Arrangement and method for controlled flow rate of a pneumatically actuated valve

Abstract

An actuator includes a housing defining an inlet port, a piston and a return spring disposed within the housing, and an elastically deformable element. The return spring is configured to apply a biasing force to the piston to move the piston to a spring return position. A first fluid pressure applied to the inlet port causes the piston to move against the biasing force of the return spring to a first actuation position, in which the piston indirectly engages a stop portion of the actuator housing. A second fluid pressure greater than the first fluid pressure applied to the inlet port causes the piston to move against the elastically deformable element to compress the elastically deformable element, causing the piston to move to a second actuation position beyond the first actuation position.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and all benefits of U.S. Provisional Patent Application Serial No. 62 / 913,769, filed on October 11, 2019, and entitled “ARRANGEMENTS AND METHODS FOR CONTROLLED FLOW RATE OF PNEUMATICACTUATED VALVES,” the entire disclosure of which is incorporated herein by reference. Background Art

[0003] Actuators are commonly used to control the operation of valves and other fluid system components. Actuators can have any number of different designs, including pneumatic, hydraulic, electric, etc. Fluid-driven actuators use a pressurized fluid such as air to move one or more fluid-driven actuator components (e.g., pistons, diaphragms, bellows, etc.) to move a valve element (e.g., a rotating valve stem, a plug, a diaphragm, and / or a bellows) to achieve control (e.g., shutoff, metering, directional control) of system fluid through the valve.

[0004] Conventional actuated valve assemblies use a spring biased pneumatic actuator for two-position operation of the valve between an actuated position (responsive to pressurization of the actuator inlet port to overcome the biasing spring and move the actuator piston and connected valve member) and a normal or reset position (responsive to release of the actuator inlet pressure and spring movement of the actuator piston and valve member).

[0005] Valve component dimensional tolerances, valve seat wear and / or deformation, and other such conditions may result in variations in valve flow in an open condition (e.g., variations in valve flow capacity over time in one valve, or between valves within a system (e.g., installed in parallel)). The resulting flow deviations may result in inconsistent and / or undesirable conditions. Summary of the invention

[0006] In an exemplary embodiment of the present disclosure, an actuator includes a housing defining an inlet port, a piston and a return spring disposed within the housing, and an elastically deformable element. The return spring is configured to apply a biasing force to the piston to move the piston to a spring return position. A first fluid pressure applied to the inlet port causes the piston to move against the biasing force of the return spring to a first actuation position, in which the piston indirectly engages a stop portion of the actuator housing. A second fluid pressure greater than the first fluid pressure applied to the inlet port causes the piston to move against the elastically deformable element to compress the elastically deformable element, causing the piston to move to a second actuation position beyond the first actuation position. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1A Shows an actuator stroke–pressure curve for a conventional spring-loaded pneumatic actuator;

[0008] Figure 1B Shows an actuator stroke–pressure curve for an exemplary pneumatic actuator provided with a return spring having an increased spring stiffness;

[0009] Figure 1C Shows an actuator stroke–pressure curve for an exemplary “normally closed” pneumatic actuator provided with an elastically deformable element that provides an adjustable flow capacity;

[0010] Figure 2 Is a schematic view of an actuator valve assembly according to an exemplary embodiment of the present disclosure, shown in a spring return position;

[0011] Figure 3 Is Figure 2 A schematic view of the actuator valve assembly, shown in a first actuation position;

[0012] Figure 4 Is Figure 2 A schematic view of the actuator valve assembly, shown in a second actuation position;

[0013] Figure 5 Is a side cross-sectional view of a pneumatic actuator according to an exemplary embodiment of the present disclosure including an elastically deformable element for pressure-related flow regulation; and

[0014] Figure 6 Is a side cross-sectional view of an actuator valve assembly having another pneumatic actuator according to an exemplary embodiment of the present disclosure including an elastically deformable element for pressure-related flow regulation. DETAILED DESCRIPTION

[0015] Although the various inventive aspects, concepts, and features of the present invention may be described and illustrated herein as being embodied in combination in exemplary embodiments, these various aspects, concepts, and features may be used alone or in their various combinations and sub - combinations in many alternative embodiments. All such combinations and sub - combinations are intended to fall within the scope of the present invention unless explicitly excluded herein. Further, although various alternative embodiments related to the various aspects, concepts, and features of the present invention - such as alternative materials, structures, configurations, methods, circuits, devices, and components, alternatives related to formation, assembly, and function, etc. - 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. One or more of the inventive aspects, concepts, or features can be readily used by those skilled in the art in additional embodiments and uses within the scope of the present invention even if such embodiments are not explicitly disclosed herein. Additionally, even though some features, concepts, or aspects of the present invention may be described herein as preferred arrangements or methods, such descriptions are not intended to imply that such features are required or necessary unless explicitly stated. Further, exemplary or representative values and ranges may be included to aid in understanding the present disclosure; however, such values and ranges should not be construed as limiting and are considered critical values or ranges only when explicitly stated. Parameters identified as "approximate" or "about" a specified value are intended to include the specified value and values within 10% of the specified value unless otherwise explicitly stated. Additionally, it should be understood that the drawings of the present disclosure may or may not be drawn to scale and may thus be understood to teach the various ratios and proportions apparent in the drawings. Further, although various aspects, features, and concepts may be explicitly identified herein as being inventive or forming part of an invention, such identification is not intended to be exclusive, but rather there may be aspects, concepts, and features of the invention fully described herein that are not explicitly identified as inventive or forming part of a particular invention, but the invention is set forth in the appended claims. The description of an exemplary method or process is not limited to including all steps required in all cases, and the order of presentation of steps should not be construed as required or necessary unless explicitly stated.

[0016] The present disclosure contemplates arrangements and methods for varying the flow capacity by actuating a shut - off valve, e.g., to establish flow uniformity among multiple valves in a system, or to correct for changes in flow capacity over time (e.g., due to valve seat wear or deformation), or to provide a degree of flow control capability when used in combination with process or position feedback.

[0017] For a conventional pneumatic or fluid-driven linear actuator, pressurized fluid is applied to the actuator through an inlet port to pressurize one or more fluid-driven pistons to axially move the pistons to an actuated position, e.g., to provide linear movement of a valve element (e.g., diaphragm, rod tip) in a valve assembled with the actuator. The actuating fluid pressure applied to the actuator is sufficient to overcome a plurality of resistances within the actuator and / or valve, including, for example, an actuator spring force (e.g., for a "normally closed" spring-biased actuator), friction between the piston and the actuator housing, and / or resistance of the valve element.

[0018] Conventional spring-loaded (e.g., "normally closed") pneumatic actuators are generally considered two-position actuators having a first unpressurized or "normal" position (e.g., closed) and a second pressurized or "actuated" position (e.g., open). While variations in actuator pressure below the pneumatic pressure required to fully actuate the actuator and valve can provide partial actuation of the actuator piston and valve element, variations in the spring stiffness of the return spring and the frictional resistance of the piston and other actuator / valve components make it difficult to accurately and predictably control the partial actuation of the actuator through variations in the applied actuator pressure. Figure 1A An actuator stroke–pressure curve of a conventional spring-loaded pneumatic actuator is shown, where actuator pressure between a spring return position s1 and a fully actuated position s2 (e.g., engagement of the actuator piston with a mechanical stop) drives actuation (e.g., engagement of the actuator piston with a mechanical stop) within a narrow pressure range between a first pressure p1 required to initiate the actuation stroke and a second pressure p2 required for full actuation.

[0019] In one embodiment, a spring return actuator may be provided with a biasing spring arrangement having an increased spring stiffness (e.g., by providing a stiffer spring and / or additional springs in parallel and / or in series) such that one or more partial flow positions may more predictably correspond to one or more predetermined applied actuator inlet pressures. As an example, compared to a conventional valve actuator spring stiffness that is one-third of the spring force in the closed position, the spring return actuator may be provided with a spring stiffness that is approximately five times greater than the spring force in the closed position. This increased spring stiffness may provide a significant, measurable, and predictable difference in the actuator pressure required to move the actuator piston and valve element to one or more incremental positions between the normal and actuated (e.g., open) positions of the valve. One such arrangement is described in co-owned U.S. Patent Application Publication No. 2019 / 0226937, entitled “SYSTEMS AND METHODS FOR CONTROL AND MONITORING OF ACTUATED VALVES” (“the ’937 application”), the entire disclosure of which is incorporated herein by reference. Figure 1B Shows an actuator stroke–pressure curve of an exemplary pneumatic actuator provided with a return spring having an increased spring stiffness, wherein the actuator pressure between the spring return position s1 and the fully actuated position s2 (e.g., engagement of the actuator piston with a mechanical stop) drives actuation to occur within a wider and more predictable pressure range between a first pressure p1 required to initiate the actuation stroke and a second pressure p2 required for full actuation, such that a desired partial actuator stroke s i can be achieved by applying a corresponding actuator pressure p between the first pressure p1 and the second pressure p2 i is achieved.

[0020] According to an exemplary aspect of the present disclosure, a pneumatic actuator may be provided with an elastically deformable (e.g., elastically compressible) element (e.g., one or more coil springs, washers, and / or Belleville spring washers, or an elastically deformable tab, flange, or other structure), the elastically deformable element being provided with a spring stiffness or compressive strength sufficient to resist or prevent deformation of the element when a first pneumatic operating pressure is applied to the actuator to move a fluid-driven piston to a first actuation position (e.g., against the spring biasing force of a return spring in the actuator) such that a valve element (e.g., diaphragm, rod tip) correspondingly moves to a first open position having a first flow capacity. When the pneumatic pressure applied to the actuator increases beyond the first pneumatic operating pressure, the elastically deformable element axially and elastically deforms to allow the piston (and the valve element associated therewith) to further axially travel to a second actuation position to provide an increased or second open position having a flow capacity greater than the first flow capacity. The significant predetermined spring stiffness or compressive strength of the elastically deformable element also provides predictable axial travel of the piston based on the applied actuator pressure exceeding the first actuation position. Figure 1C Shows an actuator stroke–pressure curve of an exemplary “normally closed” pneumatic actuator provided with an elastically deformable element that provides an adjustable flow capacity, wherein actuation between a spring return position s1 and a first actuation position s2 (e.g., engagement of the actuator piston with a mechanical stop) is achieved by a first actuation pressure that occurs within a narrow pressure range between a first pressure p1 required to initiate the actuation stroke and a second pressure p2 required for full actuation.

[0021] In some embodiments, the elastically deformable element may be axially disposed between a fluid-driven piston of the actuator and an axially fixed stop portion. Figures 2 to 4 Schematically shows an actuated valve assembly 100 including an actuator 120 assembled with a valve 110. The valve 110 includes a valve body 111 defining a flow path 112, and a valve element 113 that is axially movable relative to a valve seat 114 between a spring return (e.g., valve closed) position and a first actuation (e.g., open) position to selectively control (e.g., block or allow) fluid flow through the valve flow path 112. The actuator 120 includes a housing 121 defining a cavity 122 that receives a fluid-driven piston 123, the fluid-driven piston 123 being operably connected to the valve element 113 to move the valve element between a first (e.g., closed) position and a second (e.g., open) position. When the actuator is unpressurized (or under pressure), a return spring 124 (or other such biasing member) within the actuator cavity 122 biases the piston 123 (and the valve element 113 associated therewith) toward the spring return position ( Figure 2)Bias. When a first operating fluid pressure (e.g., from a pressurized fluid source S) is applied to the actuator 120 (at the inlet port 125), the fluid drives the piston 123 to move against the return spring 124 to a first actuation position ([ Figure 3 ) limited by the stop portion 126 of the actuator, so as to correspondingly move the valve element 113 to a first open position having a first flow capacity.

[0022] The elastically deformable element schematically represented by 127 is axially disposed within the actuator cavity 122 between the piston 123 and the actuator stop portion 126. When the pressure applied to the actuator inlet port 125 increases beyond the basic operating pressure, the elastically deformable element 127 is axially compressed to allow the piston (and the valve element associated therewith) to further axially travel to provide a second actuation (e.g., increased opening) position having, for example, a flow capacity greater than the first flow capacity ([ Figure 4 ).

[0023] In other exemplary embodiments, additionally or alternatively, the elastically deformable element may be integral with the piston (e.g., an elastically deformable web of the piston 123 or an elastically compressible shaft / rod of the piston) and / or integral with the actuator stop (e.g., an elastically deformable tab or flange of the actuator stop 126).

[0024] The elastically deformable element 127 may have a spring stiffness or compressive strength sufficient to resist or substantially prevent compression of the element when a first or base operating pressure is applied to the actuator to move the fluid-driven piston to the first actuation position. In one such embodiment, the spring stiffness of the elastically deformable element 127 may be significantly greater than the spring stiffness of the return spring 124 (e.g., at least 5 times, at least 10 times, at least 20 times, at least 50 times, up to 100 times, or between about 10 times and about 100 times), such that the element 127 does not begin to compress measurably until an actuator pressure greater than the base operating pressure is applied. In an exemplary embodiment, the actuator return spring may have a spring stiffness of about 200 pounds per inch, and the elastically deformable element may have an effective spring stiffness of about 10,000 pounds per inch. In one such arrangement, the return spring 124 may provide a base actuation (e.g., corresponding to a minimum desired flow capacity) at a first fluid pressure (e.g., about 40 pounds per square inch), while the elastically deformable element 127 may provide further actuation between the base actuation and the maximum actuation at an actuation pressure between the first fluid pressure and the second fluid pressure (e.g., about 80 pounds per square inch, or up to about twice the first fluid pressure). While the elastically deformable element 127 may provide different amounts of flow capacity regulation, in one embodiment, the movement of the piston from the spring return position to the first actuation position includes an axial movement of a first distance of the piston, and the movement of the piston from the first actuation position to the second actuation position includes an axial movement of a second distance of the piston that is less than about 20% of the first distance, such that the flow capacity regulation between the first open position and the second open or maximum flow position is limited to a small portion (e.g., less than 10%) of the total maximum flow capacity (e.g., a base actuation Cv of about 0.59 and a maximum actuation Cv of about 0.64). In other embodiments, the second distance may be greater than the first distance (e.g., about five times as large as the first distance, or about 20 times as large as the first distance), such that the valve flow rate can be adjusted to a selected flow rate over most or nearly all or all of the flow rate range between the closed position and the fully open position.

[0025] The relatively high spring stiffness of the elastically deformable element 127 (resulting in a substantially constant spring stiffness between the first and second actuation positions of the piston) may allow for precise control of the flow capacity within a relatively small flow capacity range, where an incremental increase in the fluid pressure between the first fluid pressure and the second fluid pressure causes a proportional incremental movement of the piston between the first actuation position and the second actuation position.

[0026] In use, the flow capacity can be remotely and / or automatically adjusted by regulating the fluid pressure to the actuator to control the compression of the elastically deformable element. Many different devices and arrangements (including, for example, conventional pressure regulators) can be used to control or regulate the fluid pressure to the actuator. The '937 application incorporated above describes a pilot valve arrangement that can be used to regulate the actuator inlet pressure by controlling the pulsed operation of the pressurized fluid supply and discharge valves.

[0027] Figure 5 Shown is an exemplary actuator 200 adapted to include one or more elastically deformable elements configured to provide an adjustable flow capacity in response to regulation of the actuator inlet pressure. Actuator assembly 200 includes a housing 210 that defines an inlet port 211 and a first piston chamber 212 that receives a first force transfer piston 220 and a second piston chamber 214 that receives a second force transfer piston 240 (e.g., separated by a partition 230). Second piston 240 is integral with an output shaft 245 that extends through an output port 215 in actuator housing 210 for applying an output force to a valve element in a valve (not shown) assembled with actuator 200. First piston chamber 212 also holds a biasing spring 250 that engages first piston 220 to urge first piston 220 and second piston 240 downward. To operate actuator 200, pressurized actuator fluid (e.g., air) applied to inlet port 211 passes through a passage 223 in first piston 220 and a passage 243 in second piston 240 to pressurize the lower portions of piston chambers 212, 214, thereby forcing the pistons upward against biasing spring 250 to move output shaft 245 upward and to move one of first piston 220 and second piston 240 into direct or indirect engagement with a stop portion of actuator housing 210 (described in more detail below).

[0028] As Figure 5As shown, the elastically deformable element can be disposed at multiple positions between the second piston 240 and the stop portion. As an example, one or more Belleville spring washers 260a (or other such elastically deformable elements) can be disposed between the upper first piston 220 and the lower second piston 240 (e.g., in the sink hole 226a in the first piston 220). In such an arrangement, the washer 260a travels with the first piston 220 and the second piston 240 to the first actuation position during actuation without being compressed. In the first actuation position, when the first piston 220 engages or contacts the actuator stop portion 218a, additional fluid pressure applied to the actuator that exceeds the pressure required to hold the piston against the return spring force compresses the Belleville spring washer 260a to axially advance the second piston 240 and the output shaft 245 relative to the first piston 220 and the stop portion 218a, thereby allowing the valve element to move away from the valve seat (not shown) to increase the flow capacity through the valve.

[0029] As another example, one or more Belleville spring washers (or other such elastically deformable elements) can be additionally or alternatively disposed between the upper first piston 220 and the actuator stop portion 218. In one such exemplary arrangement, the Belleville spring washer 260b can be positioned between the engagement portion 228b on the upper rod 222 of the first piston 220 and the inner peripheral rib stop portion 218b within the actuator inlet port 211. In another exemplary arrangement, the Belleville spring washer 260c can be additionally or alternatively positioned between the engagement portion 228c on the upper shoulder portion 224 of the first piston 220 and the end face stop portion 218c of the actuator inlet port 211. In such arrangements, when the first piston 220 and the second piston 240 are actuated to the first actuation position, the engagement portions 228b, 228c of the first piston 220 indirectly engage the actuator stop portions 218b, 218c. Additional fluid pressure applied to the actuator that exceeds the pressure required to hold the piston against the return spring force compresses the Belleville spring washers 260b, 260c to axially advance the pistons 220, 240 and the output shaft 245 relative to the stop portions 218b, 218c, thereby allowing the valve element to move away from the valve seat (not shown) to increase the flow capacity through the valve.

[0030] As another example, one or more Belleville spring washers (or other such elastically deformable elements) may additionally or alternatively be provided between the lower second piston 240 and the actuator stop portion 218d defined by the separator 230. In such an arrangement, when the first piston 220 and the second piston 240 are actuated to the first actuated position, the engagement portion 248d on the upper shoulder portion 244 of the second piston 240 indirectly engages the actuator stop portion 218d. Additional fluid pressure applied to the actuator that exceeds the pressure required to hold the pistons against the return spring force compresses the Belleville spring washer 260d to axially advance the pistons 220, 240, and the output shaft 245 relative to the stop portion 218d, thereby allowing the valve element to move away from the valve seat (not shown) to increase the flow capacity through the valve.

[0031] Figure 6 An exemplary actuated valve assembly 301 is shown including an actuator 300 assembled with a valve 380, where the actuator is adapted to include one or more elastically deformable elements configured to provide an adjustable flow capacity in response to an adjustment of the actuator inlet pressure. The valve 380 includes a valve body 381 defining a flow path 382, and a valve element 383 (e.g., a diaphragm) that is fixed in the valve body by a threaded valve cap nut 389 and is axially movable between a closed position and an open position relative to a valve seat 384 to selectively control (e.g., block or allow) fluid flow through the valve flow path 382. The actuator 300 includes a housing 310 (e.g., a first housing member 310-1, a second housing member 310-2, and a third housing member 310-2 assembled by threading), the housing 310 defining an inlet port 311 and a first piston chamber 312 that receives a first force transfer piston 320 and a second piston chamber 314 that receives a second force transfer piston 340 (e.g., separated by a separator 330 that may be defined by the second housing member 310-2, as shown). The second piston 340 is integral with an output shaft 345 that extends through an output port 315 in the actuator housing 310 for applying an output force to the valve element 383 in the valve 380. As shown in the illustrated embodiment, the actuator 300 may be spaced apart from the valve 380 by a valve cap extension 390 assembled between the actuator outlet port 315 and the valve cap nut 389 and a force transfer shaft 392 disposed between the output shaft 345 and the diaphragm 383 (e.g., to isolate the actuator from extreme system fluid temperatures). In other embodiments (not shown), the actuator outlet port may be directly assembled to the valve (e.g., threaded to the valve cap nut).

[0032] The first piston chamber 312 also holds a bias spring 350 that engages the first piston 320 to force the first piston 320 and the second piston 340 downward. To operate the actuator 300, pressurized actuator fluid (e.g., air) applied to the inlet port 311 passes through a passage 323 in the first piston 320 and a passage 343 in the second piston 340 to pressurize the lower portions of the piston chambers 312, 314, thereby forcing the pistons upward against the bias spring 350 to move the output shaft 345 upward and move one of the first piston 320 and the second piston 340 into direct or indirect engagement with a stop portion of the actuator housing 310 (described in more detail below).

[0033] As Figure 6 shown, an elastically deformable element can be disposed at multiple locations between one of the pistons 320, 340 and a stop portion of the actuator housing. As an example, one or more Belleville spring washers 360a (or other such elastically deformable elements) can be disposed between the lower second piston 340 and an actuator stop portion 318a defined by the separator 330. In this arrangement, when the first piston 320 and the second piston 340 are actuated to a first actuated position, a mating portion 348a on the outer radial disk portion 347 of the second piston 340 indirectly engages the actuator stop portion 318a through the elastically deformable element 360a. Additional fluid pressure applied to the actuator inlet port 311 that exceeds the pressure required to hold the pistons against the return spring force compresses the elastically deformable element 360a to axially advance the pistons 320, 340 and the output shaft 345 relative to the stop portion 318a, thereby allowing the valve element 383 to move away from the valve seat 384 to increase the flow capacity through the valve 380.

[0034] As another example, one or more Belleville spring washers 360b (or other such elastically deformable elements) can be disposed between the output shaft 345 (e.g., engaging a retaining ring 346b assembled with the output shaft) and an actuator stop portion 318b defined by the actuator output port 315 (e.g., the end face of the actuator output port). In this arrangement, when the first piston 320 and the second piston 340 are actuated to a first actuated position, a mating portion 348b on the output shaft 345 indirectly engages the actuator stop portion 318b through the elastically deformable element 360b. Additional fluid pressure applied to the actuator inlet port 311 that exceeds the pressure required to hold the pistons 320, 340 against the return spring force compresses the elastically deformable element 360b to axially advance the pistons 320, 340 and the output shaft 345 relative to the stop portion 318b, thereby allowing the valve element 383 to move away from the valve seat 384 to increase the flow capacity through the valve 380.

[0035] In other embodiments, other elastically deformable element arrangements may alternatively or additionally be used. For example, similar to Figure 5 as shown and in the above examples, one or more elastically deformable elements may be provided between the upper piston rod portion and the actuator inlet port stop portion (e.g., at position 360c in Figure 6 ), between the upper piston disk portion 327 and the actuator inlet port end face (at position 360d), or between the upper piston 320 and the lower piston (at position 360e).

[0036] In still some other exemplary embodiments, alternatively or additionally, the elastically deformable element may be integral with the piston (e.g., an elastically deformable web of the piston or an elastically compressible shaft / rod of the piston) and / or integral with the actuator stop (e.g., an elastically deformable tab or flange of the actuator stop).

[0037] Although the present invention has been disclosed and described with respect to certain exemplary embodiments, certain variations and modifications may occur to those skilled in the art upon reading this specification. Despite the limitations defined by the appended claims and their equivalents, any such variations and modifications are within the scope of the present invention. Accordingly, changes may be made to such details without departing from the spirit or scope of the general inventive concept of the applicant.

Claims

1. An actuator comprising: A housing defining an inlet port; A piston disposed within the housing; A return spring disposed within the housing and configured to apply a first biasing force to the piston to move the piston toward a spring return position; And An elastically deformable element; Wherein, without compressing the elastically deformable element, a first fluid pressure applied to the inlet port causes the piston to move against the first biasing force of the return spring to a first actuated position, in which the piston indirectly engages a stop portion of the housing through at least the elastically deformable element; and Wherein a second fluid pressure greater than the first fluid pressure applied to the inlet port causes the piston to move against a second biasing force of the elastically deformable element to compress the elastically deformable element and to move the piston to a second actuated position beyond the first actuated position; Wherein the spring stiffness of the elastically deformable element is at least 10 times the spring stiffness of the return spring; Wherein the movement of the piston from the spring return position to the first actuated position includes an axial movement of a first distance of the piston, and the movement of the piston from the first actuated position to the second actuated position includes an axial movement of a second distance of the piston that is less than 20% of the first distance; and Wherein the spring stiffness of the elastically deformable element is substantially constant between the first actuated position and the second actuated position of the piston, such that an increase in the increment of fluid pressure between the first fluid pressure and the second fluid causes a proportional incremental movement of the piston between the first actuated position and the second actuated position.

2. The actuator according to claim 1, wherein the elastically deformable element includes at least one disc spring washer.

3. The actuator according to claim 1, wherein the spring stiffness of the elastically deformable element is up to 100 times the spring stiffness of the return spring.

4. The actuator according to claim 1, wherein the second fluid pressure is up to twice the first fluid pressure.

5. The actuator according to claim 1, wherein the elastically deformable element has a spring stiffness that provides a proportional incremental movement of the piston between the first actuated position and the second actuated position in response to an increase in the increment of fluid pressure between the first fluid pressure and the second fluid pressure.

6. The actuator according to claim 1, wherein the piston includes a rod portion extending into the inlet port of the housing and a disc portion extending radially outward from the rod portion.

7. The actuator according to claim 1, wherein the piston includes an output shaft extending through an output port in the housing to apply an output force to a valve when the valve is assembled with the actuator.

8. The actuator according to claim 1, wherein the piston is a first piston, and wherein the actuator further comprises a second piston disposed within the housing, wherein the first fluid pressure applied to the inlet port causes the second piston to move to a first actuation position of the second piston against the first biasing force of the return spring.

9. The actuator according to claim 1, wherein the elastically deformable element is disposed between the piston and the stop portion of the housing.

10. The actuator according to claim 1, wherein the elastically deformable element is integral with the piston.

11. The actuator according to claim 1, wherein the elastically deformable element is integral with the stop portion of the housing.

12. An actuator comprising: a housing that defines an inlet port; a piston disposed within the housing; a return spring disposed within the housing and configured to apply a first biasing force to the piston to move the piston toward a spring return position; and an elastically deformable element; wherein a first fluid pressure applied to the inlet port causes the piston to move to a first actuation position against the first biasing force of the return spring, in which the piston indirectly engages a stop portion of the housing through at least the elastically deformable element; and wherein a second fluid pressure greater than the first fluid pressure applied to the inlet port causes the piston to move against a second biasing force of the elastically deformable element to compress the elastically deformable element and to move the piston to a second actuation position beyond the first actuation position; wherein the piston includes a rod portion extending into the inlet port of the housing and a disk portion extending radially outward from the rod portion; and wherein the stop portion is defined by an inner surface of the actuator inlet port, and the elastically deformable element is disposed between the inner surface of the inlet port and an end portion of the rod portion.

13. An actuator comprising: a housing that defines an inlet port; a piston disposed within the housing; a return spring disposed within the housing and configured to apply a first biasing force to the piston to move the piston toward a spring return position; and an elastically deformable element; wherein a first fluid pressure applied to the inlet port causes the piston to move to a first actuation position against the first biasing force of the return spring, in which the piston indirectly engages a stop portion of the housing through at least the elastically deformable element; and wherein a second fluid pressure greater than the first fluid pressure applied to the inlet port causes the piston to move against a second biasing force of the elastically deformable element to compress the elastically deformable element and to move the piston to a second actuation position beyond the first actuation position; wherein the piston includes a rod portion extending into the inlet port of the housing and a disk portion extending radially outward from the rod portion; and wherein the stop portion is defined by an end face of the inlet port, and the elastically deformable element is disposed between the end face of the inlet port and an inner radial part of the disc portion.

14. An actuator comprising: a housing that defines an inlet port; a piston disposed within the housing; a return spring disposed within the housing and configured to apply a first biasing force to the piston to move the piston toward a spring return position; and an elastically deformable element; wherein a first fluid pressure applied to the inlet port causes the piston to move against the first biasing force of the return spring to a first actuation position, in which the piston indirectly engages a stop portion of the housing through at least the elastically deformable element; and wherein a second fluid pressure greater than the first fluid pressure applied to the inlet port causes the piston to move against a second biasing force of the elastically deformable element to compress the elastically deformable element and to move the piston to a second actuation position beyond the first actuation position; wherein the piston is a first piston, and wherein the actuator further comprises a second piston disposed within the housing, wherein the first fluid pressure applied to the inlet port causes the second piston to move against the first biasing force of the return spring to a first actuation position of the second piston; and wherein the stop portion is defined by an end face of the inlet port, and the elastically deformable element is disposed between the first piston and the second piston.

15. An actuator comprising: a housing that defines an inlet port; a piston disposed within the housing; a return spring disposed within the housing and configured to apply a first biasing force to the piston to move the piston toward a spring return position; and an elastically deformable element; wherein a first fluid pressure applied to the inlet port causes the piston to move against the first biasing force of the return spring to a first actuation position, in which the piston indirectly engages a stop portion of the housing through at least the elastically deformable element; and wherein a second fluid pressure greater than the first fluid pressure applied to the inlet port causes the piston to move against a second biasing force of the elastically deformable element to compress the elastically deformable element and to move the piston to a second actuation position beyond the first actuation position; wherein the piston is a first piston, and wherein the actuator further comprises a second piston disposed within the housing, wherein the first fluid pressure applied to the inlet port causes the second piston to move against the first biasing force of the return spring to a first actuation position of the second piston; and wherein the housing includes a partition disposed between the first piston and the second piston, wherein the stop portion is defined by the partition, and the elastically deformable element is disposed between the first piston and the partition; and The elastically deformable element has a substantially constant spring stiffness between the first actuation position and the second actuation position of the first piston, such that an increase in the increment of fluid pressure between the first fluid pressure and the second fluid causes a proportional incremental movement of the piston between the first actuation position and the second actuation position.

16. An actuator comprising: a housing that defines an inlet port; a piston disposed within the housing; a return spring disposed within the housing and configured to apply a first biasing force to the piston to move the piston toward a spring return position; and an elastically deformable element; wherein a first fluid pressure applied to the inlet port causes the piston to move against the first biasing force of the return spring to a first actuation position, in which the piston indirectly engages a stop portion of the housing through at least the elastically deformable element; and wherein a second fluid pressure greater than the first fluid pressure applied to the inlet port causes the piston to move against a second biasing force of the elastically deformable element to compress the elastically deformable element and to move the piston to a second actuation position beyond the first actuation position; wherein the piston includes an output shaft that extends through an output port in the housing and extends outside the housing, and an outer portion of the output shaft is configured to apply an output force to the valve when the valve is assembled with the actuator; wherein the stop portion is defined by an outer surface of the housing surrounding the output port, and the elastically deformable element is disposed between the outer portion of the output shaft and the outer surface of the housing; and wherein the spring stiffness of the elastically deformable element is substantially constant between the first actuation position and the second actuation position of the piston, such that an increase in the increment of fluid pressure between the first fluid pressure and the second fluid causes a proportional incremental movement of the piston between the first actuation position and the second actuation position.

17. The actuator of claim 16, wherein the spring stiffness of the elastically deformable element is at least 10 times the spring stiffness of the return spring.

18. The actuator of claim 16, wherein the movement of the piston from the spring return position to the first actuation position includes an axial movement of a first distance of the piston, and the movement of the piston from the first actuation position to the second actuation position includes an axial movement of a second distance of the piston that is less than 20% of the first distance.

19. An actuated valve assembly comprising: a valve including a valve body that defines a flow path and a valve element that is axially movable to selectively control fluid flow through the flow path of the valve; an actuator as claimed in any one of claims 1 to 18, wherein the actuator is assembled with the valve, and the piston is operatively connected to the valve element for axial movement of the valve element.

20. The actuated valve assembly according to claim 19, wherein when the actuator is in the spring return position, the valve element is in a closed position against a valve seat in the valve body.

21. The actuated valve assembly according to claim 19, wherein when the actuator is in the first actuated position, the valve element is in a partial flow position.

22. The actuated valve assembly according to claim 21, wherein when the actuator is in the second actuated position, the valve element is in a full flow position, and the full flow coefficient of the valve element is greater than the partial flow coefficient in the partial flow position.

23. The actuated valve assembly according to claim 22, wherein the full flow coefficient is up to 10% greater than the partial flow coefficient.

24. An actuated valve assembly comprising: a valve including a valve body defining a flow path and a valve element, the valve element being axially movable to selectively control fluid flow through the flow path of the valve; an actuator assembled with the valve, the actuator including: a housing defining an inlet port; a piston disposed within the housing, wherein the piston is operably connected to the valve element for axial movement of the valve element; a return spring disposed within the housing and configured to apply a first biasing force to the piston to move the piston toward a spring return position; and an elastically deformable element; wherein a first fluid pressure applied to the inlet port causes the piston to move against the first biasing force of the return spring to a first actuated position, in which the piston indirectly engages a stop portion of the housing through at least the elastically deformable element; wherein a second fluid pressure greater than the first fluid pressure applied to the inlet port causes the piston to move against a second biasing force of the elastically deformable element to compress the elastically deformable element and to move the piston to a second actuated position beyond the first actuated position; and wherein the elastically deformable element has a substantially constant spring stiffness between the first actuated position and the second actuated position of the piston, such that an incremental increase in the fluid pressure between the first fluid pressure and the second fluid causes a proportional incremental movement of the piston between the first actuated position and the second actuated position.

25. The actuated valve assembly according to claim 24, wherein applying the first fluid pressure to the inlet port causes the piston to move against the first biasing force of the return spring without compressing the elastically deformable element.

26. The actuated valve assembly according to claim 24, wherein when the actuator is in the spring return position, the valve element is in a closed position against a valve seat in the valve body.

27. The actuated valve assembly according to claim 24, wherein when the actuator is in the first actuated position, the valve element is in a partial flow position.

28. The actuated valve assembly according to claim 27, wherein when the actuator is in the second actuated position, the valve element is in the fully open position, and the full flow coefficient of the valve element is greater than the partial flow coefficient in the partially open position.

29. The actuated valve assembly according to claim 28, wherein the full flow coefficient is up to 10% greater than the partial flow coefficient.

30. The actuated valve assembly according to claim 24, wherein the elastically deformable element includes at least one disc spring washer.

31. The actuated valve assembly according to claim 24, wherein the spring stiffness of the elastically deformable element is at least 5 times the spring stiffness of the return spring.

32. The actuated valve assembly according to claim 24, wherein the spring stiffness of the elastically deformable element is up to 100 times the spring stiffness of the return spring.

33. The actuated valve assembly according to claim 24, wherein the second fluid pressure is up to twice the first fluid pressure.

34. The actuated valve assembly according to claim 24, wherein the movement of the piston from the spring return position to the first actuated position includes an axial movement of a first distance of the piston, and the movement of the piston from the first actuated position to the second actuated position includes an axial movement of a second distance of the piston that is less than 20% of the first distance.

35. The actuated valve assembly according to claim 24, wherein the movement of the piston from the spring return position to the first actuated position includes an axial movement of a first distance of the piston, and the movement of the piston from the first actuated position to the second actuated position includes an axial movement of a second distance of the piston, and the second distance is greater than the first distance.

36. The actuated valve assembly according to claim 24, wherein the piston includes a rod portion extending into the inlet port of the housing and a disc portion extending radially outward from the rod portion, and wherein the stop portion is defined by the inner surface of the actuator inlet port, and the elastically deformable element is disposed between the inner surface of the inlet port and the end portion of the rod portion.

37. The actuated valve assembly according to claim 24, wherein the piston is a first piston, and wherein the actuator further includes a second piston disposed within the housing, wherein the first fluid pressure applied to the inlet port causes the second piston to move against the first biasing force of the return spring to a first actuated position of the second piston, and wherein the stop portion is defined by the end face of the inlet port, and the elastically deformable element is disposed between the first piston and the second piston.

38. The actuated valve assembly according to claim 24, wherein the piston includes an output shaft that extends through an output port in the housing to apply an output force to the valve element, wherein the stop portion is defined by the output port, and the elastically deformable element is disposed between the output shaft and the output port.

39. The actuating valve assembly according to claim 24, wherein the elastically deformable element is disposed between the piston and the stop portion of the housing.

40. The actuating valve assembly according to claim 24, wherein the elastically deformable element is integral with the piston.

41. The actuating valve assembly according to claim 24, wherein the elastically deformable element is integral with the stop portion of the housing.

42. The actuating valve assembly according to claim 24, wherein the elastically deformable element is configured to move with the piston between the spring return position and the first actuated position.

Images