Patent Publication Number: US-2007094807-A1

Title: Posturized bedding or seating product incorporating Bonnell coil springs with tapered middle portions

Description:
FIELD OF THE INVENTION  
      This invention relates to a posturized bedding or seating product in which certain sections are firmer than other sections of the product and the associated method of manufacturing such a product.  
     BACKGROUND OF THE INVENTION  
      Conventional bedding or seating products have a spring core made of a plurality of coil springs arranged into a matrix of rows and columns. Each of the coil springs has an upper end turn, a lower end turn and a plurality of central convolutions therebetween. The end turns may be knotted or unknotted. Coil springs having knotted end turns are known as Bonnell springs in the industry. The diameter of the end turns may be identical to the diameter of the central convolutions of the coil spring. Alternatively, the end turns of the coil springs may be of a larger or smaller diameter than the central convolutions of the coil spring. In some coil springs, the central convolutions taper from one end turn to the other. In other coil springs the central convolutions taper to a smaller diameter and then return to a larger diameter as they approach the end turns, thereby creating an “hourglass” shape. Typically, the coil springs are of the same height for ease of assembly.  
      The coil springs are usually connected or joined together by securing the end turns of adjacent coil springs to each other using helical lacing wire. The helical lacing wire encircles the end turns of adjacent coil springs, thus securing adjacent rows or adjacent columns of coil springs together. By lacing all of the coil springs together, a unitary spring core or spring assembly is made. Often one or two generally rectangular border wires are secured to the outermost coil springs of a spring core or spring assembly.  
      The spring core is commonly covered on one or both surfaces with padding and then wrapped in an upholstered material. Bedding or seating products made in this manner using identical coil springs typically have a uniform feel or firmness across the entire surface of the product due, at least in part, to the coil springs being identical and oriented the same direction within the spring core.  
      Other types of products are posturized, that is, different sections or zones of the bedding or seating product have different levels of firmness within the product. For example, the middle region of the mattress, which typically supports a person&#39;s torso, often requires a firmer less resilient support while other areas of the mattress which support the feet and head of a person require less support.  
      One known method of posturizing a spring unit has been to incorporate coil springs made of different gauge wire into the spring core. For example, rows of coil springs within certain sections or zones of the spring assembly are made of a heavier gauge wire than the springs incorporated into rows of the other sections or zones of the spring assembly. U.S. Pat. No. 6,173,464 discloses this concept, albeit with continuous bands of springs as opposed to individual springs. Due to the fact that different coil springs must be incorporated into the assembled spring core, the manufacturing cost of producing such a posturized product may be relatively high and assembly may be difficult.  
      Therefore, there is a need for a posturized spring assembly and associated method of manufacture which offers the advantages of posturization of the spring assembly without the higher manufacturing costs, production difficulties and inefficiencies associated with known posturized spring assemblies.  
     SUMMARY OF THE INVENTION  
      The present invention comprises a posturized bedding or seating product made of identical coil springs and its associated method of manufacture. The bedding or seating product comprises a posturized spring assembly, one or more pads and an upholstered covering surrounding the spring assembly and pad(s). The product is preferably two sided, but may be one sided.  
      The spring assembly or spring core within the product comprises a plurality of identical coil springs arranged in rows and columns and joined together with helical lacing wires at the end turns of the coil springs. Each of the coil springs comprises a first knotted end turn, a second knotted end turn and a plurality of central convolutions between the knotted end turns. In accordance with the practice of this invention, the central convolutions of the spring are conically tapered in diameter from the first knotted end turn to the second knotted end turn. Such springs are hereinafter referred to as conically tapered coil springs and are to be distinguished from cylindrical coil springs which have all of the central convolutions of approximately the same diameter or hourglass-shaped springs which have the central convolutions varying in diameter so as to form an hourglass shape from top to bottom.  
      The bedding or seating product typically has a longitudinal dimension and a transverse dimension, the longitudinal dimension being greater than the transverse dimension. However, the longitudinal dimension and transverse dimension may be identical in a square bedding or seating product. In the invention, the helical lacing wires may extend longitudinally or transversely, depending upon the desired effect.  
      At least one border wire may extend around the perimeter of the spring assembly of the bedding or seating product and be secured to select outermost coil springs. A first or lower border may be secured to the lower end turns of the outermost or perimeter coil springs. A second or upper border wire may be secured to the upper end turns of the outermost or perimeter coil springs. Alternatively, either border wire may be secured to intermediate convolutions of the outermost coil springs.  
      The spring core or assembly is divided into zones or sections of differing firmness, each of the sections comprising a plurality of rows or a plurality of columns of coil springs secured together. The zones or sections may extend from side-to-side (transversely) or from end-to-end (longitudinally) of the product.  
      Due to the conically tapered coil springs in one section, zone or region of the spring core being oriented differently than the coil springs in another section of the spring assembly, at least one section of the spring assembly has a “softer” feel when a load is placed thereon than at least one other section.  
      One aspect of the invention is a bedding or seating product which includes a spring core having a plurality of identical conically tapered coil springs. Each of the coil springs has a first knotted end turn, a second knotted end turn, and a plurality of central convolutions between the knotted end turns. The central convolutions taper in diameter from the first knotted end turn to the second knotted end turn. The spring core is divided into sections of differing firmness. All of the coil springs of at least one of the sections have the first knotted end turn above the second knotted end turn. All of the coil springs of at least one other section are inverted so as to have the first knotted end turn below the second knotted end turn. The bedding or seating product also includes padding located above the spring core and an upholstered covering surrounding the padding and the spring core.  
      Helical lacing wires join the coil springs together and can join them in adjacent rows or columns, i.e., extend laterally or longitudinally of the product. In addition, in some embodiments, a border wire is secured to some of the coil springs. The differing firmness sections can extend from one side of the product to the other side of the product, or, can extend from end-to-end in different embodiments. In some embodiments, the diameter of the knotted end turns of the coil springs are identical and in others, they may differ.  
      Another aspect of the invention is a method of manufacturing a posturized bedding or seating product having sections of different firmness. The method includes providing a plurality of identical coil springs arranged in rows and columns. Each of the coil springs has a first knotted end turn, a second knotted end turn and a plurality of central convolutions between the knotted end turns. The central convolutions are tapered conically in diameter from the first knotted end turn towards the second knotted end turn. The method also includes arranging the coil springs into rows and columns. The coil springs of several adjacent rows are oriented such that the first knotted end turn is above the second knotted end turn, and the coil springs of other adjacent rows are inverted and oriented such that the second knotted end turn is above the first knotted end turn. The method also includes joining the coil springs together with helical lacing wires.  
      Yet another aspect of the invention is a method of manufacturing a posturized bedding or seating product having sections of different firmness. The method includes providing a plurality of identical coil springs arranged in rows and columns. Each of the coil springs has a first knotted end turn, a second knotted end turn and a plurality of central convolutions between the knotted end turns. The central convolutions taper conically in diameter from the first knotted end turn towards the second knotted end turn. The method also includes arranging the coil springs into rows and columns. The coil springs of several adjacent columns or rows are oriented such that the first knotted end turn is above the second knotted end turn. The coil springs of other adjacent columns or rows are inverted and oriented such that the second knotted end turn is above the first knotted end turn. The method also includes joining the coil springs together with helical lacing wires.  
      These and other features of the present invention will be more readily apparent from the following drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view of a posturized bedding product made in accordance with the present invention comprising a spring assembly made of identical coil springs surrounded by generally rectangular border wires;  
       FIG. 2  is a perspective view of a coil spring made in accordance with the present invention in a first orientation;  
       FIG. 3  is a perspective view of the coil spring of  FIG. 2  oriented in a second inverted orientation;  
       FIG. 4  is a diagrammatic top plan view of the spring core of the spring assembly of  FIG. 1 ;  
       FIG. 4A  is a cross-sectional view taken along the line  4 A- 4 A of  FIG. 4 ;  
       FIG. 5  is a diagrammatic top plan view of an alternative embodiment of spring core assembly made in accordance with the present invention;  
       FIG. 6  is a diagrammatic top plan view of an alternative embodiment of spring core assembly made in accordance with the present invention; and  
       FIG. 7  is a diagrammatic top plan view of an alternative embodiment of spring core assembly made in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
      Referring to the drawings, and particularly to  FIG. 1 , there is illustrated a bedding or seating product in the form of a mattress  10 . Although a mattress  10  is illustrated, the present invention may be used to construct any bedding or seating product. The mattress  10  comprises a spring assembly or core  12  having a generally planar top surface  14  in a top plane P 1  and a parallel generally planar bottom surface  16  in a bottom plane P 2 . Covering pads  18  (only one being shown) may be located on the top and bottom surfaces  14 ,  16  of the spring core assembly  12 . The covering pads  18  are usually formed from a cotton, felt, foam, or a synthetic fiber, but other materials can be used in other embodiments. An upholstered covering  20  or ticking encases the spring assembly  12  and the covering pads  18 .  
      The mattress  10  has a height H defined as the distance between the top and bottom surfaces  14 ,  16  of the spring assembly  12 . Similarly, the mattress  10  has a transverse dimension or width W defined between opposed side surfaces  22  and a longitudinal dimension or length L defined as the distance between the opposed end surfaces  24  of the mattress  10 . The longitudinal dimension is illustrated as being larger than the transverse dimension of the mattress  10 , although it is within the contemplation of the present invention that the longitudinal and transverse dimensions be identical, such as in a square product.  
      The spring assembly or core  12  is divided into two sections  26 ,  28  in the embodiment illustrated in  FIGS. 1 and 4 . Any number of sections readily apparent to those skilled in the art may be used in other embodiments, such as those illustrated herein with respect to  FIGS. 5, 6  and  7 . In the embodiment illustrated in  FIG. 1 , there is a first “soft” section  26  and a second “firm” section  28 . The first section  26  is soft or has a “soft” feel because the coil springs  30  are constructed and oriented such that a predetermined amount of give or resilience exists within the springs  30 . The second section  28  is a more firm section (firmer than first section  26 ) because the coil springs  30  are constructed and oriented such that a predetermined amount of resilience exists within the coil springs  30 . The construction and orientation of the coil springs  30  are discussed in detail with respect to  FIGS. 2-7 .  
      Referring now to  FIG. 2 , a single spring  30  of the spring assembly  12  is illustrated. The coil spring  30  is usually formed from high carbon steel of between twelve and three-fourths and fifteen and a half gauge wire. However, those skilled in the art recognize that other gauges and materials can be used. The spring  30  has a first knotted end turn  32  and a second knotted end turn  34 . These types of springs are known as “Bonnell” springs in the industry. The knotted end turns  32 ,  34  are formed by bending a wire into a generally circular shape. The illustrated knotted end turns  32 ,  34  have identical diameters, but other embodiments have varying diameters. Positioned between the knotted end turns  32  and  34  is a middle section  36 . The middle section  36  includes a plurality of convolutions that taper conically from one end of the middle section  36  to the other. This conically-shaped middle section  36 , which in the illustrated embodiment comprises three full convolutions, has its largest diameter convolution  37  connected directly to or terminating at the first end turn  32 . The smallest diameter convolution  37 ′ is connected to the other or second end turn  34  by a connector section of wire  39 . The end of the wire forming the end turn  32  terminates in a knot  38  that couples the end turn  32  to the next adjacent convolution and the end turn  34  terminates in a knot  40  that couples end turns  34  to the connector section  39 . The knots  38 ,  40  are formed by bending or wrapping an end portion of the length of wire from which the spring is made around the convolution which is next adjacent the end turns  32 ,  34 . Positioning or orienting the springs  30  as illustrated in  FIG. 2  into a bedding or seating product results in providing more give or more resilience (softer feel) to the top of the bedding or seating product having springs so oriented as opposed to having the springs  30  inverted as illustrated in  FIG. 3  because the larger turns or convolutions of the middle section  30  of the spring are at the top of the product. When the springs are inverted, the smaller diameter turns of the middle section  36  of the spring  30  are at the top and the top therefore has a more firm feel and is less resilient beneath the inverted spring when compressed from the top.  
      For example, in the embodiment illustrated in  FIG. 1 , coil springs  30  are placed inside the mattress  10  in different orientations. The coil springs  30  of the first section  26  are oriented as shown in  FIG. 2 , whereas the coil springs  30  of the second section  28  are oriented as shown in  FIG. 3 . In the coil springs  30  of the first section  26 , the first knotted end turn  32  is located proximate to the generally planar top surface  14  of the mattress  10 . Accordingly, the convolutions of the middle section  36  taper from a larger diameter to a smaller diameter as they move towards the generally planar bottom surface  16 . The larger convolutions located close to the first knotted end turn  32  have a greater flexibility and deflect more than the smaller convolutions positioned close to the second knotted end turn  34 . Accordingly, the first section  26  of the mattress  10  has more give and has a softer feel than the second section  28  of the mattress  10 . As illustrated in  FIG. 1 , the springs  30  of the first section  26  of the product  10  are positioned in this manner, providing a “soft” feel.  
      Referring to  FIG. 3 , like reference characters are used to denote identical parts. The coil spring  30  is a spring identical to the coil spring  30  illustrated in  FIG. 2  except that the position or orientation of the coil spring  30  has been inverted. The first knotted end turn  32  is now below the second knotted end turn  34  in the illustration. The convolutions of the middle portion  36  now taper from a large diameter to a smaller diameter as they extend upwardly. Positioning the coil spring  30  as illustrated in  FIG. 3  in the mattress  10  results in more firmness and less resilience in a portion the bedding or seating product when the coil spring  30  is compressed from the top.  
      For example, placing the spring  30  of  FIG. 3  inside the mattress  10  of  FIG. 1  with the second knotted end turn  34  proximate to the top surface  14  of the mattress  10  provides a firmer top surface  14  than the bottom surface  16 . The second knotted end turn  34  has smaller diameter convolutions positioned close to the knotted end turn  34  that will not deflect as much as the larger diameter convolutions. Accordingly, the mattress  10  will have a firmer feel. The second section  28  of the mattress  10  illustrated in  FIG. 1  has springs  30  positioned in such a manner.  
      Referring now to  FIG. 4 , the spring core  12  of the mattress  10  of  FIG. 1  is illustrated from a diagrammical top view. The mattress  10  of  FIG. 1  is commonly referred to as a “his and her” mattress. The “his and her” name refers to the fact that there are two sections having different levels of firmness. Therefore, a couple can choose a mattress and custom design the levels of firmness to each of their personal preferences. The mattress  10  is divided into the first section  26  and the second section  28 . The first section  26  has a soft feel, which is illustrated by the coil springs  30  having two closely spaced concentric circles representing the first knotted end turn  32  and the larger diameter convolution  37  of the middle portion  36  of a coil spring  30 . In contrast, the second section  28  of the mattress  10  has a “firm” feel (firmer than the first section  26 ) illustrated by the springs  30  having two further spaced concentric circles representing the second knotted end turn  34  and the smaller diameter convolution  37 ′ of the middle portion  36  of the coil spring  30 .  
      All of the springs  30  are joined together using the helical lacing wires  42 .  FIG. 4  illustrates the springs being laced together in columns that run parallel to the length of the mattress  10  or from end-to-end.  FIG. 4  illustrates a border wire  44  surrounding the spring assembly  12  and secured to outermost coil springs  30  of the spring assembly  12 , thereby providing edge support to the spring assembly  12 , as is known in the art.  
       FIG. 5  illustrates an identical mattress  10 ′ to the one illustrated in  FIG. 4  except that the helical lacing wires  42 ′ joining the springs  30  together extend in a transverse direction connecting adjacent rows, as opposed to adjacent columns of springs  30 , the helical lacing wires  42 ′ extending from side-to-side. In addition,  FIG. 5  illustrates a border wire  44 ′ surrounding a spring assembly  12 ′ and providing edge support to the spring assembly  12 ′. The mattress  10 ′ has a “soft” section  26 ′ and a “firm” section  28 ′ due to the orientation of the coil springs  30 , as described above.  
       FIG. 4A  illustrates how the springs  30  are positioned along one of the transversely extending rows of springs  30  illustrated in  FIG. 4 . The first section  26  of the mattress  10  has springs  30  positioned so that the first knotted end turn  32  is above the second knotted end turn  34 . The first knotted end turn  32  is also proximate to the top surface  14  of the mattress  10 . Due to the springs  30  having this orientation or positioning, the first section  26  has a soft feel. Conversely, the second section  28  has springs  30  inverted and positioned with the first knotted end turn  32  below the second knotted end turn  34 . The second knotted end turn  34  and the smaller convolutions of the middle portions  36  of the springs  30  are proximate to the top surface  14  of the mattress  10 . This positioning results in a firmer feel in the second section  28  compared to the first section  26 .  
       FIG. 6  illustrates an alternate embodiment of a mattress  46  that has three sections of differing firmness. Identical reference characters are used to describe identical parts. The three sections alternate moving along the longitudinal dimension or length of the mattress  46 . Adjacent columns of springs  30  also joined together using helical lacing wires  42 ″, the helical lacing wires  42 ″ extending along the longitudinal dimension of the mattress  46  (from end-to end). The first section  48  is a soft section. This soft section  48  as illustrated includes five transversely extending rows along the longitudinal dimension. This provides a soft area that will support either the head and shoulder or the feet and legs of a person lying on the mattress. The first section  48  therefore does not need as much resilience because the first section  48  is not supporting the heavier parts of the body. The second section  50  is a firmer section that includes six transversely extending rows of springs as illustrated. The second section  50  is firmer than the first section  48  to provide support for the upper and lower torso, the heavier parts of the body. Therefore, the second section  50  needs more resistance to support those heavy parts of the body. The third section  52  is identical to the first section, positioned only on the other end of the mattress  46 . Together, the first, second and third sections  48 ,  50 , and  52  provide a posturized mattress  46  that increases the support where it is needed most, in the middle of the product or mattress.  
      Referring now to  FIG. 7 , an alternative embodiment of a mattress  54  is illustrated. Identical reference characters denote identical parts. In this embodiment, the three sections are arranged alternatively along the transverse dimension or width of the mattress  54 . The first section  56  is a firm section along the outer portion of the mattress  54 . The second section  58  is a softer section arranged in the central portion of the mattress  54 . In addition, the third section  60  is another firmer section. This positioning creates a soft central section  58  surrounded by the firmer sections  56  and  60 . A consumer that desires a soft area to sleep in with outer support would prefer this arrangement.  
      Although I have described several preferred embodiments of our invention, I do not intend to be limited except by the scope of the following claims.