Abstract:
An inflatable air cushion has at least two sets of tension members therein. Each set of tension members includes multiple and parallel tension members. The tensile directions generated by the two sets of tension members are perpendicular. One of the tension members can be a strap member, and the other tension member can be a sheet member.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an inflatable air device, such as an inflatable mattress, inflatable sofa, inflatable bridge or an inflatable boat. 
   2. Description of the Related Art 
   When an inflatable mattress, cushion or other device is inflated, the surfaces on the device are usually arc-shaped; so, in order to provide a flat surface, many sheet members are typically mounted on the inflatable air cushion, as disclosed in U.S. Pat. No. 6,754,925, No. 6,618,884 and No. 5,598,593. Taking a rectangular air cushion as an example, for all six faces the prior art technologies only provide two “approximately flat” surfaces (the surfaces which a user can lie on), but no such “approximately flat” surfaces are provided for the other four surfaces. However, some applications for three-dimensional contours require a hexahedron with four or six approximately-flat surfaces, such as inflatable sofas. 
   Therefore, it is desirable to provide an inflatable air cushion with more than two flat surfaces to mitigate and/or obviate the aforementioned problems. 
   SUMMARY OF THE INVENTION 
   An objective of the present invention is to provide an inflatable air cushion in the shape of a hexahedron having four or six approximately-flat surfaces; taking a rectangular air cushion as an example, four or six surfaces are provided that are “approximately flat” when the cushion is inflated. 
   In order to achieve the above mentioned objective, the inflatable air cushion of the present invention has at least two sets of tension members therein. Each set of tension members includes multiple and parallel tension members. The directions of tensile force generated by the two sets of tension members are perpendicular. Both tension members can be strap members, or one of the tension members may be a strap member, and the other tension member may be a sheet member. When the tension member is a sheet member, it can have at least one aperture so that the strap member can pass through the aperture. 
   The inflatable air cushion of the present invention can also have three sets of tension members, wherein all can be strap members, or two strap members matching one sheet member. Taking a rectangular air cushion as an example, with three sets of tension members, all six faces of the rectangular air cushion are “approximately flat” when the rectangle air cushion is inflated. 
   Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a first embodiment according to the present invention. 
       FIG. 2  is a perspective view showing a connection between strap members and a cover in a first embodiment according to the present invention. 
       FIG. 3  is a perspective view showing connection between strap members and a cover in a second embodiment according to the present invention. 
       FIG. 4  is a perspective view of a second embodiment according to the present invention. 
       FIG. 5  is a perspective view of a third embodiment according to the present invention. 
       FIG. 6  is a perspective view of a fourth embodiment according to the present invention. 
       FIG. 7  is a perspective view of a fifth embodiment according to the present invention. 
       FIG. 8  is a perspective view of a sixth embodiment according to the present invention. 
       FIG. 9  is a perspective view of a seventh embodiment according to the present invention. 
       FIG. 10  is a perspective view of an eighth embodiment according to the present invention. 
       FIG. 11  is a perspective view of a ninth embodiment according to the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The following description provides nine embodiments. 
   Please refer to  FIG. 1  and  FIG. 3 . As shown in  FIG. 1 , an inflatable air cushion  10  comprises a cover  20  comprising an outer surface  21  and an inner surface  22 , and a gas containment chamber  90  formed within the inner surface  22  of the cover  20 . An inlet device  30  is installed on the cover  20  to insure the chamber  90  remains full after inflation of air cushion  10 , and to provide storage convenience after deflating air cushion  10 . 
   When the gas containment chamber  90  is inflated, a three-dimensional space  91  is formed, and a first direction axis  81 , a second direction axis  82  and a third direction axis  83  define the three-dimensional space  91 , wherein the axes are perpendicular to each other. 
   The inflatable air cushion  10  further comprises a plurality of first tension members  40  and a plurality of second tension members  50 . In the first embodiment, the second tension members  50  are sheet members  56 ; each sheet member  56  includes four ends  51 ,  52 ,  53 ,  54 , wherein two ends  51 ,  52  are connected to the inner surface  22  of the cover  20  along the second direction axis  82 . Therefore, when the inflatable air cushion  10  is fully inflated, it pulls along the second direction axis  82 , but the other two ends are not connected to the inner surface  22  of the cover  20 . The sheet member  56  is a well-known member, and so requires no further description. Every first tension member  40  is a strap member  47 , and two ends  41 ,  42  of the strap member  47  are connected, along the first direction axis  81 , to the inner surface  22  of the cover  20  so the strap member  47  along the first direction axis  81  comes under tension when the inflatable air cushion is inflated. Since strap members  47  are perpendicular to the sheet member  56 , a plurality of apertures  561  on the sheet member  56  permit the strap members  47  to pass through. The strap members  47  can be connected to the cover  20  in various ways; for example, as shown in  FIG. 2 , a fixed base  71  with an aperture  711  is mounted on the inner surface  22  of the cover  20 , and one end of the strap member  47  is connected to the fixed base  71  via the aperture  711 . Another example, as shown in  FIG. 3 , has a long strip  72  mounted on the inner surface  22  of the cover  20 , and a dish  73  with a plurality of apertures  731  is fixed on the long strip  72  so that one end of the plurality of strap members  47  can be connected to the dish  73  via the apertures  731 . 
   Please refer to  FIG. 4  for a second embodiment. The major difference between the first and second embodiments is that the direction of extension of the strap member  47  of the inflatable air cushion  10   a  is identical to that of the sheet member  56 , and so the sheet member  56  has no apertures  561 . Both the strap member  47  along the first direction axis  81   a  and the sheet member  56  along the second direction axis  82   a  come under tension when the inflatable air cushion  10   a  is inflated. 
   Please refer to  FIG. 5  for a third embodiment. The major difference between the first and third embodiments is that the inflatable air cushion  10   b  further comprises a plurality of third tension members  60 . Each third tension member  60  is a strap member  67 , and has two ends  61 ,  62  connected to the inner surface  22  of the cover  20  so that the strap member  67  along the third direction axis  83  comes under tension when the inflatable air cushion  10   b  is inflated. 
   Please refer to  FIG. 6  for a fourth embodiment. The major difference between the first and fourth embodiments is that two ends  53 ,  54  of the second tension members  50 ,  56  of the inflatable air cushion  10   c  are connected to the inner surface  22  so that the sheet member  56  along the third direction axis  83  comes under tension when the inflatable air cushion  10   c  is inflated. 
   Please refer to  FIG. 7  for a fifth embodiment. The major difference between the first and fifth embodiment is that the second tension member  50  in the inflatable air cushion  10   d  is a strap member  57  instead of a sheet member  56 . 
   Please refer to  FIG. 8  for a sixth embodiment. The major difference between the fifth and sixth embodiments is that the inflatable air cushion  10   e  further comprises a plurality of third tension members  60 . Each third tension member  60  is a strap member  67  and has two ends  61 ,  62  that are connected to the inner surface  22  of the cover  20  so that the strap member  67  can pull along the third direction axis  83  when the inflatable air cushion  10   e  is inflated. The first tension member  40  (strap member  47 ) along the first direction axis  81   e  comes under tension, and the second tension member  50 , (strap member  57 ) along the second direction axis  82   e  comes under tension. 
   Please refer to  FIG. 9  for a seventh embodiment. The major purpose of this embodiment is to show that the inflatable air cushion  10   f  can have more than one set of lines for the first tension member  40  (strap member  47 ). 
   Please refer to  FIG. 10  for an eighth embodiment. The major purpose of this embodiment is to show that the inflatable air cushion  10   g  can have any shape, and is not limited to only rectangular shapes; the first tension member  40  (strap member  47 ) and the second tension member  50 , (sheet member  56 ) can be disposed at different positions or have different shapes according to the shape of the inflatable air cushion  10   g.    
   Please refer to  FIG. 11  for a ninth embodiment. The major purpose of this embodiment is to further show that the inflatable air cushion  10   h  can have any shape, is not limited to only rectangular shapes, and may have inclined surfaces; the first tension member  40  (strap member  47 ) and the second tension member  50  (sheet member  56 ) can be disposed at different positions or have different shapes according to the shape of the inflatable air cushion  10   h.    
   Although the present invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.