Membrane valve with movable pushrod

Description

[0001] The invention relates to a diaphragm valve comprising a diaphragm, a hood and a piston rod, wherein a support arrangement acts on the diaphragm.

[0002] Diaphragm valves can be used to meter various fluids, such as gases, vapors, or liquids. For example, diaphragm valves can be used to meter or distribute highly viscous or very adhesive media. Diaphragm valves effectively prevent deposits and thus contamination. Valves based on the diaphragm principle are the metering devices with the lowest dead volume. In addition to their very small dead volume, diaphragm valves are also designed for optimized drainage, ensuring residue-free removal of the medium.

[0003] This is particularly important for pharmaceutical plants and manufacturing processes, as these are subject to stringent validation requirements to ensure consistent and reproducible quality. These requirements necessitate the ability to run various processes within a single plant. Besides the actual production process, these typically include cleaning, disinfection, and sterilization. Due to their advantageous design features, diaphragm valves have become the preferred fitting in sterile process technology.

[0004] The membranes used form movable, sealing walls that separate two spaces with usually different media (gases, liquids) and often also different pressure conditions.

[0005] An important quality characteristic of a membrane is its flexibility, that is, its ability to move perpendicular to the mounting surface (membrane surface), which may be mechanically driven. Furthermore, the membrane's durability is important, especially when conveying aggressive media.

[0006] The flexibility and durability of a membrane depend primarily on the material from which it is made. Elastomers are mainly used as base materials for membranes, and these can be reinforced with fabric inserts to achieve greater strength. Membranes made of ethylene propylene diene monomer (EPDM) rubber have proven effective as elastomers. EPDM is a terpolymer elastomer (rubber) and therefore a synthetic rubber. The material is characterized by high elasticity and good chemical resistance.

[0007] The diaphragm is firmly clamped between a lower and an upper housing section. The upper housing section, also called the hood, forms the superstructure containing the diaphragm drive. The drive spindle, the spindle seal, and the drive itself are integrated within the hood. Depending on the drive system, the hood has a considerable mass that acts on the lower housing section and must be supported by it.

[0008] The piston rod in a diaphragm valve is a cylindrical machine element connected to the diaphragm by a diaphragm screw, which deforms the diaphragm into its position. The piston rod is moved in its predetermined direction by a drive mechanism. This drive can be manual, electric, pneumatic, or hydraulic.

[0009] The diaphragm screw is a pin-like element that is positively integrated into a layer of the diaphragm. The diaphragm screw is connected to the actuator spindle via the piston rod. This allows the diaphragm to be deformed.

[0010] To stabilize the membrane on the side facing away from the fluid and thus on the side facing the hood, support arrangements in the form of spirals resting on the membrane are known, which can partially compensate for permanent damaging deformation in the open position.

[0011] DE 26 19 004 relates to a shut-off device, in particular a diaphragm shut-off device with a shut-off device housing in which a fluid channel is formed, an elastic diaphragm which is clamped with its edge between the housing and a shut-off device cover and a movable suitably shaped shut-off device core which is attached to a spindle rotatably mounted in the cover in order to move the diaphragm between a position in which the fluid channel is open and a position in which the fluid channel is shut off.

[0012] EP 1 413 812 A2 discloses a diaphragm valve and the like, such as a single-seat valve, pressure-holding valve with a diaphragm which is sealed in a valve body and separates the control chamber or the movable valve stem from the product chamber, with a support device for stabilizing the inserted diaphragm.

[0013] DE 18 17 659 A1 discloses an elastic closure for closing openings, with which the flow opening of a valve can be reliably closed and opened for a long time without operational disruptions, even in the case of an operating pressure above 10 atm.

[0014] EP 0 285 573 A2 represents a membrane specifically designed for devices operating in sterile environments, comprising a plurality of concentric annular bodies connected to a surface of the membrane and a plurality of radial pins connected to the annular bodies, the arrangement of the annular bodies and the pins being designed to absorb the pressure load acting on the membrane and to transfer it to the circumferential areas of the moving and fixed bodies.

[0015] EP 3 366 961 B1 describes a valve with a diaphragm having a rim arranged in a chamber formed by a housing part and a hood. A pressure distribution element in the form of a support spiral is arranged between the pressure piece and the diaphragm to support the diaphragm in the open position.

[0016] To date, such pressure distribution elements or support spirals are only used in sufficiently large diaphragm valves, as a support spiral stiffens a small diaphragm too much and restricts its movement. The diaphragms of smaller valve series receive only limited support from any pressure piece that may be present and tend to wear out faster or be more prone to damage compared to diaphragms of larger valve series.

[0017] The object of the invention is to provide a diaphragm valve that protects the diaphragm as effectively as possible from damage. The diaphragm should be protected from damage caused by deformation through comprehensive support. Furthermore, the diaphragm valve should meet the requirements of continuous operation and maintain extremely durable properties. The diaphragm valve should be manufactured in the most cost-effective and particularly simple manner possible.

[0018] This problem is solved according to the invention by a diaphragm valve according to the features of claim 1. Preferred embodiments can be found in the dependent claims, the description and the figures.

[0019] According to the invention, the support arrangement is formed from hinged elements, wherein the piston rod has a shape for a rolling movement of the elements and a special receptacle, and the elements are movably mounted on the piston rod, whereby the shape of the piston rod enables the elements to roll for a folding movement between an open and a closed position.

[0020] A support arrangement generally comprises all elements that serve to protect and support a diaphragm. In the case of small diaphragm valves, the support arrangement does not unduly restrict the diaphragm's movement, as it is composed of small, movable elements.

[0021] Preferably, the elements are designed as prism-shaped bodies and have a trapezoidal base.

[0022] Ideally, the elements of the support assembly extend between the piston rod and the diaphragm valve's housing. This ensures that the diaphragm is completely covered by the hinged elements on the side facing away from the fluid, thus providing effective support. This support, particularly when the valve is open, prevents the diaphragm's elastomers from flowing into an unsupported space. This protection is essential for the continuous and extended operation of the diaphragm valve, especially at higher pressures.

[0023] In order to give the membrane sufficiently flexible and elastic operating behavior even with the support, the elements of the support arrangement are aligned in a star shape.

[0024] Especially in small diaphragm valves, the space between the piston rod and the valve body is very limited. To allow for flexible and elastic operation, the elements can pivot between the open and closed positions.

[0025] To achieve this folding motion in confined spaces, the piston rod features a shaped section and a special receptacle for the elements. This shaped piston rod allows the elements to roll smoothly during the folding motion between the open and closed positions.

[0026] To guide the elements in their folding motion, the piston rod has a special shape. Preferably, the piston rod tapers conically and terminates in a hyperbolic projection. This special shape allows the piston rod to guide and limit the movement of the elements. Ideally, the piston rod has a stop surface to limit the element movement. The elements encounter this stop surface at the conical tip, particularly when the diaphragm is closed.

[0027] The elements are movably mounted on the piston rod.

[0028] In this way, the elements support the membrane in its movement as well as in the open or closed position and simultaneously ensure the desired elasticity of the membrane.

[0029] In one embodiment of the invention, the elements are positively connected to the piston rod. Preferably, specially designed undercuts between the elements and the piston rod achieve the desired mobility of the elements.

[0030] The elements have a special shape for contact with the piston rod and for bearing against the hood. Specifically, the elements have a rounded edge on the piston rod side and a wedge shape on the hood side. This advantageous design, particularly the rounded edge, allows the elements to move smoothly from the open to the closed position and back again, thanks to their bearing in the piston rod. Simultaneously, the wedge shape, in combination with the hood, effectively limits the diaphragm movement.

[0031] In a particularly advantageous embodiment of the invention, the hood has a bearing surface for the elements. This ensures that the elements are fully supported on the diaphragm. The elements extend from the piston rod into the hood, so that the diaphragm is always supported in every position, effectively preventing the elastomer components of the diaphragm from flowing and ensuring reliable and long-lasting operation of the diaphragm valve.

[0032] Preferably, the hood has a cavity to accommodate the elements. This ensures that the membrane is completely covered by the elements. At the same time, the cavity in the hood allows the elements to move between the open and closed positions, since the elements protrude furthest into the cavity in the central position.

[0033] In a preferred embodiment of the invention, the hood has a stop surface to limit the movement of the elements. This allows the elements to be moved only as far as the open or closed position. Slipping, shifting, or even being pushed out of the predetermined path of movement is therefore impossible.

[0034] To ensure sufficient mobility and elasticity of the membrane deformation, the support arrangement comprises more than four, preferably more than eight, and in particular more than twelve, elements.

[0035] In a preferred embodiment of the invention, the cross-section of an element increases from the piston rod to the hood. Particularly preferably, the height of the element increases from the rounded end to the wedge-shaped end. This ensures smooth bearing of the elements in the piston rod, as well as support and limitation of movement by the stop in the hood.

[0036] In a further embodiment of the invention, the support arrangement comprises an additional pressure distribution element. Such a pressure distribution element can preferably be designed in the form of an elastic support spiral and is preferably arranged between the membrane and the elements of the support arrangement.

[0037] In a particularly preferred embodiment of the invention, the elements and the piston rod are additively manufactured simultaneously. This makes it particularly easy to achieve a positive-locking connection between the piston rod and the elements, wherein the elements are movably arranged around the piston rod.

[0038] The support arrangement with hinged elements provides excellent support for the diaphragm during movement and in the stationary position, especially for small diaphragm valves. This effectively prevents the elastomer diaphragm from flowing into an unsupported space above the diaphragm, particularly during continuous operation.

[0039] Further features and advantages of the invention will become apparent from the description of exemplary embodiments with reference to drawings and from the drawings themselves.

[0040] This shows: Fig. 1 a sectional view of a diaphragm valve according to the prior art, Fig. 2 a sectional view of a piston rod with a hinged element of the support arrangement, Fig. 3 a schematic sketch of a hinged element in two positions, Fig. 4 a top view of the star-shaped support arrangement.

[0041] The in Fig. 1 The diaphragm valve 1 shown, according to the prior art, has a lower housing part 2, which includes connections 3, 4 and a weir 5. The weir 5 serves as a seat for the diaphragm 6. The diaphragm 6 is clamped between the lower housing part 2 and the cover 8 by means of screws 7. The diaphragm is connected to the spindle 11 via a diaphragm screw 13. The elements necessary for actuating the diaphragm 6 are integrated into the cover 8, such as an actuator 9, which in this embodiment is designed as a handwheel 10, and a spindle 11. A pressure piece 12 is attached to the spindle 11. The pressure piece 12 is slidably arranged in the cover 8 and is guided by an inner wall of the cover 8. Actuation of the actuator 9 causes a vertical displacement of the pressure piece 12 via the spindle 11, so that the diaphragm 6 deforms and the free cross-section between the weir 5 and the diaphragm assembly increases.can be reduced in size.

[0042] The diaphragm valve 1 has a space 30 above the diaphragm 6 in the open position. During continuous operation, with increasing operating time and higher operating pressures, elastomer material from the diaphragm 6 can flow into the space 30 and lead to damage to the diaphragm 6.

[0043] Fig. 2 Figure 1 shows a sectional view of a piston rod 14 as an extension of the spindle 11 with a hinged element 15 of the support arrangement 16. The hinged element 15 is positively connected to the piston rod 14 by means of a movable mounting of the rounded section 19 in the recess 17. To form the recess 17, the piston rod 14 tapers conically and terminates in a hyperbolically shaped projection 25, which has a chamfer 24. In the closed position of the diaphragm 6, the element 15 rests against the stop surface 18 of the conical part of the piston rod 14. The stop surface 18 limits the element's movement and ensures permanent contact and support of the diaphragm 6's support arrangement 16, even in the closed position.

[0044] Element 15 has a rounded section 19 that abuts the piston rod 14 and further exhibits a wedge shape 20 towards the hood 8. The cross-section of the prismatic element 15 increases continuously from the rounded section 19 to the wedge shape 20.

[0045] Fig. 3 Figure 1 shows a schematic sketch of a hinged element 15 in both the open and closed positions. The cover 8 has a cavity 22 to accommodate the movement of the element 15, into which the element 15 folds when moving into the open position. In the open position, the element 15 rests against the stop surface 23 of the cover 8. The stop surface 23 supports the membrane 6 in the open position, effectively preventing the flow of the elastomeric components of the membrane 6 into unsupported spaces. When the membrane 6 is closed, the element 15 rests against the support surface 21 of the cover 8, providing support even in the closed position and thus effectively protecting and supporting the membrane 6.

[0046] Fig. 4Figure 1 shows a top view of the star-shaped support arrangement 16. In this embodiment, ten hinged elements 15 are arranged in a circle around the support arrangement 16. The rounded edges 19 point towards the center of the circle and the wedge shapes 20 point outwards towards the hood 8.

Claims

1. Diaphragm valve (1) which comprises a diaphragm (6), a hood (8) and a piston rod (14), wherein a support assembly (16) acts on the diaphragm (6), wherein the support assembly (16) is formed from foldable elements (15), wherein the piston rod (14) has a moulding (17) for a rolling movement of the elements (15) and a special receptacle, and the elements (15) are movably mounted on the piston rod (14), as a result of which the moulding (17) of the piston rod (14) enables the elements (15) to roll along for a folding movement between an open position and a closed position, wherein the elements (15) have a roundness (19) on one side, and a wedge shape (20) on the other side, wherein the wedge shape is provided for resting on the hood (5) in order to delimit the diaphragm movement.

2. Diaphragm valve according to Claim 1, wherein the elements (15) extend between the piston rod (14) and the hood (8).

3. Diaphragm valve according to Claim 1 or 2, wherein the elements (15) are oriented in a star-shaped manner.

4. Diaphragm valve according to one of Claims 1 to 3, wherein the piston rod (14) has a detent face (18) for delimiting the element movement.

5. Diaphragm valve according to one of Claims 1 to 4, wherein the hood (8) has a resting surface (21) for the elements (15).

6. Diaphragm valve according to one of Claims 1 to 5, wherein the hood (8) has a cavity (22) for receiving the elements (15).

7. Diaphragm valve according to one of Claims 1 to 6, wherein the hood (8) has a detent face (23) for delimiting the element movement.

8. Diaphragm valve according to one of Claims 1 to 7, wherein the support assembly (16) comprises more than four, preferably more than eight, in particular more than twelve, elements (15).

9. Diaphragm valve according to one of Claims 1 to 8, wherein the cross section of the element (15) increases from the piston rod (14) to the hood (8).

10. Diaphragm valve according to one of Claims 1 to 9, wherein the support assembly (16) comprises a pressure distribution element.

11. Diaphragm valve according to one of Claims 1 to 10, wherein the elements (15) are generatively manufactured.