Diaphragm valve with actuator bearing element

Abstract

The diaphragm valve includes a valve body with a valve seat disposed in a valve cavity surrounding a flow path, a diaphragm movable between a closed position in sealing engagement with the valve seat and an open position axially spaced from the valve seat, an actuator housing assembled with the valve body, and an actuator including an actuating arrangement axially movable within the actuator housing between a first position that holds the diaphragm in the closed position and a second position that allows movement of the diaphragm from the closed position to the open position, the actuating arrangement including an actuator stem extending through a lower bore in the actuator housing, an actuator button disposed between the lower end of the actuator stem and the diaphragm for contact with the diaphragm, and a bearing member disposed between the actuator stem and the actuator button.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of all U.S. Provisional Patent Application No. 63 / 438,802 (DIAPHRAGM VALVE WITH ACTUATOR BEARING ELEMENT), filed January 13, 2023, the entire disclosure of which is hereby incorporated by reference in its entirety. [Background technology]

[0002] Valves are commonly used to control the flow of fluids. Diaphragm valves are examples of flow control valves used in many industries to control the flow of gases, liquids, and other fluids, and operate by moving a diaphragm into contact with a valve seat to block flow and by allowing the diaphragm to separate from the valve seat. In many embodiments, the valve includes an actuator (e.g., manually actuated, pneumatically actuated, electrically actuated, etc.) having an actuator stem that is axially movable toward the diaphragm to hold it in a closed position and away from the diaphragm to allow movement of the diaphragm to an open position (e.g., by resilient / spring biased movement or under fluid pressure). Summary of the Invention

[0003] In an exemplary embodiment of the present disclosure, a diaphragm valve includes a valve body with a valve seat disposed in a valve cavity surrounding a flow path, a diaphragm movable between a closed position in sealing engagement with the valve seat and an open position axially spaced from the valve seat, an actuator housing assembled with the valve body, and an actuator including an actuating arrangement axially movable within the actuator housing between a first position that holds the diaphragm in the closed position and a second position that allows movement of the diaphragm from the closed position to the open position, the actuating arrangement including an actuator stem extending through a lower bore in the actuator housing, an actuator button disposed between a lower end of the actuator stem and the diaphragm for contact with the diaphragm, and a bearing member disposed between the actuator stem and the actuator button.

[0004] Further advantages and benefits will become apparent to those skilled in the art after reviewing the following description and appended claims, taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0005] [Figure 1] 1 shows a schematic cross-sectional view of an exemplary diaphragm valve assembly, according to an exemplary embodiment of the present disclosure. [Figure 2] 10 shows a perspective view of another exemplary diaphragm valve assembly according to another exemplary embodiment of the present disclosure. [Figure 3] FIG. 3 is a side cross-sectional view of the diaphragm valve assembly of FIG. 2. [Figure 3A] FIG. 3 is an enlarged partial cross-sectional view of the actuation configuration of the diaphragm valve assembly of FIG. 2. [Figure 3B] FIG. 10 is an enlarged partial cross-sectional view of an alternative actuation configuration of a diaphragm valve assembly according to another exemplary embodiment of the present disclosure. [Figure 4] FIG. 3 is an exploded perspective view of the actuation configuration of the diaphragm valve assembly of FIG. 2. [Figure 5]FIG. 3 is a bottom perspective view of the actuator stem of the diaphragm valve assembly of FIG. 2. [Figure 6] FIG. 3 is a top perspective view of the actuator button of the diaphragm valve assembly of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0006] This detailed description merely describes exemplary embodiments and is not intended to limit the scope of the claims in any way. Indeed, the invention as claimed is broader than and is not limited by the exemplary embodiments, and the terms used in the claims are given their ordinary meanings.

[0007] While various inventive aspects, concepts, and features of the present invention may be described and illustrated herein as embodied in combination in exemplary embodiments, these various aspects, concepts, and features may be used individually or in various combinations and subcombinations thereof in many alternative embodiments. Unless expressly excluded herein, all such combinations and subcombinations are intended to be within the scope of the present invention. Furthermore, while various alternative embodiments of the various aspects, concepts, and features of the present invention, such as alternative materials, structures, configurations, methods, circuits, devices and components, software, hardware, control logic, form, fit, and function, may be described herein, such descriptions are not intended to be a complete or exhaustive list of available alternative embodiments, whether currently known or later developed. Those skilled in the art may readily adopt one or more of the inventive aspects, concepts, or features for additional embodiments and uses within the scope of the present invention, even if such embodiments are not explicitly disclosed herein. Furthermore, while some features, concepts, or aspects of the invention may be described herein as preferred mechanisms or methods, such description is not intended to imply that such features are required or necessary unless expressly so stated. Furthermore, while exemplary or representative values ​​and ranges may be included to aid in understanding the present disclosure, such values ​​and ranges should not be construed in a limiting sense and are intended to be critical values ​​or ranges only if expressly so stated. Furthermore, while exemplary or representative values ​​and ranges may be included to aid in understanding the present disclosure, such values ​​and ranges should not be construed in a limiting sense and are intended to be critical values ​​or ranges only if expressly so stated. Parameters identified as "approximately" or "about" a stated value are intended to include the stated value, values ​​within 5% of the stated value, and values ​​within 10% of the stated value, unless otherwise specified.Furthermore, it is understood that the drawings accompanying this application may, but need not, be to scale and therefore various proportions and ratios apparent in the drawings may be understood as teaching. Moreover, while various aspects, features, and concepts may be expressly identified herein as inventive or forming part of the invention, such identification is not intended to be exclusive; rather, there may be aspects, concepts, and features of the invention that are fully described herein without being expressly identified as such or as part of a particular invention; instead, the invention is set forth in the appended claims. Descriptions of exemplary methods or processes are not limited to the inclusion of every step as necessary in all cases, nor should the order in which the steps are presented be construed as necessary or essential, unless explicitly stated.

[0008] In this disclosure, the terms "upper" and "lower" are used to identify the relative positions of elements of the illustrated components of an assembly as oriented in the drawings. It is understood that the valve assembly may be mounted or positioned in any suitable orientation.

[0009] Diaphragm valves generally actuate to a closed position by applying a force from an actuation element to a central flexible portion of the diaphragm, deflecting and holding the central portion against a valve seat surrounding the valve flow passage, blocking flow from the flow passage. The diaphragm-engaging surface of the actuation element may desirably be sized and contoured to maximize sealing contact between the diaphragm and the valve seat. In addition, positionability of the diaphragm-engaging surface on the actuation element may be desirable, for example, to account for small alignment misalignments and / or machining tolerances. To allow for a larger contact area and / or positionability of the diaphragm-engaging surface, the actuation element or configuration may include an actuator stem driven by an actuation mechanism (e.g., a fluid-powered actuator piston) and a diaphragm that engages an actuator button loosely assembled with or loosely held by the actuator stem.

[0010] 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 actuating components are subjected to rapid and frequent cycling, repeated impacts between the loosely assembled components can lead to accelerated wear and heating.

[0011] According to exemplary aspects of the present disclosure, a diaphragm valve may comprise an actuation structure or subassembly including a movable actuator stem, a diaphragm-engaged actuator button, and a bearing member disposed between the actuator stem and the actuator button. The bearing member may be configured to reduce or eliminate contact between the actuator stem and the actuator button. In some embodiments, the bearing member may be provided with a material selected to reduce wear between contacting surfaces, for example, by including a material having a higher hardness (e.g., compared to the material of the actuator stem and button). In other embodiments, the bearing member may additionally or alternatively be provided in a material selected to reduce thermal conductivity, for example, to provide a thermal barrier over the actuator components.

[0012] 1 schematically illustrates a cross-sectional view of an exemplary diaphragm valve 100 including a valve body 110 defining first and second flow passages 111, 112 extending to an internal valve cavity 115, with a valve seat 120 integral with or assembled therewith and positioned within the valve cavity surrounding the first flow passage 111. A diaphragm 130 is retained within the valve cavity 115 and has an axially fixed outer periphery 131 and an axially flexible central portion 132 movable between a closed position in sealing or flow-blocking engagement with the valve seat 120 and an open position axially spaced from the valve seat to permit flow through the flow passages 111, 112. The actuator 140 includes an actuator housing 150 assembled with the valve body 110 and an actuation arrangement 160 axially movable within the actuator housing between a first position that holds the diaphragm 130 in a closed position and a second position that allows movement of the diaphragm from the closed position to an open position. The exemplary actuation arrangement 160 includes an actuator stem 170 extending through a lower bore 151 in the actuator housing 150, an actuator button 180 positioned between a lower end of the actuator stem and the diaphragm 130 for contacting the central portion 132 of the diaphragm, and a bearing member 190 positioned between the actuator stem and the actuator button.

[0013] Many different actuator stem, actuator button, and bearing member configurations may be used. For example, in some embodiments, an upper portion of the bearing member may be received in a lower socket portion of the actuator stem, and a lower portion of the bearing member may be received in an upper socket portion of the actuator button. In some such embodiments, the lower socket portion of the actuator stem may be received within the upper socket portion of the actuator button. In other such embodiments, the upper socket portion of the actuator button may be received within the lower socket portion of the actuator stem.

[0014] In some embodiments, the upper socket portion of the actuator button may include an annular wall, and in some such embodiments, 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.

[0015] In some embodiments, the bearing member may be fixed in the lower socket portion of the actuator stem. In some such embodiments, the bearing member may be press-fit into the lower socket portion. In other such embodiments, the lower socket portion may be pressed onto the bearing member. In yet other such embodiments, the bearing member may be snap-fit ​​into the lower socket portion.

[0016] In some embodiments, the bearing member may be secured in an upper socket portion of the actuator button. In some such embodiments, the bearing member may be press-fit into the upper socket portion. In other such embodiments, the upper socket portion may be pressed onto the bearing member. In yet other such embodiments, the bearing member may be snap-fit ​​into the upper socket portion.

[0017] In some embodiments, the bearing member may include convex upper and lower portions. In some such embodiments, the bearing member may be spherical. In some such embodiments, the lower socket portion of the actuator stem may include a concave inner surface portion that increases surface contact with the convex upper portion of the bearing member. In some such embodiments, the upper socket portion of the actuator button may include a concave inner surface portion that increases surface contact with the convex lower portion of the bearing member.

[0018] In some embodiments, the bearing member may comprise a material that has a higher hardness than the material of the actuator stem and the material of the actuator button.

[0019] In some embodiments, the bearing member may comprise a material that has a lower thermal conductivity than the material of the actuator stem and the material of the actuator button.

[0020] In some embodiments, the bearing member may comprise a ceramic.

[0021] In some embodiments, the actuator stem and the actuator button may comprise metal.

[0022] In some embodiments, the actuator button may be fabricated from powdered metal.

[0023] In some embodiments, the actuator stem may include a fluid-driven piston.

[0024] In some embodiments, the actuator button may be loosely held together with the actuator stem and bearing member by assembling the valve body with the actuator housing.

[0025] In some embodiments, the actuator button may be angularly movable relative to the actuator stem.

[0026] 2, 3, and 3A illustrate an exemplary diaphragm valve assembly 200 including a valve body 210 defining first and second flow paths 211 and 212 extending to an internal valve cavity 215, and an actuator 240 assembled with the valve body 210. A diaphragm 230 is retained within the valve cavity 215 and is movable by operation of the actuator 240 between a closed position in which an axially fixed periphery 231 and an axially flexible central portion 232 are in sealing or flow-blocking engagement with a valve seat 220, and an open position axially spaced from the valve seat to permit flow through the flow paths 211, 212.

[0027] The valve seat may be integrally formed or integrated (e.g., crimped) with the valve body; however, the valve seat may also 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, which is sized to be installed within the valve cavity 215 and secured against the 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 that is clamped between the insert 216 and the recessed surface 214, a central port 223 that aligns with the first flow passage 211 of the valve, a sealing ring 225 (which may be formed integrally 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 allow flow between the central port and the second flow passage 212 when the diaphragm 230 is spaced from the valve seat 220 and in the open position. The outer periphery 231 of the diaphragm 230 may be welded to the seat carrier 221 or clamped between the insert 214 and the seat carrier. A similar configuration is described in commonly owned U.S. Patent No. 9,863,542, the entire disclosure of which is incorporated herein by reference.

[0028] The exemplary actuator 240 includes an actuator housing 250 assembled with the valve body 210 (e.g., by threaded engagement with insert 216, as shown), and an actuation arrangement 260 axially movable within the actuator housing between a first position that holds the diaphragm 230 in a closed position and a second position that allows movement of the diaphragm from the closed position to an open position. The exemplary actuation arrangement 260 includes an actuator stem 270 extending through a lower bore 251 in the actuator housing, an actuator button 280 positioned between a lower end of the actuator stem and the diaphragm 230 for contacting a central portion 232 of the diaphragm, and a bearing member 290 positioned between the actuator stem and the actuator button, as described in further detail below.

[0029] In the illustrated embodiment, the actuator 240 is a pneumatic actuator in which pressurized gas (provided to an inlet port 252 of the actuator housing 250) axially forces one or more actuator pistons 275 (which may be integrally formed with the actuator stem 270, as shown) into an internal chamber 253 of the actuator housing 250, moving the actuator stem 270 from a first position (e.g., holding the diaphragm in a closed position) to a second position (e.g., allowing the diaphragm to move to an open position). One or more springs 255 may be provided within the actuator housing chamber 253 to return the actuator stem 270 and piston(s) 275 to the first position upon removal / venting of the pressurized gas. O-rings 256, 257, 258 may be provided on the actuator stem 270 for a fluid seal with the actuator housing 250, and one or more bushings 259 may be provided on the actuator stem to maintain axial alignment of the actuator stem within the actuator (e.g., to minimize side loads). Other actuator designs and configurations may be used as desired.

[0030] The actuator button 280 may include a diaphragm engagement surface 281 sized and contoured to press the flexible central portion 232 of the diaphragm 230 against the valve seat 220. To allow for a larger contact area, improved manufacturability, and alignment of the diaphragm engagement surface (e.g., to account for small misalignments and / or manufacturing tolerances), the actuator button 280 may be loosely assembled or held loosely with the actuator stem 270 by assembling the actuator housing 250 with the valve body 210 while loosely holding the actuator stem and actuator button together, as shown. While many different loose assembly configurations may be utilized, in the illustrated embodiment, the actuator button 280 includes an upper annular wall portion 282 defining an upper socket portion 283 into which the lower end portion 271 of the actuator stem 270 is loosely received. The upper annular wall portion 282 of the actuator button 280 is received within an annular recess between the lower bore 251 of the actuator housing and the lower end portion 271 of the actuator stem 270.

[0031] In the illustrated embodiment, the bearing member 290 is disposed between the actuator stem 270 and the actuator button 280, with an upper portion 291 of the bearing member received in a lower socket portion 273 of the actuator stem 270 (e.g., defined by a lower annular wall portion 272 of the actuator stem), and at least a lower portion 292 of the bearing member received in an upper socket portion 283 of the actuator button 280. While the upper portion 291 of the bearing member 290 may be loosely received in the lower socket portion 273 of the actuator stem, in the illustrated embodiment, the bearing member is secured in the lower socket portion for retention with the actuator stem 270 (e.g., when the actuator stem is disassembled from its actuator). For example, the bearing member 290 may be press-fit into the lower socket portion 273 of the actuator stem. In such a configuration, the lower annular wall portion 272 of the actuator stem 270 may have a wall thickness and / or resilience that allows for press-fit or interference-fit insertion of the bearing member 290 into the actuator stem lower socket portion 273. As another example, the lower annular wall portion 272 of the actuator stem 270 may loosely receive the bearing member 290 and then be subsequently crimped or swaged onto and / or inward of the bearing member to secure the bearing member to the actuator stem. As yet another example, the lower annular wall portion 272 of the actuator stem 270 may include a radially inwardly protruding lip, flange, or undercut 276 configured to flex radially outward when the bearing member is pressed against the annular wall portion 272 and then snap radially inward above the bearing member 290 for snap-fit ​​retention of the bearing member with the actuator stem. The annular wall portion may be notched or segmented to facilitate this resilient snap-fit ​​engagement with the bearing member.

[0032] In other embodiments, the bearing member may be held or secured in an upper socket portion of the actuator button. Figure 3B shows another exemplary embodiment of an actuation arrangement 260' similar to the actuation arrangement 260 of Figure 3A (and numbered accordingly), but in which the bearing member 290' is secured in an upper socket portion 283' of the actuator button 280'. The exemplary actuation arrangement 260' includes an actuator stem 270' extending through a lower bore 251' in the actuator housing, an actuator button 280' positioned between the lower end of the actuator stem and the diaphragm 230' for contacting the central portion 232' of the diaphragm, and a bearing member 290' positioned between the actuator stem and the actuator button. The actuator button 280' may be loosely assembled or loosely held with the actuator stem 270' by assembling an actuator housing 250' with a valve body that loosely holds the actuator stem and actuator button together, as shown. Although many different loose assembly configurations may be utilized, in the illustrated embodiment, the actuator stem 270' includes an upper annular wall portion 271' having an annular wall portion 272' within which an upper annular wall portion 282' of the actuator button 280' is loosely received.

[0033] In the illustrated embodiment, the bearing member 290' is disposed between the actuator stem 270' and the actuator button 280', with at least an upper portion 291' of the bearing member received in a lower socket portion 273' (e.g., defined by a lower annular wall portion 272') of the actuator stem 270' and a lower portion 292' of the bearing member received in an upper socket portion 283' of the actuator button 280'. In the illustrated embodiment, the bearing member 290' is secured in the upper socket portion 283' for retention with the actuator button 280' (e.g., when the actuator stem is disassembled from its actuator). For example, the bearing member 290' may be press-fit into the upper socket portion 283' of the actuator button. In such a configuration, the upper annular wall portion 282' of the actuator stem 280' may have a wall thickness and / or resilience that allows for press-fit or interference-fit insertion of the bearing member 290' into the actuator button upper socket portion 283'. As another example, the upper annular wall portion 282' of the actuator button 280' can loosely receive the bearing member 290' and then be subsequently pressed or crimped onto and / or inward of 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 protruding lip, flange, or undercut 286' configured to flex radially outward when the bearing member is pressed against the annular wall portion 282' and then snap radially inward above the bearing member 290' for snap-fit ​​retention of the bearing member with the actuator button. The annular wall portion can be notched or segmented to facilitate this resilient snap-fit ​​engagement with the bearing member.

[0034] The bearing member can be provided in a variety of shapes. In some embodiments, the bearing member can include a convex upper portion for increased surface seating engagement with, for example, a concave inner surface portion of the actuator stem lower socket portion, and / or a convex lower portion for increased surface seating engagement with, for example, a concave inner surface portion of the actuator button upper socket portion. Increased surface contact between the bearing member and the actuator stem and button components can, for example, reduce contact stress between these components, thereby reducing component wear due to 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, with the actuator button and convex bearing functioning similarly to a ball-and-socket joint. This can allow the actuator button to be properly aligned with the diaphragm and valve seat for optimal valve shutoff performance (e.g., accounting for minor misalignment and / or machining tolerances of the valve seat and actuator components).

[0035] In the illustrated embodiment, the bearing members 290, 290' are spherical, thereby providing convex upper and lower portions 291, 292, 291', 292' in any orientation. The lower socket portions 273, 273' of the actuator stems 270, 270' include concave inner surface portions 274, 274' that increase the surface seating engagement with the bearing member upper portions 291, 291', and the upper and lower socket portions 283, 283' of the actuator buttons 280, 280' include concave inner surface portions 284, 284' that increase the surface seating engagement with the bearing member lower portions 292, 292'. The bearing members may alternatively have, for example, cylindrical, barrel-shaped, oval, elliptical, or any other suitable shape having convex upper and / or lower portions. The actuator button 280 may be manufactured from powdered metal, which may allow for the formation of a concave inner surface portion 284 of an appropriate size and contour. The powder metal material may additionally or alternatively provide a surface topology that allows for lubrication retention, for example, reducing wear between the bearing member and the actuator button.

[0036] In some applications, the bearing member is provided with a material that has a higher hardness compared to the material(s) of the actuator stem and actuator button, e.g., to reduce wear, increase dimensional stability, and eliminate galling of the actuator components. Additionally or alternatively, the bearing member may be provided with a material with reduced thermal conductivity, e.g., to provide a thermal barrier between the upper actuator component and the actuator button, valve diaphragm, and valve seat, improving the thermal stability of 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 may be formed from a harder metal material than the actuator stem and button components, e.g., a hardened stainless steel material such as 440C stainless steel.

[0037] Aspects of the present invention have been described with reference to exemplary embodiments. Modifications and alterations will occur to those skilled in the art upon reading and understanding 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.

Claims

1. a valve body defining a flow passage extending to an internal valve cavity; a valve seat disposed within the valve cavity and surrounding the flow passage; a diaphragm disposed within 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 including an actuator housing assembled with the valve body; and an actuation arrangement axially movable within the actuator housing between a first position that retains the diaphragm in the closed position and a second position that allows movement of the diaphragm from the closed position to the open position, the actuation arrangement comprising: an actuator stem extending through a lower bore in the actuator housing; an actuator button disposed between the lower end of the actuator stem and the diaphragm for contacting the diaphragm; a bearing member disposed between the actuator stem and the actuator button; the actuator, Including, a diaphragm valve.

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

4. 4. The diaphragm valve of claim 2, wherein the upper socket portion of the actuator button includes an annular wall.

5. 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. 6. A diaphragm valve according to claim 2, wherein the bearing member is fixed at the lower socket portion of the actuator stem.

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

8. 7. The diaphragm valve of claim 6, wherein said lower socket portion is pressed onto said bearing member.

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

10. 6. The diaphragm valve according to claim 2, wherein the bearing member is fixed at the upper socket portion of the actuator button.

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

12. 11. The diaphragm valve of claim 10, wherein the upper socket portion is pressed 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 according to any one of claims 2 to 13, wherein the bearing member includes a convex upper portion.

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

16. A diaphragm valve according to any one of claims 2 to 15, wherein the bearing member includes a convex lower portion.

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

18. The diaphragm valve according to any one of claims 1 to 17, wherein the bearing member is spherical.

19. A diaphragm valve according to any preceding claim, wherein the bearing member comprises a material having a higher hardness than a material of the actuator stem and a material of the actuator button.

20. A diaphragm valve according to any preceding claim, 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 preceding claim, wherein the bearing member comprises ceramic.

22. The diaphragm valve of any preceding claim, wherein the actuator stem and actuator button comprise metal.

23. A diaphragm valve according to any preceding claim, wherein the actuator button is manufactured from powdered metal.

24. A diaphragm valve according to any preceding claim, wherein the actuator stem comprises a fluid-driven piston.

25. A diaphragm valve according to any preceding claim, wherein the actuator button is loosely held together with the actuator stem and bearing member by assembling the valve body with the actuator housing.

26. A diaphragm valve according to any preceding claim, wherein the actuator button is angularly movable relative to the actuator stem.

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