Membrane and diaphragm valve

Abstract

A diaphragm (30) for a bellows diaphragm valve (10), comprising a central coupling section (28) provided at an axial end region of the diaphragm (30), which is configured to be coupled to an axially driven valve spindle (24) of the diaphragm valve (10), a mounting section (32) provided at an opposite axial end region, which is spaced axially from the coupling section (28), and an axial bellows (44) connecting the coupling section (28) to the mounting section (32), wherein the mounting section (32) has a radially projecting circumferential flange (34) and a transition section (70) extending radially inward from the flange (34), which connects the flange (34) to the bellows (44), wherein the diaphragm (30) is made of polyetheretherketone and the transition section (70) extends from the flange (34) with an axial thickness (H) continuously tapers to the bellows (44),wherein the wall thickness (s) of the bellows (44) is smaller than the axial thickness (H) of the flange (34).

Description

[0001] The invention relates to a diaphragm with an axial bellows (also referred to as a bellows diaphragm) for a bellows diaphragm valve and a diaphragm valve with such a diaphragm.

[0002] Bellows membranes are typically made of polytetrafluoroethylene (PTFE), which has particularly good mechanical, chemical, and thermal resistance. A disadvantage is that PTFE belongs to the per- and polyfluoroalkyl substances (PFAS), which are very difficult to break down in the environment and are therefore called "perennial chemicals."

[0003] The object of the invention is therefore to provide a diaphragm for a bellows diaphragm valve that is made of an environmentally friendly material and simultaneously exhibits good durability and a long service life. A further object of the invention is to provide a diaphragm valve with such a diaphragm.

[0004] The problem is solved by a diaphragm for a bellows-type diaphragm valve, comprising a central coupling section provided at one axial end of the diaphragm, which is configured to be coupled to an axially driven valve spindle of the diaphragm valve, a mounting section provided at an opposite axial end, which is spaced axially from the coupling section, and an axial bellows that connects the coupling section to the mounting section. The mounting section has a radially projecting, circumferential flange and a transition section extending radially inward from the flange, connecting the flange to the bellows. The diaphragm is made of polyetheretherketone (PEEK), and the transition section tapers continuously from the flange, starting with an axial thickness of [missing information], to the bellows, the wall thickness of which is less than the axial thickness of the flange.

[0005] It was discovered according to the invention that a PEEK diaphragm exhibits high media and temperature resistance. Furthermore, PEEK is not a PFAS and is therefore comparatively environmentally friendly. It was also discovered according to the invention that the diaphragm can withstand a particularly high number of switching cycles without tearing if the transition section tapers continuously from the flange, starting with an axial thickness, to the bellows. Thus, despite the lower flexibility of PEEK compared to other plastics such as fluorocarbon rubber (FKM) or ethylene propylene diene monomer rubber (EPDM), a particularly long service life can be ensured, especially when used at low temperatures around 4°C or at high temperatures up to 150°C. Compared to bellows diaphragms made of stainless steel, which are also comparatively environmentally friendly, the PEEK diaphragm has the advantage of being significantly more compact while maintaining a similar service life.In this way, the membrane according to the invention utilizes the synergistic effect from its material and its shape.

[0006] According to one aspect, the transition section in the longitudinal section is defined on one side by a radius, with this side seamlessly merging into the bellows. In this way, stresses are effectively reduced, resulting in a long service life for the membrane.

[0007] The radius can range from 0.3 to 3 mm.

[0008] In one embodiment, the transition section has an inclined surface on one side, arranged at an angle between 20 and 60° to a plane perpendicular to the axis of the bellows. This makes the transition section particularly robust.

[0009] Additionally or alternatively, the ratio of the axial thickness of the flange to the smallest wall thickness of the bellows can be between 1.5 and 5, which ensures a particularly long service life of the membrane.

[0010] In another embodiment, the wall thickness of the bellows is between 0.2 and 0.5 mm. This design has the advantage that the bellows is, on the one hand, thin enough to exhibit high elasticity, and on the other hand, thick enough to withstand many switching cycles without tearing.

[0011] Furthermore, the bellows may be designed with superimposed annular sections and, in longitudinal section, U-shaped bends connecting adjacent annular sections. These adjacent annular sections are connected by alternating radial bends located at the inner and outer edges. Moreover, the bellows has a constant wall thickness except for its first and / or last annular section in the axial direction, making it particularly resistant to stress.

[0012] According to one aspect, the ring-shaped sections are annular disc-shaped sections, i.e., flat ring discs that exhibit high elasticity.

[0013] All turns can have the same bending radius to ensure a homogeneous and correspondingly low load on the bellows.

[0014] Additionally or alternatively, the bellows can have a final annular section adjacent to the coupling section in the axial direction, which tapers continuously, and in particular constantly, from the coupling section to its radially outer edge. This design ensures that forces are transferred from the coupling section to the bellows in a material-friendly manner.

[0015] According to one embodiment, the turning points of the radially inner turns are arranged on an imaginary inner circular cylinder, and the turning points of the radially outer turns are arranged on an imaginary outer circular cylinder. Due to this symmetrical design, forces are distributed particularly evenly within the bellows, thus reducing the maximum load.

[0016] Here, the ratio of the radius of the outer circular cylinder to the radius of the inner circular cylinder can be less than 3, in particular less than 2, and greater than 1.5. In this way, the bellows can be manufactured with minimal effort, especially by means of a subtractive manufacturing process.

[0017] According to another embodiment, the coupling section is arranged radially inside the inner circular cylinder and / or the fastening section is arranged radially outside the outer circular cylinder, which makes the maximum load on the bellows particularly low.

[0018] Furthermore, the bellows can have between six and 14 turns. This number of turns ensures that the membrane has high elasticity and resilience.

[0019] According to the invention, to solve the above-mentioned problem, a diaphragm valve is also provided with a diaphragm according to the invention with the aforementioned advantages, an axially driven valve spindle which is coupled to the coupling section, and a housing with two opposing clamping surfaces by means of which the diaphragm is attached to the housing via the flange.

[0020] In one embodiment, a sealing ring is arranged between one of the clamping surfaces and the flange to ensure a high level of tightness.

[0021] Additionally or alternatively, the housing can have a support ring, wherein one of the clamping surfaces is formed at least partially by the support ring. By means of the support ring, the installation space provided in the diaphragm valve for a diaphragm can be adapted to the diaphragm according to the invention, so that the same diaphragm can be used in different diaphragm valves with different installation space sizes. In other words, a diaphragm valve can be retrofitted with a diaphragm according to the invention with minimal effort, as long as sufficient installation space is available for the diaphragm and, if necessary, the support ring.

[0022] Furthermore, the valve spindle can be axially adjustable between a first position, in which a valve seat of the diaphragm valve is closed, and a second position, in which the valve seat is open, with the diaphragm being designed such that the bellows is in an axially unloaded state in an axial position of the valve spindle. In this way, the maximum elongation of the diaphragm is lower than in an embodiment where the diaphragm is in an axially unloaded state in either the first or second position of the valve spindle. Thus, large elongations, which can significantly impair the service life of the diaphragm, are avoided.

[0023] In particular, the diaphragm can be designed such that the axial midpoint between the first and second positions of the valve spindle is in an axially unloaded state. By choosing the axial midpoint for the axially unloaded state, the maximum load is only 50%. In other words, this means that the diaphragm is stretched in both the first and second positions of the valve spindle, but only by half the distance compared to an embodiment in which the diaphragm is not stretched in either the first or the second position.

[0024] Further advantages and features will become apparent from the following description and the accompanying drawings. These show: - Fig. 1 in a longitudinal section a diaphragm valve according to the invention with a diaphragm according to the invention, - Fig. 2 in a longitudinal section the membrane from Fig. 1, and - Fig. 3 in a longitudinal section a section of the membrane from Fig. 1 according to one variant.

[0025] The detailed description below, in conjunction with the accompanying drawings, in which identical numbers refer to identical elements, is intended to describe various embodiments of the disclosed subject matter and is not meant to represent the only embodiments. Each embodiment described in this disclosure serves only as an example or illustration and should not be construed as preferable or advantageous over other embodiments.

[0026] All features disclosed below with reference to the exemplary embodiments and / or the accompanying figures can be combined alone or in any subcombination with features of the aspects of the present disclosure, including features of preferred embodiments, provided that the resulting combination of features is meaningful to a person skilled in the art.

[0027] In Fig. Figure 1 shows a diaphragm valve 10 with a housing 12, which has a lower housing part 14 with an internal fluid chamber 16 and an upper housing part 18 with an internal actuator chamber 20.

[0028] The lower housing part 14 has a valve seat 22, which is arranged in terms of flow between a fluid inlet and a fluid outlet of the fluid chamber 16.

[0029] An axially opposite the valve seat 22 is an axially adjustable valve spindle 24, which is driven by means of an actuator 26 of the diaphragm valve 10 and is attached to a coupling section 28, which forms a central axial end region of a diaphragm 30.

[0030] The membrane 30 is made of polyetheretherketone (PEEK) and separates the fluid chamber 16 from the drive chamber 20 in a fluid-tight manner, so that fluid flowing through the fluid chamber 16 cannot penetrate into the drive chamber 20.

[0031] For this purpose, the membrane 30 has a mounting section 32 with a flange 34, which is attached to the housing 12 between a lower clamping surface 36 and an axially opposite upper clamping surface 38.

[0032] The lower clamping surface 36 is in this case part of the lower housing part 14, while the upper clamping surface 38 is part of a support ring 40 which is arranged between the upper housing part 18 and the flange 34 in the drive chamber 20.

[0033] In an alternative embodiment, the upper clamping surface 38 is part of the upper housing part 18, so that the support ring 40 can be omitted.

[0034] In another alternative embodiment, the support ring 40 forms part of the upper clamping surface 38, while, for example, the upper housing part 18 forms the other part of the upper clamping surface 38.

[0035] A sealing ring 42 is arranged between the lower clamping surface 36 and the flange 34 to ensure a high degree of tightness.

[0036] Of course, in an alternative embodiment the lower clamping surface 36 can be formed by a support ring 40 and / or a sealing ring 42 can be arranged between the upper clamping surface 38 and the flange 34.

[0037] The fastening section 32 is connected to the coupling section 28 via an axial bellows 44, which extends in axial direction A in a meandering shape from the fastening section 32 to the coupling section 28.

[0038] The diaphragm 30 is therefore a bellows diaphragm and the diaphragm valve 10 is a bellows diaphragm valve.

[0039] In Fig. Figure 1 shows the diaphragm valve 10 in an axial central position, in which the valve spindle 24 is arranged axially between a first position, in which the diaphragm valve 10 is in a closed position and the valve seat 22 is tightly closed, and a second position, in which the diaphragm valve 10 is in an open position and the valve seat 22 is open.

[0040] In the closed position, the valve spindle 24 presses the coupling section 28 in axial direction A against the valve seat 22, so that a sealing section 46, which forms an axial end of the coupling section 28, lies close to the valve seat 22.

[0041] In the open position, the valve seat 22 is, for example, fully open according to the specifications of the diaphragm valve 10.

[0042] In this context, the diaphragm valve 10 is designed such that the bellows 44 is in an axially unloaded state in the axial center position.

[0043] Based on the Fig. 2 The design of membrane 30 will be explained in more detail below.

[0044] The bellows 44 is formed by several ring-shaped sections 48, which are connected to each other by radially inner turns 50 and radially outer turns 52.

[0045] Turns 50 and 52 are, viewed in longitudinal section, U-shaped.

[0046] In the illustrated embodiment, the bellows 44 has seven annular sections 48 as well as three inner turns 50 and three outer turns 52, which alternate in axial direction A.

[0047] Of course, in an alternative embodiment, the bellows 44 can have any number of turns 50, 52, for example eight, ten, twelve or 14.

[0048] The ring-shaped sections 48 extend in a radial direction and are, for example, designed in an annular disk shape, as in Fig. 2 shown.

[0049] In the unloaded state of the bellows 44, the ring-shaped sections 48 extend perpendicular to the central longitudinal axis M of the membrane 30.

[0050] In an alternative embodiment, the ring-shaped sections 48 extend obliquely, for example at an angle between 45 and 90°, to the central longitudinal axis M of the membrane 30.

[0051] Additionally or alternatively, the ring-shaped sections 48 can run in a wave-like manner in the radial direction and / or in the circumferential direction.

[0052] The bellows 44 is integrally connected to the fastening section 32 via the first annular section 54 in the axial direction A and to the coupling section 28 via the last annular section 56 in the axial direction A.

[0053] The inflection points 58 of the radially inner turns 50 lie on an imaginary inner circular cylinder 60 with a radius Ri, while the inflection points 62 of the radially outer turns 52 are arranged on an imaginary outer circular cylinder 64 with a radius Ra.

[0054] The ratio of the radius Ra of the outer circular cylinder 64 to the radius Ri of the inner circular cylinder 60 is approximately 1.8.

[0055] In an alternative embodiment, the Ra / Rb ratio is less than 3, in particular less than 2, and greater than 1.5.

[0056] In the present embodiment, the coupling section 28 is arranged completely radially inside the inner circular cylinder 60 and the fastening section 32 is arranged completely radially outside the outer circular cylinder 64.

[0057] Furthermore, all turns 50, 52 have the same bending radius Rb.

[0058] Of course, in an alternative embodiment, the turns 50, 52 can have different bending radii Rb.

[0059] The ratio of 2Rb / (Ra-Ri) is, for example, between 1 and 3.

[0060] With the exception of the last annular section 56, the bellows 44 has a constant wall thickness s of 0.3 mm.

[0061] In principle, the wall thickness s of the bellows 44 can be between 0.2 and 0.5 mm.

[0062] In an alternative embodiment, the entire bellows 44 has a constant wall thickness s.

[0063] In a further alternative embodiment, the first annular section 54 can additionally or alternatively have a wall thickness s that differs from the wall thickness s of the rest of the bellows 44, in addition to or as an alternative to the last annular section 56.

[0064] The last ring-shaped section 56, viewed in longitudinal section, transitions seamlessly into the coupling section 28 on the outside with a radius Ru in a transition area 66.

[0065] Between the transition area 66 and its radially outer edge 68, the last annular section 56 extends with constant wall thickness s.

[0066] In an alternative embodiment (see Fig. 3) the last annular section 56 tapers continuously from the transition area 66 to its radially outer edge 68, for example at a constant angle α of 2°.

[0067] In all embodiments, the fastening section 32 has a transition section 70 that connects the first annular section 54 to the flange 34 in a radial direction.

[0068] The transition section 70 tapers continuously from the axial thickness H of the flange 34 to the wall thickness s of the first annular section 54.

[0069] The axial thickness H of the flange 34 is therefore greater than the wall thickness s of the first annular section 54.

[0070] The ratio of the axial thickness H of the flange 34 to the smallest wall thickness s of the bellows 44 is, for example, between 1.5 and 5.

[0071] The transition section 70 has an inclined surface 72 which is arranged at an angle β of 30° to a plane E which is perpendicular to the central longitudinal axis M.

[0072] The inclined surface 72 is arranged opposite to the coupling section 28.

[0073] In an alternative embodiment, the angle of inclination β is between 20 and 60°.

[0074] Furthermore, the transition section 70, viewed in longitudinal section, merges seamlessly into the first ring-shaped section 54 with a radius Rv of 2 mm.

[0075] In an alternative embodiment, the radius Rv is between 0.3 and 3 mm.

[0076] To manufacture the membrane 30, a workpiece made of PEEK is removed accordingly, for example by means of a clamping process such as turning or milling.

[0077] Alternatively, the membrane 30 can be manufactured using an additive manufacturing process, for example by means of 3D printing.

[0078] To effectively couple the diaphragm 30 with the valve spindle 24, a fastening sleeve 74 can be provided which is attached in the coupling section 28, for example by form-fitting and / or material-fitting means.

[0079] In this way, a diaphragm 30 and a diaphragm valve 10 with a diaphragm 30 are provided, which has good resistance and a long service life.

[0080] Furthermore, the membrane 30 is made of an environmentally friendly material.

Claims

[1] Diaphragm (30) for a bellows diaphragm valve (10), comprising a central coupling section (28) provided at an axial end region of the diaphragm (30), which is configured to be coupled to an axially driven valve spindle (24) of the diaphragm valve (10), a mounting section (32) provided at an opposite axial end region, which is spaced axially from the coupling section (28), and an axial bellows (44) connecting the coupling section (28) to the mounting section (32), wherein the mounting section (32) has a radially projecting circumferential flange (34) and a transition section (70) extending radially inward from the flange (34), which connects the flange (34) to the bellows (44), wherein the diaphragm (30) is made of polyetheretherketone and the transition section (70) extends from the flange (34) with an axial Thickness (H) continuously tapers up to the bellows (44),wherein the wall thickness (s) of the bellows (44) is smaller than the axial thickness (H) of the flange (34). [2] Membrane (30) according to claim 1, wherein the transition section (70) is defined in longitudinal section on one side by a radius (Rv), in particular wherein the radius (Rv) is in the range of 0.3 to 3 mm, wherein this side transitions seamlessly into the bellows (44). [3] Membrane (30) according to claim 1 or 2, wherein the transition section (70) has on one side an inclined surface (72) which is arranged at an angle (β) between 20 and 60° to a plane (E) which is perpendicular to the axis (M) of the bellows (44). [4] Membrane (30) according to one of the preceding claims, wherein the ratio of the axial thickness (H) of the flange (34) to the smallest wall thickness (s) of the bellows (44) is between 1.5 and 5. [5] Membrane (30) according to one of the preceding claims, wherein the wall thickness (s) of the bellows (44) is between 0.2 and 0.5 mm. [6] Membrane (30) according to one of the preceding claims, wherein the bellows (44) has superimposed annular sections (48) and U-shaped turns (50, 52) in longitudinal section connecting adjacent annular sections (48), wherein the adjacent annular sections (48) are connected by axially alternating radial turns (50, 52) provided at the inner and outer edges, wherein the bellows (44) has a constant wall thickness (s) except for its first (54) and / or last annular section (56) in the axial direction (A). [7] Membrane (30) according to claim 6, wherein all turns (50, 52) have the same bending radius (Rb). [8] Membrane (30) according to claim 6 or 7, wherein the bellows (44) has a final annular section (56) adjacent in axial direction (A) to the coupling section (28), which tapers continuously from the coupling section (28) to its radially outer edge (68), in particular constantly. [9] Membrane (30) according to one of claims 6 to 8, wherein the turning points (58) of the radially inner turns (50) are arranged on an imaginary inner circular cylinder (60) and the turning points (62) of the radially outer turns (52) are arranged on an imaginary outer circular cylinder (64). [10] Membrane (30) according to claim 9, wherein the ratio of the radius (Ra) of the outer circular cylinder (64) to the radius (Ri) of the inner circular cylinder (60) is less than 3, in particular less than 2, and greater than 1.

5. [11] Membrane (30) according to claim 9 or 10 wherein the coupling section (28) is arranged radially inside the inner circular cylinder (60) and / or the fastening section (32) is arranged radially outside the outer circular cylinder (64). [12] Membrane (30) according to one of the preceding claims, wherein the bellows (44) has between six and 14 turns (50, 52). [13] Diaphragm valve (10) comprising a diaphragm (30) according to one of the preceding claims, an axially driven valve spindle (24) coupled to the coupling section (28), and a housing (12) with two opposing clamping surfaces (36, 38) by means of which the diaphragm (30) is attached to the housing (12) via the flange (34). [14] Diaphragm valve (10) according to claim 13, wherein a sealing ring (42) is arranged between one of the clamping surfaces (36, 38) and the flange (34), and / or the housing (12) has a support ring (40), wherein one of the clamping surfaces (36, 38) is formed at least partially by the support ring (40). [15] Diaphragm valve (10) according to claim 14, characterized by , that the valve spindle (24) is axially adjustable between a first position in which a valve seat (22) of the diaphragm valve (10) is closed and a second position in which the valve seat (22) is open, wherein the diaphragm (30) is designed such that the bellows (44) is in an axially unloaded state in an axial position, in particular an axial mid-position, between the first and second positions of the valve spindle (24).

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