Abstract:
Apparatus for controlling a pressurized fluid. In accordance with some embodiments, a valve assembly includes a piston moved between closed and open positions. A sealing member is disposed within an annular recess of the piston and characterized as an endless annular ring extending about a central axis of the piston. The sealing member has an elongated circle cross-sectional shape when the sealing member is in an uncompressed state prior to installation in said recess. The cross-sectional shape is defined by parallel top and bottom surfaces having a length L in a direction perpendicular to and intersecting the central axis, and having opposing inner and outer surfaces of a radius R, the inner and outer surfaces respectively facing toward and facing away from the central axis, and wherein the dimensional value of L is at least five times greater than the dimensional value of R.

Description:
RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 11/757,160 filed Jun. 1, 2007 and now abandoned. 
    
    
     BACKGROUND 
     Sealing members are used in a variety of applications to establish fluid seals, such as in valves in a pressurized fluid system. Generally, it is desirable that a sealing member retain its sealing capability over a wide range of operational conditions. It is further generally desirable that a sealing member remain in place when subjected to significant pressurized fluid flow, such as when the sealing member is disposed on a piston member moving from a closed position to an open position. 
     This phenomena is illustrated in  FIGS. 1A-1B , wherein is shown a prior art valve assembly  10  that includes a piston  12 , the piston selectively regulating pressurized fluid flow from an inlet port  14 . The piston  12  is depicted in its closed position in  FIG. 1A , thereby sealing the inlet port  14 . In  FIG. 1B , the piston  12  is depicted as it transits from the valve closed position to the valve open position. 
     The fluid flow is sealed in the piston closed position ( FIG. 1A ) by a conventional O-ring sealing member  16  that presses against the inner wall of the port  14 . The sealing member  16  has a circular cross-sectional shape, and is retained on the piston  12  within an annular recess  18 . The outer radial surface of the sealing member  16  forms a fluid seal against interior annular sidewall  20  of a housing  22 , and an opposing inner radial surface of the sealing member  16  forms a fluid seal against the surface of the annular recess  18 . 
     As the piston  12  moves initially to the piston open position of  FIG. 1B , significant fluid flow (arrows  24 ) can pass adjacent the sealing member  16 . Particularly in higher pressure fluid environments, a portion of the fluid can pass between the inner radial surface of the sealing member  16  and the recess  18 , exerting an outwardly (or radially) directed force on the sealing member  16 . If the hoop strength (the ability to retain its initial hoop shape) of the sealing member  16  is insufficient to resist this outwardly directed force, the sealing member  16  can be deformed and dislocated (blown out) from the annular recess  18 , as depicted in  FIG. 1B . 
     SUMMARY 
     Accordingly, various embodiments of the present invention are generally directed to an apparatus for controlling a pressurized fluid. 
     In accordance with some embodiments, a valve assembly is provided in which a piston is moved from a closed position in which a pressurized fluid flow is inhibited to an open position in which a pressurized fluid flow is established. A sealing member is disposed within an annular recess of the piston and characterized as an endless annular ring extending about a central axis of the piston. The sealing member has an elongated circle cross-sectional shape when the sealing member is in an uncompressed state prior to installation in said recess, the cross-sectional shape defined by parallel top and bottom surfaces having a length L in a direction perpendicular to and intersecting the central axis, and having opposing inner and outer surfaces of a radius R, the inner and outer surfaces respectively facing toward and facing away from the central axis, and wherein the dimensional value of L is at least five times greater than the dimensional value of R. 
     Further advantages and features of various embodiments of the present invention will be apparent from the following description when read in conjunction with the accompanying drawings and appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  generally illustrate a prior art valve assembly in which a conventional O-ring having a circular cross-sectional shape provides a fluid seal. 
         FIGS. 2A and 2B  show an exemplary valve assembly incorporating a sealing member constructed in accordance with embodiments of the present invention. 
         FIG. 3  is a top plan view of the sealing member of  FIGS. 2A-2B . 
         FIG. 4  is a cross-sectional representation of the sealing member along line  4 - 4  in  FIG. 3 , illustrating an exemplary elongated circle cross-sectional shape of the sealing member. 
         FIG. 5  is an enlarged view of a portion of  FIG. 4  showing the exemplary length and radial dimensions of the elongated circle cross-sectional shape. 
         FIG. 6  illustrates an alternative construction for the sealing member which utilizes an embedded stiffening material. 
         FIG. 7  illustrates a preferred manner in which the elastomeric material of the sealing member is extruded. 
         FIG. 8  shows a top plan view of the extruded material after processing in accordance with  FIG. 7 . 
         FIG. 9  shows an alternative extrusion process that provides sealing members with other cross-sectional shapes. 
         FIG. 10  is a cross-sectional elevational view of an alternative sealing member configuration formed by the process of  FIG. 9 . 
         FIG. 11  is a cross-sectional elevational view of another alternative sealing member formed by the process of  FIG. 9 . 
         FIG. 12  is a side elevational, cross-sectional depiction of the extrusion mechanisms generally depicted in  FIGS. 7 and 9 . 
         FIG. 13  is an end elevational, cross-sectional depiction of the extrusion mechanism of  FIG. 12 . 
         FIG. 14  provides a flow chart for an exemplary sealing member processing routine, generally illustrative of steps carried out in accordance with various embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 2A and 2B  show relevant portions of a valve assembly  100  to generally illustrate an exemplary environment in which various embodiments of the present invention can be advantageously practiced. The valve assembly  100  is contemplated as being of the type configured to selectively alter the flow of a pressurized fluid in a pressurized fluid system, although such is not limiting. 
     The valve assembly  100  comprises a housing  102  with an upstream inlet port  104  and a downstream outlet port  106 . A piston  108  selectively moves between a closed position ( FIG. 2A ) and an open position ( FIG. 2B ) to selectively inhibit or permit fluid flow of the pressurized fluid from the inlet port  104  to the outlet port  106 . A biasing member  110 , such as a spring, biases the piston  108  to the closed position. Other biasing arrangements can readily be used, however, or omitted entirely, as applicable for a particular application. 
     An annular sealing member  112  is supported in a corresponding annular groove  114  of the piston  108  by a pressure washer member  108 A that is attached to the body of the piston  108  via a bolt  108 B secured in a threaded bore (not separately numbered). The sealing member  112  contactingly engages the sidewall  116  of the inlet port  104  in the housing  102  to establish a fluid-tight seal while the valve assembly  100  remains in the closed position. 
     When the pressure of the pressurized fluid is sufficient to overcome the biasing force supplied by biasing member  110 , the piston  108  advances upwardly as depicted in  FIG. 2B . As the piston  108  moves to the open position, the sealing member  112  disengages the sidewall  116 , and as this occurs, the sealing member  112  is subjected to the pressurized fluid as the fluid passes from the inlet port  104  to the outlet port  106 . As explained more fully below, the sealing member  112  is advantageously configured to provide effective steady-state sealing in conditions such as depicted in  FIG. 1 , as well as to resist mechanical deformation and dislocation (blowout) while being subjected to substantial amounts of fluid flow pressure as depicted in  FIG. 2 . 
     As depicted in  FIGS. 3 and 4 , the sealing member  112  is generally characterized as an endless annular ring, that is, an O-ring, which extends about a central axis  118 . The sealing member  112  is preferably formed of an elastomeric material and has a cross-sectional shape characterized as a radially elongated circle. 
     As further depicted in  FIG. 5 , the elongated circle cross-sectional shape of the sealing member  112  is generally defined by opposing, parallel top and bottom flat surfaces, that is, linear segments  120 ,  122 , and opposing inner and outer radiused surfaces (semicircular end segments)  124 ,  126 ; that is, the inner radiused surface is numbered  124 , and the outer radiused surface is numbered  126 . Each of the flat surfaces  120 ,  122  has a length L in a direction perpendicular to, and which intersects, the central axis  118 . That is, each of the flat surfaces  120 ,  122  lays in a plane that is normal to the central axis  118 . Each of the radiused surfaces  124 ,  126  has a radius R that is numbered  130 . 
     The cross-sectional shape represented in  FIG. 5  is a steady-state configuration for the sealing member  112 ; that is, the sealing member  112  maintains the elongated circle cross-sectional shape while in an uncompressed state (i.e., in the absence of any externally applied support or compression force acting upon the member). For purposes of clarity, it will be noted that the cross-sections of  FIGS. 4 and 5  are taken along a plane that includes the central axis  118  of the sealing member  112 . 
     The dimensional values of L and R can vary depending on the requirements of a given application, with the dimensional value of the length L being greater than the dimensional value of the radius R; that is, L&gt;R. Preferably, the dimensional value of the length L is greater than five times the dimensional value of the radius R, that is, L&gt;5·R. As noted, the flat surfaces  120 ,  122  lay along respective planes normal to the central axis  118 , and the radiused surfaces  124 ,  126  are disposed to compressingly engage corresponding sidewalls to effect fluid sealing at the innermost diameter (ID) and outermost diameter (OD) extents of the sealing member  112 , that is, respectively, the inner radiused surface  124  and the outer radiused surface  126 . Exemplary values for the radiuses R for different industry standard classes of circular cross-sectional shaped O-rings are set forth in Table 1: 
     
       
         
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Class 
                 Radius R (inches) 
               
               
                   
                   
               
             
             
               
                   
                 2-0 
                 0.0350 
               
               
                   
                 2-1 
                 0.0515 
               
               
                   
                 2-2 
                 0.0695 
               
               
                   
                 2-3 
                 0.1050 
               
               
                   
                 2-4 
                 0.1375 
               
               
                   
                   
               
             
          
         
       
     
     The sealing member  112  can be adapted to have inner and outer radii R that correspond to any of the above classes, and used in an associated application provided that the corresponding retention groove (e.g.,  114  in  FIGS. 2A-2B ) is extended (deepened) by a sufficient distance to accommodate the length dimension L of the sealing member  112 . It will be noted that the multiple-piece configuration (pressure washer  108 A, bolt  108 B and body portion) is preferably set forth for the piston  108  in  FIGS. 2A-2B  to facilitate installation of the sealing member  112 . 
     The sealing member  112  of  FIGS. 2-4  is contemplated as comprising an equivalent class 2-3 member, with R being nominally 0.1050 inches, in (±0.0060 in). The corresponding length value L of the sealing member  112  is nominally 0.5400 in (±0.0060 in). The OD of the sealing member  112  is nominally 3.2700 in (±0.0200 in), and the ID is nominally 1.9800 in (±0.0160 in). The same L and R values can be used with different respective ID and OD values, and vice versa, as desired. 
     The elongated circle cross-sectional shape has been found by the present inventor to provide unexpected operational improvements over conventional configurations, such as the conventional circular O-ring depicted in  FIGS. 1A-1B . The elongated circle cross-sectional shape of the sealing member of the present invention significantly enhances the hoop strength of the sealing member  112 , and the length dimension L reduces the exposure of the inner radiused surface  124  to fluid pressure, that is, to pressured exerted behind the sealing member  112  within the annular groove  114  when the sealing member  112  is initially exposed to high pressure fluid as when the valve assembly  100  actuates to move from the closed position of  FIG. 2A  to the open position of  FIG. 2B . 
     With the hoop strength of the sealing member  112  retaining the sealing member appropriately seated in the annular groove  114 , the sealing member  112  is maintains a fluid-tight fluid seal in the captured sealing environment of  FIG. 2A , provides low-frictional sliding contact against the annular wall  116 , and resists damage or dislocation of the sealing member  112  in the high pressure environment of  FIG. 2B . 
     A suitable material from which the sealing member  112  can be advantageously formed is a fluoroelastomer such as is commercially available under the registered trademark Viton® by E. I. du Pont de Nemours &amp; Company, Wilmington, Del., USA. Other suitable materials can include any number of natural or synthetic rubbers, urethanes, plastics, etc. A suitable durometer (hardness) of the sealing member  112  may be in the order of 70-80, depending on the requirements of a given application, although both harder and softer materials can be used as desired. 
     Further, the seal member  112  can be stiffened with a suitable filler such as glass fibers, carbon filaments, nanotubes, etc., such as depicted in  FIG. 6  in which an alternative sealing member  132  retains the afore described elongated circle cross-sectional shape of the sealing member  112 , but additionally incorporates an internal stiffening core  134 . The core  134  generally serves to further strengthen the sealing member  132  against damage or removal during operation, that is, to enable the sealing member  132  to resist removal from the groove  114  upon application of compressive and pressure forces. 
     The sealing members  112 ,  132  can be formed in a number of ways. Taylor U.S. Pat. No. 6,315,299, assigned to the assignee of the present invention, generally discloses a compression molding process whereby a reinforcing member is placed into an annular molding cavity. Sealing material is injected into the cavity, such as a suitable elastomer, and the combination is cured to form a reinforced sealing member. While generally operable, one difficulty associated with molding processes, such as that taught by the &#39;299 patent process is consistently maintaining a ring member in a centrally disposed orientation. Injected material often deflects the ring and pushes it to one side of the annular cavity, resulting in non-uniform thicknesses of elastomeric material. 
     The various embodiments presented herein are preferably formed using an extrusion process, such as set forth in  FIG. 7 . An extrusion mechanism  142  extrudes uncured seal material  144  so that the extruded material remains in a soft, malleable state. A guide  146  at the exit portion of the mechanism  142  preferably induces a desired amount of curvilinearity to the extruded material  144  along a longitudinal length of the extruded material exiting the mechanism  142  to provide a substantially circular shape. 
     As depicted in  FIG. 8 , this advantageously forms an orthogonal mating seam  148  between the leading and trailing edges of the extruded material  144 ; that is, the leading and trailing edges nominally align at the junction or seam  148 , ensuring substantially uniform thickness and eliminating voids or other discontinuities in the sealing material. It is contemplated that the seam  148  can remain visible in the sealing member at the conclusion of the subsequent curing process without affecting the operation thereof, and will enhance the hoop strength at the seam by facilitating improved joining of the leading and trailing edges. The extruded material  144  is thereafter cured in a suitable curing operation to form the sealing member. 
     When internal stiffening material is to be incorporated into the sealing member, the extruded material  144  can be formed hollow; that is, as shown in  FIG. 7 , a central channel or interior cavity  150  extends through the extruded material  144  as it exits the extrusion mechanism  142 . A slit can be subsequently formed in the extruded material  144  along the internal cavity to facilitate placement of the stiffening material  134  therein. 
     Alternatively, as depicted in  FIG. 7 , an extruded slit  152  can be formed in the extruded material  144  during the extrusion process, facilitating subsequent insertion of the stiffening material  134 . In either case, the extruded material  144  is thereafter cured in a suitable curing operation to form the sealing member. 
     While various embodiments presented above provide a sealing member with enhanced hoop strength in conjunction with the provision of an elongated circle cross-sectional shape, other embodiments disclosed herein are provided with alternative cross-sectional shapes.  FIG. 9 , illustrating an alternative extrusion process similar to that set forth in  FIG. 7 , depicts the use of an extrusion mechanism  166  and guide  168  to provide curvilinearly extending, uncured extruded material  170  that mates at an orthogonal seam, like the seam  148  of  FIG. 8 . However, the extruded material  170  as shown in  FIGS. 9 and 10  is provided with a substantially circular cross-sectional shape, unlike the elongated circle shape formed in  FIG. 7 . 
     An interior cavity  172  is formed to extend the length of the material  170  to accommodate the placement of a suitable internal stiffening material  174 , and the formation of the interior cavity  172  during the extrusion process substantially ensures that the extruded material  170  will have a uniform thickness. 
     As desired, a slit  176  can be cut at the internal diameter (ID) of the material  170  to facilitate placement of the stiffening material, or an extruded slit  178  can be formed during the extrusion process. Because the extrusion process precisely locates the centrally disposed cavity  172 , the cross-sectional shape of the material  170  can be varied as desired, such as that of an exemplary rounded rectangle cross-sectional shape as depicted in  FIG. 11 . 
       FIGS. 12 and 13  further illustrate preferred aspects of the various extrusion processes disclosed herein. For clarity,  FIGS. 12 and 13  are illustrated with respect to the extrusion process of  FIG. 7 , although it will be understood that these figures can readily be adapted to the process of  FIG. 9 . 
     In  FIG. 12 , a housing  180  defines an interior sidewall  180  with a shape nominally conforming to the desired cross-sectional shape of the extruded material ( 144  in  FIG. 7 ). A cantilevered, centrally disposed barrier  182  is supported by a support arm  184  to form the interior cavity  150  in the extruded material. As desired, the interior sidewall  180  can include a curvilinearly shaped exit portion  186  to initiate the desired curvilinearity along the longitudinal length of the extruded material  144 , with or without the further use of the external guide  146 . 
       FIG. 13  generally provides an end view of the arrangement of  FIG. 12 . A diverting flange  188  extends from the barrier portion  182  in a direction substantially orthogonal to the support arm  184  ( FIG. 12 ). The flange  188  further interrupts the flow of the extruded material  144  to form the aforementioned slit  152  ( FIG. 7 ). 
       FIG. 14  provides a flow chart for a sealing member processing routine  200 , generally illustrative of preferred steps carried out in accordance with the foregoing discussion. 
     At extruding step  202 , a suitable sealing material is initially extruded from a suitable extrusion process such as depicted in  FIGS. 7 ,  9  and  12 - 13 . The extruded material (such as  144 ) will normally be in an uncured state such as an uncured elastomeric material. The extrusion process further imparts a desired level of curvilinearity to the extruded material  144  as it exits the extrusion process, assuring an orthogonal mating seam ( 148 ,  FIG. 8 ). 
     When an interior stiffening material is desired, the extruded material is supplied with an extruded central cavity, such as  150  in  FIG. 7  or  172  in  FIG. 9 . In such case a slit can be formed at slitting step  204  in the extruded material. This can be carried out by a separate slitting operation, or by extruding the slit into the extruded material  144  ( FIG. 13 ). Where employed, stiffening material can be inserted at a curing step  206  or at a stiffening step  208  described hereafter. 
     The extruded material is cured in a suitable curing operation at curing step  206 , which preferably involves placing the material in a molding cavity and subjecting the material to appropriate pressure and temperature conditions for a suitable dwell time associated with the material to effect the appropriate curing. Other arrangements, such as curing ovens, can also be used, as desired. 
     When an internal stiffening material is desired, the stiffening step  208  following curing will involve filling the internal cavity ( 150  or  172 ) with the selected material, and curing same as required. At application step  210 , the cured sealing member, following completion of the molding operation, can be used in an appropriate application to effect a fluid seal, such as in the valve member  100  depicted in  FIGS. 2A and 2B . The process is completed at an end step  212 . 
     For purposes of the appended claims, the recited first means will be understood to correspond to the afore described sealing members that achieve enhanced hoop strength, namely the elongated circle cross-sectional shaped sealing member  112  of  FIGS. 2A-2B  and  3 - 5 ; the elongated circle cross-sectional shaped sealing member  132  with an associated internally disposed stiffening material core  134  of  FIG. 6 ; and the extruded sealing members with respective circular and rounded rectangle cross-sectional shapes and interiorly placed stiffening material of  FIGS. 10-11 . Prior art conventional O-rings as discussed in  FIGS. 1A-1B , and prior art reinforced O-rings with molded in place reinforcement rings as disclosed by the aforementioned &#39;299 patent process, are not included within the scope of the recited first means and are explicitly excluded from the definition of an equivalent. 
     Moreover, for purposes of the appended claims the term “elongated circle” will be understood to correspond to the shape as set forth in  FIG. 5  in which a circle is linearly extended in a single direction (i.e., opposing 180 degree semicircular segments separated by linear line segments), and will thus exclude continuously curvilinear shapes such as ellipses and ovals, as well as segmented shapes such as a rounded rectangle. 
     It is to be understood that even though numerous characteristics and advantages of various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the invention, this detailed description is illustrative only, and changes may be made in detail, especially in matters of structure and arrangements of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.