Reinforced pocket spring mattress

Abstract

A pocket spring mattress may include a plurality of double layer spring units, each including an upper pocket spring unit arranged axially onto a lower pocket spring unit. The upper pocket spring unit may have an upper fabric pocket, and the lower pocket spring unit may have a lower fabric pocket. The upper fabric pocket and the lower fabric pocket may be formed from a same continuous fabric material. An upper spring may be enclosed in the upper fabric pocket and a lower spring may be enclosed in the lower fabric pocket. The upper fabric pocket and the lower fabric pocket may be welded therebetween, such that a welded seam extends between the upper and the lower springs. The springs may be reference springs having a first spring constant and frame springs having a second spring constant greater than the first spring constant.

1 . A pocket spring mattress comprising:
 a plurality of double layer spring units arranged in rows and columns to form a rectangular shaped mattress, each of the double layer spring units including
 an upper pocket spring unit arranged axially onto a lower pocket spring unit, the upper pocket spring unit having an upper fabric pocket, and the lower pocket spring unit having a lower fabric pocket, the upper fabric pocket and the lower fabric pocket being formed from a same continuous fabric material, 
 an upper spring and a lower spring, the upper spring being enclosed in the upper fabric pocket and the lower spring being enclosed in the lower fabric pocket, 
 the upper fabric pocket and the lower fabric pocket being welded therebetween to form the double layer spring unit, such that a welded seam extends between the upper spring and the lower spring; 
   wherein the upper springs or the lower springs are reference springs having a first spring constant and frame springs having a second spring constant greater than the first spring constant;   wherein frame springs are arranged in at least one of the upper and the lower pocket spring units of at least one outermost row or column of the double layer spring units in a configuration such that the edge of the mattress is reinforced; and   wherein the frame springs have a greater wire diameter than a wire diameter of the reference springs to provide the second spring constant being greater than the first spring constant.   
     
     
         2 . The pocket spring mattress according to  claim 1 , wherein a series of adjacent double layer spring units are attached to each other to form an elongated spring string. 
     
     
         3 . The pocket spring mattress according to  claim 2 , wherein each spring string is arranged side by side with another spring string forming an upper spring layer formed by the upper pocket spring units, and a lower spring layer formed by the lower pocket spring units. 
     
     
         4 . The pocket spring mattress according to  claim 1 , wherein frame springs are arranged in at least one of the upper and the lower pocket spring units of at least two adjacent outermost rows or columns of the double layer spring units. 
     
     
         5 . The pocket spring mattress according to  claim 1 , wherein frame springs are arranged only in the upper pocket spring units of two adjacent outermost rows and columns of the double layer spring units, forming a reinforced edge around the circumference of the mattress. 
     
     
         6 . The pocket spring mattress according to  claim 1 , wherein frame springs are arranged only in the lower pocket spring units of two adjacent outermost rows and columns of the double layer spring units, forming a reinforced edge around the circumference of the mattress. 
     
     
         7 . The pocket spring mattress according to  claim 1 , wherein frame springs are arranged in the upper and the lower pocket spring units of two adjacent outermost rows and columns of the double layer spring units, forming a reinforced edge around the circumference of the mattress. 
     
     
         8 . The pocket spring mattress according to  claim 1 , wherein the second spring constant of the frame springs is at least 15% higher than the first spring constant of the reference springs. 
     
     
         9 . The pocket spring mattress according to  claim 1 , wherein the continuous fabric material is a nonwoven fabric material comprising thermoplastic material. 
     
     
         10 . The pocket spring mattress according to  claim 2 , wherein each spring string comprises between 14 and 16 double layer spring units per meter of spring string; and
 wherein each spring string is attached via an adhesive side by side to another spring string.   
     
     
         11 . A method for manufacturing a plurality of double layer spring units arranged in a spring string configured to form a mattress having a plurality of double layer spring units arranged in rows and columns to form a rectangular shaped mattress, each of the double layer spring units including an upper pocket spring unit arranged axially onto a lower pocket spring unit, the upper pocket spring unit having an upper fabric pocket, and the lower pocket spring unit having a lower fabric pocket, the upper fabric pocket and the lower fabric pocket being formed from a same continuous fabric material, each of the double layer spring units including an upper spring and a lower spring, the upper spring being enclosed in the upper fabric pocket and the lower spring being enclosed in the lower fabric pocket, the upper springs or the lower springs being reference springs having a first spring constant and frame springs having a second spring constant being greater than the first spring constant, wherein frame springs are arranged in at least one of the upper and the lower pocket spring units of at least one outermost row or column of the double layer spring units in a configuration such that the edge of the mattress is reinforced, wherein the frame springs have a greater wire diameter than a wire diameter of the reference springs to provide the second spring constant being greater than the first spring constant,
 wherein the method comprises:   determining whether a reference wire or a frame wire is to be used to form the upper spring of the upper pocket spring units and whether a reference wire or a frame wire is to be used to form the lower spring of the lower pocket spring units,   feeding the determined upper wire and the determined lower wire,   heating the determined wires,   bending the determined upper wire and the determined lower wire,   cutting each wire to form the upper spring and the lower spring,   placing the upper and the lower springs in the upper and the lower fabric pockets, respectively, and   sealing the upper and the lower fabric pockets via welding to form a double layer spring unit, such that a welded seam extends between the upper spring and the lower spring.   
     
     
         12 . The method according to  claim 11 , further comprising arranging the upper spring and the lower spring in a common pocket, and sealing the common pocket around the springs and between the upper spring and the lower spring thereby forming the upper fabric pocket for the upper spring and the lower pocket for the lower spring, thus forming two pocket spring units together forming the double layer spring unit. 
     
     
         13 . The method according to  claim 11 , wherein the fabric material is cut to form a spring string after a predetermined number of double layer spring units are formed. 
     
     
         14 . The method according to  claim 13 , further comprising attaching each spring string via an adhesive, or by ultra-sonic welding, side by side to another spring string. 
     
     
         15 . The method according to  claim 12 , further comprising sealing the pockets via ultra-sonic welding. 
     
     
         16 . The pocket spring mattress according to  claim 1 , wherein the second spring constant of the frame springs is at least 30% higher than the first spring constant of the reference springs. 
     
     
         17 . The pocket spring mattress according to  claim 2 , wherein each spring string comprises 15 double layer spring units per meter of spring string; and
 wherein each spring string is attached via an adhesive side by side to another spring string.   
     
     
         18 . The pocket spring mattress according to  claim 13 , wherein each spring string comprises between 14 and 16 double layer spring units per meter of spring string; and
 wherein each spring string is attached via a hot melt adhesive, side by side to another spring string.   
     
     
         19 . The method according to  claim 13 , further comprising attaching each spring string via a hot melt adhesive side by side to another spring string.