Note: Descriptions are shown in the official language in which they were submitted.
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COMPOSITE MATERIAL SPRING MODULES WITH
INTEGRALLY FORMED ATTACHMENT FITTINGS
FIELD OF THE INVENTION
The present invention pertains generally to plastic composite
material springs for use as flexible elements in weight bearing
structures, and more particularly for use in flexible human weight
bearing structures such as bedding and seating and furniture.
BACKGROUND OF THE INVENTION
Springs for use as flexible support elements in support
structures such as seating and bedding and furniture have
traditionally and conventionally been constructed of spring steel and
wire. See, for example, U.S. Patent Nos. 188,636; 488,378; 1,887,058;
4,535,978; 4,339,834; 5,558,315. Attempts have been made to construct
spring support elements out of plastic material. See, for example
U.S. Patent Nos. 4,530,490; 4,736,932; 5,165,125 and 5,265,291.
Although fiber reinforced plastic springs are fairly well-developed,
the use thereof in flexible support structures such as seating,
furniture and bedding presents the formidable engineering challenge of
providing suitable means for attachment of the springs to a frame
structure and an overlying support surface. Plastic springs have
heretofore been simply mechanically attached to a supporting structure
such as described in U.S. Patent No. 4,411,159 on a fiber reinforced
plastic leaf spring for a vehicle. Any type of mechanical attachment
is complicated by the extreme hardness and stiffness of fiber
reinforced plastics. Ultimately it is nearly always necessary to
drill attachment holes in the spring for a mechanical fastener (such
as described in U.S. Patent No. 4,736,932) requiring additional
manufacturing and assembly steps. Also, drilling through the fiber-
reinforced structure breaks the preferred long strand/roving fibers
which are critical to providing optimal spring characteristics. The
related application discloses clips for attachment of mattress
foundation springs to a frame and an overlying grid. Although fully
operative and novel, this approach requires additional parts and
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increased assembly tasks, and does not entirely overcome the negatives
of possible slippage between the spring and the clips, and noise
generation by such relative motion.
Conventional bedding systems commonly include a mattress
supported by a foundation or "box spring". Foundations are provided
to give support and firmness to the mattress as well as resilience in
order to deflect under excessive or shock load. Foundations are
typically composed of a rectangular wooden frame, a steel wire grid
supported above the wooden frame by an array of steel wire springs
such as compression type springs which are secured to the wooden
frame. In order to properly support and maintain the firmness level
in the mattress, a large number of compression springs are needed in
the foundation, resulting in high production cost. This is the main
disadvantage of using compression springs in mattress foundations.
Also, foundations which use compression springs typically have a low
carbon wire grid or matrix attached to the tops of the springs. Both
the wires and the welds of the matrix can be bent or broken under
abusive conditions. In such steel/metal systems, fasteners are
required to secure the springs to the grid and to the frame. This
leads to metal-to-metal contact which can easily produce squeaking
sounds under dynamic loading.
In an effort to avoid the high cost of using compression springs
in foundations, another type of spring used is the torsional steel
spring formed from heavy gauge steel spring wire bent into multiple
continuous sections which deflect by torsion when compressed. See for
example U.S. Patent Nos. 4,932,535; 5,346,190 and 5,558,315. Because
torsional springs are dimensionally larger and stiffer than
compression springs, fewer torsional springs are needed in the
foundation. However, the manufacture of torsional-type springs from
steel wire requires very expensive tooling and bending equipment.
Elaborate progressive bending dies are required to produce the complex
torsional spring module shapes which may include four or more
adjoining sections. The manufacturing process is not economically
adaptable to produce different spring configurations without new
tooling, tooling reworking and/or machinery set-up changes and process
disruption, etc. Therefore, the configuration and resultant spring
rate of such springs cannot be easily or inexpensively altered to
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produce foundations with different support characteristics.
Furthermore, the many bends in these types of springs make dimensional
quality control and spring rate tolerance control very difficult to
achieve. Also, variations in steel material properties and the need
for corrosion protection and heat-treating add to the cost and
difficulty of producing steel wire spring modules. And furthermore,
the awkward geometry of the relatively large torsional springs makes
assembly of the springs in the foundation frame relatively difficult.
Another disadvantage of the use of steel wire springs in
foundations, and a particular disadvantage of torsional springs, is
the phenomenon of "spring set" in which a spring does not return
completely to an uncompressed height following excessive loading. So
long as a spring is deflected within its spring rate tolerance range,
it can be repeatedly loaded for a certain number of cycles without
noticeable change in operating characteristics. However, if deflected
past the maximum deflection range, it will undergo permanent
deformation or "set", resulting in a permanent change in operating
characteristics such as lack of reflexive support, permanent change in
shape, or catastrophic failure in the form of breakage: Spring set
in steel wire springs may also occur simply following prolonged normal
use, i.e., continuous heavy loading. This phenomenon is also
generally referred to as fatigue and can result in catastrophic
failure.
Mattresses of increased thickness dimension such as "pillow-top"
mattresses, when placed on top of traditional foundations of six to
eight inch height, can be too high in proportion to the head and foot
boards of beds, resulting in an awkward appearance and an excessively
high sleeping surface. This trend toward larger mattress and
foundations increases distribution and storage costs. Mattress
foundations in the United States typically measure on the order of
five to eight inches thick, with an average thickness (or height) of
six and one half to seven and one half inches. In conventional
foundations, most all of this dimension is attributable to the height
of the wire spring modules. In general, deflection of torsional wire
spring modules is limited to approximately 20% of the total height
dimension. Compression which exceeds the 20% range can cause spring
set or breakage. Reducing the overall height of torsional spring
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modules can make the springs too rigid and diminishes the desired
deflection characteristics and ability to absorb heavy loads with
recovery. Moreover, the number of cycles to failure during life
testing is generally harder to predict with shortened height spring
wire modules and is usually many less cycles to failure than spring
wire modules of greater height. Nonetheless, it would be desirable to
have a foundation with reduced height while retaining the desired
support and deflection characteristics.
ST7MMARY OF THE INVENTION
The present invention provides composite material spring modules
for use as flexible support elements in support structures such as
seating and bedding. The composite material spring modules include a
spring body composed of a plastic enveloping and cured about
reinforcing fibers, and a second plastic or polymeric material from
which attachment fittings are integrally formed or molded about or
bonded to the spring body. For spring modules for a mattress
foundation, the attachment fittings are selectively configured for
mechanical engagement with elements of a foundation frame structure
and a grid or support structure which overlies the frame structure.
The integral formation of plastic attachment fittings about the spring
body eliminates the need for physically separate fasteners to secure
the springs to a surrounding assembly such as a frame and a grid. The
material of the attachment fittings may be the same or different than
the plastic material of the spring body.
The invention further enables production of novel low
profile/low height abuse resistant and long life mattress foundations
which incorporate the composite material spring modules with integral
attachment fittings. The composite material spring modules are used
in place of traditional wire springs as the principle reflexive
support components. In one embodiment, the total height of a low
composite material mattress foundation is approximately 50-60% of the
height of traditional foundations, yet has improved
deflection/resilience characteristics over traditional foundations.
The invention further provides a high profile or conventional height
mattre:~s foundation which uses composite material spring modules
mounted upon a novel high profile frame.
The invention further includes a novel method of manufacturing
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foundation spring modules from composite materials such as
epoxy/polyester and fiberglass combinations, by molding such
materials in various spring shapes particularly adapted and especially
suited for use as support elements in a mattress foundation. As used
herein the term "composite" means a combination of at least two
materials mixed together in a solid form, such as any plastic material
which can be molded, extruded or pultruded and a fibrous material
bonded or encased or otherwise attached to the plastic material. The
term "composite" also refers to the integral formation of attachment
fittings from a moldable material about a spring body having
encapsulated fibers. The invention still further includes a novel
method of selective assembly of mattress foundation units using
composite material spring modules wherein the spring modules are
selectively arranged upon and fixedly attached to a frame structure
and to an overlying grid.
In a preferred embodiment of the spring modules, composite
material is pultruded in a generally planar elongate spring module to
provide a low depth/height dimension and efficient stress and load
distribution. The use of molded/pultruded composite material spring
modules, and in particular the planar elongate configuration of the
composite material spring module, provides numerous manufacturing and
assembly advantages over prior art wire springs, including simplified
foundation construction, module manufacturing and handling, and ready
adaptability to automated manufacturing and assembly processes for
both sub-assembly and final assembly of foundation units.
Furthermore, the novel method of manufacturing foundation spring
modules from composite materials is readily adaptable to the
manufacture of a wide variation of spring modules having different
shapes and support and deflection characteristics with varying spring
rates, without substantial retooling or modification of the
fundamental process. The process allows very high reproducibility of
performance characteristics.
The invention further includes novel high profile and low
profile foundation frames for supporting spring modules and an
overlying grid. A low profile frame has parallel longitudinal and
central members, transverse members with a major width parallel to
major widths of the longitudinal members, and end facia boards with a
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major width orthogonal to the major widths of the transverse members.
A high profile frame has parallel longitudinal perimeter and central
members, and transverse members and end facia boards attached
orthogonally to the longitudinal members, with major widths of the
transverse members and facia boards perpendicular to widths of the
longitudinal members, and a narrow bottom edge of the facia boards
flush with bottom surfaces of the longitudinal members.
The invention further provides a novel mattress foundation grid
crosswire or transverse member having horizontal offsets dimensioned
to engage attachment fittings of spring modules to restrict movement
of the attachment fittings along the length of the crosswire. The
invention still further provides a composite material mattress
foundation grid borderwire support spring configured for attachment to
a frame member and for frictional engagement with a flexible support
of a grid borderwire.
These and other aspects of the invention are herein described in
particularized detail with reference to the accompanying Figures
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying Drawings:
FIGS. lA-1C are perspective views of composite material spring
modules with integrally formed attachment fittings of the present
invention;
FIG. 2 is a perspective view of a mattress foundation having
composite material spring modules with integrally formed attachment
fittings of the present invention;
FIGS. 3A and 3B are perspective views of composite material
spring modules of the invention engaged with intersecting members of a
mattress foundation grid;
FIG. 4 is a perspective view of a high profile mattress
foundation with composite material springs with integrally formed
attachment fittings of the present invention;
FIG. 5 is a perspective view of a portion of an alternate
embodiment of a mattress foundation of the present invention;
FIG. 6A is a perspective view of an alternate embodiment of a
composite material spring module with integrally formed attachment
fittings of the present invention;
FIG. 6B is a perspective view of another embodiment of a spring
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module of the invention;
FIG. 6C is an elevation view of a spring module of the invention
engaged with a frame member and a grid in a mattress foundation of the
present invention;
FIG. 6D is a perspective view of an alternate embodiment of a
spring module of the invention attached to a frame member of a
mattress foundation, and
FIG. 7 is a cross-sectional view of a mattress foundation grid
borderwire support spring of the present invention.
DETAILED DESCRIPTION OF PREFERRED AND ALTERNATE
MffiODIbSENTS OF THE INVENTION
FIGS. lA-1C illustrate preferred embodiments of a composite
material spring module 16 of the invention having a generally planar
elongate composite material fiber-reinforced plastic spring body 32,
an integrally formed centrally disposed frame attachment fitting 34,
and integrally formed grid attachment stanchion fittings 36 at
opposite distal ends of body 32. Frame attachment fitting 34 and
stanchion fittings 36 (herein collectively referred to as "attachment
fittings") may be made of any structurally suitable material, such as
plastic or metal, and molded around, bonded, fastened or secured to
body 32 at the respective positions. In the preferred embodiment,
attachment fittings 34 and 36 are integrally formed about the spring
body 32 by an insert molding process. For example, a spring body 32
(of the simple planar, rectangular configuration shown or any of the
other configurations described herein and in the related application)
is placed in a mold having a cavity for receiving body 32 and
connected cavities in the forms of fittings 34 and 36. The mold is
then injected with any suitable moldable material such as
polypropylene, polyethylene, Santoprene7", nylon or ABS partially or
completely encapsulating the spring body 32. Alternatively, the
entire module 16 (including the body 32 and fittings 34, 36) may be
molded as a single piece such as from fiber reinforced plastic
material. Also, the fittings could be separately molded or pultruded
and then bonded (glued) to the spring module body.
The spring module body 32 may be produced from a wide variety of
composite materials such as fiber reinforced plastic, fibers in
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combination with epoxy or vinyl or poly-esters, high density plastic
such as polyethylene, high density plastic foam, encapsulated steel
and steel alloys, or any other material which exhibits the desired
spring rates and cycle duration. When made of a fiber-reinforced
composite material, the modules may be compound molded and/or
compression molded into the configuration of a male/female mold cavity
under heat and pressure, or pultruded. For example, continuous
fiberglass strands, approximately 60% to 80% of the product volume,
are saturated with a resin system by winding or pultrusion through a
bath of epoxy or vinyl ester which is approximately 20%~ to 40% of the
product volume. The material is then loaded into a compression mold,
molded and cured. Flash is removed by conventional methods such as a
vibrating pumice bed. The molding material can be selected and
blended to produce modules of different spring rates.
The spring bodies of generally linear configuration such as that
of FIG. 1, are preferably formed by a pultrusion process wherein the
reinforcing fibers are drawn through a bath of the plastic material in
a liquid state and through a die which defines the cross-sectional
configuration of the body, and the spring body is cut to the desired
length. Pigments can be used in the molding material to readily
identify modules of different spring rates, which greatly aids the
assembly process described below. As used herein, the term
"composite" refers to the combination of the plastic material of the
spring body and the fibers in the spring body. The term "composite"
also herein refers to the combination of the third material which is
molded about the spring body to form the attachment fittings, as
described below in detail.
Certain configurations of the composite material spring modules,
as further disclosed below, may be formed by pultrusion and continuous
pultrusion of, for example, fiber-reinforced plastic wherein fiber
strands (including but not limited to glass fibers, Kevlar , Mylar(9,
graphite, carbon or steel strands) are pulled from a reel through a
resin impregnating bath, and continuously pulled through a forming and
curing die. The continuous strand of composite material is then cut
transversely (i.e., along the cross-section of the part) to any
desired length to provide the finished spring body. Pultrusion is
especially well suited for very high volume mass production of spring
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bodies having substantially linear configurations. Curvilinear spring
module configurations may be pultruded and/or pultruded and
compression molded as described. Another significant advantage of
formation of spring modules by these processes is the ability to
easily alter the spring characteristics of modules simply by altering
the number of fibers, and/or the location or orientation of the fibers
within the modules. In the preferred embodiment, the fibers are
aligned with a length diinension of the module, and extend
substantially the entire length of the module body. In alternate
embodiments, the fibers are oriented to intersect at fixed or random
angles.
The attachment of the composite material spring modules 16 with
integrally formed attachment fittings will now be described in the
context of mattress foundations having an underlying frame structure
which supports the spring modules, and an overlying grid reflexively
supported by the spring modules. However, it will be appreciated that
it is well within the scope of the invention to attach the spring
modules to any type of supporting structure or framework, and to
optionally attach any type of structure or assembly to the spring
modules whereby the spring modules provide a reflexive surface or
object. Some specific examples of structures and assemblies to which
the spring modules may be attached include all types of furniture,
seating including vehicle and aircraft seating, energy absorbing
walls, floors or other surfaces such as vibration dampening supports,
and suspension systems.
FIG. 2 illustrates one embodiment of a low profile mattress
foundation of the invention having a plurality of composite material
spring modules 16 constructed in accordance with the invention. The
foundation 10 includes a novel low profile frame, indicated generally
at 12 which supports a plurality of composite material spring modules
16 attached to a grid or matrix 14 disposed parallel to and above
frame 12 as a mattress supporting surface. In this embodiment, frame
12 includes two longitudinally extending perimeter members 18, a
central longitudinal member 19, and a plurality of intermediate
transverse members 21, all of which may be constructed of wood or
steel or metal such as aluminum or other suitable materials such as
pultruded or extruded beam-like parts or blow-molded or structural
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foam parts, and secured together to form a rectilinear frame. In the
low profile frame the transverse members 21 are laid flat with a major
width wt parallel to and flush against the major widths wp of
longitudinal members 18 and 19, and the narrow edges e orthogonal to
the top surfaces of members 18 and 19. A plurality of longitudinally
extending upper longitudinal frame members 22 (which may be
constructed of wood or steel, or extruded or pultruded plastic such as
polyethylene or polypropylene, PVC or fiberglass reinforced plastic)
are attached orthogonal to the major widths wt (top surfaces) of
transverse members 21. An end facia board or strip 23 is attached to
each transverse end of the frame, against the outer narrow edge of the
transverse perimeter members 21 at the ends of the longitudinal
perimeter members 18. A major width wf of facia board 23 is thereby
perpendicular to the major width w, of end transverse members 21 and a
bottom narrow edge of the facia board is flush with bottom surfaces of
the longitudinal members. The bottom edge of the facia strip 23 is
flush with the bottom surfaces of the perimeter frame members to
create a smooth continuous surface for attachment of upholstery. The
facia board 23 may extend vertically above the end transverse members
21 to provide a chock against which the ends of upper longitudinal
frame members 22 abut. With the upper longitudinal frame members 22
cut to equal length, abutment of the ends against the facia strips 23
insures that the frame will be checked and square when assembled. The
spring modules 16 are attached to top surfaces of the upper
longitudinal frame members 22 as further described below.
The grid 14 is formed by a peripheral border element 24 also
called a "borderwire", of generally the same width and length
dimensions of frame 12, a plurality of longitudinal elements 26
secured to the border element by clips or welds or simply bent or
hooked around the borderwire 24, and a plurality of transverse grid
elements 28 (also referred to herein as "crosswires") which intersect
longitudinal elements 26 to define a generally orthogonal grid 14
which forms a support surface for a mattress. The grid 14 (including
elements 24, 26 and 28) may alternatively be constructed of low carbon
or high carbon steel, but may alternatively be formed of composite
material such as fiber reinforced plastic which is then glued or
ultrasonically welded or otherwise fastened in an orthogonal matrix or
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other arrangement, or formed .as a single integrated structure by
plastic or composite material molding processes suitable for
relatively large structures such as rotational molding or injection
molding of structural foam.
The terminal ends of transverse elements or crosswires 28 are
downwardly bent to form vertical support elements 30 with mounting
feet 31 secured to frame 12 to support the peripheral borderwire 24
and clipped to the grid 14 over frame 12. Support elements 30 may be
selectively formed to any desired height above frame 12 to extend from
the borderwire 24 to members 18 and to deflect in the manner of a
spring as is known in the art.
As further shown in FIG. 2, the grid 14 is supported over frame
12 by the plurality of spring modules 16 attached at a bottom point to
upper longitudinal frame members 22 and at upper points about the
intersection of elements 26 and 28 of grid 14. As further shown in
FIGS. lA-1C and FIGS. 3A and 3B, each of the grid attachment stanchion
fittings 36 include a base 41 secured to or formed about a distal end
of module body 32, an upright member 42 (also referred to as a
"stanchion") attached at one end through a flexible hinge 43 to base
41, and a pair of gripping fingers 44 at an opposite end of the
upright stanchion member 42 configured to attach about a longitudinal
grid member 26 and to straddle the transverse grid member 28 at the
intersections with longitudinal grid member 26, as shown close up in
FIGS. 3A and 3B. In this embodiment, the longitudinal grid member 26
overlaps transverse grid member 28 to lock it into channel 47.
On the grid attachment stanchion fittings of the spring modules
of FIG. lA and FIGS. 3A-3B, each of the gripping fingers 44 include a
laterally extending locking tab 44. which is generally aligned with
the length of the module body 32 and extends over an interior side
opening 46o into channel 46 in which a longitudinal grid member 26 is
received in the foundation assembly. The interior side opening 460
allows the longitudinal grid members 26 to easily enter channel 46,
and the locking tabs 44d,,, each formed with a downwardly canted
underside, guides the grid members 26 through opening 46o into channel
46. Preferably, the height of opening 46o is less than a cross
sectional width of member 26, whereby the locking tabs 44d,, are forced
upward as the member 26 passes through opening 46õ and then snap down
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to capture and retain grid members 26 within channel 46.
As shown in FIG. 1B, each of the gripping fingers 44 can
alternately be formed with a radiused head 45 which extends over
channel 46 dimensioned to receive and frictionally engage grid member
26, similarly, a second channel 47, orthogonal to channel 46, is
dimensioned to receive transverse grid member 28. As shown in FIG.
1C, second radiused heads 48 may be provided which extend over channel
47 to frictionally engage transverse member 28.
As shown in FIG. 3A, vertically offset notches 29 in transverse
member 28 are spaced to closely straddle the upper distal end of
upright member 42 to restrict movement of the grid attachment fittings
along the length of transverse member 28. The grid attachment
stanchion fittings 36 flexibly secure the intersecting grid members 26
and 28 in the correct relative positioning and facilitates rapid
assembly of the foundation. The flexible hinge 43 disposed between
the spring module body and the grid enables multi-dimensional live
response to any load placed on the grid. Formation of the entire grid
attachment stanchion fitting of a flexible plastic is particularly
advantageous for the infinite degrees of load deflection, and the
complete elimination of any possibility of noise generation at the
gripping finger 44/grid attachment interface.
As shown in FIG. 3B, the invention further includes a transverse
grid member 28 or crosswire having horizontal lateral offsets 291 of a
linear extent sufficient to traverse the second channel 47 which runs
between gripping fingers 44. By this arrangement, the grid attachment
stanchion fittings 36 are restricted from lateral displacement along
longitudinal grid members 26, and from movement along the length of
crosswire 28. Furthermore, the horizontal lateral offsets 291 are
overlapped by a portion of the locking tabs 44 which strengthens the
mechanical engagement of the intersecting grid members within the
attachment fittings. The lateral offsets 291 are horizontal in the
sense that they extend laterally in a plane defined by the.top surface
of a grid in which the crosswire 28 is incorporated.
The frame attachment fitting 34 is preferably configured for
indexed engagement with an opening in the top of longitudinal frame
members 22. For example, a key 37 is formed on the bottom of frame
attachment fitting 34 with a length generally aligned with the length
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of the module body 32. A correspondingly sized hole is provided in
the top of the upper longitudinal frame members 22 through which the
key 37 is passed and then rotated ninety degrees to mechanically
engage with the supporting frame member. For example, a neck 39
(shown in FIGS. 6A and 6B) extending from key 37 has a length
dimension greater than a width dimension of the hole in frame member
22 so that edges of the hole impinge upon the neck as it is rotated
ninety degrees within the hole, to mechanically and frictionally
engage the module with the frame member. Similarly, as shown in FIG.
6A, the length of key 37 may be made longer than the internal width of
the channel form of longitudinal member 22 to achieve a binding
compression fit of the key along a length dimension with the frame
member 22 upon ninety degree rotation. Alternatively, the hole in
frame member 22 can be dimensioned at one point to receive the key 37
and neck 39 with clearance, and further include an adjacent smaller
area which captures the key when the entire module is slid into the
smaller area of the hole. A key configured for sliding engagement in
a frame member hole is shown in FIGS. 6B and 6C.
This simple manner of attachment of the modules to the frame
structure with the integrally formed attachment fittings 34 and 36
eliminates the need for any separate fasteners to secure the modules
to the frame. The fittings 34 and 36 enable extremely simple and fast
attachment of the modules 16 to the frame and the overlying grid. The
interlocking mechanical engagement of the attachment fittings of the
spring modules with a mattress foundation or any other structure such
as seating and furniture, is ideally suited for either manual or
automated assembly of the foundations of the invention. Also, the
inherent flexibility of the fittings 34 and 36 formed of
flexible/plastic material (and preferably of a material more flexible
than the non-fiber material of the spring body) gives the entire
spring module multiple degrees of freedom relative to the frame and
grid, and eliminates any possibility of noise generation at the points
of connection of the attachment fittings to a frame or grid.
The described foundation as depicted in FIG. 2 has a relatively
low height or profile for the reason that the overall height, measured
from the bottom surface of the Ãrame to the top of the grid, is
substantially less than the height of conventional foundations having
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wire spring modules which stand as tall as seven or more inches high.
The low profile height dimension of the foundation of the invention is
attainable as a result of the minimal height dimension of the
composite material spring modules 16 and attachment fittings, yet
which have deflection characteristics comparable and superior to wire
form springs with substantially greater height.
Nonetheless, the foundation 10 can be constructed with any
desired height dimension wherein the modules 16 are free to deflect
about the point of attachment to the supporting frame members 22.
FIG. 4 illustrates a relatively high profile version of the foundation
10 having a high profile frame, indicated generally at 25, wherein the
transverse frame members 21 are oriented with a major width wt oriented
vertically to achieve a greater height dimension which elevates the
longitudinal frame members 22 (and spring modules 16) mounted on
narrow edge e. In other words, the perimeter members 18 are flat,
while the transverse members 21 are upright. The narrow bottom edges
of the transverse members 21 rest upon the top surfaces or major
widths wp of the longitudinal perimeter frame members 18 and central
longitudinal member 19. The upper longitudinal frame members 22 are
attached to the narrow top edges e of the transverse members 21. End
facia strips 23 are similarly vertically oriented along the side of
the end transverse members 21, with a major width wf oriented
vertically, perpendicular to the major widths wp of the longitudinal
members, and the narrow bottom edges of the transverse members flush
with the bottom of the longitudinal perimeter frame members 18. This
construction provides a very stiff frame with the transverse ends
reinforced by side-by-side vertically oriented double board thickness.
Of course, the rigidity of the transverse members 21 is optimized by
loading upon the narrow edges e, on which the longitudinal frame
members 22 rest. Additional frame members may be used to achieve even
greater heights and stiffness. In a high profile foundation
constructed with the high profile frame 25, the vertical support
elements 30 of the transverse grid elements 28 are increased in height
to extend from the elevated grid down to the longitudinal perimeter
frame members 18.
Alternatively, the length of upright members 42 of the grid
attachment stanchion fittings 36 can be designed to produce any
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reasonable desired height of the grid over the spring modules and
uppermost members of the frame. For example, FIG. 5 illustrates
another embodiment wherein the grid attachment stanchion fittings 36
are replaced by a single grid attachment wire 50, the ends 51 of which
are formed to engage with an alternate form of attachment fitting 36
and up to the grid interlockingly engaged by an intermediate section
52 between ends 51. The vertical extent of ends 51 can of course be
selectively varied in manufacture to produce a foundation of the
desired height.
The fundamental concept of the invention of integrally forming
attachment fittings with a composite material spring module body can
be executed with spring module bodies of any configuration. For
example, FIGS. 6A-6D illustrate generally U-shaped or C-shaped
configurations of the spring module 16 which have a generally curved
body 32 with two generally flat coplanar spring ends from which the
grid attachment stanchion fittings 36 extend vertically, with the
frame attachment fitting 34 at the approximate center of the body 32.
The U-shape spring module 16 is configured such that the
compressive stress imparted on the grid of the inventive bed system is
absorbed by the spring generally in the depth dimension, and generally
along the centerline of the module. In addition, the U-shape spring
module is configured and made from a material such that it can be
compressed to an essentially planar position without reaching its
"spring set" condition. Accordingly, even if the inventive bed
foundation is subjected to excessive load conditions, the U-shape
spring modules will not be deformed or otherwise caused to fail
because even at maximum deflection they will not take a spring set.
FIG. 6B illustrates a U-shaped spring module 16 mounted upon a
frame member 22 by insertion of key 37 through a hole in the frame
member as described above, and the frictional engagement of the
intersecting grid wires by the grid attachment stanchion fittings 36
as also described above. As shown in FIG. 6C, an additional
mechanical fastener 35, such as in the form of a wire form or staple,
may be attached across fitting 34 to further secure the module to the
frame member. For such fastener securement, as shown in FIGS. 1A and
1B, an indexing groove 38 may be provided in fitting 34 to receive
fastener 35, as shown secured to a frame member in FIG. 6D. For
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fastener securement of the spring module to, for example, a planar
surface of a support structure such as a frame member, the key 37 and
neck 39 could be eliminated to achieve flush stable mounting. In this
case the body of the frame attachment fitting 34 in which groove 38 is
formed still performs an attachment function or seating the fastener.
In combination with the reflexive spring action of modules 16
mounted to frame 12 and grid 14 in this manner, support elements 30 of
transverse wires 28 provide a dual spring/support action to the
foundation. Because support elements 30 may be formed of steel wire
or polymeric material, they may have a spring rate different from the
modules 16, especially modules formed of composite material. The
combination of these two different spring elements with different
spring rates gives the foundation an unique and improved dual spring
rate and action. For example, the wire support elements 30 may be
substituted with a composite material spring 60 such as depicted in
FIG. 7. The composite material grid support spring 60 is formed with
a generally planar mounting base 61 for attachment to a frame member
and an upright 62 which vertically supports the borderwire 24 of grid
14. An intermediate section 63 may be configured in any suitable
geometry which provides the desired deflection and spring
characteristics. At the top of upright 62 is an attachment fitting 64
having a channel 65 for receiving the borderwire 24 and a retainer cap
66 which fits over the channel to retain the borderwire in channel 65.
Furthermore, since the inventive design may use a high carbon grid,
the grid itself acts as a spring to fully return to the horizontal
plane when a load is removed, unlike low carbon welded grids which can
permanently bend and deform and break under load.
In the manufacturing and assembly methods and processes of the
invention, the assembly of the composite material mattress foundation
system is highly flexible and greatly simplified by the relatively
small size and simple geometry of the spring modules. For example, to
selectively assemble a composite material mattress foundation of the
invention the following steps are performed in any logical order. The
spring modules 16 may be attached to the inner frame members (such as
frame members 22) before or after attachment of the inner frame
members to the other frame members. The spring modules are secured to
the frame members by insertion of the key 37 through the frame member
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key hole and rotated 90 degrees to a locked position. The number of
spring module attachment points (e.g., holes for receiving keys 37)
will determine the maximum number of modules which one frame member
can support. For example, a single frame member may include as many
as forty module or more attachment points, though only twenty or fewer
evenly spaced modules may be attached in the assembly process.
The type of spring modules used may be selected by shape and/or
color (indicating spring rate) to be of either uniform or dissimilar
spring properties. For example, modules of a higher spring rate may
be placed in the hip and/or back regions of the foundation and lower
spring rates near the ends. Similarly, stiffer spring modules can be
located at the perimeter of the foundation to provide greater support
of the mattress edge where people sit. The grid 14 is then secured to
each of the grid attachment stanchion fittings 36 of the modules 16 by
top or side entry engagement of the grid intersections (of elements 26
and 28) with the stanchion gripping fingers 44, as described above.
Padding and covering is then attached. Each of the assembly steps
lends itself to automation given the small size, light weight and
simple geometry of the spring modules, and the elimination of
dimensional constraints dictated by awkward multiple bend steel wire
springs.
Although the invention has been described in detail with respect
to certain preferred and alternate embodiments, it will be appreciated
to those of skill in the art that certain modifications and variations
of the inventive principles disclosed. In particular, it will be
acknowledged that the composite material spring modules with
integrally formed attachment fittings can be attached to or utilized
with any support structure or frame and elements or members of any
overlying structure such as a grid or matrix design to transfer loads
to the springs, such as for example, but not limited to frame and
structures as found in mattresses, furniture, seating, dampening
devices, and any structure or assembly where a reflexive weight or
load bearing surface is required.
Also, any form of attachment fittings which are integrally
formed with or bonded to the spring body and configured for attachment
to a member which supports the spring module, and for attachment to a
structure supported by the spring module is well within the scope of
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the invention. All such variations and modifications are within the
scope and purview of the invention as defined for now by the
accompanying claims and all equivalents thereof.
