Patent Publication Number: US-9848711-B2

Title: Mattress assembly

Description:
FIELD OF THE INVENTION 
     The present invention relates to mattress assemblies, and more particularly to mattress assemblies for use in beds. 
     BACKGROUND OF THE INVENTION 
     Mattress assemblies are typically used in a bed to support a user&#39;s body or a portion thereof (e.g., head, shoulders, legs, etc.) while the user is at rest. Some mattress assemblies include multiple foam layers. Such mattress assemblies can be costly to manufacture and heavy. Conventional mattress assemblies can also differ in firmness and comfort feel by adjusting the number, thickness and composition of the constituent foam layers. 
     SUMMARY OF THE INVENTION 
     The invention provides, in one aspect, a mattress assembly including a first layer of viscoelastic foam defining an upper surface, and a second layer of non-viscoelastic foam supporting the first layer. The mattress assembly also includes a plurality of static spring elements positioned beneath the upper surface for enhancing a firmness of the combined first and second layers. 
     Other features and aspects of the invention will become apparent by consideration of the following detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a mattress assembly in accordance with an embodiment of the invention. 
         FIG. 2  is a cross-sectional view of the mattress assembly of  FIG. 1 , taken along line  2 - 2  in  FIG. 1 . 
         FIG. 3  is a cross-sectional view of the mattress assembly of  FIG. 1 , taken along line  3 - 3  in  FIG. 1 . 
         FIG. 4  is a cross-sectional view, similar to that of  FIG. 2 , of a mattress assembly in accordance with another embodiment of the invention. 
         FIG. 5  is a cross-sectional view, similar to that of  FIG. 3 , of the mattress assembly of  FIG. 4 . 
     
    
    
     Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. 
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a mattress assembly  1  for use in a bed. The mattress assembly  1  includes a first layer  4  of viscoelastic foam defining an upper surface  8  of the mattress assembly  1  and having a thickness T 1  ( FIG. 2 ). Viscoelastic foam is sometimes referred to as “memory foam” or “low resilience foam.” Coupled with the slow recovery characteristic of the viscoelastic foam, the first layer  4  can at least partially conform to the user&#39;s body or body portion (hereinafter referred to as “body”), thereby distributing the force applied by the user&#39;s body upon the viscoelastic foam layer  4 . The viscoelastic foam layer  4  can provide a relatively soft and comfortable surface for the user&#39;s body. 
     The viscoelastic foam layer  4  has a hardness of at least about 20 N and no greater than about 80 N for desirable softness and body-conforming qualities. Alternatively, the viscoelastic foam layer  4  may have a hardness of at least about 30 N and no greater than about 70 N. In still other alternative embodiments, the viscoelastic foam layer  4  may have a hardness of at least about 40 N and no greater than about 60 N. Unless otherwise specified, the hardness of a material referred to herein is measured by exerting pressure from a plate against a sample of the material to a compression of 40 percent of an original thickness of the material at approximately room temperature (e.g., 21 to 23 degrees Celsius). The 40 percent compression is held for a set period of time, following the International Organization of Standardization (ISO) 2439 hardness measuring standard. 
     With continued reference to  FIG. 1 , the viscoelastic foam layer  4  can also have a density providing a relatively high degree of material durability. The density of the viscoelastic foam layer  4  can impact other characteristics of the foam, such as the manner in which the viscoelastic foam layer  4  responds to pressure, and the feel of the viscoelastic foam layer  4 . In the illustrated embodiment, the viscoelastic foam layer  4  has a density of no less than about 30 kg/m 3  and no greater than about 150 kg/m 3 . Alternatively, the viscoelastic foam layer  4  may have a density of at least about 40 kg/m 3  and no greater than about 135 kg/m 3 . In still other alternative embodiments, the viscoelastic foam layer  4  may have a density of at least about 50 kg/m 3  and no greater than about 120 kg/m 3 . 
     The viscoelastic foam layer  4  can be made from non-reticulated or reticulated viscoelastic foam. Reticulated viscoelastic foam has characteristics that are well suited for use in the mattress assembly, including the enhanced ability to permit fluid movement through the reticulated viscoelastic foam, thereby providing enhanced air and/or heat movement within, through, and away from the viscoelastic foam layer  4  of the mattress assembly  1 . Reticulated foam is a cellular foam structure in which the cells of the foam are essentially skeletal. In other words, the cells of the reticulated foam are each defined by multiple apertured windows surrounded by struts. The cell windows of the reticulated foam can be entirely gone (leaving only the cell struts) or substantially gone. For example, the foam may be considered “reticulated” if at least 50 percent of the windows of the cells are missing (i.e., windows having apertures therethrough, or windows that are completely missing and therefore leaving only the cell struts). Such structures can be created by destruction or other removal of cell window material, or preventing the complete formation of cell windows during the manufacturing process. 
     With reference to  FIG. 1 , the mattress assembly  1  also includes a second layer  12  of non-viscoelastic foam supporting the viscoelastic foam layer  4 . The non-viscoelastic foam layer  12  has a thickness T 2  that is greater than the thickness T 1  of the viscoelastic foam layer  4 . Alternatively, the thickness T 2  of the non-viscoelastic foam layer  12  may be the same or less than the thickness T 1  of the viscoelastic foam layer  4 . The non-viscoelastic foam layer  12  may be a latex foam or a high-resilience (HR) polyurethane foam. Such a latex foam has a hardness of at least about 30 N and no greater than about 130 N for a desirable overall mattress assembly firmness and “bounce.” Alternatively, the latex foam may have a hardness of at least about 40 N and no greater than about 120 N, or at least about 50 N and no greater than about 110 N. The latex foam has a density of no less than about 40 kg/m 3  and no greater than about 100 kg/m 3 . In still other alternative embodiments, the latex foam may have a density of at least about 50 kg/m 3  and no greater than about 100 kg/m 3 , or at least about 60 kg/m 3  and no greater than about 100 kg/m 3 . 
     In embodiments of the mattress assembly  1  in which the non-viscoelastic foam layer  12  includes HR polyurethane foam, such a foam can include an expanded polymer (e.g., expanded ethylene vinyl acetate, polypropylene, polystyrene, or polyethylene), and the like. The HR polyurethane foam has a hardness of at least about 80 N and no greater than about 200 N for a desirable overall cushion firmness and “bounce.” Alternatively, the HR polyurethane foam may have a hardness of at least about 90 N and no greater than about 190 N, or at least about 100 N and no greater than about 180 N. The FIR polyurethane foam has a density, which provides a reasonable degree of material durability to the non-viscoelastic foam layer  12 . The HR polyurethane foam can also impact other characteristics of the non-viscoelastic foam layer  12 , such as the manner in which the non-viscoelastic foam layer  12  responds to pressure. The FIR polyurethane foam has a density of no less than about 10 kg/m 3  and no greater than about 80 kg/m 3 . In still other alternative embodiments, the HR polyurethane foam may have a density of no less than about 15 kg/m 3  and no greater than about 70 kg/m 3 , or no less than about 20 kg/m 3  and no greater than about 60 kg/m 3 . 
     With reference to  FIGS. 2 and 3 , the mattress assembly  1  further includes multiple static spring elements  16  positioned beneath the upper surface  8  of the mattress assembly  1  for enhancing a firmness of the combined viscoelastic and non-viscoelastic foam layers  4 ,  12 . Particularly, the spring elements  16  are embedded into the non-viscoelastic foam layer  12  using a molding process, and the viscoelastic foam layer  4  is attached to the upper surface  20  of the non-viscoelastic foam layer  12  (e.g., using adhesives, etc.). In the illustrated embodiment the spring elements  16  are aligned with a thickness T 3  of the mattress assembly  1  and are entirely encased within the non-viscoelastic foam layer  12  ( FIG. 2 ). In other words, each spring element  16  is separated or isolated from adjacent spring elements  16  by the non-viscoelastic foam layer  12 . Alternatively, the spring elements  16  may be partially encased within the non-viscoelastic foam layer  12  and covered by the viscoelastic foam layer  4  such that the spring elements  16  may be positioned between the viscoelastic and non-viscoelastic foam layers  4 ,  12 . 
     The spring elements  16  are arranged in an array having multiple rows and multiple columns ( FIG. 3 ). The array can be in the form of a grid, in which the spring elements  16  are spaced across a portion or all of the width and length of the mattress assembly  1 . In such cases, consecutive spring elements  16  extending in width-wise and length-wise directions along the mattress assembly  1  can extend substantially parallel to the width and length of the mattress assembly  1 . Alternatively, consecutive spring elements  16  may extend diagonally with respect to the width and length of the mattress assembly  1 . In other words, each row may be offset or shifted relative to the preceding and/or following row. In still other alternative constructions, the spring elements  16  may be arranged randomly, in a single row, in a single column, or combinations thereof. 
     With continued reference to  FIGS. 2 and 3 , the spring elements  16  are made of a polymeric material, and more specifically, a thermoplastic material (e.g., TPEE, SBS, SEBS, TPV, etc.). The spring elements  16  are configured as coil springs having the same length. Alternatively, the spring elements  16  may be configured as leaf springs, for example, or any of a number of different types of springs. In still other alternative constructions, the spring elements  16  may include different lengths. For example, a first spring element  16  may have a different length than a second spring element  16  or a first group of spring elements  16  may have a different length than a second group of spring elements  16 , and so forth. In the illustrated embodiment of the mattress assembly  1 , the spring elements  16  have the same spring rates. Alternatively, the spring elements  16  may have different spring rates. For example, a first spring element  16  may have a different spring rate than a second spring element  16  or a first group of spring elements  16  may have a different spring rate than a second group of spring elements  16 , and so forth. 
     The spring rate of the spring elements  16  can be a constant spring rate or a variable spring rate. Spring elements  16  including a constant spring rate often have the same or a constant spacing between coils of the spring element  16  as compared to a variable spring rate, in which the spacing between the coils is different or variable. 
     In some embodiments of the mattress assembly  1 , the firmness of the combined viscoelastic and non-viscoelastic foam layers  4 ,  12  can be enhanced substantially uniformly across the width and length of the mattress assembly  1 . Alternatively, the firmness of the combined viscoelastic and non-viscoelastic foam layers  4 ,  12  can be enhanced non-uniformly across the width and length of the mattress assembly  1 . For example, the non-uniform firmness of the mattress assembly  1  may be tuned (e.g., by using different spring elements, different rate spring elements, a combination of constant and variable rate spring elements, etc.) in accordance with the locations or regions of the mattress assembly  1  normally associated with certain portions (e.g., head, shoulders, legs, etc.) of the user&#39;s body that require different support. In other words, the spring elements  16  may be selected to enhance the firmness of the combined viscoelastic and non-viscoelastic foam layers  4 ,  12  a greater amount in regions of the mattress assembly  1  associated with a reclined user&#39;s lower legs, posterior, and head/neck, for example. 
     With continued reference to  FIGS. 2 and 3 , the spring elements  16  have the same wire thickness, density, shape, and ring size. However, in alternative embodiments of the mattress assembly  1 , the wire thickness, density, shape, ring size, or combinations thereof may be altered to more or less enhance the firmness of the combined viscoelastic and non-viscoelastic foam layers  4 ,  12 . 
     When using the mattress assembly  1 , the user&#39;s body contacts the upper surface  8  of the mattress assembly  1 . In turn, the spring elements  16  enhance the firmness of the combined viscoelastic and non-viscoelastic foam layers  4 ,  12  to provide comfort to the user. By replacing a portion of the non-viscoelastic foam layer  12  with the spring elements  16 , the mattress assembly  1  has a lower cost and weight as compared to conventional mattress assemblies. Additionally, the mattress assembly  1  can be readily altered with respect to the comfort and feel provided to the user by altering the spring elements  16  to have a different spring rate, wire thickness, shape, and the like. In other words, the mattress assembly  1  can be manufactured in a cost-effective manner to provide users with different mattress assemblies  1  having different properties (e.g., firmness, comfort feel, etc.) by altering the spring elements  16  as compared to a conventional mattress assembly in which an entire layer or more would need be redesigned to provide a different mattress assembly to the user. 
       FIGS. 3 and 4  illustrate a second embodiment of the mattress assembly  1   a  used in connection with beds. Like components are identified with like reference numerals with the letter “a,” and will not be described again in detail. Rather than embedding the spring elements  16  into the non-viscoelastic foam layer  12  like that shown in  FIGS. 2 and 3  and described above, the mattress assembly  1   a  includes spring elements  16   a  positioned within discrete cavities  24  within the non-viscoelastic foam layer  12   a . The cavities  24  can be formed in the non-viscoelastic foam layer  12   a  by a drilling process or a cutting process, for example. The spring elements  16   a  are placed or positioned within the cavities  24 , and the viscoelastic foam layer  4   a  is attached or fastened to the upper surface  20   a  of the non-viscoelastic foam layer  12   a  (e.g., using adhesives, etc.). 
     The mattress assembly  1   a  is used in an identical fashion as the mattress assembly  1  shown in  FIGS. 2 and 3 . 
     Various features of the invention are set forth in the following claims.