Abstract:
A reinforced plastic valve apparatus in a preferred embodiment comprises an upper valve portion, a lower valve portion, an endoskeletal structure configured as a weir support or reinforcing member and an exoskeletal framework configured as a support collar. The upper valve portion preferably includes an upper plastic valve housing or body, a resilient diaphragm and a valve actuator. The lower valve portion comprises a lower plastic valve housing or body that is preferably configured to mate with the upper valve housing to define a valve interior. The lower valve body preferably has an integral weir which, in conjunction with the resilient diaphragm, defines a fluid passage. The diaphragm is configured to sealingly engage and disengage with the weir as effected by the valve actuator. The weir support member is disposable within the lower housing to support the weir. In preferred embodiments, an exoskeletal framework configured as the support collar extends circumferentially around the valve and supports the weir support member. The invention also includes the method of manufacturing a reinforced plastic valve preferably including the step of providing a rigid support member to the weir of a lower valve housing.

Description:
RELATED APPLICATION INFORMATION  
       [0001]    This application claims benefit of U.S. Provisional Application Ser. No. 60/276,658, filed on Mar. 16, 2001. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to valves, and more particularly, to plastic diaphragm valves having a weir-type seating surface.  
         BACKGROUND OF THE INVENTION  
         [0003]    Diaphragm valves provide excellent sealing and isolation characteristics to contain fluid being controlled and prevent migration of the controlled fluid into the valve mechanisms or out of the valve. Diaphragm valves utilize a resilient diaphragm and a valve shoulder to engage a valve seat and prevent the flow of fluid past the valve seat. A weir-type diaphragm valve is a valve utilizing a resilient diaphragm that engages a weir to control flow of fluid over the weir. The diaphragm may be controllably lifted and sealed against the weir to selectively permit flow through the valve.  
           [0004]    Weir-type diaphragm valves are often employed in the biotechnological, pharmaceutical, chemical, food processing, beverage, cosmetic, and semiconductor industries. These industries often require valves that protect against product contamination and leakage within the valve, workplace and atmosphere. Weir-type diaphragm valves are well suited to meet these requirements because the mechanical valve parts are isolated from fluid flowing through the valve.  
           [0005]    Traditionally, diaphragm valves were made of metal alloys. Such metal valves provide good durability and service life in basic fluid control applications. However, metal alloys are not well suited to some process environments, such as pharmaceutical and semiconductor manufacturing. In those applications, the fluids often used are highly corrosive or caustic and also must be kept ultra pure. These corrosive fluids can erode the metal from the valve body and contaminate the ultra pure process fluids. Also, some metal alloys may act as catalysts causing the process fluids to undergo chemical reactions, thereby compromising end products, and potentially, worker safety.  
           [0006]    Specialized high strength alloys and stainless steels have been developed to minimize reactivity and erosion in the valve bodies. However, such specialized alloys are very difficult to cast or machine into valve components. The resulting valves are very costly to purchase relative to traditional metal valves. Moreover, stainless steel is not suitable in particular applications such as the semiconductor processing industry.  
           [0007]    Plastic lined metal valves were developed to allow traditional metal valve bodies to handle caustic fluids in specialized process applications. The metal valve body is first formed by casting or machining. Then, a plastic or fluoropolymer is molded in the interior of the valve body where process fluids contact the body. U.S. Pat. No. 4,538,638 discloses a plastic lined metal bodied diaphragm valve.  
           [0008]    Although, the plastic lined metal valves and plastic lined plastic valves may provide the desired resistance to degradation by process fluids, manufacturing costs are high. High costs are attributable to the complicated multi-step manufacturing process of molding a plastic lining in a support body. The plastic lining may be subject to creep with respect to its surface underneath. Creep reduces the useful life of the expensive plastic lined valve.  
           [0009]    Through advances in plastics and manufacturing technologies, valves made entirely or almost entirely of fluoropolymers have become commercially viable. Such plastic valves are capable of providing a cost effective valve having desirable non-reactive and corrosive resistant properties ideally suited for use in pharmaceutical and semiconductor manufacturing applications. U.S. Pat. Nos. 5,279, 328 and 4,977,929 disclose plastic diaphragm valves. In certain applications, plastic bodied valves may also be provided with a plastic lining. U.S. Pat. No. 4,538,638 discloses a plastic lined diaphragm valve.  
           [0010]    While fluoropolymer valves and plastic valves having fluoropolymer liners are well suited to withstanding caustic fluids, they are susceptible to dimensional degradation such as warpage and creep. Fluids used in industrial processes, such as the pharmaceutical, sanitary, and semiconductor industries, generally require the process fluids to be kept ultra pure. Components used in fluid delivery systems, such as valves, are routinely cleansed to ensure that contaminants do not become trapped in such components and thereby introduced into the process system.  
           [0011]    The cleansing processes may involve exposure to high temperature steam for a sufficient amount of time to sterilize the component. Particularly when repeated numerous times, this sterilization process can cause the plastic in the valve to change dimension slightly, resulting in warpage. Creeping results when plastic is subject to stress over a period of time. The plastic component&#39;s dimensions can change from the stress. Due to such warpage and creep, tolerances, especially at the weir, are affected and leakage may result. Therefore, a need exists to provide a plastic lined weir-type diaphragm valve that has improved dimensional stability when exposed to repeated cleansing operations or exposure to conditions normally conducive to warpage or creep.  
         SUMMARY OF THE INVENTION  
         [0012]    A reinforced plastic valve apparatus in a preferred embodiment comprises an upper valve portion, a lower valve portion, an endoskeletal structure configured as a weir support or reinforcing member and an exoskeletal framework configured as a support collar. The upper valve portion preferably includes an upper plastic valve housing or body, a resilient diaphragm and a valve actuator. The lower valve portion comprises a lower plastic valve housing or body that is preferably configured to mate with the upper valve housing to define a valve interior. The lower valve body preferably has an integral weir which, in conjunction with the resilient diaphragm, defines a fluid passage. The diaphragm is configured to sealingly engage and disengage with the weir as effected by the valve actuator. The weir support member is disposable within the lower housing to support the weir. In preferred embodiments, an exoskeletal framework configured as the support collar extends circumferentially around the valve and supports the weir support member. In particular embodiments, the valve body components may also comprise a plastic fluoropolymer lining for contacting fluids. The invention also includes the method of manufacturing a reinforced plastic valve preferably including the step of providing a rigid support member to the weir of a lower valve housing.  
           [0013]    An object and advantage of particular embodiments of the present invention is to provide a plastic diaphragm valve with improved dimensional resilience and a method of manufacturing such a valve.  
           [0014]    Another object and advantage of particular embodiments of the present invention is to provide for a fluoropolymer diaphragm valve that is dimensionally tolerant to repeated sterilization processes.  
           [0015]    Another object and advantage of particular embodiments of the present invention is to provide for a valve that is able to withstand repeated sterilization processes and that is also suitable to use in the pharmaceutical, biotechnological, chemical, and/or semiconductor industries.  
           [0016]    Another object and advantage of particular embodiments of the present invention is to provide a means for reinforcing a plastic valve.  
           [0017]    Another object and advantage of particular embodiments of the present invention is to provide for a method of reinforcing a plastic valve, thereby having improved resistance to warpage and creapage.  
           [0018]    Another object and advantage of particular embodiments of the present invention is to provide a support for the weir of a plastic valve.  
           [0019]    Further features, objects and advantages of the present invention will become apparent to those skilled in the art in the detailed description below. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    [0020]FIG. 1 is an exploded parts view of a diaphragm valve according to an embodiment of the present invention.  
         [0021]    [0021]FIG. 2 is a perspective view of the assembled diaphragm valve of FIG. 1.  
         [0022]    [0022]FIG. 3 a  is a cross sectional view of a portion of the reinforced diaphragm valve according to an embodiment of the present invention.  
         [0023]    [0023]FIG. 3 b  is a cross sectional view of a portion of the reinforced diaphragm valve of FIG. 3 a  taken at line  3   b - 3   b.    
         [0024]    [0024]FIG. 4 is a side view of the weir support member according to one embodiment of the present invention.  
         [0025]    [0025]FIG. 5 is a side view of the weir support member of FIG. 4 engaging the support collar.  
         [0026]    [0026]FIG. 6 is a cross sectional view of a lined plastic diaphragm valve according to an embodiment of the present invention.  
         [0027]    [0027]FIG. 7 is a cross sectional view of a portion of a reinforced diaphragm valve according to an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]    A reinforced weir valve  10  in accordance with the invention is illustrated and generally comprises an upper valve portion  12 , a lower valve portion  14 , a reinforcing exoskeletal framework  20  and an endoskeletal support member  22  configured as a valve seat reinforcing member. The valve has a valve body  24  or housing, an actuator  25 , a valve member  26  and valve seat  30 . In the preferred embodiment illustrated, the valve  10  is a diaphragm valve and the valve body comprises a plastic upper valve housing or body  50  and a plastic lower valve body  52 . The upper valve body  50  has an actuator housing  54  with actuation connection means  56 , for example, pneumatic line connectors. Connected to the actuator housing  54  is an upper valve housing  72  and an upper flange  58  with a plurality of upper mounting holes  62 .  
         [0029]    The lower valve body  52  has a lower flange  60  with a plurality of lower mounting holes  64  and mounting slots  65 . The lower valve body  52  has a fluid passageway  74  extending through an open interior  71  of the body  52  with a pair of inlet/outlets  75 . A seating surface  76  is located within the lower valve body  52  and also within the fluid passageway  74 . The seating surface is part of the valve seat  30  configured as a weir, which spans the open interior  71 . The seating surface  76  is sized to cooperate with the diaphragm  104  and the actuator  106  to form a fluid tight seal at the weir  78 . The lower valve body  52  further includes an aperture  80  that extends from the exterior  53  of the lower valve body  52 . The aperture  80  preferably forms a bore  81  that begins at the exterior  53  of the lower valve body  52  and extends through at least the length of the seating surface  76 . The length of the bore  81  extends through the weir  78  and is not exposed to the fluid passageway  74 .  
         [0030]    The valve is reinforced, or supported, by the provision of the endoskeletal support member  22  and is configured as a weir support member  82  and the exoskeletal framework  20  configured as support collar  90 . The weir support member  82 , as shown in FIG. 4, is preferably rod shaped having a first end  86 , a second end  88 , a longitudinal surface  87  and notches  84  in the longitudinal surface  87  at both ends  86 ,  88 . As shown in FIG. 7, the weir support member  82  may also be any suitably shaped elongated member. Those skilled in the art will recognize that many alternative embodiments of weir support member shape, such as polygonal, will provide the envisioned support without departing from the scope of the present invention.  
         [0031]    The support collar  90 , shown in FIGS. 1 and 5, comprises an upper portion  92  and a lower portion  94 . The upper portion  92  and lower portions  94  are preferably approximately U-shaped and overlap when placed on the valve housing. There are a plurality of collar mounting holes  96  and slotted mount holes  97  in the upper portion  92  that correspond to respective upper mounting holes  62 , lower mounting holes  64  and mounting slots  65 . The slotted mount holes  97  aide in joining the upper portion  92  to the lower portion  94  and the valve bodies  50 ,  52  during assembly.  
         [0032]    The lower portion  94  may be provided with two mounting posts  98  that cooperate with the mounting slots  65  and upper mounting holes  62  of the valve bodies  50 ,  52  and slotted mount holes  97  of the upper portion  92  for enabling the joining of the valve bodies  50 ,  52 . The mounting posts  98  have a threaded portion  100  and a smooth portion  102  to provide a means for fastening the valve bodies  50 ,  52  together. The lower portion  94  also has two collar mounting holes  96  that communicate with respective collar mount holes  96  of the upper portion  92 , the upper mounting holes  62  of the upper valve body  50  and the lower mounting holes  64  of the lower valve body  52 .  
         [0033]    Referring to FIG. 3 a,  the diaphragm valve has a diaphragm  104  in a disengaged position. The compressor  106  is configured to provide pressure on the diaphragm  104  when called to close the fluid passageway  74 . The compressor  106  shown is a partial hemispherical type compressor that has a similar cross section through 360 degrees of rotation. FIG. 7 shows a blade-type actuator  107  that is an alternative to the partial hemispherical actuator of FIG. 3. The blade type actuator  107  spans the length of the weir  78  and has a width approximately equal to the weir  78 . Those skilled in the art will recognize that other embodiments of the actuator  106  are functionally equivalent to those depicted and described herein without departing from the scope of the invention.  
         [0034]    The compressor  106  is moved by a drive means as in the actuator  25  such as a pneumatic means, electric means, or manual means. U.S. Pat. Nos. 4,977,929, 6,056,264, 5,368,452 and 5,279,328 disclose several suitable drive means for actuators used in weir-type diaphragm valves. U.S. Pat. Nos. 4,977,929, 6,056,264 and 5,368,452 are hereby incorporated by reference.  
         [0035]    The diaphragm valve of the present invention can utilize many different types of fittings  108 ,  138  to join the valve to pipe and piping systems. FIG. 1 shows an Entegris PureBond® fitting. FIG. 6 shows an Entegris Synergy® type sanitary fitting that utilizes an overmolded plastic portion on the fittings. Entegris Flaretek® fittings are also suitable to the present invention. These marks are all registered to Entegris, Inc. the owner of the instant application. U.S. Pat. Nos. 4,848,802, 4,929,293, 5,472,244 and 5,837,180 all disclose examples of suitable fittings for coupling a plastic valve to tubing. These four patents are incorporated herein by reference. Other fittings also may be suitable.  
         [0036]    Referring to FIG. 4, a side view of the weir support member  82  is shown.  
         [0037]    Referring to FIG. 5, the weir support member  82  is shown in cooperation with the support collar  90 . The notch  84  seats on the upper portion  92  to support the weir support member  82  and retaining the member in the aperture  80  in the lower body. The overlapping portion  92 ,  94  provide uniform support at the bottom surface  117  of the flange  60  and allow the collar to be the function equivalent of a unitary collar. The overlapping configuration allows the compression of the upper and lower valve bodies as provided by each of the bolts  66  or studs  68  to act on a large area of the flanges. The cooperation of the weir support member  82  and the support collar  90  provide support and reinforcement to the weir  78 , the valve flanges, and generally, the valve bodies  50 ,  52 . Thus, warpage and creep of the weir, the flanges and generally the valve bodies is inhibited.  
         [0038]    Referring to FIG. 6, an alternative embodiment of the present invention is illustrated. A plastic valve body  126  is provided with a plastic fluoropolymer lining  125 . The valve body  126  has a weir  136  and a weir base portion  134 . A weir support member  142  contacts the weir base portion  134  and the plastic lining  125 , thereby supporting the weir  136 . The support collar  130  engages the mounting flange  140  of the valve body  126 . The lining  125  terminates in fittings  138  for attachment to pipe or piping systems. The fitting  138  of FIG. 6 includes a support ring  139 . Valve body  126  is adapted to receive an upper valve body  50  such as that shown in FIG. 1 and described herein.  
         [0039]    The valve bodies  50  and  52  are preferably formed of fluoroploymers, including but not limited to perfluoroalkoxy resin (PFA), polyvinylidene fluoride (PVDF) or other fluoropolymers. In certain applications, other plastics may be suitable, such as polyvinyl chloride (PVC), or polypropylene (PP). The body components are preferably injection molded, although they may be machined. The wetted portion of the diaphragm  104  may be formed of polytetrafluoroethylene (PTFE). The diaphragm may be composite with a layer adjacent the PTFE layer formed of EPDM. The weir support member  82  and the support collar  90  are preferably constructed of stainless steel. Stainless steel provides the desirable amount of rigidity and durability to provide the plastic valve with the desired amount of dimensional integrity. In certain instances, other rigid materials such as carbon fiber filled PEEK or other polymers may be utilized. Those skilled in the art will recognize that the above structures may be constructed from other materials without departing from the scope of the invention.  
         [0040]    The reinforced valve according to one embodiment of the present invention is assembled as shown in the assembly drawing of FIG. 1, resulting in the completed valve of FIG. 2. The weir support member  82  is first inserted into the aperture  80  so that the notches  84  face away from the lower flange  60 . The lower portion  94  of the support collar  90  is next disposed about the lower flange  60  on the lower valve body  52  so that the collar mount holes  96  align with the lower mounting holes  64 . Next, the upper portion  92  is inserted into the space between the lower portion  94  and the lower flange  60 . The slotted mount holes  97  engage the mounting posts  98  when the collar mount holes  96  align with the lower mounting holes  64  and the collar mount holes  96  of the lower portion  94 .  
         [0041]    The upper valve body  50  is next placed onto the assembled lower valve body  52 . Two of the upper mounting holes  62  receive the mounting posts  98  and the remaining upper mounting holes  62  are aligned with respective mounting holes  64  and  96 . When the upper flange  58  is in contact with the lower flange  60 , the threaded portions  100  of the mounting posts  98  will protrude from the upper mounting holes  62  in the upper flange  58 . A plurality of washers  68  are placed over the threaded portions  100  and a nut  70  is tightened onto each of the exposed threaded portions  100 . Finally, bolts  66 , or other suitable fastener, receive a plurality of washers  68  and are inserted though the remaining aligned mounting holes  96 ,  64 ,  62  and tightened. Preferably the diaphragm housing is provided with threaded bores to receive the bolts  66 .  
         [0042]    In operation, the diaphragm  104  confronts valve seating surface  76  and moves by the actuator  25  including the compressor  106 . The diaphragm  104  approaches the seating surface  76  until a seal is formed by engagement with the seating surface  76 . Such sealing creates a fluid tight separation of the fluid flow between the halves of the valve body defined by the weir  78 . The valve is opened by displacing the diaphragm  104  from the seating surface  76  and the weir  78 .  
         [0043]    Referring to FIGS. 8, 9 and  10 , a further embodiment of a valve  158  is illustrated. This embodiment similarity has a valve body  160  comprised of an upper valve body portion  162  and a lower valve body portion  164 . The lower valve body portion has an integral weir  168 , a first flow duct  172  with a first flow passage  173 , a second flow duct  174  with a second flow passage  175 , and a third flow duct  176  with a third flow passage  177 . The first and second flow ducts are contiguous and collinear and together with the lower valve body define a central flow passage  180  that has a central flow passage axis A 1 . Said central flow passage connects to fourth flow passage extending along one face  184  of the weir  168 , to the open interior  185  above the weir where the diaphragm moves. A fifth flow passage  188  connects to the third flow passage  177  and extends up to the other face  190  of the weir to the open interior  185  above the weir  
         [0044]    The weir has a central axis A 2  centrally located through said weir. Said weir axis A 2  is preferably coaxial with an actuator axis A 3  and a valve axis A 4 . The actuator will typically have a pneumatic cylinder or manual rotatable shaft that defines said actuator axis. The third flow duct and third flow passage have a third flow passage or duct axis A 5 . The actuator axis A 3 , valve axis A 4 , and weir axis A 2  are displaced from and at preferably a right angle to the central flow duct axis A 1 .  
         [0045]    The valve  158  of FIGS. 8, 9 and  10  has reinforcing framework  198  comprising an exoskeleton framework  200 . The exoskeleton framework comprises a flange support ring  206 , a lower valve body support plate  208 . The flange support ring  206  has two U-shaped segments  212 ,  214 . The U-shaped segments overlap to define a ring portion that engages the flange  217  of the lower valve body  164 .  
         [0046]    In the embodiment of FIGS. 8, 9 and  10 , five bolts  224  extend through apertures  226  in the lower plate  208 , through the lower valve body portion  164  and into threaded holes  168  in the flange support ring  206 . Additional bolts  230  extend through the flange retainer ring through the lower valve body flange  217 , through the diaphragm flange  234 , through the upper valve body portion  162  and attach to nuts  238 . A further mounting bracket  244  may be utilized to attach the flange ring  206  to a suitable mounting surface.  
         [0047]    Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize changes may be made in form and detail without departing from the spirit and scope of the invention.