Abstract:
A flow control device having a control member for forming a seal with another part of the flow control device. The control member having a base material and a portion or surface that is a softer or more deformable than the base material or the portion of the control device that the control member forms a seal with. The differences in hardness and/or the ability of the control member portion to deform, aids in forming the seal.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. provisional patent application Ser. No. 60/648,543 for COATED VALVE DIAPHRAGM filed Jan. 31, 2005, the entire disclosure of which is fully incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Diaphragm valves are a type of flow control device. Existing diaphragm valves include a valve body and a dome shaped diaphragm. A seal is provided between the diaphragm and the valve body at or near the outer peripheral area of the diaphragm. A bonnet may be used to clamp the diaphragm to the valve body to provide the seal between the valve body and the diaphragm. In order to achieve a satisfactory seal, high compressive forces may be needed, especially where imperfections in the valve body and diaphragm surfaces exist and where the diaphragm is made of harder materials. 
         [0003]    The valve body typically includes a passageway between the inlet and the outlet of the valve. An actuator is typically employed to flex the diaphragm into engagement with a valve seat to seal off the passageway when desired. Forming a satisfactory seal between the diaphragm and valve seat is important to the performance of the valve. 
       SUMMARY OF THE INVENTION 
       [0004]    The present application relates to a flow control device having a control member that forms a seal with another part of the flow control device, such as for example, a body portion or a seat area. The control member may include a portion or surface that is a softer or more deformable than the rest of the control member or than a portion of the control device that the control member forms a seal with. The differences in hardness and/or the ability of the control member portion to deform, aids in forming the seal. As a result, the amount of force needed to form a satisfactory seal may be less that what is needed if the softer, more deformable portion of the control member is not present. 
         [0005]    In one embodiment, the flow control device is a diaphragm-style valve that includes an inlet port, an outlet port, and a valve seat. The flow control device includes a control member in the form of a coated, flexible member or diaphragm configured for sealing engagement with the valve seat. The coating may be disposed on the flexible member for sealing an interface between the flexible member and the valve seat and/or between the flexible member and a valve body. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    In the accompanying drawings, which are incorporated in and constitute a part of this specification, an embodiment of the invention is illustrated, which, together with a general description of the invention given above, and the detailed description given below, serve to illustrate the principles of this invention. 
           [0007]      FIG. 1  is an illustration of a diaphragm valve assembled with a pneumatic actuator; 
           [0008]      FIG. 2A  is an enlarged view showing the portion of  FIG. 1  that is identified by the reference  FIG. 2 ; 
           [0009]      FIG. 2B  is a view similar to the view of  FIG. 2A  showing the valve body that includes an integral valve seat; 
           [0010]      FIG. 3  is a cross-sectional view of a valve seat. 
           [0011]      FIG. 4A  is a schematic illustration of a diaphragm showing contact areas on an actuator side of the diaphragm; 
           [0012]      FIG. 4B  is a schematic illustration of a diaphragm showing contact areas on a valve seat side of the diaphragm; 
           [0013]      FIG. 5A  is an enlarged view of the portion of  FIG. 2  identified by the reference  FIG. 5A  illustrating a diaphragm with a coating disposed on both sides of the diaphragm; 
           [0014]      FIG. 5B  is a schematic illustration of a diaphragm with a coating disposed on a valve seat side of the diaphragm; 
           [0015]      FIG. 6A  is a schematic illustration that shows a coating on a diaphragm filling an imperfection in a valve member; 
           [0016]      FIG. 6B  is a schematic illustration that shows a coating on a diaphragm conforming to an imperfection in a valve member; 
           [0017]      FIG. 7  is a schematic illustration of a coating pattern on the valve seat side of a diaphragm; and 
           [0018]      FIG. 8  is a schematic illustration of a coating pattern on the actuator side of a diaphragm. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    While various aspects and concepts of the invention are described and illustrated herein as embodied in combination in the exemplary embodiments, these various aspects and concepts may be realized in many alternative embodiments, either individually or in various combinations and sub-combinations thereof. Unless expressly excluded herein all such combinations and sub-combinations are intended to be within the scope of the present invention. Still further, while various alternative embodiments as to the various aspects and features of the invention, such as alternative materials, structures, configurations, methods, devices, software, hardware, control logic and so on may be described herein, such descriptions are not intended to be a complete or exhaustive list of available alternative embodiments, whether presently known or identified herein as conventional or standard or later developed. Those skilled in the art may readily adopt one or more of the aspects, concepts or features of the invention into additional embodiments within the scope of the present invention even if such embodiments are not expressly disclosed herein. Additionally, even though some features, concepts or aspects of the invention may be described herein as being a preferred arrangement or method, such description is not intended to suggest that such feature is required or necessary unless expressly so stated. Still further, exemplary or representative values and ranges may be included to assist in understanding the present invention however, such values and ranges are not to be construed in a limiting sense and are intended to be critical values or ranges only if so expressly stated. 
         [0020]    The present invention contemplates a flow control device that includes a control member for forming a seal with another part or portion of the flow control device. In order to facilitate a satisfactory seal, the control member may be, or may include a portion or surface, that is softer or more deform able than the base material of the control member or the portion of the flow control device to which the control member seals. The softer material of the control member more readily conforms to surface of the flow control device, thus requiring less force to form a satisfactory seal. 
         [0021]    The flow control device may be, for example, a regulator or a diaphragm valve. The control member may be, for example, a flexible member, such as a diaphragm, or some other surface adapted to form a sealing interface with a portion of the flow control device. For example, the control member may form a sealing interface with a seat surface or a body portion of the flow control device. A softer portion or surface of the control member may be achieved in a variety of ways. For example, a coating may be applied to the base material of the control member or an softer insert may be attached or affixed to the base material. In addition, a portion of the base material of the control member may be configured to be softer through surface modification, such as for example, making the surface more porous, locally annealing the surface, or some other reaction or modification to achieve a softer or more deformable/elastic surface condition. 
         [0022]    Referring to the exemplary embodiment of  FIG. 1 , a coated flexible member  10  is used in a valve arrangement  12  that includes a pneumatic actuator  13 , an inlet port  14 , an outlet port  16 , and a valve seat  18 . The coated flexible member  10  in the exemplary embodiment of  FIG. 1  is realized in the form of a diaphragm for providing a sealing engagement with the valve seat  18 . It should be readily apparent that the illustrated inlet port  14  could function as an outlet port and the illustrated outlet port  16  could function as an inlet port. Furthermore, it should be readily apparent, that the diaphragm  10  could be used in a variety of different types of valve arrangements, such as for example, but not limited to, manually actuated valve arrangements, electrically actuated valve arrangements, and normally open or normally closed valve arrangements. 
         [0023]    In the exemplary embodiment of  FIG. 1 , the diaphragm  10  comprises a flexible metallic member  20  or substrate. A coating  22  is disposed on the flexible metallic member (see  FIGS. 4A and 4B ) to aid in sealing an interface between the diaphragm  10  and the valve seat  18  and/or an interface between the diaphragm and a valve body  26 . 
         [0024]    In the embodiment illustrated by  FIG. 2A , the valve seat  18  is a separate annular seat member that is assembled with the valve body  26 . The separate annular seat member  18  may be a plastic member, a metallic member, an annular metallic member that includes a thin polymer coating, or other suitable material(s). The thin polymer coating may be formed from the same materials as the coating  22  on the diaphragm  10 . In one embodiment of the diaphragm valve arrangement  12 , the valve seat  18  includes the coating  22  and the diaphragm  10  does not includes the coating in the area of contact with the valve seat. 
         [0025]    In the embodiment illustrated by  FIG. 2B , the valve seat  18  is integrally formed with the valve body  26 . For example, the valve body  26  may be a metallic member and the valve seat  18  may be a metallic portion of the valve body. The valve seat  18  may be configured in a variety of ways. For example,  FIG. 3  illustrates one possible valve seat configuration. In the example of  FIG. 3 , the integral valve seat  18  has a rounded annular bead cross-section  27 . 
         [0026]    Referring to the exemplary embodiment of  FIGS. 1 ,  2 A, and  2 B, the diaphragm  10  is assembled with the valve body  26  to flex into sealing engagement with the valve seat  18  and out of engagement with the valve seat. When assembled, the diaphragm  10  has an actuator side  28  and a valve seat side  29 . The valve body  26  and the diaphragm  10  define a flow path from the inlet port  14  to the outlet port  16  when the diaphragm is not flexed, thus allowing process fluid to flow from the inlet port  14  to the outlet port  16 . The pneumatic actuator  13  is assembled with the valve body  26  and diaphragm  10  for selectively flexing the diaphragm into and out of engagement with the valve seat  18 . When the diaphragm  10  is flexed into engagement with the valve seat  18 , the coating  22  contacts and seals with the valve seat. 
         [0027]    In the illustrated example, a bonnet  34  secures the diaphragm  10  to the valve body  26  and a bonnet nut  36  clamps the bonnet  34  and diaphragm  10  to the valve body  26 . By including the coating  22  on the diaphragm  10  in the area where the valve body  26  engages the periphery of the diaphragm  10 , the amount of force required to properly seal the diaphragm  10  to the valve body  26  is reduced. In addition, the range of acceptable forces that will properly seal the diaphragm  10  with the valve body  26  is broadened. The illustrated bonnet nut  36  includes internal threads  38  that engage outer threads  39  of the valve body  26 . A clamping surface  40  of the bonnet nut  36  engages an end surface  42  of the bonnet  34  to force the bonnet toward the valve body  26 . In the illustrated embodiment, an annular ridge  44  on the bonnet  34  and an annular ridge  46  on the valve body  26  clamp the outer periphery of the diaphragm  10  to form a seal between the outer periphery of the diaphragm  10  and the valve body  26 . The coating  22  on the periphery of the diaphragm  10  acts as a seal between the diaphragm flexible metallic member  20  or substrate and the valve body  26 . 
         [0028]    In the example illustrated by  FIGS. 1 ,  2 A, and  2 B, the actuator  13  is assembled to the valve assembly  12  by the bonnet nut  36 . The illustrated bonnet nut  36  includes internal threads  56  that engage external threads  58  of the actuator  13 . The actuator  13  selectively extends an actuator rod  60  to move a button  62  along a path of travel defined by the bonnet  34 . When the rod  60  is extended, the button  62  deflects the diaphragm  10  into sealing engagement with the valve seat  18 . When the rod  60  is retracted, the diaphragm  10  flexes away from the valve seat  18  to open the flowpath between the inlet port  14  and outlet port  16 . 
         [0029]      FIG. 4A  schematically illustrates where the bonnet annular ridge  44  engages the diaphragm  10  when the valve arrangement  12  is assembled. Phantom line  50  illustrates the contact location of the bonnet annular ridge  44  on the actuator side  28  of the diaphragm  10 . The bonnet annular ridge  44  may contact the diaphragm  10  along the phantom line  50  or may contact an area of the diaphragm  10 , such as for example, the area on the diaphragm  10  between the phantom line  50  and the outer edge of the diaphragm. 
         [0030]      FIG. 4B  schematically illustrates where the valve body annular ridge  46  and where the valve seat  18  engage the valve seat side  29  of the diaphragm  10  when the valve arrangement  12  is assembled. Phantom lines  52 ,  54  illustrate the contact location of the valve body annular ridge  46  on the diaphragm  10  and phantom lines  64 ,  66  illustrate the contact location of the valve seat  18  engages diaphragm  10 . Both the valve body annular ridge  46  and the valve seat  18  may contact the diaphragm  10  along the respective phantom lines or may contact an area of the diaphragm  10 . 
         [0031]    The coating  22  on the diaphragm  10  may be applied to one or both sides of the diaphragm  10 . In the example illustrated by  FIG. 5A , the coating  22  is disposed on both sides of the base material  20 . In the example illustrated by  FIG. 5B , the coating  22  is disposed only on the valve seat side  29  of the diaphragm  10 . 
         [0032]    The coating  22  on the diaphragm  10  may be a wide variety of different materials which may aid in sealing the interface between the diaphragm  10  and the valve seat  18  and/or valve body  26 , may sufficiently adhere or bond to the base material, and may be sufficiently temperature and chemically compatible to the valve arrangement&#39;s application. In an exemplary embodiment, the coating  22  on the diaphragm  10  comprises a fluoropolymer material, such as polytetrafluoroethylene (PTFE), perfluoroalkoxy (PFA), or perfluoroelastomer, such as for example, KALREZ®. A fluoropolymer material coating  22  facilitates a high-integrity seal with a low required actuator force. 
         [0033]    In the exemplary embodiment, the coating parameters are selected to enable the diaphragm valve arrangement  12  to operate in a wide range of environments. A thin coating allows the valve arrangement  12  to operate in an environment with a temperature up to and possibly exceeding approximately 300 degrees C. In one embodiment, the coating is less than 0.001″ thick. The coating  22  may be applied to the diaphragm  10 , such that the coating will permanently adhere to the diaphragm surface. Existing fluoropolymer coating techniques, such as the techniques used to apply fluoropolymers to non-stick pans, may be used to apply the coating  22  to the metal diaphragm  10 . 
         [0034]    Referring to  FIGS. 6A and 6B , the coating  22  facilitates a high integrity seal between the diaphragm  10  and the valve body  26  and/or the diaphragm and the valve seat  18  (which may be integrally formed with the valve body), even when the surfaces of the diaphragm, the valve body and/or the valve seat include imperfections. Examples of imperfections include voids  70  ( FIG. 6A ), such as for example, scratches, and bumps  71  ( FIG. 6B ). In the examples illustrated by  FIGS. 6A and 6B , the valve seat  18 , valve body  26 , bonnet  34 , or the diaphragm member  18  itself may include an imperfection, such as a void  70  or a bump  71 . When a force (indicated by arrow  72 ) is applied to the diaphragm  10 , the softer coating  22  fills the void  70  or conforms around the bump  71  to thereby inhibit leakage. As a result, a metallic valve body  26  that includes an integrally formed valve seat  18  may be used with a low actuation force actuator. In addition, with an integrally formed seat, no secondary operations are required to connect a seat  18  to the valve body  26 . 
         [0035]    The coating  22  may be applied to the entire actuator side  28  and/or the entire valve seat side  29  of the diaphragm  10  or the coating may be applied in a pattern to one or both sides of the diaphragm. In the example of  FIGS. 7 and 8 , a pattern of coating  22  is applied to the diaphragm  10  generally only in areas where a seal is formed by the diaphragm  10  with the valve body  26 , the valve seat  18 , and the bonnet  34  (as illustrated in  FIGS. 4A and 4B ). It should be readily apparent, that the coating  22  may be applied in any pattern desired, such as for example, to generally match the sealing areas of valve arrangements with various configurations. 
         [0036]    The coating  22  may also be applied in a buffer region surrounding the areas where a seal is formed. By limiting the area where the coating  22  is applied to the diaphragm  10 , wetting of the coating by fluid that flows through the valve arrangement  12  is reduced. In the example of  FIG. 7 , an outer ring  80  of coating  22  is applied to the valve seat side  29  of the diaphragm  10 . The illustrated outer ring  80  of coating covers the area (illustrated by phantom lines  52 ,  54  in  FIG. 4B ) of the diaphragm  10  where the valve body annular ridge  46  engages the diaphragm. In the illustrated embodiment, the outer ring  80  is wider than the area where the valve body  26  engages the diaphragm  10  to ensure proper sealing even if alignment of the diaphragm and the valve body is not precise. In one embodiment, the outer ring  80  is sized to be the same width, or slightly narrower than the area where the valve body annular ridge  46  engages the diaphragm  10 . In this embodiment, wetting of the outer ring  80  of the coating  22  by process fluid is substantially eliminated. 
         [0037]    In the example of  FIG. 7 , an inner ring  82  of coating  22  is applied to the valve seat side  29  of the diaphragm  10 . The illustrated inner ring  82  of coating covers the area (illustrated by phantom lines  64 ,  66  in  FIG. 4B ) of the diaphragm  10  where the valve seat  18  engages the diaphragm. In the illustrated embodiment, the inner ring  82  is wider than the area where the valve seat  18  engages the diaphragm  10  to ensure proper sealing even if alignment of the diaphragm and the valve seat is not precise. In one embodiment, the inner ring  82  is sized to be the same width, or slightly narrower than the area where the valve seat  18  engages the diaphragm  10 . In this embodiment, wetting of the inner ring  82  of the coating  22  by process fluid when the diaphragm valve is closed is substantially eliminated. 
         [0038]    In the example of  FIG. 8 , a ring  88  of coating is applied to the actuator side  28  of the diaphragm  10 . The illustrated ring  88  of coating  22  covers the area (illustrated by phantom line  50  in  FIG. 6 ) of the diaphragm to where the bonnet  34  engages the diaphragm. In the illustrated embodiment, the ring  88  is wider than the area where the bonnet  34  engages the diaphragm  10  to ensure proper sealing even if alignment of the diaphragm and the bonnet is not precise. In one embodiment, the ring  88  of coating  22  is sized to be the same width, or slightly narrower than the area where the bonnet  34  engages the diaphragm. 
         [0039]    By patterning the coating  22  on the diaphragm  10  only in areas where a seal is formed between the diaphragm  10  and another member, the potential for particle generation and the overall surface area of polymer coating exposed to process fluid is reduced. Reducing the exposed coating surface area reduces the amount of process fluid that could potentially be absorbed by the coating  22  and thereby reduces the possibility that purge performance will be compromised by using a coated diaphragm  10 . 
         [0040]    In one exemplary embodiment, the valve body  26  comprises a metallic member, the valve seat  18  is an integrally formed metallic portion of the valve body  26 , the diaphragm  10  comprises a metallic member, and the coating  22  comprises a polymer, such as fluoropolymer material. In this embodiment, the coating  22  acts as a seal between the metallic valve seat  18  and/or the metallic valve body  26 . If the seal provided by the diaphragm coating  22  is damaged, for example, by contamination or an environmental problem, the diaphragm  10  can be easily removed and replaced with a new coated diaphragm that provides a fresh seal. The inclusion of an integrally formed metallic seat  18  allows for an increased flow of process fluid as compared with valve bodies that include staked-in plastic valve seats. The flow is higher with an integral seat, because the combination of the structure needed to stake-in the valve seat and the valve seat itself is larger than an integral valve seat and the valve porting can thus be made larger for a given valve body size. 
         [0041]    The invention has been described with reference to the preferred embodiments. Modification and alterations will occur to others upon a reading and understanding of this specification. It is intended to include all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.