Membrane valve with a secondary seal

Description

[0001] The invention relates to a valve comprising a housing, a hood, and a diaphragm, wherein the diaphragm is formed in one piece from a polymeric material and has a flat area and a bead-like edge which is pressed between the housing and the hood in a chamber, wherein the upper part of the housing is also referred to as the hood and forms the superstructure with the drive of the diaphragm and integrates the drive spindle, the seal of the spindle, and the drive itself, wherein the housing has a plate-shaped recess into which an annular projection of the hood engages to act on the edge of the diaphragm, wherein the chamber is formed by a plate-shaped recess of the housing and an annular projection of the hood engaging therein, wherein the housing has a support element for a contact area of ​​the hood for force transmission, and the hood is connected to the housing by fastening elements.

[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 the main base materials used 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. EPDM is a terpolymer elastomer (rubber) and therefore a synthetic rubber. This 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 this weight must be transferred to it.

[0008] 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.

[0009] To stabilize the membrane, support arrangements in the form of spirals resting on the membrane are known on the side facing away from the fluid and thus on the side facing the hood, which can partially compensate for permanent damaging deformation in the open position.

[0010] 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.

[0011] DE 18 28 572 U discloses a diaphragm valve, in particular an electromagnetically controlled valve, wherein the diaphragm edge projects into an annular gap whose height is greater than the diaphragm thickness, and has means for pressing against at least one boundary wall.

[0012] JP H09 217 844A discloses a fluid control valve, intended for use on the fuel meter of a filling station, equipped with an electromagnetic valve unit with two solenoid valves as the actuation means to obtain two flow rates, high and low. Furthermore, a mounting element for a diaphragm is formed on one end of the main body of the fluid control valve and is connected to a pressure chamber formed with the diaphragm and a cover body to create a pilot flow path. An annular groove is then formed in the upper mounting surface of the main body so that it surrounds the pilot flow path. An O-ring is tightly fitted into the annular groove and positioned in a height-differentiated section between the upper and lower mounting surfaces.

[0013] DE 20 2015 102 015 U1 describes a diaphragm valve comprising a valve body having at least one flow channel for fluid flow, a valve actuator with a housing, and a diaphragm which can be deflected by the valve actuator to selectively open and close the flow channel. The diaphragm is axially clamped fluid-tight at its edge between the valve body and the valve actuator, and the clamping of the diaphragm is effected by a screw-nut connection. The screw and nut surround the diaphragm at its edge when viewed in the direction of actuation of the valve actuator. One of the two parts formed by the screw and nut is non-rotatably mounted on the valve body or the valve actuator, and the other part is screwable and rotatable. The movable part is supported by a rolling bearing on the valve actuator or the valve body.

[0014] EP 3 401 580 A1 describes a lift valve, which is designed in particular for aseptic product lines, and comprises a valve housing with line connections and a valve seat formed in between in the valve housing, as well as a closing element axially adjustable in the valve housing and cooperating with the valve seat and a diaphragm that extends around the closing element and from it to a clamping point on the housing side.

[0015] WO 2005 / 003605 A2 discloses a diaphragm valve for use in an atomic layer deposition (ALD) system. In one embodiment, a heating element forms a heat-conducting path between the diaphragm and the valve body to maintain an operating temperature at the diaphragm and to prevent condensation or freezing of high-temperature ALD precursor gases in the valve channel.

[0016] Document EP 1 098 120 A1 discloses a diaphragm valve with a diaphragm, with a reinforcing fabric insert and a bead-like thickened rim serving to hold the diaphragm in a chamber formed by two housing parts.

[0017] The action of the fluid at a given pressure and temperature leads to relaxation of the elastomer components of the membrane. In chambered membranes, the membrane tension cannot be increased again by tightening or retensioning. This can lead to small leaks at the valve, allowing the fluid to escape. With increasing duration of the reduced tension in the membrane, irreversible damage can occur, potentially causing larger quantities of fluid to leak from the valve. This is particularly undesirable with hot and toxic media, as well as with fluids in nuclear applications.

[0018] The object of the invention is to provide a valve with a diaphragm that can prevent material leakage and ensure safe valve operation. Furthermore, the diaphragm should meet the requirements of continuous operation and retain extremely durable properties.

[0019] This problem is solved according to the invention by a valve with a diaphragm according to the features of claim 1. Preferred embodiments can be found in the dependent claims, the description and the drawings.

[0020] According to the invention, a cavity for positioning during assembly is arranged between the chambering and the support element, wherein at least one sealing element is arranged between the support element of the housing and the contact area of ​​the hood, wherein the sealing element is arranged between the fastening elements and the plate-shaped recess of the housing.

[0021] The support element is part of the housing and is therefore integrally formed with it. The support element has a front contact surface and a circumferential inner wall surface, with the contact area of ​​the hood directly adjacent to both surfaces.

[0022] The contact area is the part of the hood that is in direct contact with the mounting element of the housing. This contact area has a support surface that rests on the end face of the mounting element and an adjacent contact surface that is in direct contact with the surrounding inner wall surface of the mounting element.

[0023] A sealing element is defined as an element that prevents or at least significantly limits unwanted material transfer from one space to another.

[0024] In a valve with a chambered diaphragm, the diaphragm preferably has an edge that is pressed between a plate-shaped recess in the housing and an annular projection of the bonnet. The force generated by the mass of the bonnet, including the diaphragm actuator, is transferred via the bonnet's support element into the contact area of ​​the housing. The bonnet is connected to and fixed to the housing by fasteners.

[0025] In a preferred embodiment of the invention, a sealing element is arranged as a secondary seal between the support element of the lower housing part and the contact area of ​​the hood and effectively prevents the fluid from escaping even in the case of a damaged membrane, which in its undamaged state fulfills the function of a primary seal.

[0026] Alternatively, two or three sealing elements can be provided as a secondary seal. In this case, the sealing elements do not have direct contact with each other. Furthermore, the sealing elements can all be located in the mounting element of the housing, all in the contact area of ​​the hood, or both in the mounting element of the housing and in the contact area of ​​the hood.

[0027] In one variant of the invention, the sealing element can be arranged in the end-face bearing surface or in the circumferential inner wall surface of the bearing element.

[0028] In an alternative version of the invention, the sealing element can be arranged in the support surface or in the adjacent contact surface of the contact area.

[0029] Preferably, the sealing element is arranged in a groove that is integrated into the contact area of ​​the valve cover. This prevents any forces from acting on the sealing element and causing wear. Furthermore, the sealing element within the groove does not come into contact with the media during normal operation of the valve, thus providing it with exceptional protection against valve diaphragm relaxation and ensuring the desired valve tightness even in the event of diaphragm damage.

[0030] Alternatively and / or additionally, the sealing element can be arranged in a groove that is incorporated into the support element of the housing.

[0031] In a particularly advantageous embodiment of the invention, the sealing element is integrated into the contact area between the hood and the housing, which runs between the fastening elements and the plate-shaped recess of the housing. This advantageous method ensures particularly reliable operation of the valve with a diaphragm and reliably prevents unwanted fluid leakage.

[0032] To ensure a permanent sealing effect, the sealing element preferably has a larger volume than the groove for pressing in and completely filling the groove.

[0033] Preferably, the sealing element is designed in the form of a classic O-ring.

[0034] In a particularly preferred embodiment of the invention, the sealing element is elastic, preferably designed as an elastomeric sealing element. The term "elastic" here refers to the sealing element's ability to change its shape under the influence of force and to return to its original shape when the force is removed. This property of the secondary seal ensures the reliable operation of the valve with a diaphragm even in the event of diaphragm damage and effectively prevents unwanted fluid leakage from the valve.

[0035] In an advantageous embodiment of the invention, the sealing element is designed to be particularly resistant to pressure and temperature. The sealing element can be made of the same material as the membrane. Furthermore, different material configurations are also conceivable that reliably fulfill the sealing function of a secondary seal.

[0036] Ideally, a partial cavity can be provided between the chambering of the membrane and the support element of the housing, in particular at the plate-shaped recess of the housing onto which the membrane is placed during assembly, to position the membrane and to facilitate assembly.

[0037] In a favorable embodiment of the invention, a sensor for detecting a leak is arranged between the primary and secondary seals, thus indicating when a membrane replacement is necessary. This allows for particularly reliable assurance, within the framework of condition-based maintenance, that the sealing element, acting as the secondary seal, prevents fluid leakage until the membrane is replaced. For example, the sensor can communicate with a higher-level process control system via radio or a sealed data line.

[0038] 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.

[0039] This shows: Fig. 1 an exploded view of a diaphragm valve, Fig. 2 a sectional view of a valve with a diaphragm, Fig. 3 a detailed view of the arrangement of the sealing element, Fig. 4 a further detailed view of the arrangement of the sealing element, Fig. 5 an alternative detailed view of the arrangement of the sealing element, Fig. 6 a fourth variant of the detailed view of the arrangement of the sealing element.

[0040] Fig. 1 Figure 1 shows an exploded view of a valve with a diaphragm 2. The valve comprises a housing 1, a diaphragm 2, a pressure distribution element 3, a pressure piece 4 and a hood 5.

[0041] In this embodiment, the pressure distribution element 3 is shown in use with a chambered membrane 2. The membrane 2 is formed in one piece from a polymeric material and has a flat area 6 to which an edge 7 adjoins. The flat area 6 is curved downwards. The edge 7 extends vertically upwards in the drawing. The flat area 6 is disc-shaped. The edge 7 is bead-like.

[0042] The edge 7 of the membrane 2 projects vertically upwards and has a circumferential end face 23 on its upper surface. The end face 23 is curved. Thus, the end face 23 of the edge 7 of the membrane 2 does not lie in a horizontal plane, but is curved in the vertical direction. The curvature of the end face 23 reaches its lowest point in the region of the membrane web or weir and then rises towards both sides, so that the end face 23 of the edge 7 of the membrane 2 has its highest elevation in the inlet area, then decreases continuously to the valve seat or the web or weir, and then rises again towards the outlet and then increases to the same height again. The curvature of the end face 23 of the edge 7 of the membrane 2 thus runs parallel to the flow direction.

[0043] In the exemplary embodiment, the diaphragm 2 is designed such that the least stress acts on the material of the diaphragm 2 in the closed position. When the valve opens, the diaphragm 2 is deformed and the stress in the diaphragm material increases. An element is positively embedded in the diaphragm 2, which is connected to a drive (not shown) for deforming the diaphragm 2. In the exemplary embodiment, the element 8 is a diaphragm screw. The element 8 is connected to a pressure piece 4. The cross-shaped pressure piece 4 can be moved vertically within the hood by means of a drive (not shown). The pressure distribution element 3 distributes the pressure exerted by the pressure piece 4 over the planar area 6 of the diaphragm 2.

[0044] The pressure piece 4 has an internal opening 9 for connection to a drive. Four arms 10 extend outwards, giving the pressure piece 4 a cross-shaped form in plan view. The hood 5 has a flat contact area 11, which is convex downwards. A circumferential annular projection 12 extends downwards. Together with the plate-shaped recess 31, into which the annular projection 12 engages on the inside and abuts the support element 32 on the outside, the chamber 36 for the edge 7 of the membrane 2 is formed.

[0045] The hood 5 has a hollow cylindrical neck 13 in its center, with a circular opening 14 for drive elements (not shown), such as a spindle. The hood 5 has a cavity 15 in which the pressure piece 4 is arranged to be slidably mounted in the vertical direction. In the open position, the pressure distribution element 3 is pressed against the diaphragm 2 by a limiting shoulder 15 of the hood 5.

[0046] In this embodiment of the invention, the support element 32 of the housing 1 has four bores 38 which are aligned with the four bores 39 of the contact area 11 of the hood 5. The fastening elements 34, through which the hood 5 is connected to the housing 1, are guided through the bores 38 and 39.

[0047] To form a secondary seal in the event of a membrane failure, the contact area 11 of the hood 5 has a groove 35 into which a sealing element 33 can be inserted and which, with the help of a pressed support through the support element 32, can effectively prevent media leakage, thus ensuring safe operation of the valve.

[0048] The in Fig. 2 The illustrated valve with a diaphragm 2 has a housing 1 which includes ports 40, 42 and a weir 41. The weir 41 serves as a seat for the diaphragm 2. The diaphragm 2 is clamped between the housing 1 and the cover 5 by means of the chamber 36, while the cover 5 is connected to the housing 1 by means of the fastening elements 34.

[0049] The chamber 36 is formed by the saucer-shaped recess 31, on which the membrane 2 rests and the bead-like rim 7 projects vertically. The rim 7 abuts the support element 32 of the housing 1. The saucer-shaped recess 31 and the support element 32 form a limiting shoulder for the rim 7 of the membrane 2. Viewed from the outside in, the annular projection 12 of the cover 5 engages behind the bead-like rim 7 and presses the membrane 2 onto the saucer-shaped projection 31, thus completing the chamber 36 of the membrane 2. A small cavity 37 is provided for positioning during assembly.

[0050] Within the hood 5 in the contact area 11, a sealing element 33 is arranged, which acts as a secondary seal in the event of diaphragm damage. In this embodiment, the sealing element 33 is designed as an elastic O-ring. In this advantageous way, the unwanted escape of hazardous media from the valve can be effectively prevented and safe operation ensured.

[0051] In this embodiment of the invention, the sealing element 33 is elastically designed and arranged in a groove 35, wherein the sealing element 33 has a slightly larger volume to ensure a secondary seal. The groove 35 with the sealing element 33 is spatially arranged between the fastening elements 34 and the plate-shaped recess 31 of the housing 1.

[0052] The hood 5 integrates the elements necessary for actuating the diaphragm 2, such as an actuator 45, which in this embodiment is designed as a handwheel, and a spindle 43. A domed pressure piece 4 is attached to the spindle 43. The pressure piece 4 is slidably arranged within the hood 5 and is guided by an inner wall 46 of the hood 5. The diaphragm 2 is connected to the pressure piece 4 by means of the element 8. Actuating the actuator 45 causes a vertical displacement of the pressure piece 4 via the spindle 43, thus deforming the diaphragm 2 and increasing or decreasing the free cross-section between the weir 41 and the diaphragm 2. A pressure distribution element 3 is arranged between the pressure piece 4 and the diaphragm 2 for improved force transmission and simultaneous support. The spindle 43 is additionally equipped with seals 44 to prevent unwanted media leakage in the event of diaphragm damage.

[0053] In the Fig. 3 bis 6 Various secondary sealing variants are shown with regard to the arrangement of the groove 35 with the sealing element 33 inserted therein in the area of ​​the contact area 11 and the support element 32.

[0054] Fig. 3 Figure 1 shows a variant in which the sealing element 33 is arranged in the groove 35, the groove 35 being positioned in the circumferential inner wall surface of the support element 32. The sealing element 33, which is designed as an elastic O-ring, acts as a seal with the adjacent contact surface of the contact area 11. The annular projection 12, which acts on the edge 7 of the membrane 2, is integrally connected to the adjacent contact surface of the contact area 11.

[0055] In Fig. 4 The groove 35 is positioned at the lowest point of the adjacent contact surface of the contact area 11. In the illustrated embodiment, the support element 32 has a shoulder 47 which, together with the groove 35, achieves a positioning of the sealing element 33.

[0056] The Fig. 5 Figure 1 shows an arrangement of the groove 35 in the adjacent contact surface of the contact area 11. The sealing element 33 positioned in the groove 35 acts in a sealing manner with the circumferential inner wall surface of the support element 32.

[0057] In the Fig. 6 The arrangement of the groove 35 is as shown in Fig. 5 executed, wherein the support element 32 has a step 47 which directly adjoins the edge 7 of the membrane 2.

[0058] In all illustrated variants of the arrangement of the groove 35 with the sealing element 33 in the Fig. 3 bis 6This can effectively prevent the unwanted release of hazardous media from the valve and ensure safe operation.

Claims

1. Valve having a housing (1), having a cover (5) and having a diaphragm (2), wherein the diaphragm (2) is formed in one piece from a polymer material and has an areal region (6) and a bead-like rim (7), which is pressfitted between the housing (1) and the cover (5) in a chambering (36), - wherein the cover (5) forms the superstructure with the drive of the diaphragm (2), and the drive spindle (43), the seal of the spindle (43) and the drive (45) itself are integrated, - wherein the housing (1) has a plate-shaped depression (31) into which an annular projection (12) of the cover (5) engages in order to act on the rim (7) of the diaphragm (2), - wherein the chambering (36) is formed by the plate-shaped depression (31) of the housing (1) and the annular projection (12) of the cover (5) that engages into it, - wherein the housing (1) has a bearing element (32) for a contact region (11) of the cover (5) for introduction of force, - and the cover (5) is connected to the housing (1) by way of fastening elements (34), characterized in that a cavity (37) for positioning during assembly is arranged between the chambering (36) and the bearing element (32), wherein at least one sealing element (33) is arranged between the bearing element (32) and the contact region (11), wherein the sealing element (33) is arranged between the fastening elements (34) and the plate-shaped depression (31) of the housing (1).

2. Valve according to Claim 1, characterized in that the sealing element (33) is arranged in a groove (35) which runs in the contact region (11) of the cover (5).

3. Valve according to either of Claims 1 and 2, characterized in that the sealing element (33) is introduced in a groove (35) which runs in the bearing element (32) of the housing (1).

4. Valve according to one of Claims 1 to 3, characterized in that the sealing element (33) has a larger volume than the groove (35) for pressing in and complete filling of the groove (35).

5. Valve according to one of Claims 1 to 4, characterized in that the sealing element (33) is of elastic form.