Flame barrier with expanded metal

Abstract

The invention relates to a flame barrier (10), which is designed to prevent a flashback of flammable gases from one flow side (18) of the flame barrier (10) to an opposite flow side (20) of the flame barrier (10), wherein the flame barrier (10) comprises a first main part (12) and a second main part (14), wherein the first main part (12) and the second main part (14) are arranged substantially coaxially to one another, as seen in relation to a respective central axis (X) formed by the cylindrical shape of the respective main part (12), wherein both the first main part (12) and the second main part (14) are made of an expanded metal, the expanded metal of the first main part (12) having a free open cross section ranging from 10% to 50% and the expanded metal of the second main part (14) having a free open cross section of at least 45%.

Description

[0001] Flame barrier with expanded metal

[0002] Description

[0003] The present invention relates to a flame arrestor which is designed to prevent the flame propagation of flammable gases from one flow side of the flame arrestor to an opposite flow side of the flame arrestor.

[0004] Flame arresters, or so-called flame arresters, are generally known from the prior art. Their purpose is to prevent the propagation of deflagration in virtually pressureless closed systems by extinguishing the flame within the arrester. These known flame arresters are used, for example, in the ventilation and aeration systems of tank systems or in the intake air systems of internal combustion engines. For this purpose, the flame arresters often have two nested cylindrical base bodies. However, it is generally common practice in flame arresters known from the prior art to construct at least one of the two base bodies from a metal mesh.

[0005] However, metal fabrics offer limited possibilities for customization with regard to their flame-retardant properties. Furthermore, metal fabrics are expensive, which also increases the cost of a flame barrier system incorporating a metal fabric.

[0006] It is therefore an object of the present invention to provide a flame arrestor which offers improved adaptability to different flame-retardant properties and at the same time reduces costs compared to flame arrestors from the prior art. This object is achieved according to the present invention by a flame arrestor which is designed to prevent flame propagation of flammable gases from one flow side of the flame arrestor to an opposite flow side of the flame arrestor, wherein the flame arrestor comprises a substantially cylindrical first base body and a substantially cylindrical second base body, wherein the first base body and the second base body are arranged substantially coaxially with respect to a respective central axis formed by the cylindrical shape of the respective base body.wherein both the first base body and the second base body are formed from expanded metal, wherein the expanded metal of the first base body has a free open cross-section in the range of 10% to 50%, in particular in the range of 20% to 40%, and wherein the expanded metal of the second base body has a free open cross-section of at least 45%, in particular of at least 50%, advantageously of at least 80%.

[0007] It should be noted at this point that the flame arrestor according to the present invention can be configured to prevent flame propagation from one side upstream of the flame arrestor to one side downstream of the flame arrestor as well as in the reverse direction.

[0008] A flame arrestor according to the invention can, for example, form part of an exhaust system.

[0009] Thus, the first basic body of the flame barrier according to the invention can take over the actual flame-retardant function, whereas the second basic body of the flame barrier according to the invention primarily provides support and protection for the first basic body.

[0010] Depending on the application and flow direction through the flame arrestor, the first base body can be arranged radially inside the second base body, or vice versa. To prevent pressure-induced deformation of the first base body, it can be arranged upstream of the second base body; that is, in the case of a radial inward to radial outward flow through the flame arrestor's outer wall, the first base body can be arranged radially inside the second base body.

[0011] In general, for a flame arrestor to function properly, it is crucial that a permissible mesh size, i.e., the area of ​​each opening in a surface of the corresponding base body, particularly the first base body, is not exceeded. Otherwise, flame propagation from one flow side of the base body to the other can occur. Conversely, it is advantageous to minimize the reduction of fluid flow through the surface of the base body in order to keep pressure loss to a minimum. Additionally, flame arrestors must possess a minimum thermal mass so that, in the event of a flame flashback, sufficient thermal energy can be absorbed in the base material of each flame arrestor base body.

[0012] The use of expanded metal, as opposed to metal mesh, can now increase the thermal mass of the respective base body, particularly the first base body of the flame barrier. This is primarily due to the fact that a web positioned between two adjacent openings of the base body, unlike a web in metal mesh which has a round cross-section due to the metal wire used, can have a rectangular or even square cross-section. This cross-section of the web allows, for example, a larger surface area to be achieved compared to metal mesh with the same volume and / or thermal mass, thus increasing heat transfer from a gas passing through the base body to the expanded metal base body.

[0013] Furthermore, the use of expanded metal for the first base body of the flame barrier according to the invention makes it possible to adjust the web width between adjacent meshes of the expanded metal independently of the shape and / or area of ​​the respective mesh, without increasing the wall thickness of the base body. With metal meshes, due to the round wire cross-section, an increase in the web width between adjacent meshes always entails an increase in the wall thickness.

[0014] Furthermore, the shape of a mesh in expanded metal can be adapted relatively freely, which is only possible to a very limited extent with a metal mesh. For example, a mesh in the first basic body of expanded metal can have a slender diamond shape.

[0015] In particular, the expanded metal of the first base body can have a mesh size, measured on a long side of the mesh, of at most 0.8 mm, in particular of at most 0.5 mm, advantageously of at most 0.3 mm.

[0016] Furthermore, the expanded metal of the first base body can have a ratio of one long side of a mesh to one short side of that mesh of 1.0 to 2.0, in particular of 1.3 to 1.7. This allows for a significant reduction in the shortest distance from the center of a mesh to the material bordering the mesh, compared to a square mesh of a metal fabric. This, in turn, can increase heat transfer from a gas passing through the mesh to the surrounding material.

[0017] The expanded metal of the first base body can have a wall thickness between two adjacent meshes of at most 0.25 mm, in particular at most 0.2 mm, and advantageously at most 0.15 mm. Depending on the desired thermal mass available as the wall thickness of a web for absorbing heat energy between two adjacent meshes, a greater web wall thickness can be selected to provide a high thermal mass. However, this usually also results in an increase in the overall weight of the flame barrier and, if necessary, a reduction in the total free cross-section for gas passage through the surface of the base body. Alternatively, the web wall thickness can be reduced to obtain a lower thermal mass but increased gas permeability and a reduced weight of the flame barrier or the first base body.

[0018] Advantageously, the expanded metal of the first base body can have a ratio of the area of ​​a web arranged between two adjacent meshes to the area of ​​each mesh of 1.0, in particular 1.2, and advantageously 1.5. Such mesh-to-web ratios have proven to be a particularly advantageous combination of provided thermal mass on the one hand and gas permeability properties or weight on the other.

[0019] The expanded metal of the second base body can have a mesh size, measured along a long side of the mesh, of at least 5.0 mm, and in particular at least 8.0 mm, advantageously at least 10.0 mm. In this way, the second base body can provide good support for the first base body without significantly affecting gas passage through any surface of the flame barrier. In this context, it is also important to note that the mesh size of the second base body, measured along a long side of the mesh, does not exceed a predetermined upper limit in order to continue providing support for the first base body. Such an upper limit can be, for example, approximately 12.0 mm or approximately 15.0 mm, or optionally approximately 20.0 mm. As described above, this upper limit can depend significantly on the properties of the first base body.Thus, it may be advantageous to choose a larger mesh size for the second basic body (possibly even larger than 20.0 mm) if the first basic body has a higher wall thickness (and therefore higher intrinsic stability), and to choose a smaller mesh size for the second basic body if the first basic body has a lower wall thickness (and therefore lower intrinsic stability).

[0020] In particular, the expanded metal of the second base body can have a ratio of one long side of a mesh to one short side of that mesh of 1.0 to 2.0, especially of 1.3 to 1.7. The diamond-shaped meshes with the aforementioned ratio offer good protection for the first base body against mechanical damage and / or pressure-induced deformation.

[0021] For example, the expanded metal of the second base body can have a wall thickness between two adjacent meshes of 0.2 mm to 2.0 mm, in particular of 0.3 mm to 1.5 mm, advantageously of 0.3 mm to 1.0 mm. Although it was described above that the first base body provides the actual flame-retardant function, heat transfer can of course also occur into the material of the second base body, either directly from the flowing gas or from the first base body. In particular, the expanded metal of the second base body can have a ratio of the area of ​​a web arranged between two adjacent meshes to the area of ​​each mesh of at most 0.4, in particular of at most 0.3, advantageously of at most 0.2.As mentioned above, this allows both the mechanical stability and the thermal mass of the second base body to be set.

[0022] Advantageously, the first and second base bodies can be in contact with each other, and in particular, connected to each other. This prevents deformation of the first base body directly through contact with the second base body, which is more stable than the first, and also allows heat transfer from the first to the second base body.

[0023] The connection between the first and second base bodies can be formed by welding and / or soldering and / or by bonding and / or by pressing the two base bodies together, particularly at at least one end face, and in particular both end faces, of the two base bodies by means of a crimp ring and / or by means of an elastic sealing unit, and / or by pressing the two base bodies together. For example, the connection between the first and second base bodies can be linear and substantially parallel to a central axis of the flame barrier. Such a linear connection can be provided several times on the flame barrier according to the invention, and these linear connections can be arranged, in particular, in a uniformly distributed manner relative to one another when viewed in the circumferential direction of the flame barrier.The flame barrier according to the invention can in particular be designed such that a space velocity of the flame barrier of up to 200,000,000 h. -1 The spatial velocity relates a volume flow rate to a spatial volume by forming a quotient. The spatial velocity of the flame barrier can, in particular, refer to the area of ​​the flame barrier that is formed by subtracting the outer diameter of the first base body from the inner diameter of the first base body.

[0024] Typically, a flame arrestor is arranged in a gas-carrying unit such that gas enters the interior of the flame arrestor through an opening at the front and then exits through a surface of the flame arrestor, or that gas enters the interior of the flame arrestor from the outside via the surface of the flame arrestor and then exits through at least one of the two openings at the front.

[0025] In order to optimize gas passage through the flame barrier, the ratio of an end-face opening of the flame barrier, through which gas enters the flame barrier, to a flowable area of ​​a shell surface of the flame barrier can be from 1 to 15, in particular from 2 to 10, advantageously from 3 to 7.

[0026] The term "flowable area of ​​a flame barrier's surface" can be understood in particular as the sum of all free openings of the flame barrier's surface through which gas can pass.

[0027] In a further development of the present invention, the first base body and / or the second base body can have a folded section at at least one longitudinal end, wherein the folded section is provided at least partially at the longitudinal end, in particular, viewed in the circumferential direction of the base body, over the entire longitudinal end, which is bent at an angle of 85° to 270° relative to the lateral surface of the base body. Depending on the arrangement of the first base body and the second base body in the flame barrier, as described above, in the case in which the first base body is arranged radially inside the second base body, the first base body can be bent back radially outwards and in a manner that at least partially encompasses the associated longitudinal end of the second base body, thus forming the aforementioned angle of 85° to 270°.Alternatively or additionally, the longitudinal end of the second base body can be bent radially inwards so that it at least partially encompasses the corresponding longitudinal end of the first base body, allowing an angle of 85° to 270° to be formed between the folded section and the adjacent surface of the base body. This can be implemented analogously if the first base body is arranged radially outside the second base body. The choice of whether the first base body is arranged radially inside or outside the second base body is usually made based on the direction of flow through the surface of the flame barrier, in order to reduce or even prevent pressure-induced deformation of the first base body due to the supporting effect of the second base body.

[0028] The folded section can be formed by a section of the expanded metal of the base body or by a separately manufactured crimp ring, which can, in particular, have a substantially P-shaped cross-section. That is, either a longitudinal end of at least one of the two base bodies can form the folded section, or the longitudinal ends of the two base bodies can be connected by the crimp ring. Naturally, a combination of both is also conceivable. For example, the crimp ring can have a substantially U-shaped cross-section in its unassembled state. If the crimp ring is then placed on an end face of the flame barrier and crimped, it can acquire a substantially P-shaped cross-section, with the straight side of the P-shaped cross-section optionally positioned radially outside or radially inside the flame barrier.

[0029] Furthermore, the flame arrestor can comprise at least one sealing unit arranged at each longitudinal end of the flame arrestor. Such a sealing unit can, in particular, prevent gas from flowing past the flame arrestor without first passing through its outer surface. If, for example, the predefined flow path is that gas enters the interior of the flame arrestor through an opening at the end face and from there passes radially outward through the outer surface, the sealing unit can prevent gas striking the end face of the flame arrestor from flowing directly along a radially outer side of the flame arrestor. It is also conceivable that a sealing unit arranged on the flame arrestor is designed to be closed, such that an inner diameter of the flame arrestor is sealed at one longitudinal end.Thus, the gas flowing into the flame arrestor through the open longitudinal end is forced to flow out through the outer surface of the flame arrestor. Similarly, the gas flowing into the outer surface of the flame arrestor is forced to flow out through the open longitudinal end of the flame arrestor.

[0030] At least one hook section can be arranged at at least one longitudinal end of the first base body and / or the second base body. This hook section projects radially inwards and / or radially outwards and rises from the surface of the flame barrier, from a respective longitudinal end towards a longitudinal center of the flame barrier. This hook section can be formed, for example, by cutting out a tab in the longitudinal end of one of the two base bodies, which is then folded back to form a flap section. That is, the folded-back portion of the flap section simultaneously forms a hook section.Alternatively or additionally, the at least one hook section can be punched out of the outer surface of at least one of the two base bodies in such a way that a tab is formed which is located adjacent to the longitudinal end, but is not part of the longitudinal end, and which can then be projected radially outwards or radially inwards. Alternatively or additionally, the at least one hook section can also be provided by the crimp ring. The feature that the at least one hook section, viewed from a respective longitudinal end of the flame barrier towards a longitudinal center of the flame barrier, projects in a gradually increasing direction radially outwards or radially inwards, can enable a respective sealing unit to be slid onto the end face of the longitudinal end of the flame barrier and also onto the at least one hook section, and be prevented from detaching from the longitudinal end by the hook section acting as a barb.

[0031] The present invention will be described in greater detail below with reference to the accompanying drawings. It represents:

[0032] Figure 1 shows a perspective view of a flame barrier according to the invention;

[0033] Figure 2 shows a detailed sectional view of a longitudinal end of the flame barrier from Figure 1; and

[0034] Figure 3 shows a detailed view of the outside of the flame barrier from Figure 1.

[0035] Figure 1 shows a perspective view of a flame barrier according to the present invention, which is generally designated by reference numeral 10. The flame barrier 10 comprises a first cylindrical base body 12, which is made of expanded metal. The first base body 12 is surrounded on its radially outer side by a second base body 14, which also has a cylindrical shape. The two cylindrical base bodies 12 and 14 form a central axis X, with respect to which the two cylindrical base bodies 12 and 14 are arranged coaxially.

[0036] The flame barrier 10 has a sealing unit 16 at each of its two end faces, the two sealing units 16 shown in Figure 1 being identical. The sealing unit 16 surrounds the longitudinal ends of the two base bodies 12 and 14.

[0037] Furthermore, arrows A in Figure 1 illustrate the flow path of a gas through the flame barrier 10. In the embodiment shown here, gas can enter the interior of the flame barrier 10 according to arrow A shown on the left end face and then exit the flame barrier 10 through the walls of the first base body 12 and the second base body 14. Consequently, the interior of the flame barrier 10 can be considered a flow side 18 with respect to the gas flow, and the area radially outside the flame barrier 10 can be considered an opposite flow side 20. The expanded metal of the second base body 14 can thus support the expanded metal of the first base body 12 and prevent deformation.

[0038] Figure 2 shows a detailed enlarged side cross-sectional view of a longitudinal end of the flame barrier 10. As described above, the sealing unit 16 encompasses the longitudinal ends of the two base bodies 12 and 14; that is, the sealing unit 16 is located on a radially outer side, an axial end face, and a radially inner side of the two base bodies 12 and 14.

[0039] In particular, to protect the sealing unit 16 from damage caused by a sharp-edged longitudinal end of the first base body 12 and / or the second base body 14, a crimp ring 22 is shown in the embodiment depicted here. This crimp ring 22 grips both longitudinal ends of the base bodies 12 and 14 before the sealing unit 16 is attached, thus providing the sealing unit 16 with a smoother contact surface. The crimp ring 22 can also serve a retaining function to secure the first base body 12 and the second base body 14 to one another. The crimp ring 22 can, in particular, be made of a metal.

[0040] To prevent the sealing unit 16 from unintentionally detaching, various measures can be taken to secure it to the first base body 12 and / or to the second base body 14 and / or to the crimp ring 22.

[0041] For example, a recess 24 of the sealing unit 16 can be designed to be narrower than the wall thickness of the respective longitudinal end (here consisting of the wall thickness of the first base body 12, the wall thickness of the second base body 14 and the radially inner and radially outer wall thickness of the crimp ring 22), so that, due to elastic recovery properties of the material from which the sealing unit 16 is formed, a section of the sealing unit 16 is able to engage behind a radially inner edge 26 of a folded section 28 of the crimp ring 22, which is folded over from radial outside to radial inside.

[0042] Alternatively or additionally, at least one of the two base bodies 12 and 14 and / or the crimp ring 22 can have a hook section 30 which is configured to engage with a section of the sealing unit 16 in order to secure the sealing unit 16 against unintentional release by means of a barb. In Figure 2, the hook section 30 is shown as a tab arranged on the folded section 28 of the crimp ring 22, which extends obliquely radially inwards from the folded section 28 in order to form the barb at its free end.

[0043] Figure 3 shows that the mesh size 32 of the expanded metal of the first base body 12 is significantly smaller than the mesh size 34 of the expanded metal of the second base body 14. Accordingly, it can be stated that the expanded metal of the first base body 12 performs at least a large part of the flame-retardant function of the flame barrier 10, and that the second base body 14 primarily provides support to prevent the expanded metal of the first base body 12 from deforming, for example, due to pressure acting on the first base body 12.

[0044] Using a mesh 34 of the expanded metal of the second base body 14 as an example, it is explained here that the meshes usually have a diamond shape, which has a long side 36 and a short side 38.

[0045] The meshes 34 of the second base body 14 are each separated from one another by webs 40, which are formed by the expanded metal. In an analogous manner, the meshes 32 of the first base body 12 are separated by webs 42.

[0046] It is thus evident that by selecting the size, shape, and location of the cuts (e.g., punching) of the expanded metal during the production process, and by determining the extent (and, if applicable, direction) of the stretching, the shape and size of the meshes of the respective expanded metal can be adjusted. This fundamental principle of the present invention now makes it possible to produce flame barriers 10 with a wide variety of gas permeability properties or with a wide variety of thermal masses, which are provided by the webs arranged between the meshes, without having to change the wall thickness of the flame barrier 10 (although this is, of course, possible).

[0047] For example, by selecting meshes 32 of the first base body 12 (shown in Figure 3 at mesh 34 for clarity) with a strong rhombic shape, i.e., a ratio of long side 36 of mesh 32 to short side 38 of mesh 32 greater than 1.0, in particular greater than 1.5 or greater than 1.5, the shortest distance from a web to the center of a surface of mesh 34, which here lies at the intersection between long side 36 and short side 38 of mesh 32, can be shortened. This better ensures that thermal energy from the gas flowing through mesh 32 can be transferred to the material of the first base body 12.

Claims

Claims 1. Flame arrestor (10) which is configured to prevent flame propagation of flammable gases from one flow side (18) of the flame arrestor (10) to an opposite flow side (20) of the flame arrestor (10), wherein the flame arrestor (10) comprises a substantially cylindrical first base body (12) and a substantially cylindrical second base body (14), wherein the first base body (12) and the second base body (14) are arranged substantially coaxially with respect to a respective central axis (X) formed by the cylindrical shape of the respective base body (12, 14), wherein both the first base body (12) and the second base body (14) are formed from expanded metal, wherein the expanded metal of the first base body (12) has a free open cross-section in the range of 10% to 50%, in particular in the range of 20% to 40%,wherein the expanded metal of the second base body (14) has a free open cross-section of at least 45%, in particular of at least 50%, advantageously of at least 80%.

2. Flame barrier (10) according to claim 1 , characterized in that the expanded metal of the first base body (12) has a mesh size, measured on a long side (36) of the mesh (32), of at most 0.8 mm, in particular of at most 0.5 mm, advantageously of at most 0.3 mm.

3. Flame barrier (10) according to one of the preceding claims, characterized in that the expanded metal of the first base body (12) has a ratio of one long side (36) of a each stitch (32) to a short side (38) of this stitch (32) has a length of 1.0 to 2.0, in particular from 1.3 to 1.

7.

4. Flame barrier (10) according to one of the preceding claims, characterized in that the expanded metal of the first base body (12) has a wall thickness between two adjacent meshes (32) of at most 0.25 mm, in particular of at most 0.2 mm, advantageously of at most 0.15 mm.

5. Flame barrier (10) according to one of the preceding claims, characterized in that the expanded metal of the first base body (12) has a ratio of an area of ​​a web (42) which is arranged between two adjacent meshes (32) to an area of ​​a respective mesh (32) of 1.0, in particular of 1.2, advantageously of 1.

5.

6. Flame barrier (10) according to one of the preceding claims, characterized in that the expanded metal of the second base body (14) has a mesh size, measured on a long side (36) of the mesh (34), of at least 5.0 mm, and in particular of at least 8.0 mm, advantageously of at least 10.0 mm.

7. Flame barrier (10) according to one of the preceding claims, characterized in that the expanded metal of the second base body (14) has a ratio of a long side (36) of a respective mesh (34) to a short side (38) of this mesh (34) of 1.0 to 2.0, in particular of 1.3 to 1.

7.

8. Flame barrier (10) according to one of the preceding claims, characterized in that the expanded metal of the second base body (14) has a wall thickness between two mutually - 18 - adjacent meshes (34) from 0.2 mm to 2.0 mm, in particular from 0.3 mm to 1.5 mm, advantageously from 0.3 mm to 1.0 mm.

9. Flame barrier (10) according to one of the preceding claims, characterized in that the expanded metal of the second base body (14) has a ratio of an area of ​​a web (40) which is arranged between two adjacent meshes (34) to an area of ​​a respective mesh (34) of at most 0.4, in particular of at most 0.3, advantageously of at most 0.

2.

10. Flame barrier (10) according to one of the preceding claims, characterized in that the first base body (12) and the second base body (14) are in contact with each other, in particular connected with each other.

11. Flame barrier (10) according to the preceding claim, characterized in that the connection of the first base body (12) and the second base body (14) to each other is made using a welding process and / or a soldering process and / or by bonding and / or by pressing the two base bodies (12, 14) to each other, in particular at least one end face, in particular both end faces, of the two base bodies (12, 14) by means of a crimp ring (22) and / or by means of an elastic sealing unit (16), and / or by pressing the two base bodies (12, 14) to each other.

12. Flame arrestor (10) according to one of the preceding claims, characterized in that a space velocity of the flame arrestor (10) is up to 200,000,000 IT 1 amounts.

13. Flame arrestor (10) according to one of the preceding claims, - 19 - characterized in that the ratio of an end-face opening of the flame barrier (10), through which gas enters the flame barrier (10), to a flowable area of ​​a shell surface of the flame barrier (10) is from 1 to 15, in particular from 2 to 10, advantageously from 3 to 7.

14. Flame barrier (10) according to one of the preceding claims, characterized in that the first base body (12) and / or the second base body (14) has / has a folded section (28) at at least one longitudinal end thereof, wherein the folded section (28) is provided at least sectionally at the longitudinal end, in particular, viewed in the circumferential direction of the base body (12, 14), over the entire longitudinal end, which is bent by an angle of 85° to 270° relative to the lateral surface of the base body (12, 14).

15. Flame barrier (10) according to the preceding claim, characterized in that the folding section (28) is formed by a section of the expanded metal of the base body (12, 14) or by a separately manufactured crimp ring (22), wherein the crimp ring (22) in particular has a substantially P-shaped cross-section.

16. Flame barrier (10) according to one of the preceding claims, characterized in that the flame barrier (10) further comprises at least one sealing unit (16) which is arranged at a respective longitudinal end of the flame barrier (10).

17. Flame arrestor (10) according to one of the preceding claims, characterized in that at least one hook section (30) is arranged at at least one longitudinal end of the first base body (12) and / or the second base body (14), which extends radially - 20 - protrudes inwards and / or radially outwards and rises from the outer surface of the flame barrier (10) from a respective longitudinal end of the flame barrier (10) to a longitudinal center of the flame barrier (10).

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