Metal seals for flap valves

Abstract

The invention relates to a metal seal for a flap valve (1), the flap valve (1) having a valve housing (2) with a flow channel (3), in the flow cross section of which a valve disc (4) is arranged so that it can be pivoted about a pivot axis (5) between an open position and a closed position. Sealing elements (7a, 7b, 9) that can be pressed against each other are arranged on the outer circumference of the valve disc (4) and on the inner circumference of the valve housing, the sealing elements having at least one annular metal sealing lip (7a, 7b) which is supported by elastic preload on an oppositely located, likewise annular metal mating sealing surface (9) in the closed position. The object of the invention is to develop such a metal seal in order to improve the sealing effect, to simplify the actuation of the valve disc (4) when opening and closing the flap valve and to prevent damage caused by resonant vibrations as far as possible. According to the invention, it is proposed that the metal sealing lips (7a, 7b) are produced from a metal material by an additive process so as to have a shape, a cross-sectional geometry and / or a composition adapted to the different circumferential regions of the metal sealing lips (7a, 7b).

Description

Technical Field

[0001] The invention relates to a flap valve having a valve housing with a flow channel, in the flow cross section of which a valve disk is arranged so that it can be pivoted about a pivot axis between an open position and a closed position, wherein sealing elements which can be pressed against each other are arranged on the outer circumference of the valve disk and on the inner circumference of the flow channel, and these sealing elements have at least one annular metal sealing lip which is produced from a metal material by an additive process and which bears with elastic preload in the closed position on an oppositely located, likewise annular metal mating sealing surface, wherein

[0002] - a metal sealing lip is arranged on the outer circumference of the valve disc and a mating sealing surface is arranged on the inner circumference of the flow channel;

[0003] - Alternatively, the mating sealing surface is arranged on the outer circumference of the valve disk and the metal sealing lip is arranged on the inner circumference of the flow channel.

[0004] Firstly, a flap valve with a metal sealing lip has in principle advantages over a flap valve with a plastic (polymer) sealing lip, because the metal sealing lip is extremely durable and heat resistant, ie, has properties that cannot be obtained with a plastic (polymer) sealing lip. Background Art

[0005] Flap valves with such metal seals have been known for some time. In this regard, reference is made, for example, to WO 2019 / 0677725. The metal sealing lip used in such metal seals has the advantage that the sealing effect, which is initially limited only by elastic restoring forces, is enhanced when the cross section of the sealing lip extends in a curved or inclined manner opposite to the direction of the pressure gradient.

[0006] In order to be able to use this reinforcing effect in both flow directions, it is also known to provide two metal sealing lips instead of just one metal sealing lip, which are arranged at a distance from each other in the flow direction of the flap valve. In this regard, reference is made, for example, to a metal seal from EP 0 663 549 B1, in which the cross-sectional area of ​​the two metal sealing lips extends outwards in an inclined or curved manner relative to the hollow space remaining between them in the sealing position. This embodiment of the metal seal has the advantage that the reinforcing effect described above is achieved in both possible flow directions and in particular at the respective metal sealing lips located on the high-pressure side.

[0007] In the case of using two metal sealing lips arranged at a distance from each other in the flow direction, an even better and in particular more precisely controllable sealing effect is obtained when the cross-sectional area of ​​the two metal sealing lips extends in an inclined and / or curved manner (cf. US 4 396 199 A) in the direction of the interior of the annular hollow space located between them. The enhanced effect described above is also achievable in this case in both flow directions, but always only at the second metal sealing lip located in a backward position in the flow direction, while the first metal sealing lip located in a forward position in the flow direction already allows flow under the sealing effect defined by its elastic preload. This specific feature opens up a variety of possibilities for monitoring and / or influencing the sealing effect of such a flap valve equipped with two metal sealing lips, for example by pressurizing or depressurizing the hollow space located between the two metal sealing lips, or in an emergency, by filling this hollow space with a bonded closing medium. However, due to the difficulty in matching the sealing effects of the two metal sealing lips arranged in sequence, this specific form of metal seal has not yet been widely used in practice.

[0008] A frequently occurring problem with metal seals of the type mentioned in the introduction is the fact that the sealing conditions and mechanical stresses vary greatly over the circumference of the valve disk or over the circumference of the valve housing, and in fact especially with regard to the distance of the corresponding circumferential area from the pivot axis of the flap valve. The reason for this is firstly the relative movements between the metal sealing lip on the one hand and the mating sealing surface mating with the metal sealing lip on the other hand, which relative movements differ depending on the distance to the pivot axis. In particular, the position of the pivot axis relative to the valve disk has a major influence on these movement paths. Here, a distinction is made between different configurations, such as

[0009] - a central configuration, in which the pivot axis of the valve disc extends through the center of the circular sealing arrangement,

[0010] - a single eccentric configuration, in which the pivot axis of the valve disk is axially displaced in the flow direction along the axis of the flow channel,

[0011] - a double eccentric configuration, in which, in addition to the single eccentric configuration, the pivot axis of the valve disc is displaced perpendicularly to the axis of the flow channel,

[0012] - a triple eccentric configuration, in which, in addition to the double eccentric configuration, the plane of the sealing arrangement is no longer arranged perpendicular to the axis of the flow channel,

[0013] - a quadruple eccentric configuration, in which, in addition to the triple eccentric configuration, the sealing arrangement is not formed in a circular but in an elliptical shape,

[0014] - and a five-eccentric configuration, wherein, in addition to the four-eccentric configuration, the plane of the sealing cone is arranged outside the axis of the flow channel.

[0015] The invention relates to flap valves of all known configurations.

[0016] In fact, only in the central configuration does the sealing arrangement have a precisely circular shape. In contrast, in all eccentric configurations, the shape of the sealing arrangement deviates more or less from a circular shape, which results in a complex relative movement between the metal sealing lip on the one hand and the mating sealing surface on the other hand.

[0017] In particular, the pivoting torques required for closing and opening the valve disc, and in particular the breakaway torques required for opening the flap valve, are of great importance for the configuration of the metal seal. These closing and breakaway torques are naturally dependent on which sliding or static friction forces must be overcome at what distance from the pivot axis during opening and closing of the valve disc.

[0018] Additional difficult problems frequently arise due to the fact that in those circumferential regions of the metal sealing lips where the opening process begins, violent resonant vibrations are generated by the so-called Bernoulli effect, which relatively quickly lead to damage to the corresponding circumferential regions of these metal sealing lips and of the mating sealing surface. Attempts have been made to counteract these phenomena by matching the mass distribution and the elastic restoring forces in the metal sealing lips to one another in such a way that these vibrations are suppressed as much as possible.

[0019] The above-mentioned problems can hardly be solved in the known metal seals, because for reasons of manufacturing technology, the metal sealing lip usually consists of the same material over the entire circumference and therefore has the same physical properties over the entire circumference. In view of the specific features discussed above, there are therefore practically unsolvable conflicting objectives for the production of metal sealing lips for metal seals of the type mentioned in the introduction, as a result of which such metal sealing systems are usually usable only to a limited extent.

[0020] The object of the present invention is therefore to further develop a metal seal of the type mentioned in the introduction with regard to its physical properties in order to achieve the following effects: the sealing effect is improved, the actuation of the valve disc is facilitated during the opening and closing of the flap valve and damage caused by resonant vibrations is prevented as far as possible.

[0021] In the context of this specification, physical properties are to be understood primarily as mechanical properties, i.e. properties associated with the effect of external forces (strength, stiffness, yield point, damping, etc.). However, depending on the application, other physical material properties are also important, e.g. thermal conductivity, coefficient of thermal expansion, permeability, etc. Summary of the invention

[0022] In order to achieve the set task, the invention starts from a metal seal of the type mentioned in the introduction and proposes that the metal sealing lip is made by additive manufacturing from a metal material having a shape, cross-sectional geometry and / or alloy adapted to different circumferential areas of the metal sealing lip.

[0023] By producing the metal sealing lip using an additive process, it is possible for the first time to give different circumferential areas of the metal sealing lip properties that are optimally adapted to different requirements with regard to sealing effect, static and sliding friction, relative movement between the metal sealing lip and the mating sealing surface, and vibration behavior.

[0024] Preferably, the metal sealing lip has circumferential sections, wherein the flexural strength differs depending on the distance of these circumferential sections relative to the pivot axis of the valve disc. In particular, it has been found that the distance between the pivot axis of the valve disc and the corresponding circumferential area of ​​the metal sealing lip is a very important criterion for the configuration of the adaptation thereof, firstly because this distance has a considerable influence on the relative movement between the metal sealing lip on the one hand and the sealing surface facing the metal sealing lip on the other hand.

[0025] In this regard, it is provided, for example, that the circumferential portion of the metal sealing lip which is arranged at the greatest distance from the pivot axis of the valve disk has a higher flexural strength than the circumferential portion of the metal sealing lip which is arranged at the smallest distance from the pivot axis.

[0026] In order to achieve this specific distribution of the bending strength of the metal sealing lip, the present invention proposes that the cross-sectional area of ​​the circumferential portion at the greatest distance from the pivot axis of the valve disc has a higher cross-sectional moment of inertia than the cross-sectional areas of the circumferential portion at the smallest distance from the pivot axis of the valve disc.

[0027] This adaptation of the section moments of inertia of the cross section of the metal sealing lip in different circumferential sections has an influence not only on the flexural strength in the circumferential section in question, but also additionally on the mass distribution, whereby the vibration behavior can in turn be influenced. According to the teaching of the invention, all these physical properties can be matched to one another so that destructive resonant vibrations caused by the Bernoulli effect are suppressed as much as possible, and in fact, because the circumferential section of the metal sealing lip arranged at the greatest distance from the pivot axis of the valve disc has a higher degree of damping than the circumferential section of the metal sealing lip arranged at the smallest distance from the pivot axis.

[0028] The desired difference in flexural strength can also be produced and influenced by using different production materials in the circumferential area in question of the metal sealing lip, as is directly possible in additive manufacturing. In this regard, the invention proposes that the circumferential portion at the greatest distance from the pivot axis of the valve disc is composed of a metal alloy having a higher stiffness than the stiffness of the metal alloy from which the circumferential portion at the smallest distance from the pivot axis of the valve disc is made. In this regard, suitable stainless steel alloys (alloys based on Fe, Ni and Co) with a sufficiently high yield point and a high work hardening coefficient can be used to produce the metal sealing lip. In the additive manufacturing process, suitable material gradients can also be produced in the volume of the metal sealing lip, and specifically in the cross-sectional direction and the circumferential direction. Finally, in the case of additive manufacturing, it is also possible to carry out inherent heat treatments in specific volume areas during the manufacturing process in order to produce different properties within the volume of the metal sealing lip.

[0029] Finally, and equally importantly, according to the teaching of the invention, the differently formed circumferential sections of the metal sealing lip gradually merge into one another over the circumference of the metal sealing lip, thereby achieving a uniform support of the metal sealing lip on the mating sealing surface despite the different configurations of the plurality of circumferential regions.

[0030] In order to improve the sealing effect, it can also be provided that the surface area of ​​the metal sealing lip in contact with the counter-sealing surface is coated with a soft sealing metal layer. Here, a coating of silver or nickel is considered as an example.

[0031] A particularly preferred embodiment of the invention provides that the second metal sealing lip is associated with the metal sealing lip and has a distance to the first metal sealing lip in the flow direction of the flap valve, so that the two metal sealing lips together enclose an annular hollow space while bearing on a mating sealing surface in the closed position of the flap valve, and so that the cross-sectional area of ​​the two metal sealing lips extends in an inclined and / or curved manner in the direction of the interior of this annular hollow space, wherein the two metal sealing lips are made of metal material by additive manufacturing and have a shape, elasticity and hardness adapted to local requirements, and the two metal sealing lips have different physical properties distributed over the circumference. Due to the use of metal sealing lips of the aforementioned type, i.e. for the use of metal sealing lips produced by additive manufacturing, it is possible for the first time to precisely match the quite specific requirements of the two cooperating metal sealing lips to each other, whereby this metal sealing system, which is advantageous in principle, is multi-purpose in practice for the first time. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Exemplary embodiments of the present invention will be described in more detail below based on the accompanying drawings, in which

[0033] Figure 1Schematically shows a front view of the flap valve as seen in the flow direction;

[0034] Figure 2 Shown along Figure 1 The section of line AA in;

[0035] Figure 3 Shows Figure 2 An enlarged view of details B and C in FIG. 1 , i.e. the metal seal according to the invention in the circumferential region at the greatest distance from the pivot axis;

[0036] Figure 4 Shown along Figure 1 The section of line DD in;

[0037] Figure 5 Shows Figure 4 An enlarged view of details D and E in FIG. 1 , i.e. the metal seal according to the invention in the circumferential region at the smallest distance from the pivot axis;

[0038] Figure 6 , Figure 7 , Figure 8 and Fig. 9 Various possible cross-sections of the metal sealing lip in different circumferential regions of the metal seal are shown;

[0039] Fig.10 A cross section through the metal sealing lip is shown for a metal seal having only one single metal sealing lip. DETAILED DESCRIPTION

[0040] In the figures, the flap valve is generally indicated by reference numeral 1. The flap valve 1, which can be built into a pipeline, has, for example, a valve housing 2, which is provided with a circular flow channel 3, in which a valve disk 4 is arranged in the flow direction, which can be rotated about a pivot axis 5. A pivot drive 6 fastened to the outside of the valve housing 2 serves to move the valve disk 4 about the pivot axis 5. In the figures, the valve disk 4 is in a closed position, in which the valve disk 4 completely closes the flow channel 3 of the valve housing 2.

[0041] Two annular metal sealing lips 7a and 7b are fastened to the inner circumference of the flow channel 3, and the two annular metal sealing lips are arranged at a short distance from each other in the flow direction of the flow channel 3 and leave an annular hollow space 8 therebetween. The cross-sections of the two metal sealing lips 7a and 7b extend in an inclined or curved manner in the direction of the inside of the hollow space 8.

[0042] The valve disc 4 of the flap valve 1 is provided on its outer circumference with an annular mating sealing surface 9, which bears on annular metal sealing lips 7a and 7b in the shown closed position of the valve disc 4. In the shown closed position, the two metal sealing lips 7a and 7b are subject to elastic preload and therefore form a more secure metal seal together with the mating sealing surface 9 of the valve disc 4.

[0043] Compared to the exemplary embodiment shown, it is also possible to provide the metal sealing lip on the outer circumference of the valve disk 4 and the mating sealing surface on the inner circumference of the flow channel 3 of the valve housing 2 instead of the metal sealing lips 7a and 7b. In addition, it is also possible to provide only a single metal sealing lip instead of two metal sealing lips 7a and 7b. However, as explained in the introduction, such a metal seal with only one metal sealing lip then only acts in a self-reinforcing manner in one flow direction.

[0044] According to the teaching of the present invention, the metal sealing lips 7a and 7b are additively manufactured from a metal material having a shape, elasticity and hardness adapted to local requirements and having various bending strengths distributed over their circumference.

[0045] The following will be based on Figure 3 and Figure 5 The comparison illustrates this particular feature. Figure 3 The metal sealing lips 7a and 7b are shown through the circumferential region at the greatest distance from the pivot axis 5 (ie, Figure 2 ). A comparison of details B and C shows that the metal sealing lips 7a and 7b differ significantly from one another in terms of geometry and cross-sectional area in these two circumferential regions. The difference in geometry serves firstly to better adapt to the different relative movements occurring during the opening and closing process between the metal sealing lips 7a and 7b on the one hand and the mating sealing surface 9 on the other hand. The different cross-sectional areas of the metal sealing lips 7a and 7b enable their flexural strength and mass to be matched to the special requirements in these circumferential regions. In this context, correctly matched elasticity and distribution of the mass in these circumferential regions are very important for counteracting the particularly strongly occurring resonant vibrations caused by the Bernoulli effect in these circumferential regions during the opening and closing process.

[0046] In contrast, Figure 4 and Figure 5The sealing conditions are simpler in the circumferential regions at the smallest distance from the pivot axis 5, as shown on the basis of details E and F. In these circumferential regions, the metal sealing lips 7a and 7b can then be constructed to be equal to each other in shape and cross-section, and advantageously thin, since the relative movement relative to the mating sealing surface 9 permits such a construction, and resonance phenomena are less to be feared. A further advantage is that smaller closing and separation torques are required, due to the lower friction between the metal sealing lips 7a and 7b and the mating sealing surface 9.

[0047] Finally, it is further important for the functional performance of the new metal seal that the differently constructed circumferential sections (compare the details B and C described above on the one hand and the details E and F described on the other hand) transition continuously into each other in the circumferential direction, which is not a problem in additive manufacturing. Only by such a gradual transition can it be ensured that the metal sealing lips 7a and 7b bear uniformly and completely around the counter-sealing surface 9.

[0048] at last, Fig.10 The cross-sectional configuration of the metal sealing lip 7 alone for a metal seal is shown, the metal seal being provided with only a single metal sealing lip.

Claims

1. A flap valve (1), comprising a valve housing (2) with a flow channel (3), a valve disc (4) being arranged in a flow cross section of the flow channel (3) so that the valve disc (4) can be pivoted about a pivot axis (5) between an open position and a closed position, wherein: Sealing elements (7, 7a, 7b, 9) that can be pressed against each other are arranged on the outer circumference of the valve disk (4) and on the inner circumference of the flow channel (3), and the sealing elements (7, 7a, 7b, 9) have at least one annular metal sealing lip (7, 7a, 7b), which is made of metal material by additive manufacturing and is supported by elastic preload on an oppositely positioned, likewise annular metal mating sealing surface (9) in the closed position, wherein - the metal sealing lip (7, 7a, 7b) is arranged on the outer circumference of the valve disc (4) and the matching sealing surface (9) is arranged on the inner circumference of the flow channel (3), - Alternatively, the mating sealing surface (9) is arranged on the outer circumference of the valve disc (4) and the metal sealing lip (7, 7a, 7b) is arranged on the inner circumference of the flow channel (3), It is characterized in that The metal sealing lip (7, 7a, 7b) has a circumferential portion having different flexural strengths depending on the shape and / or alloy material of the metal material and depending on the distance of the circumferential portion relative to the pivot axis (5) of the valve disc (4), The circumferential portion of the metal sealing lip (7, 7a, 7b) arranged at the greatest distance from the pivot axis (5) of the valve disc (4) has a higher flexural strength than the circumferential portion of the metal sealing lip (7, 7a, 7b) arranged at the smallest distance from the pivot axis (5).

2. The flap valve according to claim 1, It is characterized in that The cross-sectional area of ​​the metal sealing lip (7, 7a, 7b) in the circumferential portion at the greatest distance from the pivot axis (5) of the valve disc (4) has a higher section moment of inertia than the cross-sectional area of ​​the metal sealing lip (7, 7a, 7b) in the circumferential portion at the smallest distance from the pivot axis (5) of the valve disc (4).

3. The flap valve according to any one of claims 1 to 2, It is characterized in that The circumferential portion of the metal sealing lip (7, 7a, 7b) at the greatest distance from the pivot axis (5) of the valve disc (4) has a higher degree of damping than the circumferential portion at the smallest distance from the pivot axis (5) of the valve disc (4).

4. The flap valve according to any one of claims 1 to 2, It is characterized in that The circumferential portion of the metal sealing lip (7, 7a, 7b) at the greatest distance from the pivot axis (5) of the valve disc (4) is composed of a metal alloy, and the rigidity of the metal alloy is greater than the rigidity of the metal alloy constituting the circumferential portion of the metal sealing lip (7, 7a, 7b) at the smallest distance from the pivot axis (5) of the valve disc (4).

5. The flap valve according to any one of claims 1 to 2, It is characterized in that The differently formed circumferential portions of the metal sealing lips (7, 7a, 7b) gradually transition into each other in the circumferential direction of the metal sealing lips (7, 7a, 7b).

6. The flap valve according to any one of claims 1 to 2, It is characterized in that The surface area of ​​the metal sealing lip (7, 7a, 7b) in contact with the mating sealing surface (9) is coated with a soft sealing metal layer (10).

7. The flap valve according to any one of claims 1 to 2, It is characterized in that The at least one annular metal sealing lip (7, 7a, 7b) comprises a first metal sealing lip (7a) and a second metal sealing lip (7b), wherein the second metal sealing lip (7b) is associated with the first metal sealing lip (7a) and has a distance from the first metal sealing lip (7a) in the flow direction of the flap valve (1), so that the first metal sealing lip (7a) and the second metal sealing lip (7b) together enclose the annular hollow space (8) in the closed position of the flap valve (1) and are supported on the mating sealing surface (9), and the cross-sectional areas of the first metal sealing lip (7a) and the second metal sealing lip (7b) extend in an inclined and / or curved manner in the direction inside the annular hollow space (8).

Images