Patent Publication Number: US-11391279-B1

Title: Compressor valve assembly with removably affixed guide in a reciprocating compressor

Description:
Disclosed embodiments relate generally to compressor valves, and, more particularly, to a compressor valve assembly for a reciprocating compressor. 
     BACKGROUND 
     A reciprocating compressor is a positive displacement compressor. In a reciprocating compressor, a fluid to be compressed enters a chamber via an inlet and exits the chamber through an outlet. The compression is a cyclical process in which the fluid is compressed by a reciprocating movement of a piston head. A plurality of compressor valve assemblies may be arranged around the chamber. The compressor valve assemblies are switched between a close state and an open state due to a pressure difference across the compressor valve assemblies in response to the reciprocating movements of the piston head. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic cross-sectional view of a disclosed compressor valve assembly including an embodiment of a guide that can be removably affixed to structures of the compressor valve assembly. 
         FIG. 2  is a fragmentary isometric view of the disclosed compressor valve assembly including a cross-sectional view along a cutting plane defined by line  2 - 2  in  FIG. 4 . 
         FIG. 3  is a fragmentary isometric view of the disclosed compressor valve assembly including a cross-sectional view along a cutting plane defined by line  3 - 3  in  FIG. 4 . 
         FIG. 4  is a top view of disclosed compressor valve assemblies as may be arranged throughout a stop plate. 
         FIG. 5  is an isometric view of an embodiment of the guide illustrating structural details of certain portions of the guide. 
         FIG. 6  is graph useful to conceptualize an increased outlet flow area that can be effectively realized by disclosed compressor valve assemblies. 
     
    
    
     DETAILED DESCRIPTION 
     The present inventors have recognized that a given structural design of compressor valve assembly can affect several aspects of the operation of the valve assembly and ultimately the overall operation of the compressor. For example, the configuration of the valve assembly may affect the fluid flow dynamics through the valve assembly, including, for example, seal effectiveness, pressure drop, and operational costs. Fluid flow calculations can, for example, indicate the resistance caused by a fitting and/or component in the valve assembly by way of a dimensionless coefficient K, where a higher K value can indicate higher resistance to fluid flow, which, generally, is not a desirable characteristic in a valve assembly. In addition, the design of the valve assembly may affect its reliability, maintenance frequency, complexity, costs of manufacturing, difficulty of installation and/or serviceability. 
     For example, certain known valve assembly designs, such as involving a mushroom-style valve head have been used to increase flow area (e.g., resulting in a relatively lower K value). However, the mushroom-style valve head are susceptible to bending stresses and this may reduce broad applicability of such valve assembly designs. By comparison, a bullet-style valve head can be operated at relatively higher pressures and is less susceptible to bending stresses, which improves reliability of the valve assembly. However, the bullet-style valve head tends to reduce the flow area of the valve assembly (e.g., resulting in a relatively higher K value). A hybrid valve head design involving certain aspects of both the bullet-style valve head and the mushroom-style valve head (e.g., colloquially referred to as a hammer-head style) provides a compromise that attempts to resolve the foregoing issues but may fall somewhat short in certain aspects, such as having a somewhat reduced flow area. 
     At least in view of the foregoing considerations, the present inventors disclose a compressor valve assembly that cost-effectively and reliably incorporates the full benefits of the so-called bullet-style valve head design and effectively increases the flow area. Additionally, the disclosed compressor valve assembly effectively permits the guide to be removably affixed to the stop plate and hence the disclosed design is conducive to user-friendly serviceability of individual guides while realizing an increased flow area with the full benefits of a bullet-style valve head. 
     In the following detailed description, various specific details are set forth in order to provide a thorough understanding of such embodiments. However, those skilled in the art will understand that disclosed embodiments may be practiced without these specific details that the aspects of the present invention are not limited to the disclosed embodiments, and that aspects of the present invention may be practiced in a variety of alternative embodiments. In other instances, methods, procedures, and components, which would be well-understood by one skilled in the art have not been described in detail to avoid unnecessary and burdensome explanation. 
     Furthermore, various operations may be described as multiple discrete steps performed in a manner that is helpful for understanding embodiments of the present invention. However, the order of description should not be construed as to imply that these operations need be performed in the order they are presented, nor that they are even order dependent, unless otherwise indicated. Moreover, repeated usage of the phrase “in one embodiment” does not necessarily refer to the same embodiment, although it may. 
     It is noted that disclosed embodiments need not be construed as mutually exclusive embodiments, since aspects of such disclosed embodiments may be appropriately combined by one skilled in the art depending on the needs of a given application. 
       FIG. 1  is a cross-sectional view of a disclosed compressor valve assembly  10  including a seat  12  disposed at an inlet side  14  of compressor valve assembly  10 . Seat  12  includes a plurality of inlet flow apertures  16 . By way of example,  FIG. 1  illustrates just two such inlet flow apertures  16 , with typical seats  12  having any number of inlet flow apertures  16  that may be desired for a given application. 
       FIG. 1  further illustrates a stop plate  18  disposed at an outlet side  20  of compressor valve assembly  10 . Stop plate  18  is in abutting relationship against seat  12 . Stop plate  18  includes a plurality of guides  22  that can each be removably affixed to stop plate  18 . By way of example,  FIG. 1  illustrates just two such guides  22 . 
     Each guide  22  has a cylindrical cup portion  24  and a cylindrical stem portion  26  that extends axially in a socket  28  defined by a cylindrical wall  30  in stop plate  18 . In one non-limiting embodiment, a base perimeter  25  of the cylindrical cup portion is spaced apart relative to the bottom of stop plate  18 . In one non-limiting embodiment, guide  22  further includes a conical transition  27  disposed between the base perimeter  25  of cylindrical cup  24  and cylindrical stem portion  26 . In one non-limiting embodiment, an inner surface  31  of cylindrical wall  30  has a thread configured to provide a threaded connection with a threaded mating surface  29  ( FIG. 5 ) of cylindrical stem portion  26 . At least some of the foregoing structural portions of guide  22  may be better appreciated in the isolated isometric view of guide  22  shown in  FIG. 5 . 
     In one embodiment, conical transition  27  defines a taper angle δ ( FIG. 5 ), such as may defined relative to a line parallel to the longitudinal axis  50  of the guide. In one non-limiting embodiment, the taper angle may have a range from 25 degrees to 65 degrees. In another non-limiting embodiment, the taper angle may have a range from 30 degrees to 60 degrees. In still another non-limiting embodiment, the taper angle may have a range 35 degrees to 55 degrees. It will be appreciated that disclosed embodiments need not include conical transition  27 . 
     Returning to  FIG. 1 , in one non-limiting embodiment, a seal element  32  and a spring  34  are disposed in cylindrical cup portion  24 . An inner surface  36  of cylindrical cup portion  24  is configured to guide travel of seal element  32  along the inner surface  36  of cylindrical cup portion  24  so that a seal head  33  of seal element  32  moves to close inlet flow aperture  16  when spring  34  is uncompressed and moves away from inlet flow aperture  16  when spring  34  is compressed during operation of the compressor valve assembly. This latter condition allows a flow of working fluid to pass from inlet side  14  of compressor valve assembly  10  to outlet side  20  of compressor valve assembly  10  and this is schematically represented by lines  38  with arrow-heads. 
     Without limitation, seal head  33  may have a streamlined configuration. That is, seal head  33  belongs to the category of seal heads described above as involving the bullet-style valve head, and therefore seal head  33  provides all the benefits noted above in connection with a bullet-style valve head. Non-limiting example of such benefits include operational capability at relatively higher pressures and less susceptibility to bending stresses. 
     In one non-limiting embodiment, a group of outlet flow apertures  40  is disposed in stop plate  18 . The group of outlet flow apertures  40  is arranged about cylindrical stem portion  26 . By way of example,  FIG. 1  illustrates two such outlet flow apertures  40  about each of the cylindrical stem portions  26  shown in  FIG. 1 . In one non-limiting embodiment, a segment (s) of respective cross sections of the group of outlet flow apertures  40  is spanned by cylindrical cup  24  and in one non-limiting embodiment segment (s) extends up to a point circumscribed by the outer surface of cylindrical wall  30 . 
     In one non-limiting embodiment, each segment (s) of the respective cross sections of the group of outlet flow apertures  40  has an outlet flow area defined by a partial intersection of a circle (for example circle C 2  in  FIG. 6 ) having a radius (r 2 ) formed by a respective outlet flow aperture  40  and a circle (for example circle C 1  in  FIG. 6 ) having a radius (r 1 ) formed by base perimeter  25  of cylindrical cup  24 . (To further facilitate understanding, radii (r 1 ) and (r 2 ) are also labeled in  FIG. 3 ). These circles have respective center points at a distance (d) from one another, (for example, this distance d is labelled in  FIGS. 3 and 6 ). It will be appreciated that the radius (r 2 ) of the respective outlet flow aperture  40  is smaller relative to the radius (r 1 ) of the base perimeter of the cylindrical cup. Since the outlet flow apertures  40  and base perimeter  25  of cylindrical cup  24  are on different planes (e.g., axially spaced-apart from one another) it will be further appreciated that circle C 1  represents a projection onto circle C 2 . This is schematically represented by illustrating circle C 1  with a dashed line. 
       FIG. 2  is a fragmentary isometric view of the disclosed compressor valve assembly  10  including a cross-sectional view along a cutting plane defined by line  2 - 2  in  FIG. 4  and together with the isometric shown in  FIG. 3  these views should allow to better visually appreciate at least the structural details of compressor valve assembly  10  that have been described above. 
     As may be appreciated in  FIG. 4 , in one non-limiting embodiment, the group of outlet flow apertures—about the cylindrical stem portion of any given guide  22 —may be formed by four outlet flow apertures ( 40   1  through  40   4 ) arranged in a square centered about the longitudinal axis of the guide  22 . It will be understood that aspects of disclosed embodiment are not limited either to a group of four outlet flow apertures about the cylindrical stem portion of any given guide  22  or to a square arrangement. It will be appreciated that the outlet flow apertures through the stop plate  18  can be placed relative closer to the respective longitudinal axes (e.g., the respective center lines) of each neighboring guide  22 . This allows an increased quantity of guides and associated valve elements to be installed and a corresponding increased quantity of flow holes to be used for given size of valve assembly diameter. In one non-limiting example, without limitation, this results in an increase in valve flow area of approximately 33% compared to a prior similarly sized valve. 
     As noted above,  FIG. 6  shows two intersecting circles C 1  and C 2  of radii r 1  and r 2  respectively and where the distance between the centers of the circles is d. Circle  2  with radius (r 2 ) is indicative of the respective outlet flow aperture and circle  1  with radius (r 1 ) is indicative of the base perimeter of the cylindrical cup. It can be shown that the intersection area (A int ) of the circles is defined by the following: 
     
       
         
           
             
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     Where 
     
       
         
           
             
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     Area (A int ) represents an increased outlet flow area that is effectively realized by a disclosed compressor valve assembly. 
     For readers interested in an elegant derivation of the above equations, reference is made to article titled “The intersection Area of Two Circles” by Diego Assencio posted in the following URL https://diego.assencio.com/?index=8d6ca3d82151bad815f78addf9b5c1c6 
     In operation, disclosed embodiments implement a compressor valve assembly that cost-effectively and reliably incorporates the full benefits of the so-called bullet-style valve head design and effectively increase the flow area of the compressor valve assembly. Additionally, disclosed embodiments effectively permit guides that can individually be removably affixed to the stop plate and hence the disclosed design is conducive to user-friendly serviceability of individual guides while realizing an increased flow area with the full benefits of a bullet-style valve head. 
     While embodiments of the present disclosure have been disclosed in exemplary forms, it will be apparent to those skilled in the art that many modifications, additions, and deletions can be made therein without departing from the scope of the invention and its equivalents, as set forth in the following claims.