall 38. The
damper piston 42 includes a longitudinal cantilevered piston rod 52 for
supporting the piston head 44 within the longitudinal damper tubular housing
34.
The damper piston 42 is supported within the longitudinal damper
tubular housing 34 with an upper piston rod bearing assembly 54 disposed
between the longitudinal damper tubular housing 34 and the longitudinal
piston rod 52. The piston rod bearing assembly 54 has a piston rod bearing
seal interface length BL with BL>HL and contact between the piston head 44
and the damper tubular housing inner wall 38 is inhibited. Preferably the
bearing assembly 54 has a minimal bearing gap Bgap between the bearings
56 and the OD of the piston rod 52. As shown in FIG. 6G, preferably
[Pgap/(HL+Stroke)] is greater than (Bgap/BL). Preferably the piston head 44
is a wear-band-free piston head, with the fluid flow gap 50 maintained
between piston head sides OD and tubular housing inner wall ID with no wear
band or seal on the piston between piston head 44 OD and inner wall 38 ID.
In embodiments such as shown in FIG. 6L-6N, axially aligned coil guides 95
are preferably utilized to maintain fluid flow gap 50 and inhibit contact
between the piston head 44 and the housing wall 38. Preferably the axially
aligned coil guides 95 are aligned with axis 36, and preferably substantially
equally spaced around the outside perimeter of EM coil 94, preferably with at
least three coil guides 95, more preferably at least four guides, more
preferably at least five guides , and more preferably at least six guides
spaced
around the OD of EM coil 94, preferably with the guides 95 occupying less
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than 15% of the perimeter of the EM coil, and more preferably no greater than
10% of the perimeter of the EM coil. Preferably the guides 95 are a
nonmagnetic material, preferably a polymer, preferably with the guides 95
comprised of injection pressurized polymer 110 with the guides molded
integral and simultaneously with their adjacent bobbin polymer overmold 110
that is pressure injected into a overmold 106, with the nonmagnetic polymer
guides and overmold polymer 110 encompassing and covering the underlying
wound EM coil wiring 102. Preferably the axially aligned guides 95 axially
extend over the adjacent magnetic poles 96 in FIG. 6L. Referring again to
FIG. 6G, the cantilevered damper piston 42 preferably minimizes the off state
resistance of the damper with a minimized parasitic drag and resistance.
Preferably the cantilevered damper piston 42 off state energy dissipation is
minimized by substantially inhibiting contact between piston head 44 and
housing wall 38 while maintaining the predetermined fluid flow gap 50 and the
gap width Pgap, preferably while not utilizing a piston wear band or piston
seal that encircles the piston perimeter.
Preferably the piston 42 has a constant bearing length in that the piston
head 44 has no substantial bearing contact with the housing inner wall 38,
with the cantilevered piston 42 providing a single ended damper 32 as
compared to a double-ended damper. Preferably the rod 52 terminates with
the piston head 44, with the piston head unconnected to the housing 34
except for the single bearing assembly 54. Preferably the rod 52 and the
piston head 44 are unconnected to the lower housing end 58 distal from the
piston rod bearing 54 and the upper housing end 60. Preferably the only
mechanical connection of the piston head 44 is with the single piston rod 52
extending to the upper bearing assembly 54, with rod 52 terminating with the
piston head 44, with no contact of piston head 44 with housing inner side
walls 38 or the lower damper end 58 distal from the upper damper end 60 with
the bearing 54. In embodiments contact of piston head 44 is inhibited with
minimized perimeter occupying axially aligned guides 95. Preferably the
piston head 44 is free of internal fluid flow conduits, preferably with
substantially all fluid flow between the piston head 44 and housing 34 through
the fluid flow gap 50, preferably with the fluid flow gap maintained with
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assistance of guides 95 which assist in ensuring that substantial contact
between the piston head 44, particularly the magnetic poles (96 in FIGS. 6L-
6N), and the housing inner side walls 38 is inhibited.
Preferably the magnetorheological fluid damper 32 includes an upper
volume compensator 62. The magnetorheological fluid damper volume
compensator 62 preferably is proximate the piston rod bearing assembly 54.
Preferably the volume compensator 62 is adjacent the upper piston rod
bearing 54. Preferably the bearing holder support structure housing 55 and
the volume compensator housing are integrated together to provide an upper
bearing gas charged compliance member. Preferably the gas compliance
volume compensator 62 is in fluid communication with the first upper variable
volume magnetorheological fluid chamber 46, with the volume compensator
proximate the upper bearings 56 and the piston rod 52, preferably with upper
fluid chamber 46 and volume compensator 62 in use in the suspension
system 20 oriented on top relative to the force of gravity to allow gas bubble
migration into volume compensator 62. Preferably the damper 32
configuration provides for a dry assembly process with the
magnetorheological fluid filled into the damper after the piston 42 is
assembled into the housing 34, and preferably then gas pressure charging of
gas compliance volume compensator 62.
Preferably the strut 30 includes a longitudinal air gas spring 64, with
the longitudinal gas spring 64 aligned with the longitudinal damper tubular
housing longitudinally extending axis 36. Preferably the strut 30 includes the
strut air spring 64 and the magneto-rheological fluid damper 32 aligned with
the common center axis 36 and packaged together with the gas spring 64
encompassing the damper 32, with the upper end of the damper including the
piston rod 52, substantially housed within the gas spring 64. Preferably the
upper end of the strut 30 includes an upper strut end head member 66 (also
shown in FIG. 6J) for attachment to the uppermost first body 22. Referring to
FIGS. 6G and 6J, preferably the upper strut end head member 66 includes an
electrical power input 68 and an air compressed gas input 70. Preferably the
upper strut end head member 66 has an internal head cavity housing that
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includes a strut control system 72 with an electronic control circuit board
74,
gas spring air sleeve leveling valve 76, and preferably also includes a high
speed electrical communications connection 78, such as a CAN-Bus, for
receiving outside the strut signals in addition to electrical power input 68.
Preferably the upper strut end head member 66 includes a strut sensor
system 80, preferably the upper sensor head end of the magneto-strictive
longitudinal sensor 80 that is aligned with the piston rod 52 and axis 36 and
housed within the piston rod the 52. Preferably the piston rod 52 is comprised
of a nonmagnetic material, preferably a nonmagnetic metal such as stainless
steel, wherein the inner housed magneto-strictive longitudinal sensor 80
provides for sensing the stroke position of the piston along the stroke length
of
the damper. Preferably the upper strut end member housing 66 includes the
strut control system with sensors inputs, sensors, current supply, and also
the
pneumatic leveling valve to control leveling of the gas spring 64 in addition
to
controlling the magnetorheological fluid damper 32.
Referring again to FIG. 6G, preferably the upper piston rod bearing
assembly 54 includes a bearing holder support structure 55 which receives a
first upper bearing 56 and a distal second lower bearing 56 to provide the
piston rod bearing seal interface length BL. Preferably the bearing holder
support structure 55 receives a bearing seal 53 between the lower bearing 56
and the upper fluid chamber 46. Preferably the upper piston rod bearing
assembly 54 includes the bearing holder support structure 55 which receives
the at least first bearing 56 and includes compliance member cavity 82 for
receiving a volume compensator gas compliance member 84, preferably with
the gas compliance member flexible fluid gas partition diaphragm 84 flexibly
fixed to the support structure 55 allowing expansion and contraction of the
gas
filled diaphragm cavity to compensate for magnetorheological fluid volume
changes, preferably with the gas compliance member flexible elastomer fluid
gas partition diaphragm 84 radially expandable between the support structure
55 and the housing 34. Preferably the upper piston rod bearing assembly 54
includes the bearing holder support structure 55 which receives the at least
first bearing 56 and includes a sensor target magnet holder 86 which receives
a target magnet 88 for the magnetostrictive sensor 80 in the non-magnetic
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piston rod 52. Preferably the upper volume compensator 62 is vertically
oriented relative to gravity in operation of the suspension system with the
volume compensator proximate the piston rod bearing.
Preferably volume compensator 62 is adjacent the upper piston rod
bearing assembly 54, preferably with the bearing holder support structure 55
and volume compensator housing cavity 82 integrated to provide an upper
damper rod bearing gas charged compliance member. Preferably the rod
bearing gas charged compliance member support structure 55 includes a gas
compliance charging conduit 90 for filling the cavity 82 with a pressurized
gas,
preferably after the piston has been assembled into the housing and bearing
and the damper has been filled with the magnetorheological fluid. Preferably
the volume compensator 62 is in fluid communication with the adjacent
damper fluid chamber 46 through a plurality of fluid volume compensating
conduits (92 in FIG. 6K) between the housing 34 and the piston rod 52, which
allow flow of fluid into and out of the volume compensator, preferably with
the
conduits 92 providing for greater flow than the piston head gap 50, preferably
a relatively high flow into and out compared to piston head flow, with
relatively
low resistance to flow into the volume compensator such that it is not
dynamically isolated from the rest of the working magnetorheological fluid.
Referring to FIGS. 7A-7N, the piston head 44 includes the
electromagnetic coil 94 and an upper and lower magnetic pole 96 for
controlling the flow of magneto-rheological fluid 40 between the upper and
lower chambers 46 and 48, preferably with the electromagnetic coil 94
comprised of an electrically insulated encapsulant injected pressurized
polymer overmolded electromagnetic magnetorheological fluid coil 94. The
preferred modular component injected pressurized polymer overmolded
electromagnetic magneto-rheological fluid coil 94 is shown in FIG. 7B.
Preferably the EM coil insulated wire (102 in FIGS. 7C, 7H-7N) is wound on a
non-magnetic plastic bobbin (104 in FIGS. 7C, 7G-71), with the coiled wire 102
on the bobbin 104 pressure overmolded with an injected pressurized non-
magnetic polymer (110 in FIGS. 7C, 7D, 71) in a pressurized injection
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overmold 106 under an applied pressure 107. Preferably the pressurized
injection overmolded EM coil 94 includes a first and second wire pins 108 for
connection with a current supply wire circuit 100. Preferably the modular
component pressurized injection overmolded EM coil 94 is sandwiched
between upper and lower magnetic metal poles 96, to provide the current
controllable EM coil piston head 44, with the modular component pressurized
injection overmolded EM coil 94 overmolded EM coil and poles 96 sized to
provide the predetermined gap 50 with the housing inner wall 38, with the
pressurized injection overmolded EM coil magnetic field controlling
magnetorheological fluid flow proximate the piston head EM coil, with
preferred embodiments molded with axially aligned guides 95 as shown in
FIG. 7L-7N. FIG. 6N show two overmolded EM coils with molded guides 95
placed head to head to illustrate how the guides 95 extend beyond the coil top
and bottom sides such that they will overlap the adjacent magnetic poles
when assembled into the piston head, with the guides equally spaced around
the EM coil outer perimeter in a piston axially centering pattern centered and
aligned with the longitudinal extending axis 36 of damper 32.
Referring again to FIG. 3, preferably the controllable suspension
system 20 includes a first strut 30 and at least a second cantilevered
magnetorheological fluid damper strut 32 between the first body (22 in FIGS.
1, 2A, 2B) and the second body (24 in FIGS. 1, 2A, 2B), preferably with both
struts 30 having outer encompassing air spring sleeves 64. Preferably the
controllable suspension system 20 includes a third cantilevered
magnetorheological fluid damper strut 30 between the first body and the
second body. In one embodiment, at least two of the more than one struts 30
operate independently with their own self contained sensor and control
systems in their strut head member housing 66, preferably with no master
control signals communicating between the at least two struts from a
suspension system master controller. In one embodiment, the struts 30 are
self-contained, self-controlled struts that house their own control systems,
preferably with only electrical power and compressed gas supplied from a
master suspension system source, such as a vehicle battery electrical power
system and a compressed air system. In a preferred embodiment with the
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more than one strut 30 operating, preferably such as with four struts, a first
master controlling strut 30" controls a second controlled dependent strut 30'
with master control signals communicating between the at least two struts 30"
and 30', such as with the master strut 30" that sends controls to the other
dependent strut 30" in addition to its own control.
In a preferred embodiment the suspension system 20 is a cab
suspension system with two back cab struts 30 and the front of the vehicle
cab is mounted without such controllable cantilevered magnetorheological
fluid damper struts 30, such as hard mount or mounted with noncontrolled
elastomer mounts. In a preferred cab suspension system 20 embodiment
with two rear back cab struts 30 and the front of the vehicle cab is mounted
without such controllable cantilevered magnetorheological fluid damper struts
30, the struts 30 are self controlled and autonomous with each having its own
circuit board control system, with the strut control system sharing and
communicating its sensor data, such as its processed accelerometer
information, with each other through the electrical communication connection
78 link to control roll of the cab body. In preferred embodiments the
controllable magnetorheological fluid damper struts 30 are self controlled and
autonomous with each having its own circuit board control system 72 housed
in its upper strut end head member 66, with the struts control system sharing
its sensor data through its electrical communication connection 78 to control
a
motion of the cab relative to the frame, such as to control roll, or with a
four
point strut suspension controlling roll and pitch of the cab with the four
self
controlled sensor data sharing struts 30. In a preferred embodiment, as
illustrated in FIG. 8, at least three struts 30 provide for a three point cab
suspension system for control of roll and pitch, preferably with three
independent self-controlled struts 30, 30, and 30' and one dependent strut
30".
In an embodiment the invention includes a controllable damper for
controlling motion. The controllable damper 32 provides for the controlling or
relative motion between a first body 22 and a second body 24, preferably with
the damper controlling motion in a vehicle, most preferably in a suspension
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system 20 between a vehicle frame and the vehicles cab. In alternative
embodiments the damper 32 provides for controlling motion in non-vehicle
stationary suspensions. The controllable damper 32 includes a longitudinal
damper tubular housing 34 having a longitudinally extending axis 36. The
longitudinal damper tubular housing 34 has an inner wall 38 for containing a
magnetorheological fluid 40 within the tubular housing, with the damper
housing having an upper damper end 60 and a lower damper end 58. The
controllable damper 32 includes a cantilevered single ended damper piston
42. The damper piston 42 includes a piston head 44 movable within the
damper tubular housing 34 along a longitudinal stroke length of the tubular
housing, with the damper piston head 44 providing a first upper variable
volume magnetorheological fluid chamber 46 and a second lower variable
volume magnetorheological fluid chamber 48. The damper piston head 44
has a fluid flow gap 50 between the first upper variable volume
magnetorheological fluid chamber 46 and the second lower variable volume
magnetorheological fluid chamber 48 with a piston head fluid flow interface
length HL, preferably with the gap 50 having a width Pgap between the piston
head OD and inner surface ID of the tubular housing 34. The damper piston
42 has a longitudinal piston rod 52 for supporting the piston head 44 within
the longitudinal damper tubular housing 34. Preferably the cantilevered piston
rod 52 is the only mechanical support for supporting the piston head within
the
damper housing with a bearing. The piston 42 is supported within the
longitudinal damper tubular housing with an upper piston rod bearing
assembly 54 disposed between the longitudinal damper tubular housing 34
and the longitudinal piston rod 52. The piston rod bearing assembly 54 having
a piston rod bearing seal interface length BL, wherein contact between the
piston head 44 and the damper tubular housing inner wall 38 is inhibited.
Preferably the piston head 44 is a wearbandfree piston head, with the
magnetorheological fluid flow gap width Pgap maintained between piston
head OD sides and tubular housing inner wall with no wear band or seal on
the piston head or between the piston OD sides and the inner wall. Preferably
the damper 32 minimizes off state resistance a minimized parasitic drag and
resistance. Preferably the off state energy dissipation of damper 32 when no
controlling current is supplied to the piston head EM coil 94 is minimized by
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inhibiting contact between the piston head and housing wall while maintaining
the predetermined magnetorheological fluid flow gap cylindrical shell of
length
HL and thickness Pgap. Preferably the piston 42 has a constant bearing
length BL in that the piston head 44 has no bearing contact with the housing
inner wall 38. Preferably the damper 32 is a single ended damper as
compared to a double ended damper, preferably with the rod 52 terminating
with the piston head 44, with the piston head otherwise unconnected to the
housing and the lower housing end 58 distal from the piston rod bearing 54,
preferably with the only mechanical connection of the piston head 44 with the
single piston rod extending to the upper bearing assembly, with the rod
terminating in the piston head. Preferably the piston head 44 is free of
internal fluid flow conduits inside the piston head OD, preferably with
substantially all fluid flow of the magnetorheological fluid 40 between the
piston head and the housing through the magnetorheological fluid flow gap
50. Preferably the controllable damper 32 cantilevered piston length BL is
greater than the piston head cylindrical shell gap length HL.
Preferably the controllable magnetorheological fluid damper 32
includes an upper damper volume compensator 62. The volume
compensator 62 is proximate the piston rod bearing assembly 54. Preferably
the gas compliance volume compensator 62 is adjacent the upper piston rod
bearing 54, preferably with the bearing holder support structure 55 and the
volume compensator housing cavity 82 integrated into an upper bearing gas
charged compliance member. Preferably the gas compliance volume
compensator 62 is in fluid communication with the first upper variable volume
magnetorheological fluid chamber 46, with the volume compensator
proximate the upper bearing and the piston rod, preferably with upper fluid
chamber 46 and volume compensator 62 in use oriented on top of lower fluid
chamber 48 relative to the force of gravity to allow gas bubble migration
upward into volume compensator 62. Preferably the damper 32 provides for a
dry assembly process with magnetorheological fluid filled after the piston 42
is
assembled in the housing 34, preferably through a lower housing end opening
59, then gas pressure charging of the gas compliance volume compensator
62 through an upper end conduit 90. Preferably the piston rod bearing
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assembly bearing holder support structure 55 includes fluid flow conduits 92
to allow flow of fluid into and out of the volume compensator, preferably with
conduits 92 providing for greater flow than the magnetorheological piston
head gap 50, preferably with relatively high flow into and out of the volume
compensator as compared to piston head flow, with relatively low resistance
to flow into volume compensator.
Preferably the controllable magnetorheological fluid damper 32
includes an upper strut end head member 66 with an electrical power input
68. Preferably the upper strut end head member houses the damper control
system 72 with electronic control circuit board 74. In a preferred embodiment
the power input is included with a multiple wire array connector 78, such as a
CAN bus electrical connector 78, preferably with the multiple wire electrical
connection providing for receiving outside the strut damper control signals in
addition to electrical power input that generates the magnetorheological fluid
controllable magnetic field. Preferably the upper strut end head member
houses the damper control sensor system, preferably including the upper
head end of the magneto-strictive longitudinal sensor 80 that is aligned axis
36 and housed within the piston rod 52. Preferably the upper strut end head
member housing includes the control system for also controlling leveling with
the gas spring with a leveling valve 76 for controlling pneumatic leveling of
the
strut 30. Preferably the strut and damper with the upper strut end head
member 66 is an intelligent self-contained damper system with the head
member containing the electronics control system circuit boards 74 that
receives sensor inputs such as from the magnetostrictive sensor 80 and
accelerometers 120, and controls the electrical current supplied to the piston
head EM coil 94 through the current supply wire circuit 100 to control the
damper 32, preferably with the control electronics including accelerometer
sensors 120, preferably an at least one accelerometer axis acceleration
sensed, preferably with a first accelerometer axis 122 aligned with the damper
axis 36 (shown in FIG. 10). Preferably the accelerometer sensor 120 is an at
least two axis accelerometer, and most preferably a three axis accelerometer,
with the first axis 122 aligned with the damper axis 36, the second and third
axis normal to the damper axis 36.
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Preferably the controllable magnetorheological fluid damper upper
piston rod bearing assembly 54 includes a bearing holder support structure 55
which receives a first upper bearing 56, a distal second lower bearing 56, and
a piston rod seal 53 to provide the piston rod bearing seal interface length
BL.
Preferably the controllable magnetorheological fluid damper upper piston rod
bearing assembly 54 includes bearing holder 55 which receives at least first
bearing 56 and a compliance member cavity 82 for receiving a volume
compensator gas compliance member 84. Preferably the controllable
magnetorheological fluid damper upper piston rod bearing assembly 54
includes bearing holder 55 which receives at least first bearing 56 and a
sensor target magnet holder 86 which receives a target magnet 88 for
producing a sensor signal in the proximate magnetostrictive sensor 80 in the
non-magnetic piston rod 52, to provide a sensed measurement of the location
of the target magnet along the length of sensor 80 to provide a measurement
of the stroke position of the piston head in the damper housing that is used
as
an input into the damper electronic control system.
Preferably the controllable magnetorheological fluid damper piston
head 42 includes an insulating encapsulant injected pressurized polymer
overmolded electromagnetic coil 94, with the piston head, overmolded
electromagnetic coil and magnetic poles ODs sized to provide the
predetermined gap Pgap with the housing inner wall ID, with the gap 50
maintained to inhibit contact with the wall 38 and to provide the fluid flow
gap
50 with the coil 94 producing a magnetic field for controlling
magnetorheological fluid flow through the gap. The controllable piston head
electromagnetic coil 94, upper and lower magnetic poles 96 with a variable
applied current producing a controlling magnetic field for controlling the
flow of
magnetorheological fluid 40 between the upper and lower chambers 46 and
48, with the electromagnetic coil 94 comprised of an electrically insulated
injected pressurized polymer overmolded electromagnetic magnetorheological
fluid coil 94. The preferred modular component injected pressurized polymer
overmolded electromagnetic magnetorheological fluid coil 94 is shown in
FIG.7A-71. Preferably the EM coil insulated wire 102 is wound on the non-
magnetic plastic bobbin 104, with the coiled wire 102 on the bobbin 104
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pressure overmolded with the injected pressurized polymer 110 in the
pressurized injection overmold 106 under an applied pressure 107.
Preferably the pressurized injection overmolded EM coil 94 includes first and
second wire pins 108 for connection with a current supply wire circuit 100
that
supplies the controlling current output by the control system. Preferably the
modular component pressurized injection overmolded EM coil 94 is
sandwiched between the upper and lower magnetic metal poles 96, to provide
the current controllable EM coil piston head 44, with the modular component
pressurized injection overmolded EM coil 94 overmolded EM coil and poles
96 sized to provide the predetermined gap 50 with the housing inner wall 38,
with the pressurized injection overmolded EM coil magnetic field controlling
magnetorheological fluid flow proximate the piston head EM coil.
In an embodiment the invention includes a method of making a
controllable suspension system for controlling the relative motion between a
first body and a second body. Preferably the invention provides a method of
making a controllable vehicle suspension system for controlling the relative
motion between a first vehicle body and a second vehicle body, most
preferably a method of making a vehicle cab suspensions for controlling the
motion between a first body cab 22 and a second body frame 24. The
method includes providing the longitudinal damper tubular housing having a
longitudinally extending axis, the longitudinal damper tubular housing 34
having inner wall 38 for containing a magnetorheological fluid within the
tubular housing. The provided longitudinal damper tubular housing 34 has a
first upper end 60 and a second distal lower end 58, with the housing
centered about axis 36. The method includes providing piston rod bearing
assembly 54 having piston rod bearing seal interface length BL for supporting
damper piston 42 within the longitudinal damper tubular housing 34. The
method includes providing cantilevered damper piston 42 including piston
head 44 and longitudinal piston rod 52. Cantilever piston rod 52 supports the
piston head 44 within the longitudinal damper tubular housing, with the upper
piston rod bearing assembly 54 disposed between the longitudinal damper
tubular housing and the longitudinal piston rod. The method includes
disposing the piston rod bearing assembly 54 in the longitudinal damper
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tubular housing 34 proximate the first upper end 60. The method includes
receiving the damper piston longitudinal piston rod 53 in the piston rod
bearing assembly 54, wherein the piston head 44 is movable within the
damper tubular housing along the longitudinal length of the tubular housing,
with the damper piston head providing a first upper variable volume
magnetorheological fluid chamber 46 and a second lower variable volume
magnetorheological fluid chamber 48, the damper piston head having a fluid
flow gap 50 between the first upper variable volume magnetorheological fluid
chamber and the second lower variable volume magnetorheological fluid
chamber with a piston head fluid flow interface length HL with contact
between the piston head and the damper tubular housing inner wall inhibited.
The method includes providing magnetorheological damper fluid 40 and
disposing the magnetorheological damper fluid 40 in the damper tubular
housing 34. The damper provides for controlling the relative motion between
the first body 22 and the second body 24. Preferably the method includes
providing the longitudinal air strut gas spring 64, and aligning the
longitudinal
strut gas spring with the longitudinal damper tubular housing longitudinally
extending axis 36 with the strut air spring and magnetorheological damper
aligned and packaged together with the gas spring encompassing the
magnetorheological damper, preferably with the upper end 60 and the piston
rod 52 substantially housed within the gas spring 64, preferably with the
upper
end of strut including the upper strut end head member 66 for attachment to
the uppermost first or second body. Preferably the upper strut end head
member 66 includes the electrical power input and the compressed air gas
input, along with the strut control system with electronic control circuit
boards
74, gas spring air sleeve leveling valve 76. In preferred embodiments the
upper strut end head member 66 includes the CAN-Bus electrical connection
for receiving outside the strut control signals in addition to electrical
power
input into the strut. In preferred embodiments the upper strut end head
member 66 includes the damper sensor system with the end of magneto-
strictive longitudinal sensor 80 that is aligned and housed within the piston
rod. Preferably the piston rod bearing assembly 54 is provided with the piston
rod bearing seal interface length BL greater than the HL. Preferably the upper
volume compensator 62 is provided and disposed proximate the piston rod
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bearing assembly 54. Preferably the upper piston rod bearing assembly
includes the bearing holder which receives the first upper bearing and the
distal second lower bearing to provide the piston rod bearing seal interface
length BL. Preferably the upper piston rod bearing assembly includes the
bearing holder which receives the at least first bearing and includes the
compliance member cavity for receiving the volume compensator gas
compliance member. Preferably the upper piston rod bearing assembly
includes the bearing holder which receives the at least first bearing and has
the sensor target magnet holder which receives the target magnet for the
magnetostrictive sensor in the non-magnetic piston rod. Preferably the
magnetorheological fluid damper includes the upper volume compensator,
with the volume compensator proximate the piston rod bearing. Preferably at
least a first cantilevered magnetorheological fluid damper, and at least a
second cantilevered magnetorheological fluid damper are disposed between
the first body and the second body. Preferably the at least a third
cantilevered
magnetorheological fluid damper is disposed between the first body and the
second body.
Preferably the invention includes the method of making the controllable
damper for controlling motion. Preferably the method includes providing the
longitudinal damper tubular housing having the longitudinally extending axis,
the longitudinal damper tubular housing having the inner wall for containing
the magnetorheological fluid within the tubular housing, the longitudinal
damper tubular housing having the first upper end and the second distal lower
end. The method includes providing the piston rod bearing assembly, the
piston rod bearing assembly having the piston rod bearing seal interface
length BL for supporting the damper piston within the longitudinal damper
tubular housing. The method includes providing the cantilevered damper
piston, the damper piston including the piston head and the longitudinal
piston
rod for supporting the piston head within the longitudinal damper tubular
housing. The method includes disposing the piston rod bearing assembly in
the longitudinal damper tubular housing proximate the first upper end. The
method includes receiving the damper piston longitudinal piston rod in the
piston rod bearing assembly, wherein the piston head is movable within the
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damper tubular housing along the longitudinal length of the tubular housing,
with the damper piston head providing the first upper variable volume
magnetorheological fluid chamber and the second lower variable volume
magnetorheological fluid chamber, the damper piston head having the fluid
flow gap between the first upper variable volume magnetorheological fluid
chamber and the second lower variable volume magnetorheological fluid
chamber with the piston head fluid flow interface length HL , with HL< BL and
contact between the piston head and the damper tubular housing inner wall
inhibited. Preferably the method includes providing the upper volume
compensator, and disposing the volume compensator proximate the piston
rod bearing assembly. Preferably the method includes providing the upper
strut end head member with the electrical power input and disposing the strut
end head member proximate the damper tubular housing first end. Preferably
the method includes providing the upper piston rod bearing assembly with the
bearing holder support structure which receives the first upper bearing and
the distal second lower bearing to provide the piston rod bearing seal
interface length BL. Preferably the method includes providing the upper
piston rod bearing assembly with the bearing holder support structure which
receives at least the first bearing and includes the compliance member cavity
for receiving the volume compensator gas compliance member. Preferably
the method includes providing the upper piston rod bearing assembly with the
bearing holder support structure which receives at least the first bearing and
includes the sensor target magnet holder which receives the target magnet.
Preferably the method includes providing the piston head with the injected
pressurized polymer overmolded electromagnetic coil.
In an embodiment the invention includes a method of making a
controllable damper for controlling motion. The method includes providing a
longitudinal damper tubular housing 34 having a longitudinally extending axis
36. The provided longitudinal damper tubular housing 34 has an inner wall 38
for containing a magnetorheological fluid 40 within the tubular housing. The
longitudinal damper tubular housing 34 has a first upper end 60 and a second
distal lower end 58. The method includes providing a piston rod bearing
assembly 54, the piston rod bearing assembly having a piston rod bearing
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seal interface length BL for supporting a damper piston 42 within the
longitudinal damper tubular housing 34. The method includes providing a
damper piston 42, the damper piston including a magnetorheological fluid
piston head 44 and a longitudinal piston rod 52 for supporting the piston head
within the longitudinal damper tubular housing 34. The magnetorheological
fluid piston head 44 includes an insulating injected pressurized polymer
overmolded electromagnetic magnetorheological fluid coil 94. The
controllable magnetorheological fluid damper piston insulating encapsulant
injected pressurized polymer overmolded electromagnetic coil 94 and
magnetic poles 96 preferably having ODs sized to provide the predetermined
gap 50 Pgap with the housing inner wall ID, with the gap 50 maintained to
inhibit contact with the wall 38 and to provide the fluid flow gap 50 with the
coil
94 producing a magnetic field for controlling magnetorheological fluid flow
through the gap. The controllable piston head electromagnetic coil 94, upper
and lower magnetic poles 96 with a variable applied current producing a
controlling magnetic field for controlling the flow of magnetorheological
fluid
40 between the upper and lower chambers 46 and 48, with the
electromagnetic coil 94 comprised of the modular component electrically
insulated injected pressurized polymer overmolded electromagnetic
magnetorheological fluid coil 94. The preferred modular component injected
pressurized polymer overmolded electromagnetic magnetorheological fluid
coil 94 is shown in FIG.7A-71. Preferably the EM coil insulated wire 102 is
wound on the non-magnetic plastic polymer bobbin 104, with the coiled wire
102 on the bobbin 104 pressure overmolded with the injected pressurized
polymer 110 in the pressurized injection overmold 106 under an applied
pressure 107. Preferably the non-magnetic plastic polymer bobbin 104 and
the injected pressurized polymer 110 are comprised of substantially the same
base polymer, in a preferred embodiment the bobbin 104 and the pressurized
injection overmold polymer 110 are comprised of nylon. In a preferred
embodiment the bobbin 104 is comprised of a glass filled nylon and the
pressurized injection overmold polymer 110 is comprised of a nylon,
preferably a non-glass-filled nylon. In a preferred embodiment the bobbin 104
and the overmold polymer 110 are comprised of a common polymer,
preferably with the common polymer comprised of a nylon. Preferably the
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pressurized injection overmolded EM coil 94 includes first and second wire
pins 108 for connection with a current supply wire circuit 100 that supplies
the
controlling current outputted by the damper control system. Preferably the
modular component pressurized injection overmolded EM coil 94 is
sandwiched between the upper and lower magnetic metal poles 96, to provide
the current controllable EM coil piston head 44. The modular component
pressurized injection overmolded EM coil 94 overmolded EM coil and poles
96 provide a magnetic field for controlling magnetorheological fluid flow
proximate the piston head EM coil. The method includes disposing the piston
rod bearing assembly 54 in the longitudinal damper tubular housing 34
proximate the first upper end 60. The method includes receiving the damper
piston longitudinal piston rod 52 in the piston rod bearing assembly 54,
wherein the magnetorheological fluid piston head 44 is movable within the
damper tubular housing along the longitudinal stroke length of the tubular
housing and the axis 36, with the damper piston head 44 providing first upper
variable volume magnetorheological fluid chamber 46, second lower variable
volume magnetorheological fluid chamber 48, and the fluid flow gap between
the first upper variable volume magnetorheological fluid chamber and the
second lower variable volume magnetorheological fluid chamber. The
method includes providing a magnetorheological damper fluid 40 and
disposing the magnetorheological damper fluid 40 in the damper tubular
housing 34 wherein a current supplied to the injected pressurized polymer
overmolded electromagnetic magnetorheological fluid coil 94 controls the flow
of the magnetorheological damper fluid 40 proximate the injected pressurized
polymer overmolded electromagnetic magnetorheological fluid coil 94. The
method includes injection molding a polymer 110 with a positive pressure into
a overmold 106 containing the wire wrapped electromagnetic coil
nonmagnetic plastic bobbin 104 to provide the plastic modular injected
pressurized polymer overmolded electromagnetic magnetorheological fluid
coil 94 for assembly into the piston head 44. Preferably the EM coil insulated
wire 102 is wound on a non-magnetic plastic bobbin 104 with the coiled wire
and bobbin pressure overmolded with an injected pressurized polymer 110 in
a predetermined sized cavity overmold 106 under pressure. Preferably the
overmolded EM coil 94 includes first and second wire pins 108 for connection
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with a current supply circuit 100. Preferably the modular component EM coil
94 is sized and shaped to be sandwiched between upper and lower magnetic
metal poles 96. Preferably the wire 102 is wound on non-magnetic plastic
bobbin 104, and then placed in coil overmold 106, with insulating injected
pressurized polymer nylon polymer 110 overmolded around the bobbin and
wire. Preferably the piston head 44 and its overmolded EM coil 94 and poles
96 are sized to provide predetermined gap 50 with the housing inner wall 38,
with the EM coil magnetic field controlling fluid flow 40 proximate the piston
head EM coil 94. Preferably the damper overmolded EM coil 94 in damper 32
provides for controlling the relative motion between first body 22 and the
second body 24, preferably with the damper 32 providing a controllable strut
30. Preferably the damper overmolded EM coil 94 is utilized in the making of
single ended dampers 32 as compared to double ended dampers, preferably
with the rod 52 terminating with the piston head 44 that contains the coil 94.
Preferably the piston head 44 is free of internal fluid flow conduits,
preferably
substantially all fluid flow is between piston head and housing through the
magnetorheological fluid flow gap proximate the EM coil OD, preferably with
the piston 42 having a constant bearing length with the piston head 44 having
no bearing contact with the housing inner wall 38. In alternative preferred
embodiments the piston head 44 has a wear band and contact with the
housing wall 38. Preferably the method includes providing upper volume
compensator 62, and disposing the volume compensator 62 proximate the
piston rod bearing assembly 54. Preferably the volume compensator 62 is
adjacent the upper piston rod bearing 54, preferably with the bearing holder
support structure and volume compensator housing integrated into an upper
bearing gas charged compliance member. Preferably the gas compliance
volume compensator 62 is in fluid communication with the first upper variable
volume magnetorheological fluid chamber 46, with the volume compensator
proximate the upper bearing 56 and the piston rod 52, preferably with the
upper fluid chamber 46 and volume compensator 62 in use oriented on the
top end of the damper relative to the force of gravity. Preferably the damper
components provide for dry assembly of the damper piston in the housing with
magnetorheological fluid 40 disposed into the damper after the piston is
assembled into the housing, and then gas pressure charging of gas
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compliance volume compensator 62. Preferably the piston rod bearing
assembly bearing holder support structure 55 includes fluid flow conduits 92
to allow flow of fluid 40 into and out of the volume compensator 62,
preferably
with the conduits providing for greater flow than the magnetorheological
piston
head gap 50. Preferably the method includes providing upper strut end head
member 66 with an electrical power input 68 and disposing the strut end head
member 66 proximate the damper tubular housing first end 60, with the head
member providing the controlling current to the EM coil 94 through circuit
100.
Preferably the strut end head member 66 includes the control system 72 with
electronic control circuit boards 74, preferably also including CAN-Bus
electrical connection 78 for receiving outside the strut control signals in
addition to electrical power input 68. Preferably the head member 66 includes
a damper sensor system, preferably with the end of the magneto-strictive
longitudinal sensor 80 that is aligned and housed within the piston rod 52.
Preferably the upper strut end head member housing 66 includes the control
system of the magnetorheological damper 32 and the gas spring 64 for
controlling pneumatic leveling of the strut. Preferably the damper is an
intelligent self-contained damper system with the head member 66 containing
the electronics control system that receives sensor inputs and control the
electrical current supplied to the EM coil in the piston head to control the
damper, preferably with control electronics including accelerometer sensors
120, preferably with a 2-axis alignment oriented with the axis 36. Preferably
the upper strut end head member housing cavity 66 houses the electronic
control sensor system circuit board or boards 74, preferably with the circuit
board plane in alignment with the damper longitudinal axis 36 so the circuit
board 74 is substantially vertically oriented in use with a lower end and an
upper end, with the circuit board having a first accelerometer 120 and a
second accelerometer 120 normal to the first, preferably with first
accelerometer sensing axis 122 in alignment with the damper longitudinal axis
36 and the second accelerometer sensing axis 122 oriented perpendicular
thereto. Preferably the provided upper piston rod bearing assembly 54
includes bearing holder support structure 55 which receives first upper
bearing 56 and distal second lower bearing 56 to provide the piston rod
bearing seal interface length BL. Preferably the upper piston rod bearing
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assembly 54 includes a bearing holder support structure 55 which receives at
least a first bearing 56 and includes a compliance member cavity 82 for a
volume compensator gas compliance member 84. Preferably the upper
piston rod bearing assembly 54 includes a bearing holder support structure 55
which receives at least a first bearing 56 and includes a sensor target magnet
holder 86 which receives a target magnet 88 for the magnetostrictive sensor
80 in the non-magnetic piston rod 52. Preferably the damper is dry
assembled, then filled with magnetorheological fluid 40, then closed and
sealed, preferably through the second lower end 58, preferably with a lower
end stopper member which closes off and seal the damper and provides a
lower end attachment member for attaching to the lower moving body 22,24.
Preferably the piston rod 52 is hollow with an inner longitudinal chamber
which includes a longitudinal magnetostrictive sensor 80, preferably with the
piston rod nonmagnetic such that the permanent magnet target 88 produces a
magnetic field sensed along the length of the sensor 80 and detected by the
sensor head end preferably in the upper strut end head member 66.
Preferably the piston rod inner longitudinal chamber includes the current
supply connection circuit 100, preferably insulated wires providing
connections from the current source in upper strut end head member down
through rod and connected to the overmolded EM coil pins 108. Preferably
the lower end of the piston rod inner longitudinal chamber is sealed off,
preferably with a sealing member 98 between the lower rod end and piston
head, preferably integrated with the rod and piston head attachment joint.
Preferably the overmolded EM coil 94 includes an inner overmolded core
receiving chamber 112, overmolded to receive a ferromagnetic core member
114, preferably with the magnetic metal core member 114 that is received in
the inner overmolded core receiving chamber including an extending pole
member 116 that extends out of the receiving chamber 112, preferably having
an OD substantially matching the OD of the overmolded coil and the OD of
the piston head, with the extending pole member 116 providing the upper
magnetic pole member 96 of the piston head 44. Preferably the OD of the
piston head and the overmolded coil are sized to provide the piston gap Pgap
between the OD and the damper tubular housing inner wall ID. Preferably the
overmolded coil includes the coil guides 95, preferably with the guides
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extending longitudinally along the axis 36 such that they extend over the
magnetic pole members 96, with the guides 95 extending radially outward
from the OD into the piston gap Pgap towards the damper tubular housing
inner wall ID.
Preferably the received core member 114 includes an inner core center
chamber 118 centered inside the core and extending pole member OD, the
inner core center chamber 118 receiving the lower piston rod end and
preferably the overmolded coil wire pin connectors 108, preferably with the
sealing member 98 between the lower rod end and overmolded coil 94,
preferably with the inner core center chamber and the lower piston rod end
having mating attachment means, preferably such as matching threads for
attaching the piston rod 52 with the piston head 44. Preferably the
overmolded EM coil 94 includes a longitudinal center axis hub member 124
with the EM coil wire pins 108 and a radially extending wire coil connecting
arm structure spokes (126 in FIG. 9) which provides a containment structure
for the coil connection wire leads leading from the longitudinal extending
wire
pins 108 radially outward to the wound coil on the bobbin, and the received
core member 114 includes lower end arm receiving radially extending
channels 115 for receiving the extending wire coil connecting arms structure
126 including the overmold encapsulated radially extending wire leads.
Preferably the overmolded coil includes the coil guides 95 centered around
the axis 36 and extending longitudinally along the axis 36 such that they
extend partially over an adjacent part of the magnetic pole members 96
proximate the overmolded coil, with the guides 95 extending radially outward
from the OD into the piston gap Pgap towards the damper tubular housing
inner wall ID, with the guide radial height from the OD sized to the piston
gap
dimension Pgap.
FIG. 11 depicts a magneto-rheological fluid damper 200 according to
another embodiment of the invention. In the magneto-rheological fluid strut
described above, the magneto-rheological fluid damper 200 may replace the
previously-described magneto-rheological fluid damper (32 in FIGS. 1-10).
Alternatively, the magneto-rheological fluid damper 200 may be used alone to
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control motion in a suspension system. For example, the magneto-
rheological fluid damper 200 may be connected between the body and wheel
of a vehicle, in a manner similar to that depicted for the magneto-rheological
fluid strut (30 in FIGS. 1-3), as illustrated in FIG. 12. The vehicle may be a
land vehicle or any other type of vehicle. The magneto-rheological fluid
damper may be used in a primary vehicle suspension system or in a
secondary vehicle suspension system of a vehicle, such as for the suspension
system for the vehicle cab or the vehicle seat. Altematively, the magneto-
rheological fluid damper may be used in a semi-active system not coupled to
a vehicle. In a primary suspension system, the magneto-rheological fluid
damper would be positioned between the tire and chassis of the vehicle.
The magneto-rheological fluid damper 200 includes a damper body
202. In this example, the damper body 202 is made of several parts,
including a cylinder part 202a and end caps 202b, 202c. However, these
parts may be integrated to form a unitary body in alternate embodiments. The
end caps 202b, 202c are coupled to distal ends of the cylinder part 202a. The
cylinder part 202a is preferably a hydraulic cylinder. The cylinder part 202a
contains a reservoir of magneto-rheological fluid (not shown) and a piston
(not
shown). The piston is coupled to a piston rod 214, which extends through the
end cap 202b. The piston rod 214 extends through the end cap 202b and
includes a rod end 203 for coupling to a frame or other devices.
In FIGS. 12 and 13, the magneto-rheological fluid damper 200 includes
a damper body 202. As in the case of the magneto-rheological fluid damper
(32 in FIG. 6F), in a strut assembly, the longitudinal axis of the damper body
202 would be aligned with a strut spring, such as the longitudinal axis gas
spring (64 in FIG. 6F). The damper body 202 has a hollow interior 204 in
which a piston rod guide 206 is arranged. The damper body 202 may be
made of a magnetic metal material, preferably a low magnetic metal material
such as carbon steel. The magneto-rheological fluid damper 200 may be a
monotube damper having a single reservoir 208, defined below the piston rod
guide 206, for containing a magneto-rheological fluid, with the single
reservoir
208 being divided by a piston 215 into a first variable volume magneto-
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rheological fluid damper chamber 208a and a second variable volume
magneto-rheological fluid damper chamber 208b with at least one EM coil
controllable magneto-rheological fluid flow conduit 213 between the first and
second chambers for controlling the fluid flow (controllable current supplied
to
EM coil 219 produces controllable magnetic field strength for a controllable
yield strength of the magneto-rheological fluid). The magneto-rheological
fluid
contains micron-sized magnetizable particles in a carrier fluid. Such
magneto-rheological fluid is available from, for example, Lord Corporation,
Cary, NC. In one example, the magneto-rheological fluid contains iron
particles and is such that the rheology of the fluid changes from a free
flowing
liquid to a flow resistant semi-solid with controllable yield strength when
exposed to a magnetic field. In one example, the magneto-rheological fluid
contains magnetizable particles having a mean particle size of about 1
micron.
FIGS. 14-16 show an enlargement of an end portion of the magneto-
rheological fluid damper 200. In comparison to the magneto-rheological fluid
damper 32 in FIG. 6G, this would be the end portion including the upper
piston rod bearing assembly (54 in FIG. 6G). The remaining portions of the
magneto-rheological fluid damper 200 not shown may be the same as
depicted in FIGS. 12 and 13, or may be as shown for the magneto-rheological
fluid damper 32 in FIG. 6G.
Referring to FIG. 14, the piston rod guide 206 has an annular body 210
with a passage 212 for receiving the piston rod 214. In an embodiment the
piston rod 214 is made of a nonmagnetic material, such as stainless steel. A
position sensor 216 is housed within the piston rod 214. In one example, the
position sensor 216 is a magnetostrictive sensor which senses stroke position
of the piston along the stroke length of the damper. The position sensor 216
may communicate with an external control system or may include an internal
control system. A magnetic field generator 217 may be provided proximate
the piston rod 214 to create a magnetic field around the position sensor 216.
The magnetic field generator 217 in one example may be a permanent
magnet, which may be in the form of a ring circumscribing the piston rod 214
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or position sensor 216. Alternatively, the magnetic field generator 217 may be
an electromagnetic coil that is supplied with current to generate a magnetic
field for the position sensor 216.
The annular body 210 includes an inner annular recess 218 circumscribing
the passage 212 for receiving the piston rod 214. A filtering media 220, which
may be annular in shape, is disposed within the annular recess 218. The
magnetic field generator 217 described above may be included in the filtering
media 220, for example, arranged in a pocket or otherwise supported on or in
the filtering media 220. In one example, the filtering media 220 is made of a
porous non-magnetic, corrosion-resistant material. In one example, the
porous filtering media 220 has pore size less than or equal to 250 nm. In one
example, the porous filtering media 220 is made of porous stainless steel
having pore size less than or equal to 250 nm. The filtering media 220
includes a pocket 222 inside of which is disposed an inner piston rod seal
224. The annular body 210 includes a pocket 226 inside of which is disposed
an outer piston rod seal 228. The inner and outer piston rod seals 224, 228
are arranged to engage the wall of the piston rod 214, thereby forming inner
and outer seals between the piston rod guide 206 (or annular body 210) and
the piston rod 214. The seals 224, 228 may be made of suitable sealing
materials such as elastomeric materials.
The filtering media 220 may include a pocket 230 for receiving a piston
rod bearing assembly 232. When the piston rod 214 is received in the
passage 212, the piston rod bearing 232 is arranged between the piston rod
214 and the filtering media 220. Further, the piston rod bearing 232 engages
with and supports reciprocal motion of the piston rod 214. Any suitable piston
rod bearing 232 capable of supporting reciprocal motion of the piston rod 214
may be used. For example, Glacier Garlock DU or DP-4 bearings, available
from AHR International, may be used. These bearings offer a smooth low
friction bearing surface and are self-lubricating. The permanent magnet 217
or other suitable magnetic field generating component may be placed above
the piston rod bearing 232, as shown in FIG. 14, or may be placed between
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the piston rod bearing 232 and the inner seal 224, as shown in FIG. 15 and
16.
A fluid chamber 234 is formed between the filtering media 220, the
inner piston rod seal 224, the piston rod bearing 232, and the piston rod 214.
The fluid chamber 234 is in communication with the reservoir 208 containing
the magneto-rheological fluid. Preferably in operation, magneto-rheological
fluid enters the inner annular recess 218 through ports 236 in the base of the
piston rod guide 106 and flows through the filtering media 220 into the
filtered
fluid chamber 234. That is, the filtering media 220 is disposed in a
communication path between the reservoir 108 and the fluid chamber 234.
The filtering media 220 strains or filters out the magnetizable particles in
the
magneto-rheological fluid and allows the filtered carrier fluid to enter the
fluid
chamber 234. In a preferred embodiment, the permanent magnet 217 is
mounted at an end of the filtering media 220 to collect magnetic particle dust
left unfiltered by the filtering media 220, preferably providing magnetic
filtering
of magnetic particles thereby ensuring that the outer piston rod seal 228 is
exposed to only filtered non-particulate clear carrier fluid. Protecting the
outer
seal 228 from particulates prolongs the useful life of the seal. In a
preferred
embodiment, the filtering media 220 inhibits the migration of magnetic
particles from the inner piston rod seal 224 to the outer seal 228, with the
outer seal filtered non-particulate clear carrier fluid having less than one
percent of the magnetizable (iron) particle fraction of the magneto-
rheological
fluid contacting the inner piston rod seal 224. The filtering media 220
preferably provides a static charge pressure between the two seals 224, 228,
and preferably provides that the inner seal 224 is only exposed to fluid
dynamic pressure and that the outer seal 228 is only exposed to static
pressure. By exposing the outer seal 228 to only static fluid pressure, air
ingestion into the reservoir 108 is prevented.
The annular body 210 of the piston rod guide 206 further includes an
outer annular recess 238. A diaphragm or bladder 240 is mounted in the
outer annular recess 238 and abuts an inner wall 242 of the damper body 202
of the damper body 202. The diaphragm 240 defines an air-volume which
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functions as an accumulator 242. In use, the accumulator 244 is charged with
an inert gas such as nitrogen. Although not shown, a port may be provided in
the inner wall 242 of the damper body 202 or in the annular body 210 through
which gas can be supplied into the accumulator 244. The diaphragm 240 is
exposed to the magneto-rheological fluid in the reservoir 208 through a gap
between the annular body 210 of the piston rod guide 206 and the inner wall
242 of the damper body 202. The accumulator 242 serves to minimize
pressure transients in the magneto-rheological fluid in the reservoir 208,
thereby minimizing the risk of cavitation or negative pressure. Thus, the
accumulator 244 minimizes pressure transients while the porous filter media
220 filters out pressure transients from the outer piston rod seal 228. The
combined effect is low charge pressures, e.g., on the order of 200 to 300
psig,
without risk of air ingestion and with minimal risk of cavitation. Preferably
the
piston rod guide 206 includes and houses an accumulator, preferably a gas
charged accumulator.
FIG. 16 shows an alternative example of the magneto-rheological fluid
damper 200. In this example, the annular body 210 of the piston rod guide
206 includes inner annular recesses 260, 262, which hold inner piston rod
seal 224 and outer piston rod seal 228, respectively. This embodiment
includes the piston rod guide 206 with a gas charged accumulator. A fluid
conduit or passage 264 extends from the base of the annular body 210 and
terminates in an inner surface 266 of the annular body 210 adjacent to the
piston rod 214. A filtering media 266, having properties described for the
filtering media 220 (FIGS. 14 and 15) above, is disposed in the passage 264
to filter magnetizable particles from fluid entering the fluid chamber 234
defined between the piston rod 214, the inner surface 216 of the annular body
210, and the seals 224, 228. In this example, the annular body 210 includes
an outer annular recess 268 which is open at the outer surface 270 of the
annular body 210. The outer surface 270 of the annular body 210 abuts the
inner wall 242 of the damper body 202, thereby defining a chamber 272,
which serves as an accumulator. A piston 274 is disposed in the chamber
272 and can slide within the chamber 272 in response to pressure differential
across it. The piston 274 includes sealing members 276, which engage an
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inner wall 278 of the annular body 210 and the inner wall 242 of the damper
body 202, thereby partitioning the chamber 272 into a gas chamber 278 and a
magneto-rheological fluid chamber 280. The gas chamber 278 may be filled
with an inert gas such as nitrogen. Although not shown, a port may be
provided in the damper body 202 or annular body 210 through which gas can
be supplied to the gas chamber 278. The magneto-rheological fluid chamber
280 is in communication with the reservoir 208 through a gap between the
base of the annular body 210 and the inner wall 242 of the damper body 202
or through ports in the base of the annular body 210. The accumulator
provided by the chamber 272 and piston 274 serves the same purpose as
described for the accumulator 244 (FIGS. 14 and 15) above. Preferably the
piston rod guides include and house a gas charged accumulator, preferably
between the piston rod 214 and the damper body 202, and preferably
proximate the seal 224.
FIG. 17 depicts an exemplary vehicle 314 with magneto-rheological
fluid dampers 200 between the body 310 and the wheels 312 of the vehicle.
The magneto-rheological fluid dampers 200 are in communication with a
suspension control system 316 including a control unit 318. In one example,
the control unit 318 receives sensor signals from sensors, which may reside in
the dampers 200, on the vehicle 314 and calculates forces at the dampers
200. These desired force values are converted and amplified into current,
e.g., via closed loop current control, to the dampers 200. In one example, the
sensors (not shown) are accelerometers, and the control unit 318 receives
signals from the accelerometers and uses those signals to calculate forces at
the dampers 200. In a preferred embodiment, five or six accelerometers are
arranged in different locations and orientations in the vehicle in order to
provide the sensor signals to the control unit 318. In another example, the
sensors include accelerometers and roll-rate sensors, and the control unit 318
receives signals from the accelerometers and roll-rate sensors and uses
those signals to calculate forces at the dampers 200. In a preferred
embodiment, three accelerometers and two roll-rate sensors are arranged in
different locations in the vehicle in order to provide the sensor signals to
the
control unit 318. The vehicle 314 in preferred embodiments is a land vehicle,
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preferably a wheeled land vehicle which preferably transports variable
payloads over varied land conditions, such as a truck or off-road vehicle, as
shown in FIG. 17, or may be another type of vehicle. In preferred
embodiments the magneto-rheological fluid dampers are primary vehicle
suspension magneto-rheological fluid dampers in the primary suspension of
the vehicle between the vehicle body 310 and the wheels 312. In alternative
embodiments the magneto-rheological fluid dampers are secondary vehicle
suspension magneto-rheological fluid dampers in the secondary suspension
systems of vehicles, such as for the suspension system for the vehicle cab or
the vehicle seat. Alternatively, the magneto-rheological fluid dampers 200
may be used in a semi-active suspension system that is not coupled to a
vehicle.
It will be apparent to those skilled in the art that various modifications
and variations can be made to the invention without departing from the spirit
and scope of the invention. Thus, it is intended that the invention cover the
modifications and variations of this invention provided they come within the
scope of the appended claims and their equivalents. It is intended that the
scope of differing terms or phrases in the claims may be fulfilled by the same
or different structure(s) or step(s).
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