ELECTRICALLY DECOUPLED HIGH-TEMPERATURE THERMAL INSULATION

Abstract

An insulation element for the thermal insulation of an inductively heatable high-temperature treatment zone. A wall of the insulation element contains a flat material, the resistivity of which is ρF 10-5 to 10-1 Ωm and which encloses a hollow space extending through the insulation element and includes a discontinuity, in which the resistivity ρU is greater than ρF. The discontinuity extends from the external surface of the flat material into the flat material but does not interrupt the flat material over the entire cross section of the flat material.

Claims

1-15. (canceled)

16. An element for thermally insulating an inductively heatable high-temperature treatment zone, wherein a wall of the insulation element contains a flat material, the specific electrical resistance ρF of which is 10-5 to 10-1 Ωm, surrounds a cavity extending through the insulation element and includes a break in which the specific electrical resistance ρU is greater than ρF, wherein the break extends from the outer surface of the flat material and into the flat material but does not create a break in the flat material across the entire flat material cross section.

17. The insulation element according to claim 16, wherein the break is a cut made in the flat material.

18. The insulation element according to claim 16, wherein at least part of the break does not extend orthogonally to the two surfaces of the flat material.

19. The insulation element according to claim 16, wherein the flat material has a degree of thermal conductivity of less than 10 Wm-1K-1.

20. The insulation element according to claim 19, wherein the flat material comprises carbon fibres and/or expanded graphite.

21. The insulation element according to claim 16, wherein the number of breaks equals at least 2, at least 3, at least 4 or at least 6.

22. The insulation element according to claim 16, the shape of which can be approximated by a hollow cylinder, wherein the length, shape and orientations of the break(s) at the outer surface of the flat material is (are) selected such that the following applies:
LU>a.Math.Lt whereby Lt is the length of the shortest path around the flat material that extends along the outer surface of the flat material, across the break(s) and into a central sectional plane that divides the flat material into two halves of equal flat material volume orthogonally to the longitudinal axis of the hollow cylinder, Lu is the length of the shortest path around the flat material (3) that extends from break to break in the central sectional plane in each case but does not pass across the breaks(s), instead passing around the break(s), and a is 2, preferably 5.

23. The insulation element according to claim 16, wherein ρU is at least 100.Math.ρ.sub.F.

24. The insulation element according to claim 16, wherein the break is at a spacing from the two edges of the flat material.

25. The insulation element according to claim 21, wherein at least two breaks are inclined in the same direction with respect to the outer surface of the flat material.

26. The insulation element according to claim 16, wherein the flat material is a circumferentially continuous flat material containing carbon fibres.

27. The insulation element according to claim 16, wherein the flat material is formed from a set of flat material elements and at least one joint region that breaks the flat material across the entire flat material cross section is additionally provided between the flat material elements.

28. A set of insulation element portions for forming an insulation element comprising the insulation element portions, wherein at least one of the insulation element portions comprises a flat material, the specific electrical resistance ρF of which is 10-5 to 10-1 Ωm, and comprises a break in which the specific electrical resistance ρU is greater than ρF, wherein the break extends from the outer surface of the flat material and into the flat material but does not create a break in the flat material across the entire flat material cross section.

29. A method for producing a flat material that can be used to insulate an inductively heated high-temperature treatment zone, wherein a flat material having a specific electrical resistance ρF in the region of 10-5 to 10-1 Ωm is cut from a main surface of the flat material into the flat material without cutting through the entire flat material.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0053] The invention will be illustrated by the following drawings without being limited thereto.

[0054] FIG. 1 is a perspective view of a first insulation element according to the invention, in which the coil and susceptor are indicated

[0055] FIG. 1A shows the first insulation element according to the invention

[0056] FIG. 1B is a section through the first insulation element according to the invention FIG. 10 shows the lengths of paths around the flat material of the first insulation element according to the invention

[0057] FIG. 1D shows the lengths of paths around the flat material of the first insulation element according to the invention

[0058] FIG. 2A shows the second insulation element according to the invention

[0059] FIG. 2B is a section through the second insulation element according to the invention

[0060] FIG. 3A shows the third insulation element according to the invention

[0061] FIG. 3B is a section through the third insulation element according to the invention

[0062] FIG. 4A is a section through a fourth insulation element according to the invention, and

[0063] FIG. 4B is a cut-out from FIG. 4A.

DETAILED DESCRIPTION

[0064] The four different embodiments of the invention shown in the drawings are all insulation elements 1 for thermally insulating an inductively heatable hight-temperature treatment zone 2. A perspective view indicating the coil and the outer surface 6 and susceptor and the inner surface is only shown for the first embodiment (FIG. 1). The other three embodiments can be used in exactly the same way that is indicated here for the first embodiment.

[0065] As is clearly visible in particular in FIGS. 1B, 2B, 3B and 4A, a wall of the insulation element 2 comprises a flat material 3 in all four embodiments. The wall is made from the flat material (soft carbon fibre felt having a degree of thermal conductivity of considerably less than 10 Wm.sup.−1K.sup.−1) in each case. The specific electrical resistance ρ.sub.F thereof is 10.sup.−5 to 10.sup.−1 Ωm. The soft carbon fibre felt surrounds the cavity 4 extending through the insulation element 1. These drawings also clearly show that the number of breaks 5 in each of the embodiments shown here equals 12. In none of the embodiments do the breaks extend orthogonally to the two surfaces 6 and 7 of the flat material 3 and are all inclined in the same direction. Each of the breaks are cuts. They are therefore electrically insulating.

[0066] In FIGS. 1A, 2A and 3A, regions of the breaks 5 covered by the flat material 3 are each shown by dashed lines. Likewise shown by dashed lines are the covered inner surfaces of the flat material. The specific electrical resistance ρ.sub.U of the breaks 5 is several times greater than the specific electrical resistance ρ.sub.F of the soft carbon fibre felt on account of the air located therein and the carbon fibres that are cut through. The breaks 5 extend from the outer surface 6 of the flat material 3 into the flat material 3 in all four embodiments.

[0067] It is clear from FIG. 1A that the breaks 5 do not create a break in the flat material 3 across the entire flat material cross section in the first embodiment. The cuts are not made as far as the two edges 9 and 10 indicated in FIG. 1. The breaks 5 are therefore at a spacing from the two edges 9 and 10 of the flat material 3 here. It is clear from FIG. 1B that the cuts are also not made as far as the inner surface 7 in the first embodiment either. The breaks 5 are therefore at a spacing from the inner surface 7 here, too.

[0068] FIG. 2A shows that the cuts intersect the two edges in the second embodiment. However, according to the invention, they still do not create a break in the flat material 3 across the entire flat material cross section. It is clear in FIG. 2B that the cuts are not made as far as the inner surface 7, alike in the first embodiment. The breaks 5 are at a spacing from the inner surface 7 here, too.

[0069] In the third embodiment, the cuts are not made as far as the two edges (FIG. 3A). Therefore, they do not create a break in the flat material 3 across the entire flat material cross section. In contrast to the first and second embodiment, the cuts cut the inner surface 7 in the third embodiment (FIG. 3B).

[0070] In the first, second and third embodiment, the flat material 3 is therefore a circumferentially continuous flat material 3 containing carbon fibres.

[0071] For the first embodiment, FIGS. 10 and 1D show that the length, shape and orientations of the breaks 5 at the outer surface of the flat material 3 are selected such that L.sub.U>a.Math.L.sub.t applies when a equals 2. FIG. 10 shows L.sub.U. L.sub.U is the length of the shortest path around the flat material 3 that extends from break 5 to break 5 in the central sectional plane in each case and does not pass across the breaks 5, instead passing around the breaks 5. The central sectional plate divides the flat material 3 into two halves of equal flat material volume orthogonally to the longitudinal axis of the hollow cylinder. L.sub.t is the length of the shortest path around the flat material 3 that extends along the outer surface of the flat material 3 across the breaks 5 in the central sectional plane that divides the flat material 3 into two halves of equal flat material volume orthogonally to the longitudinal axis of the hollow cylinder. It is evident that L.sub.U is approximately 3-times the size of L.sub.t in the embodiment shown here.

[0072] In the fourth embodiment (FIGS. 4A and 4B), the flat material 3 is formed from a set of two flat material elements 11. In the embodiment shown here, two joint regions 12 are also provided between the flat material elements 11. Each joint region creates a break in the flat material 3 across the entire flat material cross section. The joint regions are therefore formed from edge to edge across the entire length of the insulation element and cut through it across the entire length from the outer surface 6 up to the inner surface 7. In contrast to the first, second and third embodiment, the flat material 3 in the fourth embodiment is therefore not a circumferentially continuous flat material 3 containing carbon fibres.

LIST OF REFERENCE NUMERALS

[0073] 1 insulation element [0074] 2 high-temperature treatment zone [0075] 3 flat material [0076] 4 cavity [0077] 5 break [0078] 6 outer surface [0079] 7 inner surface [0080] 8 flat material cross section [0081] 9, 10 edges [0082] 11 flat material element [0083] 12 joint region