Cushion structure

Abstract

A cushioning structure effective to alleviate a blood stream trouble and loads on muscles and to prevent an outbreak of trouble caused by them such as economy-class syndrome and the like is provided. The structure includes an upper elastic member 11 composed of a three-dimensional net member formed by connecting a pair of ground knitted fabrics disposed apart from each other using connecting yarn, and a spring constant in the range of initial load during a pressurizing process is set in the range of 0.1 to 20 N/mm and, at the same time, during a restoring process, a spring constant after restoring to an amount of displacement of 20 mm or less, at the latest, to 2 mm, is set to be lower than the spring constant in the range of initial load during the aforementioned pressurizing process. As a result, when a person comes into contact with a cushioning member by a sitting movement or a standing movement, temporal set in fatigue (stroke) of about several millimeters to about ten and several millimeters is created, thereby improving a feeling of fitting (compatibility) which makes a person feel comfortable, and effectively alleviate a blood stream trouble and loads on muscles.

1 . A cushioning structure including an elastic member composed of a three-dimensional net member formed by connecting a pair of ground knitted fabrics disposed apart from each other using connecting yarn, 
 wherein, as a load bearing characteristic of the cushioning structure, a spring constant during a pressurizing process is set in the range of 0.1 to 10 N/mm and, at the same time, during a restoring process, a spring constant after restoring to an amount of displacement of 20 mm or less, at the latest, to 2 mm, is set to be lower than the spring constant in the aforementioned pressurizing process.    
     
     
         2 . The cushioning structure according to  claim 1 , wherein the spring constant in the aforementioned pressurizing process is set in the range of 0.1 to 5 N/mm.  
     
     
         3 . The cushioning structure according to claims  1  or  2 , wherein the amount of hysteresis loss between the pressurizing process and the restoring process in the load bearing characteristic is in the range of 40 N or less.  
     
     
         4 . The cushioning structure according to any one of  claim 1  to  claim 3 , wherein the elastic member composed of the three-dimensional net member is configured to have a small reaction force such that as a load bearing characteristic during the pressurizing process the three-dimensional net member with a board for press of 30 mm in diameter alone, a spring constant after restoring to an amount of displacement of 20 mm or less, at the latest, to 1 mm during the restoring process is lower than the spring constant during the pressurizing process in the whole load bearing characteristic.  
     
     
         5 . The cushioning structure according to  claim 4 , wherein said three-dimensional net member formed in a structure having a small reaction force has a thickness in the range of 5 to 30 mm.  
     
     
         6 . The cushioning structure according to  claim 4  or  claim 5 , wherein said three-dimensional net member formed in a structure having a small reaction force is provided with concave and convex portions at least on one surface, and the elasticity of the concave portion and that of the convex portion are different from each other.  
     
     
         7  The cushioning structure according to  claim 6 , wherein said three-dimensional net member formed in a structure having a small reaction force has a structure in which the convex portion is formed substantially in an arch shaped cross section between adjacent concave portions, and the elasticity in a bending direction of the convex portion having the substantially arch shaped cross section and the damping caused by friction accompanying sliding of the connecting yarn disposed in the concave portions can be utilized.  
     
     
         8 . The cushioning structure according to any one of  claims 4  to  7 , wherein another elastic member serving as a function to prevent the cushion from bottom touch during the pressurizing process is provided below an elastic member composed of said three-dimensional net member formed in a structure with a small reaction force.  
     
     
         9  The cushioning structure according to  claim 8 , wherein aforementioned another elastic member serving as a function to prevent the cushion from bottom touch is a net type elastic member, a sheet type elastic member, or a net or sheet type elastic member supported via metal springs.  
     
     
         10 . The cushioning structure according to  claim 8  or  claim 9 , wherein aforementioned another elastic member serving as a function to prevent bottom touch is disposed at a predetermined interval to the elastic member composed of a three-dimensional net member formed in a structure with a small reaction force.  
     
     
         11 . The cushioning structure according to any one of  claim 4  to  claim 9 , wherein still another elastic member higher in surface stiffness than the elastic member composed of the three-dimensional net member formed in a structure with a small reaction force is layered, in addition to the elastic member composed of said three-dimensional net member formed in a structure with a small reaction force and aforementioned another elastic member serving to prevent bottom touch.  
     
     
         12 . The cushioning structure according to  claim 11 , wherein an elastic member composed of the three-dimensional net member formed in a structure with a small reaction force is laminated on the upper portion of still another elastic member described above, and another elastic member described above serving as a function to prevent bottom touch is arranged on the lower portion of still another elastic member described above at a predetermined interval.  
     
     
         13 . The cushioning structure according to any one of  claim 1  to  claim 12 , wherein the cushioning structure is applied to various seat structures including a vehicle seat and a furniture chair or a mat for furniture or for seating.  
     
     
         14 . The cushioning structure according to  claim 13 , wherein the cushioning structure is applied to a seat structure for an aircraft.