Patent Publication Number: US-8978183-B1

Title: Pocketed spring assembly

Description:
RELATED APPLICATIONS 
     N/A 
     FIELD OF THE INVENTION 
     This invention relates generally to bedding and seating products, and more particularly to pocketed spring assemblies used in bedding and seating products. 
     BACKGROUND OF THE INVENTION 
     Mattress spring core construction over the years has been a continuously improving art with advancements in materials and machine technology. A well known form of spring core construction is known as a Marshall spring construction wherein metal coil springs are encapsulated in individual pockets of fabric and formed as elongate or continuous strings of pocketed coil springs. In an earlier form, these strings of coil springs were manufactured by folding an elongate piece of fabric in half lengthwise to form two plies of fabric and stitching transverse and longitudinal seams to join the plies of fabric to define pockets within which the springs were enveloped. 
     More recently, improvements in spring core constructions have involved the use of fabrics which are thermally or ultrasonically weldable to themselves. By using such welding techniques, these fabrics have been advantageously used to create strings of individually pocketed coil springs wherein transverse and longitudinal welds instead of stitching are used to form the pockets encapsulating the springs. 
     Once strings of pocketed springs are constructed, they may be assembled to form a spring core construction for a mattress, cushion or the like by a variety of methods. For example, multiple or continuous strings may be arranged in a row pattern corresponding to the desired size and shape of a mattress or the like and adjacent rows of strings may be interconnected by a variety of methods. The result is a unitary assembly of pocketed coil springs serving as a complete spring core assembly. 
     One improvement upon pocketed coil springs as described is a compound nested pocketed coil spring in which each pocket of a string includes two nested coil springs. In such designs, a first inner spring is typically shorter and smaller than a second outer spring. The first inner spring is nested within the second outer spring. Commonly, the inner spring of the nested compound spring unit is individually encased in a pocketed fabric material to minimize noise or interference during the flexing or compression of the compound spring unit. 
     Spring core constructions employing compound nested pocketed springs provide the advantage of offering differing degrees of hardness to the spring unit. Varying degrees of hardness are usually achieved by varying the number of springs per unit area, commonly referred to as the “spring count” of the unit, or by changing the gauge of the wire from which the springs are manufactured. The inner and outer coil springs are nested so that the lower portion of the combined spring unit is reinforced by the inner spring making this portion of the unit much stronger than the upper portion. The upper portion may be flexible enough to provide a resilient and comfortable seating or sleeping surface and the lower portion strong enough to absorb abnormal stresses, weight concentrations or shocks without discomfort or damage. 
     Notwithstanding the above, there remains room for improvement in spring core construction. 
     SUMMARY OF THE INVENTION 
     In one aspect, a bedding or seating product is provided. The product comprises a pocketed spring assembly comprising a plurality of parallel strings of springs, each string joined to an adjacent string, each string comprising first and second opposed plies of fabric and a plurality of pockets formed along the length of the string by transverse seams joining the first and second plies, and at least one spring positioned in each pocket. At least one string has a single spring in one pocket and a pair of nested springs in an adjacent pocket in alternating fashion along the length of the string, the pair of nested springs having a taller spring and a shorter spring. A portion of each transverse seam forming the adjacent pockets of the at least one string is divided from an upper surface of the spring assembly downwardly so as to partially separate the adjacent pockets. Cushioning materials are placed on the pocketed spring assembly, and an upholstered covering encases the pocketed spring assembly and cushioning materials. 
     Each transverse seam separating the adjacent pockets of the at least one string can be divided from the upper surface of the spring assembly downwardly to below an uppermost portion of the shorter spring. Each spring can have upper and lower end turns and a plurality of central convolutions between the end turns. The strings of springs can extend longitudinally or transversely. If transversely, the product can include a plurality of the strings having a single spring in one pocket and a pair of nested springs in an adjacent pocket in alternating fashion along the length of the string, the plurality of strings arranged in a plurality of zones longitudinally spaced apart. For example, the product can include five such zones. The five zones can comprise a central zone, a pair of head end zones, and a pair of foot end zones. The central zone can have four strings of springs having a single spring in one pocket and a pair of nested springs in an adjacent pocket in alternating fashion along the length of strings, and each of the head end zones and foot end zones can have two strings of springs having a single spring in one pocket and a pair of nested springs in an adjacent pocket in alternating fashion along the length of the strings. The strings of springs having a single spring in one pocket and a pair of nested springs in an adjacent pocket in alternating fashion along the length of strings can be arranged such that the single springs and the nested springs are staggered relative to one another longitudinally. 
     In another aspect, a pocketed spring assembly for a bedding or seating product is provided. The pocketed spring assembly comprises a plurality of parallel strings of springs, each string joined to an adjacent string, each string comprising first and second opposed plies of fabric and a plurality of pockets formed along the length of the string by transverse seams joining the first and second plies, and at least one spring positioned in each pocket. At least one string has a single spring in one pocket and a pair of nested springs in an adjacent pocket in alternating fashion along the length of the string, the pair of nested springs having a taller spring and a shorter spring. A portion of each transverse seam forming the adjacent pockets of the at least one string is divided from an upper surface of the spring assembly downwardly so as to partially separate the adjacent pockets. 
     In another aspect, a string of springs for a pocketed spring assembly for a bedding or seating product is provided. The string of springs comprises first and second opposed plies of fabric and a plurality of pockets formed along the length of the string by transverse seams joining the first and second plies. A single spring is positioned in one pocket and a pair of nested springs is positioned in an adjacent pocket in alternating fashion along the length of the string, the pair of nested springs having a taller spring and a shorter spring. A portion of each transverse seam forming the adjacent pockets is divided from an upper surface of the string of springs downwardly so as to partially separate the adjacent pockets. 
     The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the summary of the invention given above, and the detailed description of the drawings given below, serve to explain the principles of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view, partially broken away, of a bedding or seating product incorporating a pocketed spring assembly according to the principles of the present invention. 
         FIG. 2  is an enlarged perspective view of a portion of one of the strings of springs of  FIG. 1 . 
         FIG. 3A  is a cross-sectional view, partially broken away, of the string of springs of  FIG. 2  in an unloaded condition. 
         FIG. 3B  is a view similar to  FIG. 3A  in a loaded condition. 
         FIG. 4  is a top view of the pocketed spring assembly of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring first to  FIG. 1 , there is illustrated a bedding product in the form of a single-sided mattress  10  incorporating the principles of the present invention. This product or mattress  10  comprises a pocketed spring assembly  12  over the top of which there lay conventional padding or cushioning layers  14 ,  16  which may be foam, fiber, gel or any other suitable materials. The pocketed spring assembly  12  is surrounded with a border  17  made of foam or any other suitable material (only a portion being shown in  FIG. 1 ). Although one type of border  17  is illustrated, the border may assume other forms or shapes of any desired size. Alternatively, the border  17  may be omitted in this embodiment or any embodiment described or shown herein. This complete assembly is mounted upon a base  18  and is completely enclosed within an upholstered covering material  20 . The base  18  and border  17  are known in the industry as a “bucket” into which a pocketed spring assembly  12  is inserted before the “bucket” is covered with one or more padding or cushioning layers. 
     As shown in  FIG. 1 , fully assembled, the product  10  has a length “L” defined as the linear distance between opposed end surfaces  22  (only one being shown in  FIG. 1 ). Similarly, the assembled product  10  has a width “W” defined as the linear distance between opposed side surfaces  24  (only one being shown in  FIG. 1 ). In the product shown in  FIG. 1  the length is illustrated as being greater than the width. However, it is within the scope of the present invention that the length and width may be identical, as in a square product. 
     As shown in  FIG. 1 , pocketed spring assembly  12  is manufactured from multiple strings  30 ,  32  of pocketed springs joined together. String  30  is formed of pocketed single springs  34 , and string  32  is formed from pocketed single springs  34  and pocketed compound nested springs  36  that alternate along the length of the string  32 . Each string  30 ,  32  of pocketed springs extends from side-to-side or transversely across the full width of the product  10 . Although the strings  30 ,  32  of pocketed springs are illustrated as extending transversely or from side-to-side in the pocketed spring assembly  12  of  FIG. 1 , they may extend longitudinally or from end-to-end in this or any other pocketed spring assembly shown or described herein. 
     These strings  30 ,  32  of pocketed springs are connected in side-by-side relationship as, for example, by gluing the sides of the strings together in an assembly machine, 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 or assemblies. 
     Referring to  FIGS. 1 and 4 , the strings  30 ,  32  of pocketed springs may be joined so that the individually pocketed springs are aligned in transversely extending rows and longitudinally extending columns. Alternatively, the strings  30 ,  32  of pocketed springs may be offset from one another in a pocketed spring assembly. In such an arrangement, the individually pocketed springs are not aligned in rows and columns; instead the individually pocketed springs fill gaps or voids of the adjacent strings of pocketed springs. 
     While the mattress  10  illustrated in  FIG. 1  is a single-sided mattress, the pocketed spring assembly  12 , or any other pocketed spring assembly shown or described herein, may be incorporated into any bedding or seating product, including a double-sided mattress or seating cushion. 
     Each string  30 ,  32  comprises a row of interconnected pockets. Referring to  FIGS. 2 ,  3 A, and  3 B, the construction will be described in connection with string  32  of springs  34 ,  36 . Each string  32  comprises a row of interconnected fabric pockets  40 . Every other pocket  40  contains a single spring  34 . Each pocket  40  between the single springs  34  contains a compound nested spring  36 . The single springs  34  and compound nested springs  36  thus alternate along the length of string  32 . Each spring  34  is a coil spring having an upper end turn  50 , a lower end turn  52  and a plurality of central convolutions  54  between the end turns. Each compound nested spring  36  is a pair of coil springs, a taller outer coil spring  60  and a shorter inner coil spring  70 . Taller outer spring  60  has an upper end turn  62 , a lower end turn  64 , and a plurality of central convolutions  66  between the end turns. Shorter inner spring  70  has an upper end turn  72 , a lower end turn  74 , and a plurality of central convolutions  76  between the end turns, and is encapsulated in its own individual fabric pocket  81 . Note that the coil springs  34  and the coil springs  60  of the compound nested springs  36  can be the identical spring. 
     Preferably, the interconnected fabric pockets  40  are formed from a single piece of fabric  80  folded over onto itself and around the coil springs. Overlapping edges of the opposite sides or plies  82 ,  84  of the fabric  80  can be sewn, adhered, welded, or otherwise secured together creating a longitudinal seam (not shown). Transverse seams  90 , likewise formed by sewing, adhering, welding, etc. form the individual pockets  40 . Although the seams in all of the embodiments shown herein are shown as being heat welded spaced rectangles, any of the seams may be spaced dots, triangles or solid line segments without spaces. Further construction details of the pockets  40  of strings  30 ,  32  may be seen with reference to the Applicant&#39;s co-pending U.S. patent application Ser. No. 13/921,499 filed Jun. 19, 2013, hereby incorporated by reference herein as if fully set forth in its entirety. 
     Referring to  FIGS. 3A and 3B , the strings  30 ,  32  of pocketed springs have a generally planar top or upper surface  92  in a top plane P 1  and a parallel generally planar bottom or lower surface  94  in a bottom plane P 2 . The linear distance between the top and bottom surfaces  92 ,  94  of the strings  30 ,  32  of pocketed springs defines a height H of the strings  30 ,  32  of pocketed springs. This linear distance further defines the height H of the pocketed spring assembly  12  because each of the strings  30 ,  32  of springs has the same height. However, it is within the scope of the present invention that different strings of springs of a pocketed spring assembly have different heights. 
     In accordance with an embodiment of the present invention, in strings  32 , the transverse seams  90  forming the adjacent pockets  40  are divided as at  96  to thereby form a cut, slit, or notch by, for example, cutting, slitting, severing, melting, or the like, from the upper surface  92  of the string  32  inwardly (downwardly as illustrated), so as to partially separate the adjacent pockets  40 . Preferably, the divide  96  extends to beyond or below the upper end turn  72  of the shorter spring  70  of compound nested spring  36 . By way of a non-limiting example, the shorter coil springs  70  can be 7 inches tall and the taller coil springs  60  can be 8 inches tall. In strings  30 , however, the transverse seams  90  extend the full height of the strings, i.e. there is no divide  96 . 
     The significance of divide  96  may be appreciated with reference to  FIG. 3B . Divide  96  essentially decouples each compound nested spring  36  from its adjacent single springs  34  during initial deflection of compound nested spring  36 . This creates more of an individual coil performance and allows the shorter coil spring  70  to engage a person sleeping on the mattress  10  sooner while giving the person a softer feel at the beginning of the coil deflections. It is believed that this arrangement provides a more comfortable product  10 . 
     Referring now to  FIG. 4 , the strings  30 ,  32  of springs are shown in one preferable arrangement for a spring core  12  for a mattress  10 . As can be seen, the strings  32  of alternating single springs  34  and compound nested springs  36  are arranged in a plurality of zones  98  on the mattress  10 . By way of example, five zones  98  are illustrated, with the zones corresponding roughly to the location of a sleeper&#39;s head, shoulders, mid-section, knees, and feet. By way of further example, the two upper zones are each formed from two strings  32 , the middle zone is formed from four strings  32 , and the two lower zones are formed from two strings  32 . The strings  32  are arranged such that the single springs  34  and compound nested springs  36  are staggered relative to one another in the longitudinal direction. The balance of the spring core is made up of strings  30  of pocketed single springs  34 . Of course, other arrangements are within the scope of the invention. 
     The various embodiments of the invention shown and described are merely for illustrative purposes only, as the drawings and the description are not intended to restrict or limit in any way the scope of the claims. Those skilled in the art will appreciate various changes, modifications, and improvements which can be made to the invention without departing from the spirit or scope thereof. The invention in its broader aspects is therefore not limited to the specific details and representative apparatus and methods shown and described. Departures may therefore be made from such details without departing from the spirit or scope of the general inventive concept. The invention resides in each individual feature described herein, alone, and in all combinations of any and all of those features. Accordingly, the scope of the invention shall be limited only by the following claims and their equivalents.