Non-circular pressure vessel

Abstract

A reservoir assembly includes one or more pressure vessels each having a non-circular cross-sectional shape including a rounded rectangle having four generally flat sides with rounded corners. The pressure vessels may be formed of extruded metal, such as aluminum, and have a generally constant cross-section. The pressure vessels include stiffening ribs and varying wall thicknesses to improve strength and to minimize stresses when pressurized, such as during operation when filled with compressed gas. The stiffening ribs meet in the center of each of the pressure vessels and divide the interior volumes into four equal sections. A cap of stamped aluminum is fitted and fully welded to enclose each end of the pressure vessels. One or both of the caps on each of the pressure vessels has a pressure fitting. Two or more pressure vessels extend parallel to one another and are attached together to form the reservoir assembly.

1 . A reservoir assembly comprising:
 a first pressure vessel surrounding a first volume and having a constant cross-section along a first length between two ends;   wherein the constant cross-section defines a closed shape of a rounded rectangle having four generally flat sides with rounded corners; and   a second pressure vessel enclosing a second volume outside of the first volume, the second pressure vessel having a constant cross-section defining a closed shape of a rounded rectangle extending along a second length that extends parallel to the first length.   
     
     
         2 . (canceled) 
     
     
         3 . The reservoir assembly of  claim 1 , wherein at least one of the first pressure vessel or the second pressure vessel is formed of extruded metal. 
     
     
         4 . The reservoir assembly of  claim 1 , wherein the constant cross-section of the first pressure vessel includes a stiffening rib within the first volume. 
     
     
         5 . The reservoir assembly of  claim 4 , wherein the stiffening rib is one of a plurality of stiffening ribs within the first volume, with each of the stiffening ribs extending outwardly from a center of the constant cross-section of the first pressure vessel to divide the first volume of the first pressure vessel into equal sections. 
     
     
         6 . The reservoir assembly of  claim 5 , wherein each of the stiffening ribs extends to a midpoint of an associated one of the generally flat sides. 
     
     
         7 . The reservoir assembly of  claim 1 , wherein the first pressure vessel has a varying wall thickness. 
     
     
         8 . The reservoir assembly of  claim 1 , further comprising a cap enclosing each of the two ends of the first pressure vessel for sealingly enclosing the first volume. 
     
     
         9 . (canceled) 
     
     
         10 . The reservoir assembly of  claim 1 , wherein the second pressure vessel is attached to the first pressure vessel to define a constant cross-section of the reservoir assembly configured to fit within an irregularly shaped space. 
     
     
         11 . A method of forming a reservoir assembly comprising:
 forming a first pressure vessel surrounding a first volume and having a constant cross-section of a first rounded rectangle having four generally flat sides with rounded corners along a first length between two first ends;   sealing each of the two first ends with a cap to enclose the first volume;   forming a second pressure vessel surrounding a second volume and having a constant cross-section of a second rounded rectangle having four generally flat sides with rounded corners along a second length between two second ends; and   attaching the second pressure vessel to the first pressure vessel.   
     
     
         12 . The method of  claim 11 , wherein forming the first pressure vessel further includes extruding aluminum into the constant cross-section of the first rounded rectangle. 
     
     
         13 . The method of  claim 11 , wherein sealing each of the two first ends further includes welding the cap onto each of the two first ends. 
     
     
         14 . The method of  claim 13 , further comprising machining each of the two first ends prior to sealing each of the two first ends. 
     
     
         15 . (canceled) 
     
     
         16 . The reservoir assembly of  claim 1 , wherein the first volume of the first pressure vessel is in fluid communication with the second volume of the second pressure vessel. 
     
     
         17 . The reservoir assembly of  claim 1 , wherein the first volume of the first pressure vessel is in fluid communication with the second volume of the second pressure vessel. 
     
     
         18 . The reservoir assembly of  claim 3 , wherein the first pressure vessel and the second pressure vessel are each formed of extruded metal. 
     
     
         19 . The reservoir assembly of  claim 4 , wherein the stiffening rib is one of a plurality of stiffening ribs within the rounded rectangle, with at least one of the plurality of stiffening ribs extending perpendicularly to another one of the plurality of stiffening ribs. 
     
     
         20 . The reservoir assembly of  claim 8 , further comprising a pressure fitting disposed on one of the caps enclosing one of the two ends of the pressure vessel to provide fluid communication between the first volume of the first pressure vessel and the second volume of the second pressure vessel. 
     
     
         21 . The method of  claim 11 , wherein forming the first pressure vessel further includes forming stiffening ribs within the constant cross-section of the first rounded rectangle. 
     
     
         22 . The method of  claim 11 , wherein forming the second pressure vessel further includes extruding aluminum into the constant cross-section of the second rounded rectangle; and
 wherein forming the second pressure vessel further includes forming stiffening ribs within the constant cross-section of the second rounded rectangle.   
     
     
         23 . The method of  claim 11 , further including: sealing each of the two second ends with a cap to enclose the second volume.