Diaphragm valve with actuator bearing element

Abstract

A diaphragm valve includes a valve body having a valve seat disposed in a valve cavity surrounding a flow passage; a diaphragm movable between a closed position in sealing engagement with the valve seat and an open position axially spaced from the valve seat; the actuator comprises an actuator shell and an actuating device which are assembled with the valve body; the actuating device is axially movable within the actuator housing between a first position holding the diaphragm in the closed position and a second position permitting movement of the diaphragm from the closed position to the open position. In one embodiment, the actuator device includes an actuator rod extending through a lower aperture in the actuator housing; an actuator button disposed between a lower end of the actuator rod and the diaphragm to be in contact with the diaphragm; and a bearing member disposed between the actuator rod and the actuator button.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and all benefits of U.S. Provisional Patent Application No. 63 / 438,802, filed on January 13, 2023, "DIAPHRAGM VALVE WITH ACTUATOR BEARING ELEMENT," the entire disclosure of which is incorporated herein by reference. Background Art

[0003] Valves are commonly used to control the flow of fluids. Diaphragm valves are an example of flow control valves, and diaphragm valves are used in many industries to control the flow of gases, liquids, and other fluids, and are used to prevent flow by moving a diaphragm into contact with a valve seat and to allow flow by allowing the diaphragm to separate from the valve seat. In many embodiments, the valve includes an actuator (e.g., manually operated, pneumatically operated, electrically operated, etc.) having an actuator stem that is movable axially toward the diaphragm to maintain the diaphragm in a closed position and away from the diaphragm to allow the diaphragm to move to an open position (e.g., by elastic / spring bias, or under fluid pressure). Summary of the Invention

[0004] In an exemplary embodiment of the present disclosure, a diaphragm valve includes: a valve body having a valve seat disposed in a valve cavity and surrounding a flow channel; a diaphragm movable between a closed position in sealing engagement with the valve seat and an open position axially spaced from the valve seat; and an actuator including an actuator housing assembled with the valve body and an actuator device movable axially within the actuator housing between a first position for retaining the diaphragm in the closed position and a second position for permitting movement of the diaphragm from the closed position to the open position. The actuator device includes: an actuator rod extending through a lower hole in the actuator housing; an actuator button disposed between a lower end of the actuator rod and the diaphragm to contact the diaphragm; and a bearing member disposed between the actuator rod and the actuator button. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Other advantages and benefits will become apparent to those skilled in the art upon consideration of the following description and appended claims in conjunction with the accompanying drawings, in which:

[0006] Figure 1 illustrates a schematic cross-sectional view of an exemplary diaphragm valve assembly according to an exemplary embodiment of the present disclosure;

[0007] Figure 2 illustrates a perspective view of another exemplary diaphragm valve assembly according to another exemplary embodiment of the present disclosure;

[0008] Figure 3 for Figure 2 a side cross-sectional view of a diaphragm valve assembly;

[0009] Figure 3A for Figure 2 An enlarged partial cross-sectional view of an actuating device of a diaphragm valve assembly;

[0010] Figure 3B is an enlarged partial cross-sectional view of an alternative actuation device for a diaphragm valve assembly according to another exemplary embodiment of the present disclosure;

[0011] Figure 4 for Figure 2 An exploded perspective view of an actuating device of a diaphragm valve assembly;

[0012] Figure 5 for Figure 2 a lower perspective view of an actuator stem of a diaphragm valve assembly; and

[0013] Figure 6 for Figure 2 Upper perspective view of the actuator button of the diaphragm valve assembly. DETAILED DESCRIPTION

[0014] This detailed description describes only exemplary embodiments and is not intended to limit the scope of the claims in any way. In fact, the claimed invention is broader than and is not limited by the exemplary embodiments, and the terms used in the claims have their full ordinary meaning.

[0015] Although various innovative aspects, concepts and features of the present invention can be described and illustrated as embodied in combination in exemplary embodiments herein, these various aspects, concepts and features can be used individually or in various combinations and subcombinations thereof in many alternative embodiments. Unless explicitly excluded herein, all such combinations and subcombinations are intended to be within the scope of the present invention. Further, although various alternative embodiments of various aspects, concepts and features of the present invention, such as alternative materials, structures, configurations, methods, circuits, devices and components, software, hardware, control logic, substitutes for appearance, coordination and function, etc., can be described herein, such descriptions are not intended to be a complete or exhaustive list of available alternative embodiments (whether currently known or developed later). Those skilled in the art can easily apply one or more of innovative aspects, concepts or features to additional embodiments and uses within the scope of the present invention, even if such embodiments are not explicitly disclosed herein. In addition, although some features, concepts or aspects of the present invention may be described as preferred arrangements or methods herein, such descriptions are not intended to indicate that such features are necessary or essential, unless explicitly stated. Furthermore, exemplary or representative values and ranges may be included to aid understanding of the present disclosure; however, such values and ranges should not be construed in a limiting sense and are intended to be critical values or ranges only when expressly stated as such. Further, exemplary or representative values and ranges may be included to aid understanding of the present disclosure; however, such values and ranges should not be construed in a limiting sense and are intended to be critical values or ranges only when expressly stated as such. Unless expressly stated otherwise, a parameter identified as “about” or “approximately” a specified value is intended to include that specified value, values within 5% of that specified value, and values within 10% of that specified value. Furthermore, it will be understood that the drawings of the present application may, but need not, be to scale and, therefore, may be understood to teach various ratios and proportions apparent from the drawings. Furthermore, while various aspects, features, and concepts may be expressly identified herein as innovations or forming part of an invention, such identification is not intended to be exclusive, and rather, there may be innovative aspects, concepts, and features fully described herein that are not expressly identified as such or as part of a particular invention, the invention being instead set forth in the appended claims. Descriptions of exemplary methods or processes are not limited to requiring inclusion of all steps in all cases, nor should the order of presentation of steps be construed as required or necessary unless explicitly so stated.

[0016] In this disclosure, the terms "upper" and "lower" are used to identify the relative positions of elements of the described components of the assembly, as oriented in the accompanying drawings. It will be understood that the valve assembly may be mounted or arranged in any suitable orientation.

[0017] A diaphragm valve is typically actuated to a closed position by applying a force from an actuating element to a flexible central portion of the diaphragm to deflect the central portion of the diaphragm and hold the central portion of the diaphragm against a valve seat surrounding a flow passage of the valve, thereby preventing flow from the flow passage. The size and contour of the diaphragm-engaging surface of the actuating element are ideally designed to maximize sealing contact between the diaphragm and the valve seat. Additionally, positional adjustability of the diaphragm-engaging surface on the actuating element may be desirable, for example, to account for small misalignments and / or machining tolerances. To allow for a larger surface contact area and / or positional adjustability of the diaphragm-engaging surface, the actuating element or device may include an actuator stem driven by an actuating mechanism (e.g., a fluid-driven actuator piston) and a diaphragm-engaging actuator button loosely assembled with or loosely retained by the actuator stem.

[0018] Many diaphragm valve applications, such as atomic layer deposition (ALD) applications, require rapid and continuous cycling between open and closed positions, resulting in millions of actuation cycles in a relatively short period of time. In such applications where loosely assembled actuated components are exposed to rapid, frequent cycling, repeated impacts between the loosely assembled components can cause accelerated wear and heating.

[0019] According to exemplary aspects of the present disclosure, a diaphragm valve can be provided with an actuating device or subassembly comprising a movable actuator rod, a diaphragm engaging actuator button, and a bearing member disposed between the actuator rod and the actuator button. The bearing member can be configured to reduce or eliminate contact between the actuator rod and the actuator button. In some embodiments, the bearing member can be provided by a material selected to reduce wear between contacting surfaces, such as by including a material having a greater hardness (e.g., compared to the material of the actuator rod and the actuator button). In other embodiments, additionally or alternatively, the bearing member can be provided by a material selected to reduce thermal conductivity, such as to provide a thermal disconnect across the actuator components.

[0020] Figure 1A cross-sectional view of an exemplary diaphragm valve 100 is schematically illustrated. The diaphragm valve includes a valve body 110 defining a first flow channel 111 and a second flow channel 112 extending into an internal valve cavity 115. The valve body has a valve seat 120 integral or assembled with the valve body, which is seated in the valve cavity and surrounds the first flow channel 111. A diaphragm 130 is retained in the valve cavity 115 and has an axially fixed outer periphery 131 and an axially flexible central portion 132 that is movable between a closed position in sealing or flow-blocking engagement with the valve seat 120 and an open position in which the diaphragm is axially spaced from the valve seat to permit flow through the flow channels 111, 112. An actuator 140 includes an actuator housing 150 assembled with the valve body 110 and an actuating device 160 that is axially movable within the actuator housing between a first position that retains the diaphragm 130 in the closed position and a second position that permits movement of the diaphragm from the closed position to the open position. The exemplary actuator 160 includes an actuator stem 170 extending through a lower hole 151 in the actuator housing 150, an actuator button 180 disposed between a lower end of the actuator stem and the diaphragm 130 to contact a central portion 132 of the diaphragm, and a bearing member 190 disposed between the actuator stem and the actuator button.

[0021] Many different actuator stem, actuator button, and bearing member configurations can be used. For example, in some embodiments, the upper portion of the bearing member can be received in the lower socket portion of the actuator stem, while the lower portion of the bearing member is received in the upper socket portion of the actuator button. In some such embodiments, the lower socket portion of the actuator stem can be received in the upper socket portion of the actuator button. In other such embodiments, the upper socket portion of the actuator button can be received in the lower socket portion of the actuator stem.

[0022] In some embodiments, the upper socket portion of the actuator button may include an annular wall.In some such embodiments, the lower hole of the actuator housing and the lower socket portion of the actuator rod define an annular recess that receives the annular wall of the upper socket portion.

[0023] In some embodiments, the bearing member can be secured to the lower socket portion of the actuator rod. In some such embodiments, the bearing member can be press-fitted into the lower socket portion. In other such embodiments, the lower socket portion can be crimped onto the bearing member. In still other such embodiments, the bearing member can be snap-fitted into the lower socket portion.

[0024] In some embodiments, the bearing member can be secured to the upper socket portion of the actuator button. In some such embodiments, the bearing member can be press-fit into the upper socket portion. In other such embodiments, the upper socket portion can be crimped onto the bearing member. In still other such embodiments, the bearing member can be snap-fit into the upper socket portion.

[0025] In some embodiments, the bearing member can include a convex upper portion and a convex lower portion. In some such embodiments, the bearing member can be spherical. In some such embodiments, the lower socket portion of the actuator stem can include a concave inner surface portion that provides increased surface contact with the convex upper portion of the bearing member. In some such embodiments, the upper socket portion of the actuator button can include a concave inner surface portion that provides increased surface contact with the convex lower portion of the bearing member.

[0026] In some embodiments, the bearing member can include a material that is harder than the material of the actuator stem and the material of the actuator button.

[0027] In some embodiments, the bearing member can include a material having a lower thermal conductivity than the material of the actuator stem and the material of the actuator button.

[0028] In some embodiments, the bearing member may comprise ceramic.

[0029] In some embodiments, the actuator stem and actuator button can comprise metal.

[0030] In some embodiments, the actuator button can be manufactured from powdered metal.

[0031] In some embodiments, the actuator rod may include a fluid-driven piston.

[0032] In some embodiments, the actuator button may be loosely retained with the actuator stem and bearing member by assembling the valve body and actuator housing.

[0033] In some embodiments, the actuator button may be capable of angular movement relative to the actuator stem.

[0034] Figure 2 、 Figure 3 and Figure 3AAn exemplary diaphragm valve assembly 200 is shown, which includes a valve body 210 defining a first flow passage 211 and a second flow passage 212 extending into an internal valve cavity 215, and an actuator 240 assembled with the valve body 210. A diaphragm 230 is retained in the valve cavity 215 and has an axially fixed outer periphery 231 and an axially flexible central portion 232. The diaphragm is movable by operation of the actuator 240 between a closed position in which the diaphragm is in sealing or flow-blocking engagement with the valve seat 220, and an open position in which the diaphragm is axially spaced from the valve seat to permit flow through the flow passages 211, 212.

[0035] While the valve seat can be integrally formed or integrated with the valve body (e.g., staked in), the valve seat can be provided on a separate, removable component, for example, to facilitate replacement of a worn or damaged valve seat. In the illustrated embodiment, the valve seat 220 is provided on a seat carrier 221 that is sized to fit within the valve cavity 215 and secured against a recessed surface 214 of the valve body 210 by a threaded nut or insert 216. The seat carrier 221 includes an outer rim portion 222 sandwiched between the insert 216 and the recessed surface 214, a central port 223 aligned with the valve first flow passage 211, a sealing ring 225 (which can be integrally formed with the valve seat 220) that surrounds the central port 223 and seals against the recessed surface, and one or more peripheral ports 224 that permit flow between the central port and the second flow passage 212 when the diaphragm 230 is in the open position, spaced from the valve seat 220. The outer periphery 231 of the diaphragm 230 may be welded to the seat carrier 221 or sandwiched between the insert 214 and the seat carrier.A similar arrangement is described in commonly owned US Patent No. 9,863,542, the entire disclosure of which is incorporated herein by reference.

[0036] The exemplary actuator 240 includes an actuator housing 250 assembled with the valve body 210 (e.g., by threaded engagement with the insert 216, as shown) and an actuator device 260 that is movable axially within the actuator housing between a first position that maintains the diaphragm 230 in the closed position and a second position that permits the diaphragm to move from the closed position to the open position. The exemplary actuator device 260 includes an actuator stem 270 extending through a lower hole 251 in the actuator housing, an actuator button 280 disposed between a lower end of the actuator stem and the diaphragm 230 to contact a central portion 232 of the diaphragm, and a bearing member 290 disposed between the actuator stem and the actuator button, as described in more detail below.

[0037] In the illustrated embodiment, the actuator 240 is a pneumatic actuator in which pressurized gas (provided to the gas inlet 252 of the actuator housing 250) axially forces one or more actuator pistons 275 (which can be integrally formed with the actuator rod 270, as shown) within the internal chamber 253 of the actuator housing 250 to move the actuator rod 270 from a first position (e.g., maintaining the diaphragm in a closed position) to a second position (e.g., permitting the diaphragm to move to an open position). One or more springs 255 can be provided in the actuator housing chamber 253 to return the actuator rod 270 and piston 275 to the first position after the pressurized gas is removed / exhausted. O-rings 256, 257, 258 can be provided with the actuator rod 270 to form a fluid-tight seal with the actuator housing 250, and one or more bushings 259 can be provided with the actuator rod to maintain axial alignment of the actuator rod within the actuator (e.g., to minimize side loads). Other actuator designs and configurations may be used as appropriate.

[0038] The actuator button 280 can include a diaphragm engaging surface 281 that is sized and contoured to press the flexible central portion 232 of the diaphragm 230 against the valve seat 220. To allow for a larger surface contact area, improved manufacturability, and positional adjustment of the diaphragm engaging surface (e.g., to account for small misalignments and / or machining tolerances), the actuator button 280 can be loosely assembled or loosely retained with the actuator stem 270 by loosely retaining the actuator stem and the actuator button together by assembling the actuator housing 250 with the valve body 210, as shown. Although many different loose assembly configurations can be utilized, in the illustrated embodiment, the actuator button 280 includes an upper annular wall portion 282 defining an upper socket portion 283, in which the lower end portion 271 of the actuator stem 270 is loosely received. An upper annular wall portion 282 of the actuator button 280 is received in an annular recess between the lower aperture 251 of the actuator housing and the lower end portion 271 of the actuator stem 270 .

[0039] In the illustrated embodiment, the bearing member 290 is disposed between the actuator rod 270 and the actuator button 280, with the upper portion 291 of the bearing member being received in the lower socket portion 273 of the actuator rod 270 (e.g., defined by the lower annular wall portion 272 of the actuator rod), and at least the lower portion 292 of the bearing member being received in the upper socket portion 283 of the actuator button 280. Although the upper portion 291 of the bearing member 290 can be loosely received in the lower socket portion 273 of the actuator rod, in the illustrated embodiment, the bearing member is fixed to the lower socket portion to retain it with the actuator rod 270 (e.g., when the actuator rod is removed from the actuator). For example, the bearing member 290 can be press-fit into the lower socket portion 273 of the actuator rod. In this arrangement, the lower annular wall portion 272 of the actuator rod 270 can have a wall thickness and / or resiliency that allows the bearing member 290 to be inserted into the lower socket portion 273 of the actuator rod with a press fit or interference fit. As another example, the lower annular wall portion 272 of the actuator rod 270 can loosely accommodate the bearing member 290 and then be crimped or staked inwardly onto and / or against the bearing member to secure the bearing member to the actuator rod. As yet another example, the lower annular wall portion 272 of the actuator rod 270 can include a radially inwardly projecting lip, flange, or undercut 276 that is configured to flex radially outwardly when the bearing member is pressed against the annular wall portion 272 and then snap radially inwardly onto the bearing member 290 to maintain a snap fit between the bearing member and the actuator rod. The annular wall portion can be notched or segmented to facilitate this resilient snap-fit engagement with the bearing member.

[0040] In other embodiments, the bearing member may be retained or secured within an upper socket portion of the actuator button. Figure 3B Graphics and Figure 3AAnother exemplary embodiment of an actuator device 260′ is shown that is similar to the actuator device 260 of FIG. 2 (and numbered accordingly), but with a bearing member 290′ secured to an upper socket portion 283′ of an actuator button 280′. The exemplary actuator device 260′ includes an actuator stem 270′ extending through a lower aperture 251′ in the actuator housing, an actuator button 280′ positioned between a lower end of the actuator stem and the diaphragm 230′ to contact a central portion 232′ of the diaphragm, and a bearing member 290′ positioned between the actuator stem and the actuator button. As shown, the actuator stem and the actuator button are loosely held together by assembling the actuator housing 250′ with the valve body, and the actuator button 280′ can be loosely assembled or loosely held with the actuator stem 270′. While many different loose assembly configurations may be utilized, in the illustrated embodiment, the actuator stem 270' includes a lower end portion 271' having an annular wall portion 272' into which an upper annular wall portion 282' of the actuator button 280' is loosely received.

[0041] In the illustrated embodiment, the bearing member 290′ is disposed between the actuator stem 270′ and the actuator button 280′, wherein at least the upper portion 291′ of the bearing member is received in the lower socket portion 273′ (e.g., defined by the lower annular wall portion 272′) of the actuator stem 270′, and the lower portion 292′ of the bearing member is received in the upper socket portion 283′ of the actuator button 280′. In the illustrated embodiment, the bearing member 290′ is secured to the upper socket portion 283′ to remain with the actuator button 280′ (e.g., when the actuator stem is removed from the actuator). For example, the bearing member 290′ can be press-fit into the actuator button upper socket portion 283′. In such an arrangement, the upper annular wall portion 282′ of the actuator rod 280′ can have a wall thickness and / or resiliency that allows the bearing member 290′ to be inserted into the actuator button upper socket portion 283′ with a press fit or interference fit. As another example, the upper annular wall portion 282′ of the actuator button 280′ can loosely accommodate the bearing member 290′ and then be crimped or staked inwardly onto and / or against the bearing member to secure the bearing member to the actuator button. As yet another example, the upper annular wall portion 282′ of the actuator button 280′ can include a radially inwardly projecting lip, flange, or undercut 286′ that is configured to flex radially outwardly when the bearing member is pressed against the annular wall portion 282′ and then snap radially inwardly onto the bearing member 290′ to maintain a snap fit between the bearing member and the actuator button. The annular wall portion may be notched or segmented to facilitate this resilient snap-fit engagement with the bearing member.

[0042] The bearing member can be configured in a variety of shapes. In some embodiments, the bearing member can include a convex upper portion, for example, to increase surface seating engagement with a concave inner portion of a lower socket portion of the actuator stem, and / or a convex lower portion, for example, to increase surface seating engagement with a concave inner portion of an upper socket portion of the actuator button. The increased surface contact between the bearing member and the actuator stem and button components can, for example, provide reduced contact stress between these components, thereby reducing component wear caused by valve cycling. The convex-concave seating engagement between the bearing member and the actuator button can further facilitate angular adjustment of the actuator button on the actuator stem, wherein the actuator button and the convex bearing function similarly to a ball-and-socket joint. This can allow the actuator button to be properly aligned with the diaphragm and valve seat to achieve optimal valve closing performance (e.g., to account for small misalignments and / or machining tolerances in the valve seat and actuator components).

[0043] In the illustrated embodiment, the bearing members 290, 290' are spherical, thereby providing convex upper and convex lower portions 291, 292, 291', 292' in any installed orientation. The lower socket portions 273, 273' of the actuator stems 270, 270' include concave interior portions 274, 274' that provide increased surface seating engagement with the bearing member upper portions 291, 291', and the upper socket portions 283, 283' of the actuator buttons 280, 280' include concave interior portions 284, 284' that provide increased surface seating engagement with the bearing member lower portions 292, 292'. Alternatively, the bearing members may be, for example, cylindrical, barrel-shaped, oval, elliptical, or any other suitable shape, which may, but need not, have convex upper and / or lower portions. The actuator button 280 can be manufactured from powdered metal, which can allow for the formation of a suitably sized and contoured concave inner portion 284. Additionally or alternatively, the powdered metal material can provide a surface topography that allows lubrication to remain, for example, to reduce wear between the bearing member and the actuator button.

[0044] In some applications, the bearing member is provided by a material having increased hardness relative to the material of the actuator stem and actuator button, for example to reduce wear, improve dimensional stability and eliminate galling of the actuator components. Additionally or alternatively, the bearing member can be provided by a material having reduced thermal conductivity, for example to provide thermal isolation between the upper actuator component and the actuator button, the valve diaphragm and the valve seat, thereby providing improved thermal stability to the valve assembly. In an exemplary embodiment, the actuator stem and actuator button are metal components (e.g., stainless steel) and the bearing member is a ceramic component. In other embodiments, the bearing member can be formed of a harder metal material (e.g., a hardened stainless steel material, such as, for example, 440C stainless steel) than the actuator stem and button components.

[0045] The innovative aspects have been described with reference to exemplary embodiments. Modifications and alterations may occur to others upon reading and understanding this specification. It is intended to include all such modifications and alterations as long as they come within the scope of the appended claims or their equivalents.

Claims

1. A diaphragm valve, comprising: a valve body defining a flow passage extending to an interior valve cavity; a valve seat disposed in the valve cavity and surrounding the flow channel; a diaphragm disposed in the valve cavity, the diaphragm including an axially fixed outer periphery and an axially flexible central portion movable between a closed position in sealing engagement with the valve seat and an open position axially spaced from the valve seat; an actuator comprising an actuator housing assembled with the valve body and an actuating device, the actuating device being movable axially within the actuator housing between a first position retaining the diaphragm in the closed position and a second position permitting movement of the diaphragm from the closed position to the open position, wherein the actuating device comprises: an actuator rod extending through a lower aperture in the actuator housing; an actuator button disposed between a lower end of the actuator rod and the diaphragm to contact the diaphragm; as well as A bearing member is disposed between the actuator stem and the actuator button.

2. The diaphragm valve of claim 1 , wherein an upper portion of the bearing member is received in a lower socket portion of the actuator stem, and a lower portion of the bearing member is received in an upper socket portion of the actuator button.

3. The diaphragm valve of claim 2, wherein the lower socket portion of the actuator stem is received in the upper socket portion of the actuator button.

4. The diaphragm valve of any one of claims 2 and 3, wherein the upper socket portion of the actuator button includes an annular wall.

5. The diaphragm valve of claim 4, wherein the lower bore of the actuator housing and the lower socket portion of the actuator stem define an annular recess that receives the annular wall of the upper socket portion.

6. A diaphragm valve as claimed in any one of claims 2 to 5, wherein the bearing member is fixed to the lower socket portion of the actuator stem.

7. The diaphragm valve of claim 6, wherein the bearing member is press-fit into the lower socket portion.

8. The diaphragm valve of claim 6, wherein the lower socket portion is crimped onto the bearing member.

9. The diaphragm valve of claim 6, wherein the lower socket portion is snap fit onto the bearing member.

10. A diaphragm valve as claimed in any one of claims 2 to 5, wherein the bearing member is fixed to the upper socket portion of the actuator button.

11. The diaphragm valve of claim 10, wherein the bearing member is press-fit into the upper socket portion.

12. The diaphragm valve of claim 10, wherein the upper socket portion is crimped onto the bearing member.

13. The diaphragm valve of claim 10, wherein the upper socket portion is snap fit onto the bearing member.

14. A diaphragm valve as claimed in any one of claims 2 to 13, wherein the bearing member comprises a convex upper portion.

15. The diaphragm valve of claim 14, wherein the lower socket portion of the actuator stem includes a concave interior surface portion that provides increased surface contact with the convex upper portion of the bearing member.

16. A diaphragm valve as claimed in any one of claims 2 to 15, wherein the bearing member comprises a convex lower portion.

17. The diaphragm valve of claim 16, wherein the upper socket portion of the actuator button includes a concave interior surface portion that provides increased surface contact with the convex lower portion of the bearing member.

18. A diaphragm valve as claimed in any one of claims 1 to 17, wherein the bearing member is spherical.

19. The diaphragm valve of any one of claims 1 to 18, wherein the bearing member comprises a material having a harder hardness than a material of the actuator stem and a material of the actuator button.

20. The diaphragm valve of any one of claims 1 to 19, wherein the bearing member comprises a material having a lower thermal conductivity than a material of the actuator stem and a material of the actuator button.

21. The diaphragm valve of any one of claims 1 to 20, wherein the bearing member comprises ceramic.

22. The diaphragm valve of any one of claims 1 to 21, wherein the actuator stem and the actuator button comprise metal.

23. The diaphragm valve of any one of claims 1 to 22, wherein the actuator button is manufactured from powdered metal.

24. A diaphragm valve as claimed in any one of claims 1 to 23, wherein the actuator stem comprises a fluid driven piston.

25. The diaphragm valve of any one of claims 1 to 24, wherein the actuator button is loosely retained with the actuator stem and the bearing member by assembling the valve body and the actuator housing.

26. A diaphragm valve as claimed in any one of claims 1 to 25, wherein the actuator button is angularly movable relative to the actuator stem.

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