Abstract:
A pressure vessel suitable for use in an automotive air-conditioning system includes a cylindrical body ( 10, 40 ) including an annular wall ( 14, 44 ). The cylindrical body preferably includes an opposite closed end, an initially opened end ( 12, 42 ), and a closure member ( 20, 50 ) inserted into the open end of the cylindrical body. The closure member and the cylindrical body each have extensions or annular flanges ( 28, 58 ) which are spin welded together. The cylindrical body is fused to the closure member when the annular flange ( 28, 58 ) of the closure member is spin welded to an annular, outermost portion ( 18, 48 ) of the cylindrical body. The closure member and the cylindrical body are further locked together by inwardly rolling a portion of the annular wall into an annular groove ( 30, 60 ) and an outermost surface of the closure member.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This is a divisional application of Ser. No. 08/721,829 now filed on Sep. 27, 1996 U.S. Pat. No. 5,855,293, issued Jan. 5, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a pressure vessel and to a method of manufacturing the pressure vessel. More particularly, this invention relates to a pressure vessel of the type used in an automotive air conditioning system such as a refrigerant receiver or an accumulator dehydrator. 
     2. Description of the Prior Art 
     U.S. Pat. No. 5,191,775, (Shiina et al.) discloses a receiver of the type used in an automotive air conditioning system and a method for the manufacture of such receiver. The receiver of the Shiina et al. reference is composed of a generally cylindrical body having a thin annular wall, a first integral and unitary end, and a disk-shaped closure member, commonly referred to as a puck, inserted into an opposed open end of the cylindrical body. The closure member is secured to the cylindrical body, after insertion of a desiccant material or other elements of the receiver, as used in a refrigerant circuit, into the interior of the cylindrical body. Shiina et al. disclose that the open end of the cylindrical body is reshaped by electromagnetic forming, after insertion of the closure member, to closely conform the interior of the open end of the cylindrical body to the exterior of the closure member to thereby secure the closure member and the cylindrical body to one another. Shiina et al. teach that the closure member and cylindrical body are sealed using O-rings. Nevertheless, the assembly of the closure member and the cylindrical body to one another according to this reference does not result in a receiver that is pressure-tight, i.e., that it eliminates all leak paths for the molecules of refrigerant fluid. Consequently, the O-rings must be used between the exterior of the closure and the interior of the cylindrical body to retain the refrigerant fluid within the receiver of this reference. 
     U.S. Pat. No. 5,425,250, to Hutchinson et al., also discloses a receiver for an automotive air conditioning system that consists of a generally cylindrical aluminum body with a thin annular wall and an initially open end which is closed, after the insertion of a desiccant material or other elements into the cylindrical body, by a disk-shaped aluminum closure member, or puck, inserted into the open end of the cylindrical body. According to the Hutchinson et al. reference, the closure member is joined to the cylindrical body using an annular weld. However, it is very well known in the art that welded joints, or even brazed joints, in an air conditioning system receiver are subject to leakage, and, therefore, have not been totally satisfactory in service because of such phenomena. 
     It is also well known to use spin welding for pressure vessels in an air-conditioning circuit, as disclosed, for example, in U.S. Pat. Nos. 4,628,704; 4,675,971; 5,245,842; and 5,375,327. 
     The disclosures of the aforesaid U.S. Pat. Nos. 5,191,775; 5,425,250; 4,628,704; 4,675,971; 5,245,842; and 5,375,327 are incorporated by reference herein. 
     SUMMARY OF THE INVENTION 
     The foregoing and other problems of prior art refrigerant receivers are overcome by the receiver of the present invention, and by the method of its manufacture, in which an aluminum disk-shaped closure member, or puck, is secured to an initially open end of a generally cylindrical thin-walled aluminum body utilizing a spin welding process. The spin welding process of the present invention is preferably used in conjunction with a rolling operation to roll an annular portion of the wall of the cylindrical body into an annular recess in the exterior of the closure member to form a positive mechanical lock between the cylindrical body and the closure member. The positive mechanical lock between the closure member and the cylindrical body, which results from the rolling operation, serves to overcome the tendency of the closure member to eject from the receiver under significant internal pressure, and the spin welding step of the present invention results in a continuous, leak-free seam between the cylindrical body and the closure member, eliminating the need for an O-ring or other sealing member therebetween, and does so without using a conventional welding or brazing operation to form a seam between the closure member and the cylindrical body, thereby eliminating the known processing problems associated with any such conventional welding operation. 
     To effect the spin welding of the cylindrical body of the receiver of the present invention to the closure member, the closure member and the cylindrical body are provided with relatively thin annular flanges, which are spaced close to one another when the closure member and the cylindrical body are properly positioned for the beginning of the spin welding operation. In one embodiment of the present invention, the annular flanges of the closure member and the cylindrical body extend in a direction essentially parallel to a longitudinal central axis of the cylindrical body, in which case the spin welding step is preferably accomplished by spinning a spinning tool, whose axis of rotation is aligned with the longitudinal central axis of the cylindrical body, relative to the cylindrical body and the closure member while they are held in fixed positions. In another embodiment of the present invention, the annular flanges of the closure member and the cylindrical body extend substantially perpendicular to the longitudinal central axis of the cylindrical body, in which case the welding is preferably accomplished by rotating the closure member and the cylindrical body with respect to a tool moving rectilinearly along an axis that extends substantially perpendicular to the longitudinal central axis of the cylindrical body. 
     Accordingly, it is an object of the present invention to provide an improved pressure vessel of a type having a cylindrical body having a thin annular wall and a closure member inserted into an initially open end of the cylindrical body and secured thereto, as well as an improved method for manufacturing such a pressure vessel. 
     For a further understanding of the present invention and the objects thereof, attention is directed to the drawings and the following brief description thereof, to the detailed description of the preferred embodiment of the invention, and to the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary view, in cross section, of a cylindrical body with an initially open end that is to be closed by a closure member to produce a pressure vessel in accordance with the preferred embodiment of the present invention; 
     FIG. 2 is a fragmentary view, in cross section, schematically illustrating a processing step to be performed on the cylindrical body and closure of FIG. 1 to produce a receiver according to the preferred embodiment of the present invention from the cylindrical body and closure of FIG. 1; 
     FIG. 3 is a fragmentary view, in cross section, schematically illustrating a subsequent processing step to be performed after the processing step of FIG. 2 to produce a receiver according to the preferred embodiment of the present invention from the cylindrical body and closure of FIG. 1; 
     FIG. 4 is a view similar to FIG. 2 of the cylindrical body and closure of FIG. 1 after completion of the processing step illustrated in FIG. 3; and 
     FIG. 5 is a view similar to FIG. 1 of an alternative embodiment of a cylindrical body and a closure to be joined to one another to produce a receiver in accordance with an alternative embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 illustrates a cylindrical body  10 , shown fragmentarily, the cylindrical body  10  having an initially open end  12  and preferably being formed from aluminum or an aluminum alloy. The cylindrical body  10  has a thin annular wall  14 , and the end  12  of the cylindrical body  10  is preferably enlarged, for example, by an impacting or expanding operation or as part of a deep draw process, such that the cylindrical body  10  preferably will have an outwardly projecting shoulder  16  which may, as illustrated in FIG. 1, also extend upwardly toward the open end  12 . 
     The open end  12  of the cylindrical body  10  is to be closed by a closure or puck  20  that is inserted into the open end  12 , and is later secured to the cylindrical body  10  as will be hereinafter described more fully. The closure  20  is formed of a material that is compatible with the material of the cylindrical body  10 , so as to be weldable to the cylindrical body  10  by spin welding. Thus, the closure  20  is also preferably formed of aluminum or an aluminum alloy when the cylindrical body  10  is formed of such a material. In any case, the closure  20  is preferably formed in its illustrated complex configuration by machining in a known manner, and has a main body portion  22  that fits snugly within the open end  12  of the cylindrical body  10 , a smaller end portion  24  and a shoulder  26  extending between the main body portion  22  and the end portion  24 . Preferably, the shoulder  26  of the closure  20  extends substantially or approximately parallel to the shoulder  16  of the cylindrical body  10 . 
     The closure  20  includes a relatively thin, annular flange  28  extending outwardly from the main body portion  22  of the closure  20  and substantially parallel to a longitudinal central axis of the cylindrical body  10 . The annular flange  28  is spaced close to an outermost portion  18  of the initially open end  12  of the cylindrical body  10 , for reasons which will be hereinafter described more fully. The axial position of the closure  20  relative to the open end  12  of the cylindrical body  10 , and thus the axial position of the annular flange  28  relative to the outermost portion  18  of the open end  12 , is preferably accurately fixed by the shoulder  16  of the cylindrical body  10 , which limits the distance the closure  20  can be inserted into the cylindrical body  10 . 
     The main body portion  22  of the closure  20  is also provided with an annular groove  30 . After the closure  20  is in the position shown in FIG. 1 relative to the cylindrical body  10 , a rolling tool R preferably engages the exterior of the open end  12  of the cylindrical body  10 , at a location in alignment with the annular groove  30 , to roll a portion  12   a  of the open end  12  into the annular groove  30  as illustrated in FIG.  2 . The engagement between the rolled portion  12   a  of the open end  12  of the cylindrical body and the annular groove  30  of the closure  20  serves to lock the closure  20  and the cylindrical body  10  to one another and prevent ejection of the closure  20  from the cylindrical body  10  as a result of positive pressure within the cylindrical body  10 , which is common within a receiver for an automotive air conditioning system, the intended application for the combined cylindrical body  10  and closure  20  at the conclusion of the manufacturing operations to be performed thereon. However, it is possible to use any known technique, besides rolling, for forcing the portion  12   a  into the annular groove  30 . 
     At the conclusion of the processing step illustrated in FIG. 2, the cylindrical body  10  and closure  20 , now mechanically locked together but not sealed, are axially aligned with a spinning tool S, which is caused to spin at a relatively high rotational velocity about its central axis and is axially translated toward the cylindrical body  10  and closure  20 , while the cylindrical body  10  is held in a fixed position, for example, in a conventional chuck, not shown. The axial advance of the spinning tool S gradually traps the outermost portion  18  of the open end  12  of the cylindrical body  10  and the annular flange  28  of the closure  20  in a generally V-shaped groove G of the spinning tool S to urge the outermost portion  18  and the annular flange  28  toward one another. The high rotational speed spinning of the spinning tool S relative to the fixed cylindrical body  10  generates heat sufficient to weld the outermost portion  18  and the annular flange  28  to one another in a continuous piece, which will be completely leak-free as opposed to a seam formed by brazing, a conventional process for joining aluminum components to one another, or by any other welding process. 
     It should be appreciated that it is also possible to further roll form the outermost portion  18  to further conform with the annular flange  28  prior to the spinning operation. 
     The nonillustrated end of the cylindrical body  10  that is opposed to the open end  12  is preferably integral to the annular wall  14 , or further the cylindrical body  10  may be formed in a unitary one-piece configuration by a deep drawing operation as is known in the art. For example, the aforesaid U.S. Pat. No. 5,191,775 discloses such a one-piece body, which is identified by reference numeral  11  therein. Alternatively the nonillustrated end of the cylindrical body  10  may also be closed by a separate closure, not shown, similar to the closure  20  that is affixed to the open end  12  of the cylindrical body  10 , and affixed thereto in a similar manner, as heretofore described. 
     While not illustrated, it is to be understood that the closure  20  may be, and preferably is, provided with openings extending therethrough to permit necessary inlet and outlet tubes, not shown, to be affixed to the closure  20  for the purpose of permitting refrigerant fluid to flow into and out of the cylindrical body  10 , as is also shown, for example, in the aforesaid U.S. Pat. No. 5,191,775. 
     FIG. 5 illustrates a vessel that is made up of a cylindrical body  40  with an initially open end  42 . The cylindrical body  40  is preferably formed of aluminum or an aluminum alloy and is defined by an annular wall  44 . The free end of the initially open end  42  of the cylindrical body  40  is provided with a radially outwardly projecting annular flange  48 . A closure  50 , which is also preferably formed of aluminum or an aluminum alloy and preferably by machining, has a radially outwardly projecting annular flange  58 , and is inserted into the open end  42  of the cylindrical body  40  until the radial flange  58  of the closure  50  abuts against the radial flange  48  of the cylindrical body  40  and the radial flanges  48  and  58  are aligned for further processing. 
     The closure  50  also has an annular groove  60  in its exterior side, similar to the annular groove  30  of the closure  20  of the embodiment of FIGS. 1 through 4, and the annular wall  44  of the cylindrical body  40  preferably is rolled into the annular groove  60  to positively lock the closure  50  and the cylindrical body  40  to one another, though such step is not positively illustrated in FIG.  5 . Moreover, the closure  50  has an opening  62  extending therethrough, the opening  62  having a small diameter innermost portion  62   a  and a larger diameter outermost portion  62   b , separated by an annular shoulder  62   c . An annular tube  70  is inserted into the cylindrical body  40  through the opening  62  to introduce refrigerant fluid into the cylindrical body  40 . The tube  70  has an outermost annular flange  70   a  that abuts against the annular shoulder  62   c  of the opening  62 , and a bead  70   b  that abuts against an inner surface  64  of the closure  50  to positively position the tube  70  axially with respect to the closure  50 . The bead  70   b  may be formed using any known process such as cold forming or, preferably, rolling. 
     To form a leak-free seal between the closure  50  and the cylindrical body  40 , and specifically between the annular flange  48  and the annular flange  58 , the assembly of the cylindrical body  40  and the closure  50  is caused to spin about the longitudinal central axis of the cylindrical body  40  at a relatively high rotational velocity, and a translating tool T is advanced toward the annular flange  48  and the annular flange  58  while the cylindrical body  40  and the closure  50  are rotating. The tool T has a generally V-shaped groove G 1  that engages the annular flange  48  and the annular flange  58  while they are spinning, to generate a level of heat that will cause the annular flange  48  and the annular flange  58  to fuse, or weld, to one another to eliminate any potential leak path for the molecules of the refrigerant fluid. A pressure vessel formed by the method of FIG. 5 will, thus, have an external lip that can be used to facilitate the assembly of such a pressure vessel to an automotive vehicle as well as provide a sealed, secured pressure vessel. 
     Although the best mode contemplated by the inventor for carrying out the present invention as of the filing date hereof has been shown and described herein, it will be apparent to those skilled in the art that suitable modifications, variations and equivalents may be made without departing from the scope of the invention, such scope being limited solely by the terms of the following claims and the legal equivalents thereof.