Patent Publication Number: US-2007094806-A1

Title: Air mattress with pressure control system

Description:
The present invention relates to a mattress, and in particular to a mattress in which the support of the user&#39;s body can be adjusted in a manual or automatic manner.  
      Some known mattresses comprise an external cover in which a padding including one or more air chambers suitable for being inflated for supporting the body of at least one user is arranged. However, the pressure inside these air chambers is fixed or, as in the case of the medical mattresses for preventing decubitus ulcers, is periodically changed with alternated pressures in the adjacent air chambers, so that the user cannot directly intervene for modifying in a stable manner the support of the mattress according to his comfort needs.  
      U.S. Pat. No. 5,142,717, US 2003/0221261 A1 and EP 663169 disclose mattresses comprising air chambers connected to an electric compressor by means of an air inlet provided with a valve which is opened or closed by a control unit according to control signals coming a pressure sensor. However, these air chambers are relatively wide or long, so that the air pressure supporting the users cannot be precisely controlled and/or adapted according to the users&#39; weight, position and movements on the mattresses.  
      It is therefore an object of the present invention to provide a mattress which is free from said disadvantage. Said object is achieved with a mattress, the main features of which are disclosed in the first claim and other features are disclosed in the subsequent claims.  
      Thanks to the electric compressor, the electric valves, the pressure sensors and the control unit, the users can adjust in a precise and stable manner the pressure in the mattress according to the present invention, which is preferably provided with more groups of air chambers in which the pressure can be adjusted in a different manner for each portion of the body, so as to improve the user&#39;s comfort.  
      According to a particular advantageous aspect of the invention, the groups of air chambers can be obtained by an upper sheet of a deformable material, which is shaped and welded to a lower sheet so as to obtain in a simple and inexpensive manner not only a plurality of alveoli for the air chambers, but also the ducts which mutually connect these alveoli in each group of air chambers.  
      According to another particular advantageous aspect of the invention, the control unit is provided with a digital memory and can communicate with a remote control, so as to automatically adapt the pressure in each group of air chambers according to the user&#39;s weight and/or to modify said pressure for further improving the comfort of the same user. 
    
    
      Further advantages and features of the mattress according to the present invention will become clear to those skilled in the art from the following detailed and non-limiting description on an embodiment thereof, with reference to the attached drawings, wherein:  
       FIG. 1  shows a cross-sectioned top view of the mattress according to the present invention;  
       FIG. 2  shows and enlarged view sectioned along plane II-II of  FIG. 1 ; and  
       FIG. 3  shows a scheme of the mattress of  FIG. 1 . 
    
    
      Referring to  FIG. 1 , it is seen that the mattress according to the present invention comprises in a known way an external cover  1  in which a padding  2  including one or more air chambers  3  suitable for being inflated for supporting the body of at least one user is arranged. In the present embodiment, padding  2  has a substantially parallelepiped shape with four side walls and a base of polyurethane foam. The air chambers  3  have a substantially parallelepiped shape and are arranged in padding  2 , between its side walls and above its base, along more horizontal rows and columns so as to form at least one uniform layer of alveoli. For example, the present embodiment of the mattress, single and having a standard size, comprises sixteen rows by forty columns of air chambers  3 , which are in turn grouped into four groups of air chambers  3  mutually connected in each group. These four groups of air chambers  3  correspond to the head zone A, the lumbar zone B, the sacral zone C and the leg zone D of the user, respectively, wherein the depth of the latter zone is greater, in particular substantially twice, than the depth of any other zone A, B or C. For example, zones A, B and C comprise eight columns of air chambers  3  and zone D comprises  16  columns of air chambers  3 .  
      According to the invention, the air chambers  3  are connected by means of air inlets  4  and to an electric control device  5  which is suitable for controlling and modifying the air pressure in the air chambers  3  and is arranged in a space made in padding  2 , for example in a side wall thereof, so as to be accessible from the outside.  
      Referring also to  FIG. 2 , it is seen that the air chambers  3  are preferably obtained by an upper sheet  6  of a deformable material, for example natural lattice or neoprene, PVC or polyurethane, which is shaped so as to form a plurality of alveoli with a substantially parallelepiped shape which are open downwards and are mutually connected by stripes of the same material along their lower edges. A lower sheet  7  of a deformable material, for example the same material of the upper sheet  6 , is welded along said stripes so as to hermetically close the alveoli and to obtain the air chambers  3 . In each of the four groups A, B, C and D, the air chambers  3  communicate with one or more adjacent air chambers  3  through a slit  8  made between the upper sheet  6  and the lower sheet  7 . Slit  8  is obtained by preventing the welding between the two sheets  6 ,  7  along a portion of the stripe which joins the lower edges of the relevant alveoli, for example by arranging a tape of an non-adhering material under the upper sheet  6  and/or on the lower sheet  7  in the zone of the stripe in which slit  8  is desired, or by obtaining a thin canal, preferably with a section lower than 1 mm 2 , during the shaping of the alveoli in the upper sheet  6 .  
      Reinforcing members  9  which have a complementary shape and a smaller size with respect to the inside of the air chambers  3  and are made of a deformable material, for example polyurethane foam, are further arranged in the air chambers  3  for assuring that they maintain a minimum volume even if deflated. A flexible net  10 , for example made of nylon, which distributes the load from the top on a wider surface, as well as a sheet  11  of a deformable material, for example polyurethane foam with closed cells, which maintains the deformed shape for a determinate period, in particular at least  10  seconds, are arranged on the air chambers  3  so as to improve the user&#39;s comfort.  
      With reference to  FIG. 3 , it is seen that the control device  5  suitably comprises an electric compressor  12  which can suck air from the outside through a duct  13  and pump it through inlets  4  into one or more groups A, B, C and/or D of air chambers  3 . Inlets  4  are provided with an electric valve  14  connected to an electronic control unit  15 , for example provided with a microprocessor. This control unit  15  is connected also to electric valves  16 , arranged along outlets  17  which connect the groups A, B, C and D of air chambers  3  with the outside, as well as to an automatic switch  18 , for example a relay or a transistor, arranged along an electric line between compressor  12  and an electric power source  19 , in particular a battery. The electric valves  14 ,  16  are normally closed and the automatic switch  18  is normally open, so as to save electric energy during the use. The control unit  15  opens or closes the electric valves  14  or  16 , as well as the controlled switch  18  according to control signals coming from a plurality of pressure sensors  20 , each connected to a group A, B, C or D of air chambers  3  and preferably arranged on the side opposite to inlets  4  and/or outlets  17 . The control unit  15  is provided or connected with at least one digital memory  21  suitable for storing some pressure values of the groups A, B, C and D of air chambers  3  and can communicate with an external remote control  22 , for example through a radio transceiver  23  or a cable. The remote control  22  is provided with a display  24 , for example LCD, a keyboard  25  and a power switch  26 , as well as with other electric and/or electronic devices, also of the known kind, which are necessary for its working, such as batteries, connection and power circuits, control units and/or a transceiver for the exchange of control signals with transceiver  23 .  
      During the use, the control unit  15  compares the signals coming from the pressure sensors  20  with a series of pressure values stored in the digital memory  21 . These values can correspond to a series of standard pressure values or to values preset by the user.  
      The following table shows an example of the minimum and maximum standard values expressed in Pa in each group A, B, C, and D of air chambers  3  according to the total user&#39;s weight.  
               TABLE 1                          standard pressure values                                 User&#39;s weight   Zone A   Zone B   Zone C   Zone D               15-40 kg   14660-15330   17995-19330   16660-17995   15330-16660       40-50 kg   14660-15990   17330-18670   16660-17995   15330-16660       50-60 kg   14660-15990   16660-17995   16660-17995   15330-16660       60-70 kg   15330-16660   15990-17330   15330-16660   15990-17330       70-80 kg   15330-16660   15330-16660   14660-15990   15990-17330       80-90 kg   15990-17330   15330-16660   13990-16660   15990-17330       90-100 kg    15990-17330   14660-15990   13330-14660   15990-17330       100-110 kg    16660-17330   12660-13990   12660-13990   16660-17995       110-120 kg    16660-17330   11330-12660   12000-13330   16660-17995       120-130 kg    17330-18670    9990-11330   11330-12660   17330-18670       130-140 kg    17330-18670    9990-11330   10665-12000   17330-18670       140-150 kg    17330-18670    9330-10665    9330-10665   14660-15990                  
 
      The user can therefore input his own weight by means of keyboard  25  of the remote control  22 , so that the control unit  15  loads from the digital memory  21  the series of pressure values corresponding to said weight. These values correspond to the inner pressure of the air chambers  3  without the user on the mattress and may vary according to the control signals sent by the user through keyboard  25  of the remote control  22 , so that the user can increase or decrease the pressure in one or more air groups of chambers  3  according to his needs. In any case, the standard or the user&#39;s settings are detected by the pressure sensors  20  and stored into the digital memory  21  when no force is exerted onto the air chambers, i.e. when the user does not lie down on the mattress, so as to obtain a greater reading precision.  
      The control device  5  therefore acts as a manostat by suitably opening or closing the electric valves  14  or  16  and/or the automatic switch  18  for keeping the pressure constant, for example within a range of 500 Pa, in one or more groups of air chambers  3  according to the real pressure detected by the pressure sensors  20  and to the ideal pressure values stored in the digital memory  21 . All these pressure values can be transmitted in real time from the control unit  15  and displayed by display  24  of the remote control  22 .