Slow Acting Pocketed Spring Core

Technical Field of the Invention

This invention relates to resilient cushions and, more particularly, to

spring cores used in seating cushions or bedding mattresses.

Background of the Invention

Spring cores are commonly used in seating or bedding products.

Such spring cores commonly are made from assemblies or matrixes of multiple springs joined together directly as by helical lacing wires, or indirectly as by fabric

within which each individual spring is contained. Such spring cores, whether the

springs of the cores are connected directly or indirectly, are generally covered on

the top and often on the bottom by pads of resilient foam, as for example, a pad

of urethane or iatex/urethane mix of foamed material. Within the last several years, more expensive cushions or mattresses have had the spring cores covered by a visco-elastic foam pad which is slow acting. That is, the visco-elastic foam pad is slow to compress under load and slow to recover to its original height when

the load is removed from the visco-elastic foam pad. These visco-eiastic pads

impart a so-called luxury feei to the mattress or cushion, but these pads also, because of their closed cell structure, retain heat and are slow to dissipate body heat when a person sits or lies atop such a visco-elastic foam pad-containing

cushion or mattress.

It is therefore been an objective of this invention to provide a seating

or bedding cushion or mattress which has the same luxury feel as a visco-elastic

pad-containing cushion, but without the heat retention characteristics of such a

visco-elastic pad-containing cushion or mattress. Still another objective of this invention has been to provide a cushion

or mattress having the same or a very similar slow-to-compress and slow-to-

recover to its original height luxury feel cushion or mattress as one containing

visco-elastic foam pads, but which is substantially less expensive to manufacture.

Summary of the Invention

The invention of this application which accomplishes these

objectives comprises a seating or bedding spring core made from an assembly of

pocketed springs, each spring of which is contained within a sealed fabric pocket. The fabric pocketing material within which the springs are contained is semi-

impermeable to air flow through the fabric material. As used herein, the term

"semi-impermeable" means that the fabric material, while permitting some air fiow

through the material, does so at a rate which retards or slows the rate at which a spring maintained in a sealed pocket of the fabric may compress under load or return to its original height when a load is removed from the sealed pocketed spring. In other words, air may pass through such a semi-impermeable material,

but at a very reduced rate compared to the rate at which air usually flows freely

through a fabric materia!.

In one embodiment of the invention, the semi-impermeable fabric

material within which the springs of the pocketed spring assembly are contained

and sealed is a spun-bonded polypropylene fabric availablefrom Hanes Industries of Conover, North Carolina under the name Elite 200. This Elite 200 fabric is

coated with a layer of polyurethane. Such a non-woven fabric has a few pinholes, some of which may be covered by the coating. However, the fabric is not air tight

due to the presence of some holes. The air permeability or porosity of a material is commonly measured using the American Society of Testing Materials ("ASTM")

method ASTM-D737, which is fully incorporated herein. However, when tested

using this method the material for this application may be not be quantified

because the porosity is so low. Of course, the fabric material within which the

pocketed springs are contained may be any semi-impermeable fabric material

which, at ambient air pressure, retards or slows air pressure through the material .

The fabric may be a woven or unwoven material which may be coated in a secondary process with a polymer to achieve the requisite semi-impermeable air

flow characteristics described hereinabove.

In accordance with the practice of this invention, the pocketed spring

core assembly having the slow acting compression and siow-to-recover original height characteristics of this invention may be inexpensively manufactured upon the same pocketed spring machinery, with very little modification, which is now

utilized to manufacture conventional pocketed spring assemblies. Expressed another way, the advantageous spring cushion assembly of this invention may be

manufactured upon existing pocketed spring equipment without any substantial

modification of that equipment or machinery. As a result, this advantageous pocketed spring core assembly with its unique compression and recovery

characteristics is, in accordance with the practice of this invention, manufactured according to the current manufacturing processes of existing pocketed spring

assemblies with only the fabric materia! utilized in the practice of the process being changed from an air permeable fabric, as is now conventional, to an air

semi-impermeabie fabric material. This conventional process, absent the unique

fabric utilized in the practice of this invention, is completely illustrated and

described in prior art patents as, for example, Stumpf U.S. Patent No. 4,439,977; Stumpf et al U.S. Patent No. 6,101 ,697; and, Santis et al U.S. Patent No. 6,591 ,436. These patents all describe apparatus for manufacturing continuous

strings of coil springs contained within fabric pockets. The fabric pockets of these

springs are generally unsealed from one pocket to the next. But in accordance

with the practice of this invention, the seals are all continuous and preferably by sinusoidal-shaped seals, so as to entrap air within each seal pocket. After being

formed into continuous strings of pocketed springs, the springs are in accordance

with the practice of this invention are cut into strings of predetermined discrete

lengths which are then assembled by gluing together the strings either directly or

indirectly via a sheet of fabric on the top or bottom of the side-by-side juxtapositioned strings of coils. Mossbeck U.S. Patent No. 6,159,319 discloses

such an assembly process.

One patent which discloses a point bonded non-woven fabric and method of making that fabric suitable for use in the practice of this invention is Stokes U.S. Patent No. 5,424,115. The disclosures and contents of the above-

identified patents are hereby incorporated by reference in their entirety for

purposes of completing the disclosure of this application.

The primary advantage of this invention is that it gives rise to a relatively inexpensive seating or bedding cushion which has the luxurious slow-

acting compression and height recovery characteristics of heretofore expensive

visco-elastic foam containing cushions. And in accordance with the practice of

this invention, the cushion having these characteristics may be relatively inexpensively manufactured on currently existing equipment with very little modification of that production equipment.

These and other objects and advantages of this invention will be

more readily apparent from the following drawings, in which:

Brief Description of the Drawings

FlG. 1 is a perspective view, partially broken away, of a cushion incorporating the pocketed spring core invention of this invention;

FIG. 2 is a schematic drawing of the process by which cushion

spring cores made in accordance with the practice of this invention are

manufactured; and

FiG. 3 is an enlarged perspective view of a portion of a string of

pocketed coil springs used in the pocketed spring core of FIG. 1.

Detailed Description of the Drawings

With reference to FIG. 1 , there is illustrated a cushion in the form of

a single-sided mattress 10 incorporating this invention. This cushion or mattress

10 comprises a pocketed spring core 12 over the top of which there is a conventional foam pad 14 covered by a fiber pad 16. This complete assembly is

mounted upon a base 18 and is completely enclosed within an upholstered

covering material 20.

While one embodiment of the invention described herein is

illustrated and described as being embodied in a single-sided mattress, it is equally applicable to doub!e-sided mattresses or seating cushions. In the event

that it is utilized in connection with a double-sided mattress, then the bottom side of the spring core usually has a foam pad applied over the bottom side of the

spring core and that pad is in turn covered by a fiber pad of cushioning material.

According to the practice of this invention, though, either the foam pad or the fiber

pad or both may be omitted while still practicing the invention of this application

wherein the novel features reside in the pocketed spring core 12.

The pocketed spring core 12 may be made upon any conventional

pocketing spring manufacturing machine and by any conventional pocketing

spring process so Song as the machine and process utilized the special fabric material to be described hereinbelow for pocketing the springs of the assembly.

One machine and process suitable for creating the pocketing spring assembly 12

is described in Santis et al U.S. Patent No. 6,591 ,436 assigned to the assignee of this application. With very little modification as described hereinbelow, that

machine and process may be used in the practice of this invention. While that machine creates so-called "side seam pocketed coil springs", this invention is equally applicable to spring cores wherein the strings of springs have the

longitudinal seam on the top of the string of pocketed springs rather than on the sides of the springs. Such top seamed pocketed spring cores and the methods by which they are manufactured are described, for example, in Stumpf U.S. Patent No. 4,439,977 and Stumpf et ai U.S. Patent No. 6,101 ,697. With very little

modification, as explained more fully hereinbelow, the machines and processes of these top seam pocketed spring assemblies may also be utilized in the practice

of this invention.

Still with reference to FiG, 1 , it will be seen that the pocketed spring core 12 is manufactured from multiple strings 12A of pocketed springs, each string

of which extends across the full width of the product 10. These strings are connected in side-by-side relationship as, for example, by gluing the sides of the

strings together in an assembly machine, such as the assembly machine disclosed

in Mossbeck U.S. Patent No. 6,159,319, so as to create an assembly or matrix of springs having multiple rows and columns of pocketed springs bound together as

by gluing, welding or any other conventional assembly process commonly used

to create pocketed spring cores.

With reference now to FlG. 3, there is illustrated a portion of one string 12A of the pocketed spring core 12. This string differs from the strings of

coil springs illustrated and described in U.S. Patent No. 6,591 ,436 on!y in that the overlapped seam 21 of fabric is secured together by a sinusoidal wave-shaped

welded seam 22 and the vertical welded seams 24 between adjacent coil springs

in a string of pocketed coil springs is a continuous sinusoidal welded seam 24 rather than a discontinuous seam as in U.S. Patent No. 6,591 ,436. These seams

are accomplished bythe welding horn of the machine having a sinusoidal-shaped

welding element rather than multiple spaced protrusions on the welding head. As

a result of these welded seam seals defining the spring-containing pockets of the string of coil springs, each spring of the string is sealingly enclosed within its individual pocket. If the fabric material defining these pockets and enclosing the springs therein were completely air-impermeable, then these pockets could only

be compressed by compressing the air contained within the pockets. In actuality, and as explained more fully hereinafter, this fabric material is semi-impermeable

so that the rate at which the springs compress when a load is placed upon the top of a pocketed spring core assembly containing the springs is only slowed or

retarded by the air entrapped within the individual pockets as the pocketed spring

assembly is compressed and similarly, the rate of return of the compressed coil

spring assembly to its original height after compression is retarded or slowed by the rate at which air may pass through the semi-impermeabie fabric material into

the interior of the individual pockets of the coil spring assembly.

With reference now to FIG. 2, there is illustrated the process by which the coi! spring assembly of FIG. 1 is manufactured utilizing the machines

and processes of the above-identified patents. This process comprises starting with a roll of fabric material which is unrolled and has springs either inserted

between a fold of the fabric or placed onto the fabric. Thereafter, the fabric is

enclosed around the individual spaced springs located either between the folded

springs or on the top of the fabric material. The fabric is then closed around the

spring by forming a longitudinal seal either along the side or tops of the spring. The individual pockets within which the springs are contained are then defined by

vertical seams which extend for the height of the pocketed springs with each

spring separated from the adjacent spring by the vertical seam. The resulting continuous string of pocketed springs is then cut into discrete lengths of pocketed

springs which are then assembled and secured together in a side-by-side relationship to create the matrix of strings of pocketed springs illustrated in FiG. 1. The cushion is then completed by adding top cushioning materials as, for

example, the pad of resilient foam material 14 and/or fiber 16 after which the complete assembly is encased within upholstered finishing material 20.

!n accordance with the practice of this invention, the fabric material

15 within which the springs of the pocketed spring assembly are enclosed is a

point bonded, non-woven fabric material as, for example, the point bonded, non- woven fabric material disclosed in U.S. Patent No.5,424,115. In accordance with

the practice of this invention, this material has a coating of polyethylene or other

suitable material sprayed onto or roller coated onto one side of the fabric so as to

make it semi-impermeable to air flow as described hereinabove. While we have described only a single preferred embodiment of this

invention, persons skilled in this art will appreciate that other semi-impermeable fabric materials may be utilized in the practice of this invention. Simiiariy, such

persons will appreciate that the individual coi! springs may not all be seaϋngly

enclosed within individual pockets, but groups of springs may be seaϋngly enclosed while practicing the invention of this application. Therefore, we do not

intend to be limited except by the scope of the following appended claims.

We claim: