Abstract:
A flow control device includes a first body and a second body; a threaded engagement for clamping the bodies together in an axially aligned relationship; a diaphragm seal that is disposed axially between the first and second bodies to form a seal there between; each of the first and second bodies having a generally flat surface portion near its respective outer periphery; at least one of the generally flat surfaces being adjacent an outer corner thereof; the diaphragm being singularly clamped between the generally flat portions; the diaphragm having an outer peripheral portion adjacent the generally flat surfaces and that bends over and seals at the corner.

Description:
RELATED APPLICATIONS 
     This application is a divisional application of Ser. No. 09/015,751, filed Jan. 30, 1998, now U.S. Pat. No. 6,092,550 which claims the benefit of priority from U.S. provisional application Nos. 60/037,698 filed Feb. 3, 1997 and 60/072,995 filed Jan. 29, 1998 for DIAPHRAGM VALVE, the entire disclosures of which are fully incorporated herein by reference. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The subject invention is directed to a high flow diaphragm valve of the general type shown in U.S. Pat. Nos. 4,671,490; 4,732,363; and, 4,750,709. More particularly, the invention is directed to a diaphragm valve having an improved valve seat arrangement and an improved body seal using a single clamp and corner arrangement. 
     BACKGROUND OF THE INVENTION 
     Diaphragm valves are generally known and include a body seal arrangement and a valve seat arrangement. The body seal typically is achieved at or near the outer peripheral area of the diaphragm by clamping and compressing the diaphragm between facing surfaces of the valve body. Imperfections in the body surf aces and diaphragm surface, however, can require very high compression of the diaphragm to achieve a satisfactory seal. Harder materials for the diaphragm exacerbate the body seal problem at the clamping surfaces. 
     A valve seat is used to seal off an inlet and outlet passageway by engaging with the diaphragm. Prior designs tend to have large surface areas of the seat exposed to the fluid, thus providing possible leak paths and contamination. Valve seat surfaces can be pre-formed with specific contours to improve sealing, but such steps tend to be time consuming and thus more expensive. 
     Accordingly, it is a general objective of the present invention to provide a diaphragm-type valve that has improved body seal and valve seat arrangements and that can be manufactured at competitive costs and performance, with higher flow rates achieved using similar overall device dimensions. 
     SUMMARY OF THE INVENTION 
     In accordance with one embodiment of the invention, a flow control device such as a diaphragm valve includes a first body and a second body; means for clamping the bodies together in an axially aligned relationship; a diaphragm seal that is disposed axially between the first and second bodies to form a seal there between; each of the first and second bodies having a generally flat surface portion near its respective outer periphery; at least one of the generally flat surfaces being adjacent an outer corner thereof; the diaphragm being singularly clamped between the generally flat portions; the diaphragm having an outer peripheral portion adjacent the generally flat surfaces and that bends over and seals at the corner. 
     In accordance with another aspect of the invention, a valve seat arrangement is provided for a diaphragm valve of the type having a first body with fluid inlet and outlet openings therein and a second body axially coupled to said first body with a contoured diaphragm seal clamped there between for controlling flow between said inlet and outlet passages, the valve seat arrangement including a first collar that surrounds one of said fluid openings and that extends axially toward the diaphragm; a second collar that is radially spaced outward from the first collar to form a recess there between; the second collar extending axially toward the diaphragm a distance greater than the first collar; a valve seat disposed in the recess; the seat extending axially beyond the second collar and being retained in the recess by the first collar; the seat having an upper surface that engages with and forms a seal with a portion of the diaphragm to close the one opening; the upper surface generally conforming to the diaphragm contour when engaged therewith. 
     These and other aspects and advantages of the present invention will be readily understood and appreciated by those skilled in the art from the following detailed description of the preferred embodiments with the best mode contemplated for practicing the invention in view of the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The valves of the subject application can best be understood by reference to the accompanying drawings wherein: 
     FIG. 1 is a vertical cross-sectional view through a hand operated version of the diaphragm valve; 
     FIG. 2 is an exploded isometric view of the operating portion of the valve of FIG. 1; 
     FIG. 3 is a partial section view taken on line  3 — 3  of FIG. 1 but showing the indicator dial used with the manual operating system of FIG. 2; 
     FIG. 4A is an elevational view of the body element used in all versions of the subject valve; 
     FIG. 4B is a view taken on line  4 B— 4 B of FIG. 4A; 
     FIG. 4C is a greatly enlarged view of the circled area of FIG. 4B; 
     FIGS. 5A and 5B are views showing the circled area of FIG. 1 immediately before the bonnet is clamped into engagement with the diaphragm and immediately after completion of the clamping; 
     FIGS. 6A,  6 B, and  6 C show the circled seat area of FIG. 1 during the sequence of forming and staking the resilient seat element into position in the body; 
     FIG. 7 is a vertical cross section through an air-actuated version of the valve (this version is a normally closed air actuator); and 
     FIG. 8 is a vertical cross-sectional view through a normally open air actuator which can be used on the valve body of FIG. 1 or FIG.  7 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As mentioned herein earlier, the valves of the subject invention all use a common body design and construction which can best be understood by reference to FIGS. 1,  4 A,  4 B,  4 C,  5 A,  5 B,  6 A,  6 B, and  6 C. As illustrated therein, the body  10  is machined from a suitable metal such as stainless steel and comprises an inlet passage  12  which connects with a vertically extending flow passage  14  leading to a valved outlet opening  16  at the upper end of body  10 . An exit or discharge passage  18  extends downwardly parallel to the passage  14  and connects an outlet  20 . The upper end of the body  10  is circumferentially threaded at  22  for threaded receipt of a bonnet nut member  24 . Positioned over the upper end of the body  10  and clamped thereto by a bonnet member  26  is a multiple layer metal diaphragm  28 . The general construction and arrangement of the diaphragm  28  can be, for example, as described in the above-mentioned U.S. patents which are incorporated herein by reference. Of importance to the subject invention is the manner in which the peripheral edge of the diaphragm assembly  28  are clamped and sealed relative to the body  10 . In this regard, attention is directed to FIGS. 4A 4 C,  5 A, and  5 B. As shown in FIG. 4C, a raised flange  30  extends circumferentially about the upper end of the body  10  and encircles both the outlet from passage  14  and the inlet to passage  18 . The outer wall of the collar  30  is preferably inclined as shown so that the included outer corner angle  32  is in the range of about 120° to 145°; this range is exemplary, however, with the included angle being selected at any suitable value based on the overall apparatus design and configuration. 
     FIGS. 5A and 5B are greatly enlarged showings of the relationship between the flange or collar  30 , the diaphragm assembly  28 , and the lower clamping edge portion of the bonnet  26 . The diaphragm  28  is shown in position on the top planar surface  30   a  of the collar  30 . Preferably, the diaphragm is provided with a convex center section (see FIG. 1) and a generally planar, radially extending peripheral edge section  28   a  as illustrated in FIG.  5 A. The bonnet  26  itself has a contoured lower peripheral surface which includes a flat  26   a  that is surrounded by a cylindrical wall  26   b  that terminates in a corner  26   c.  When the bonnet is driven into clamping engagement as shown in FIG. 5B, the flat  26   a  clamps the top surface of the diaphragm assembly  28  as shown. The corner  26   c,  however, deflects and bends the outer peripheral portion of the diaphragm downwardly creating a high sealing pressure over corner.  32  of collar  30 . The final relationship is shown in FIG.  5 B. 
     The clamping sequence is as follows. When the bonnet is driven into initial clamping engagement as in FIG. 5A, the corner  26   c  deflects and bends the outer peripheral portion  28   a  of the diaphragm downward and over the corner  32  of the collar  30  (see FIG.  5 A). The flat  26   a  then begins clamping the top surface of the diaphragm  28  against the top planar surface  30   a  of the collar  30  and the diaphragm may be made of a material that is substantially harder than the body  10  material. (preferably but not necessarily the flat  26   a  is generally parallel to the flat  30   a  when the bonnet and body are clamped together), while the corner  26   c  continues acting on the diaphragm peripheral portion  28   a  thus bending and crimping the diaphragm  28  around the corner  32 . The force applied during this make-up procedure is sufficient to deform or yield the diaphragm  28  and the corner  32  to create a primary body seal there between. The deformation or yielding of the corner  32  and the diaphragm to form the primary seal is controlled by proper sizing of the corner  26   c  diameter and hardness, the corner  32  diameter, the length of the cylindrical wall  26   b  and the diaphragm  28  thickness. It is preferred but again not required that the deformation or yielding occur primarily at the corner  32  and the diaphragm in order to produce a good primary seal; therefore the bonnet  26  can be made of a harder material than the collar  30 . A suitable material is 17-4PH (precipitation hardened) stainless steel although this is but one example of stainless steel and other materials that are well known to those skilled in the art. The primary seal corner  32  deformation is limited when the diaphragm  28  is clamped between the flat planar surfaces  26   a  and  30   a,  which clamping produces a secondary seal between the bottom surface of the diaphragm  28  and the top planar surface  30   a  of the collar  30 . This secondary seal and clamping helps reduce or eliminate entrapment areas. The radial inner edge  30   b  of the collar  30 , and the clamping force applied to the diaphragm  28  radially inward from the corner  32  primary seal area also operate to reduce stress applied to the primary seal under cyclic operation of the diaphragm  28  by acting as pivot points for the diaphragm  28  as the diaphragm cycles up and down. These pivot points are radially spaced inward of the primary seal and thereby reduce stresses applied to the primary seal area during such diaphragm movement. The described body seal design significantly reduces the interior space required to sealingly clamp the diaphragm  28  within the valve, thus freeing more internal space to increase fluid flow. Still further, during the initial engagement when the corner  26   c  engages the diaphragm flat outer peripheral portion  28   a,  the diaphragm  28  is placed in tension prior to being clamped between the flats  26   a,    30   a.  This tension increases the radius of the diaphragm dome and the transition radius to the peripheral flat portion  28   a.  The tension thus reduces the cyclic stress caused by “snap-through” action of the diaphragm. Both of these effects improve fatigue life of the diaphragm  28 . 
     The portion of the bonnet  26  radially outward of corner  26   c  can vary as shown by the dotted line. Additionally, the included angle of the corner  26   c  can vary from less than 90° to somewhat in excess of 100° or more. The angle should be selected, however, so as to control the necessary deflection of the diaphragm over the corner  32  and assure a sealing contact as required. 
     Referring again to FIG. 1, it will be seen that the clamping forces necessary to drive the peripheral edge of the bonnet into sealing engagement with the diaphragm assembly  28  and produce the necessary sealing and clamping about the peripheral edge of the diaphragm is generated by the bonnet nut  24  being threadedly engaged with the body and suitably driven downwardly. As previously mentioned, the diaphragm  28  preferably has a preformed convex shape as illustrated in FIG. 1 so that in its normal, non-deflected position, it extends above the outlet  16  from passage  14 . 
     FIGS. 6A-6C illustrate the seat and the manner it relates to the diaphragm assembly  28 . In the subject embodiment, the seat is defined by a resilient seat ring member  40  that is positioned in a recess  42  formed circumferentially about the upper end of the passage  14 . Referring to FIG. 4C, this recess  42  is formed to extend axially in from the top surface of body  10  and provide an axially extending flange or collar  44 . Radially outward of the recess  42  is a raised collar  46  having the contour and general configuration shown. Referring again more particularly to FIGS. 6A-6C, the resilient seat ring  40  has the normal non-deformed configuration shown in FIG.  6 A and is formed from any suitable resilient material such as PCTFE (polychlorotrifluoroethylene) or any of the materials suggested in the above-identified U.S. patents depending upon the operating environment and conditions. 
     The assembly of the seat into the recess  42  is carried out in the sequence suggested by FIGS. 6A-6C. FIG. 6A shows the seat element positioned in the recess  42  subsequent to deformation of the inner collar or flange  44 . With the seat element  40  positioned in the recess, a staking tool is brought into position as generally illustrated by item  50 . The staking tool item  50  is then driven downwardly to deflect radially outward the collar or flange  44  to a position as shown in FIG. 6B wherein the seat element is mechanically locked, tightly gripped and sealed between the collar  44  and the surrounding body sections including the collar  46 . This staking process causes the upper surface  40   a  of the seat  40  to become slightly concave to more closely match or conform with the contour of the diaphragm  28  lower surface (as viewed in FIG. 6B) during shutoff. When the body and the seat assembly are subsequently assembled into position in an operative valve, the diaphragms can be deflected downwardly during the first cycle and they generally follow the contour of the lower end of the operating stem and/or operating button in a manner subsequently to be described. That is, the generally convex configuration of the diaphragm assembly becomes concave and engages in sealing fashion with the upper concave end surface  40   a  of the seat ring  40 . The diaphragm  40  further engages the upper surface  46   a  to reduce diaphragm and seat damage due to over-torque or excessive force during shutoff. Over repeated cycling the seat upper surface  40   a  will tend to further conform to the diaphragm contour. 
     The outer perimeter  40   b  of the seat  40  is nearly entirely supported by the collar  46  to reduce or limit seal strain during high shut-off forces. Also, the radially inner collar  44  is substantially shorter in its axial length than the axial length of the outer collar  46 . For example, the inner collar  44  axial length may be between about 25% and about 75% of the axial length of the outer collar  46 . This arrangement provides space for the upper portion of the seat  40  to deform (such as, for example, in the nature of a bulge as represented in FIG. 6 c ) inward during shut-off and to increase resiliency of the upper portion of the seat  40  to elastically deform under shut-off forces typically incurred in the various embodiments herein, thus permitting the upper surface  40   a  of the seat  40  to conform to and seal against the diaphragm  28 . 
     The above-described seat  40  configuration and assembly staking process allow a more economical finishing of the seat  40  sealing surface  40   a.  The seat seal surface  40   a  can be initially formed as a flat horizontal surface to simplify the finishing step thereof. If the seat surface  40   a  were formed concave, it would be significantly more costly to finish the surface. The concave contour of the seat surface  40   a  that is produced by the staking operation also increases the contact surface area between the seat  40  and the diaphragm. This increased sealing area including the increased radial distance of the contact area improves seat seal performance and reduces permeation leakage across the sealing area. 
     The basic structure thus far described is used with a hand operator as well as a normally closed and normally opened manual operator or air actuator. Specifically, FIGS. 1,  2 , and  3  illustrates the manual operator whereas FIGS. 7 and 8 illustrate the two forms of air actuators or operators. Referring in particular to FIGS. 1-3, the bonnet  26  of the hand or manual operator is provided with internal threads which receive an externally threaded operator element  56  having a cylindrical lower end  58  that passes through a reduced diameter opening  60  at the lower end of the bonnet  26 . The lower end of the operator is slightly convex as shown at  62  and directly engages the top surface of the diaphragm assembly  28 . The lower surface of the operator  62  closely matches the upper surface  46   a  of the outer collar  46  and biases the seat  40  sealing forces in a radial outward direction where the seat  40  is supported by the raised outer collar  46 . Preferably, a suitable lubricant, either solid or liquid, is positioned between the upper surface of the diaphragm assembly  28  and the operating convex surface  62  of the operator  58 . 
     At its upper end, the operating element  56  is provided with a reduced diameter keyed end portion  64  that receives the manual operating handle  66 . It will be noted that the handle  66  includes a central opening  68  that is also keyed to correspond to the end portion  64  of operating member  56 . The outermost end of the operating element is threaded as shown at  70  and adapted to receive a clamp nut  72  that holds the handle  66  in position. A suitable end cover  74  is snapped in position in the handle to cover nut  72 . 
     Movement of the handle is limited to a three-quarter turn arrangement between full open and full closed. This is accomplished by a stop element  76  molded within the handle and arranged to engage opposite sides of a rigid stop element  78  extending upwardly from the top end of bonnet  26 . Movement of the handle is, of course, limited by engagement between the stop  76  and element  78  at opposite ends of rotation. 
     Located between the bonnet  26  and the handle  66  is a base element  80  which includes a central cylindrical portion and an upper radially extending flange  82 . At its lower end, there is a reduced diameter sleeve portion  84  which extends downwardly within the upper end of bonnet  26  as best seen in FIG. 1. A suitable opening  88  is formed through the base member  80  to allow the stop  78  to extend upwardly therethrough for engagement by stop member  76  of the handle  66 . 
     The top surface of the flange  82  of the base  80  is provided with indicia of the type shown in FIG.  3 . Similarly, the handle is provided with an opening through its upper surface so that the indicia on flange  82  is visible therethrough. Preferably, the opening through the handle is a 90° slot which generally corresponds to the portion indicated with the letter C in the indicia markings. Thus, when the handle is in the full closed position, the red C area of the indicia shows through the opening indicating to an observer that the valve is in a closed position. However, as the valve handle is moved counterclockwise, the indicia is shown to change from a white/green combination to a full green open position. 
     In addition to the manual operated arrangement, it is possible to operate the valve with other types of actuators such as the normally open actuator shown in FIG.  8 . This actuator is arranged so as to thread directly to the upper end of the body  10  and includes a bonnet nut  24 ′ which clamps a shorter and modified bonnet element  90  into position to clamp the diaphragm in sealing engagement with the body  10 . The interior of the bonnet  90  is threaded as shown at  92 . The air actuator  94  has a housing  96  including a lower housing portion  98  that has a reduced diameter threaded end  100  which is threaded into the bonnet nut  90  as shown. The housing portion  98  defines a multiple diameter internal chamber which is threaded at its upper end as shown at  102  and receives a cap  104 . The cap  104  is provided with a threaded inlet port  106  for connection to a suitable air supply line (not shown). Positioned within the chambers defined by housing component  98  is a first piston member  108  which is mounted for vertical reciprocation and is continually biased in an upward valve open direction by a relatively heavy coil spring  110 . The lower end or reduced diameter portion  108   a  of piston  108  receives a wear resistant bushing  108   b  to guide the lower piston  108  within the reduced diameter housing portion  100 . The lower end of the piston  108  bears against a drive button member  112  that is guided and retained within the portion  100  and acts directly against a top surface of the diaphragm  28  of the associated valve body. Preferably, the button  112  is formed from a suitable plastic material having lubricating qualities. The lower end surface  112   a  of the button  112  is slightly convex to closely match the top concave surface  40   a  of the seat  40 . The piston  108  is sealed by a suitable 0-ring  114  located about its upper end. Normally, the piston is biased upwardly as shown to a valve opening position. The area below the piston  108  is vented to atmosphere through an opening  98   a.  A second piston member is carried above the first piston  108 . The second piston  116  has a reduced diameter portion  118  that extends through an intermediate wall defining piston-like member  120  located generally centrally of the housing  94 . The intermediate wall  120  is sealed by an O-ring  122  and the reduced diameter portion  118  is also sealed by an O-ring  124  where it passes through the wall  120 . The area between the upper piston  116  and the intermediate piston  120  is vented to atmosphere through an opening  98   b.    
     Air supplied through inlet port  106  acts against the top surface of the piston  116  and is also conducted through the center opening  116   a  and the radial grooves  116   b  so as to fill the space between the lower surface of the wall  120  and the top surface of piston  108 . Thus, this allows the downward force of both the area of the top piston  116  and the top of piston  108  to act against the force of spring  110  and move the valve to a closed position. Thus, the two piston arrangement provides a great force multiplication. 
     In addition to the normally open air actuator as shown in FIG. 8, a normally closed air actuator is also proposed and illustrated in FIG.  7 . The FIG. 7 showing shows the assembly directly connected to the valve body  10 . The normally closed actuator assembly  130  is connected to the valve body  10  by the previously-mentioned bonnet nut  24 ′ and the bonnet  90 . Here, again, a button element  112  with a lower surface  120  slightly convex to closely match the top concave surface  40   a  of the seat  40 , is used to act directly against the diaphragm assembly  28 . The actuator assembly  130  includes a main housing member  132  having a lower end  134  of reduced diameter and threadedly received in the bonnet  90 . The housing  132  has a stepped diameter interior as shown and carries a first piston member  136  at its lower end. The piston  136  is mounted for vertical reciprocation and is sealed by a central O-ring  138 . At its lower end, reduced diameter portion  140 , it is also provided with an O-ring  142  and is sealed within the reduced diameter opening within the end portion  134 . Centrally of the housing member  132  there is a wall defining disk-like member  144  which is sealed about its outer periphery by an O-ring  146 . The area under the wall  144  is vented to atmosphere through an opening  148 . The reduced diameter upper end portion  150  of the piston  136  is sealingly and sliding received through the central opening in the wall member  144  and sealed during movement therethrough by an O-ring  152 . 
     Positioned above the wall  144  for acting against the upper end of piston portion  150  is a second actuating piston  160  which is mounted for vertical reciprocation in the upper end of the housing member  132  and sealed about its periphery by an O-ring  162 . The reduced diameter upper end portion  164  of the upper piston  160  is provided with an O-ring  166  and is slidably received within a cylindrical bore  168  carried in an end cap member  170 . The area above the upper piston  160  is vented to atmosphere through an opening  148   a.  The end cap member is threadedly and sealing received on the upper end of the housing member  132  and carries a relatively heavy coil spring  172  which acts downwardly against the piston  160  which in turn acts against the upper end  150  of piston  136 . Thus, the valve is normally biased to a closed position. The showing of FIG. 7 shows the valve in its open position however. To achieve this open position, air is supplied through the port  170   a  at the upper end of cap  170 . It then flows through the central opening  160   a  to a position under the piston  160  where it exerts an upper force tending to act against the bias of spring  172 . Additionally, air is supplied through the central opening  136   a  to a position where it flows radially through a passage  136   b  to the space under piston  136 . This biases piston  136  upwardly with the upper end portion  150  bearing against the underside of piston  160 . This produces a multiplication of force acting in an upward direction allowing the diaphragm assembly  28  to move to the open position shown. 
     While the invention has been shown and described with respect to specific embodiments thereof, this is for the purpose of illustration rather than limitation, and other variations and modifications of the specific embodiments herein shown and described will be apparent to those skilled in the art within the intended spirit and scope of the invention as set forth in the appended claims.