Abstract:
An apparatus for increasing the longevity of reed valves. Machines such as automotive air conditioning compressors operate with a centrally-located rotating shaft that requires lubricant seals. Assembly of such machines with access for installation of one or more shaft seals commonly dictates an annular cavity between the shaft outer diameter and the housing inner diameter. For reed valves radially deployed around the shaft, the result is an anchor point that, coupled with the commercial need for minimum overall machine diameter, restricts the allowable length of the valve reeds. A cylindrical insert that fits in the annular cavity provides for an anchor point close to the shaft, and a clamping device that anchors the reed to a retainer and its valve plate permits the use of longer reeds that offer enhanced life.

Description:
[0001]     This patent claims priority from and incorporates by reference the provisional U.S. patent application Ser. No. 60/646825, filed Jan. 25, 2005. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to the field of valves, more specifically to the field of reed valves. U.S. Pat. Nos. 6,454,545 B1 (Ikeda, 2002), 6,231,315 B1 (Ikeda, 2001), 5,454,397 (Miszczak, 1995), 5,355,910 (Gies, 1994), 5,226,796 (Okamoto, 1993), 5,186,475 (Kawai, 1993), 4,714,416 (Sano, 1987), 4,696,263 (Boyesen, 1987), 4,580,604 (Kawaguchi, 1986), 3,994,319 (Airhart, 1976), 3,983,900 (Airhart, 1976), 3,939,876 (Lundvik, 1976), 2,906,281 (Pillote, 1959), 2,881,795 (Waldenmaier, 1959), 2,864,394 (Hempel, 1958), and 2,476,320 (Paulus, 1949) disclose various valves comprising various cantilever or reed components. None of the cited patents disclose or claim the apparatus of the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0003]     The structure and operation of the invention will become apparent upon reading the following detailed description of the preferred embodiment and upon reference to the accompanying drawings in which like details are labeled with like identification numbers throughout. The drawings do not conform to a consistent scale.  
         [0004]      FIG. 1  is a cross sectional view of an air-conditioning compressor in which the preferred embodiment of the present invention bulkhead insert and reed stabilizer are installed.  
         [0005]      FIG. 2  is a cross-sectional view of the front bulkhead of a state-of-the-art air-conditioning compressor that does not embody the present invention.  
         [0006]      FIG. 3  is a cross-sectional view of the front bulkhead of the compressor of  FIG. 1  in which the preferred embodiment of the present invention bulkhead insert and reed stabilizer are installed.  
         [0007]      FIG. 4  is a cross-sectional view of the preferred embodiment of the present invention bulkhead insert.  
         [0008]      FIG. 5  is an isometric view of the cantilever portions of a reed valve, its integrated annular support structure, and two integrated tabs with alignment holes. The entire  FIG. 5  structure is herein referred to as a “reed.” 
         [0009]      FIG. 6  is a plan view of a reed retainer.  
         [0010]      FIG. 7  is a sectional view of one of the curved radial arms of a reed retainer.  
         [0011]      FIG. 8  is a plan view of a gasket.  
         [0012]      FIG. 9  is a plan view of a valve plate.  
         [0013]      FIG. 10  is a plan view of a suction reed.  
         [0014]      FIG. 11  is a cross-sectional view of a cylinder block assembly.  
         [0015]      FIG. 12  is a plan view of a shaft.  
         [0016]      FIG. 13  is an isometric view of a shaft, two valve plates, a gasket, a suction reed, a discharge reed, a discharge reed retainer, a piston, four alignment pins, and the preferred embodiment of the present invention bulkhead insert.  
         [0017]      FIG. 14  is a rotated view of  FIG. 13 .  
         [0018]      FIG. 15  is a cross-sectional view of a reed stabilizer.  
         [0019]      FIG. 16  is a large-scale view of the front bulkhead area of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0020]     The inventors present herein the best mode for carrying out the present invention in terms of its preferred embodiment, depicted within the aforementioned drawings. Herein, the preferred embodiment of the present invention will be considered to have a front end and a rear end. The end of the preferred embodiment where splined end  25  of shaft  12  in  FIGS. 1 and 12  protrudes from front bulkhead  2  will be referred to as the “front,” and the opposite end will be referred to as the “rear.” “Outboard” herein refers to the direction radially outward from the longitudinal axis of shaft  12 .  
         [0021]     A reed valve is a valve having a cantilever that is anchored, pinned, clamped, or otherwise held at one end, with the opposite end free to undergo displacement in the process of opening and closing a port or ports that provide ingress or egress of gases, fluids, and substances that have some fluidic characteristics including, but not limited to, grain, sand, and pellets. As is common in the many industries that employ valves, “reed” is used herein to denote the cantilever portion of a reed valve. Although it can be used in any application calling for a reed valve, the preferred embodiment of the present invention is incorporated in an air-conditioning compressor commonly understood in the automotive industry.  
         [0022]      FIG. 1  shows cylinder blocks  1  assembled between front bulkhead  2  and rear bulkhead  3  of an automotive compressor  100 . Within the interior cavities of cylinder blocks  1  are at least one piston  10  and a swash plate  9 . A drive belt, chain, gear, or other transfer means transfers automotive engine energy to splined end  25  (see  FIG. 12 ) of shaft  12 , and shaft  12  in turn imparts rotational motion to a swash plate  9  that is attached to shaft  12 . Motion of swash plate  9  converts rotary motion of shaft  12  into linear reciprocating motion of piston  10 .  
         [0023]     That reciprocating motion of piston  10  in a cylinder provides the refrigerant compression required in a cooling system. A cooling cycle includes stages of compression and expansion of a refrigerant gas. At the end of a compression stage, the pressure of the compressed gas forces valves to open, thus providing routes by which the gas can escape the compression chambers and proceed to the expansion part of the system where the desired cooling is achieved. The cantilever portion of a valve that provides for such gas transfer is called a discharge reed. Front discharge reed  7  and rear discharge reed  26  can be seen in  FIG. 1 . Front discharge reed  7  and rear discharge reed  26  are free to bend as far as front and rear reed retainers  8  and  24 , respectively, permit.  
         [0024]      FIGS. 2 and 3  show, respectively, a portion of a prior art air-conditioning compressor, and a like portion of a compressor equipped with the present invention.  FIG. 2  shows that the prior art anchor point of reed  14  is a distance (D 1 )/ 2  from the centerline of shaft  12 .  FIG. 3  shows that the anchor point of the present invention discharge reed  7  is a shorter distance (D 2 )/ 2  from the shaft centerline. The result is a present invention reed of length R 2  ( FIG. 3 ) greater than the prior art reed length R 1  ( FIG. 2 ). Because the bending stress imposed on a flexed cantilever is inversely proportional to the cantilever length, longevity of discharge reed  7  will be greater than that of reed  14  for the same displacement, cross-section, and material. MARKS&#39; STANDARD HANDBOOK FOR MECHANICAL ENGINEERS 5-24 (Theodore Baumeister ed., McGraw-Hill 8th ed. 1978).  
         [0025]     As shown in  FIGS. 3, 4 , and  16 , insert  13  is the present invention that provides for the increased length of discharge reed  7 . After shaft seal  11  is pressed into front bulkhead  2 , O-ring  19  and insert  13  are pressed into front bulkhead  2 . A sealant may be used to enhance the sealing capability of seal  11  and/or insert  13 . As illustrated in  FIGS. 3, 4 , and  16 , O-ring  15  is then fitted into circumferential cavity  27  in insert  13 .  
         [0026]     As shown in  FIG. 16 , front discharge reed  7  is placed concentrically on top of the surface of front valve plate  4  marked with the letter “F” (to denote “front”; see  FIG. 9 ), and front discharge reed retainer  8  is placed on top of front discharge reed  7  so that reed and reed retainer alignment holes  28  and  29 , respectively, align with the two alignment holes in front valve plate  4 . As shown in  FIG. 16 , the small diameter rear end D 3  of reed stabilizer  17  (see  FIG. 15 ) is slip-fitted into the concentric inner holes in reed retainer  8 , reed  7 , and front valve plate  4 , and then crimped. This riveting process creates a subassembly consisting of front reed retainer  8 , front reed  7 , front valve plate  4 , and reed stabilizer  17 .  
         [0027]     Next, front gasket  5 , shown in  FIGS. 1 and 8 , is installed on the side of front valve plate  4  marked with the letter “F,” shown in  FIGS. 1, 9 ,  13 , and  14 , so that front gasket  5  and front valve plate  4  are concentric, and holes  32  in gasket  5  align with holes  31  in valve plate  4 . The subassembly consisting of front reed retainer  8 , front reed  7 , front valve plate  4 , and reed stabilizer  17  is then installed so that gasket  5  is against front bulkhead  2 , stabilizer  17  is against O-ring  15 , and gasket holes  32  and valve plate holes  31  align with pins  34  (see  FIGS. 13 and 14 ) pressed into alignment holes (not shown) in front bulkhead  2 . A second set of pins (not shown) penetrates holes  28  and  29  in front discharge reed  7  and front reed retainer  8 , respectively, and the mating alignment holes in front valve plate  4 . Front suction reed  20 , shown in  FIGS. 1 and 10 , is then concentrically installed against valve plate  4  using pins  34  and holes  33  for alignment.  
         [0028]     Front suction reed  20 , shown in  FIG. 10 , in the described compressor featuring the preferred embodiment of the present invention, is a thin, flat, spring steel stamping partially comprising five integral lollipop shaped suction reeds  6  (see  FIG. 10 ) that each open to admit uncompressed refrigerant gas into a compression chamber as the piston in that chamber moves away from top dead center. Like the discharge reeds, the suction reeds are cantilevers, but in the described compressor design they are subjected to significantly less bending stress than are the discharge reeds. The present invention is not employed in the design of the suction reeds of the described compressor, but could be employed in a design in which suction reed valves are radially deployed around a shaft or some other central feature of a machine.  
         [0029]      FIG. 11  shows cylinder block assembly  300 , which includes shaft  12 , swash plate  9 , piston  10 , thrust washer and bearing assemblies  18  for swash plate retention, shaft needle bearings  16 , and cylinder blocks  1 . O-rings (not shown) are fitted in circumferential grooves  36  and  37  in the front and rear faces, respectively, of cylinder blocks  1 . Cylinder block assembly  300  is installed concentrically with front bulkhead  2  and against front valve plate  4  so that splined end  25  of shaft  12  protrudes through the center holes of front valve plate  4 , gasket  5 , front discharge reed  7 , front reed retainer  8 , insert  13 , shaft seal  11 , and front bulkhead  2 .  
         [0030]     Rear suction reed  21  (see  FIG. 1 ), a duplicate of front suction reed  20 , is then installed on the front side of rear valve plate  22 , and is aligned with pins  35  shown in  FIGS. 13 and 14 . Rear valve plate  22  is installed against the O-ring in groove  37  of the rear face of cylinder block assembly  300 . Rear discharge reed  26 , a duplicate of front discharge reed  7 , is installed against rear valve plate  22 . Rear reed retainer  24 , a duplicate of front reed retainer  8 , is then installed over shaft  12  and against rear discharge reed  26 .  
         [0031]     Utilizing receiver  19  (see  FIG. 13 ), rear reed retainer  24  and rear discharge reed  26  are secured to rear valve plate  22 . Gasket  23 , the mirror image of gasket  5  (see  FIG. 1 ) is concentrically installed on the rear side of rear valve plate  22 , which is marked with the letter “R” (not shown). Finally, rear bulkhead  3  is installed over shaft  12  and bolted to cylinder block assembly  300  and front bulkhead  2  with bolts  30 .  
         [0032]     In the described compressor featuring the preferred embodiment of the present invention, many variations are feasible. The O-rings such as O-rings  15  and  19  in  FIG. 16  could be gaskets. In the preferred embodiment, discharge reeds  7  and  26  are shaped like flowers with petals, but they could have the shape of a star, or any other shape resembling a disc with radiating arms, and they could be constructed of materials other than metal. Reed retainers  8  and  24  could also be shaped like a star, or any other disc having radiating arms. Reed retainers  8  and  24  could also be simple discs. Insert  13 , front discharge reed  7 , and front reed retainer  8  are not required to be separate pieces, and their compositions are not limited to any particular material. In a tradeoff between parts count and total compressor weight, reed stabilizer  17  could be eliminated with a more substantial bulkhead. The present invention is not limited to use in compressors; it can also be incorporated in any number of machines that require valves situated around the circumference of a shaft.  
         [0033]     It will be apparent to those with ordinary skill in the relevant art having the benefit of this disclosure that the present invention provides an apparatus for improving the longevity of prior art reed valves by decreasing the bending stress on the reeds of such valves during operation. It is understood that the forms of the invention shown and described in the detailed description and the drawings are to be taken merely as currently preferred examples, and that the invention is limited only by the language of the claims. The drawings and detailed description presented herein are not intended to limit the invention to the particular embodiments disclosed. While the present invention has been described in terms of one preferred embodiment, it will be apparent to those skilled in the art that form and detail modifications can be made to the described embodiment without departing from the spirit or scope of the invention.