PROTECTIVE TUBE HAVING VIBRATION REDUCTION

Abstract

A protective tube, in particular for sealed introduction into a process space having a flow directed in a direction, having a hollow body, which is closed at its lower end, an opening at its upper end for introducing a temperature sensor; and at its upper end has a contour for sealing to a process space. The hollow body is cylindrical inwardly, an outer contour of the hollow body tapers toward the closed lower end, and at least in sections, at least one helix structure is arranged on the outer contour and/or at least in sections, at least one helix structure is arranged in the outer contour. A gas sample collector for introduction into a process space is also provided.

Claims

1. A protective tube for sealed introduction into a process space having a flow directed in a direction, the protective tube comprising: a hollow body; a closed lower end; an upper end with an opening configured to introduce a temperature sensor; and a contour formed at the upper end, the contour configured for sealing to a process space, wherein the hollow body has an outer contour and an inner surface, wherein the inner surface comprises a cylindrical shape, wherein at least one section of the outer contour tapers toward the closed lower end, and wherein at least one helix structure is provided, the helix structure being arranged on the outer contour at least in sections or arranged in the outer contour at least in sections.

2. The protective tube according to claim 1, wherein the outer contour of the hollow body is conically shaped at least in sections or provided with a diameter decreasing at least in sections toward the closed lower end in a nonlinear manner.

3. The protective tube according to claim 1, wherein the outer contour has an upper section devoid of a helix structure, wherein the upper section is conical or provided with a diameter decreasing toward the closed lower end in a nonlinear manner, wherein the outer contour has a lower section, wherein the lower section is cylindrical and comprises at least one helix structure, and wherein the helix structure is arranged on the outer contour or arranged in the outer contour.

4. The protective tube according to claim 3, wherein a length ratio of the upper section to the lower section of the outer contour is 1:2.0 to 1:3.5 or 1:2.5 to 1:3.0.

5. The protective tube according to claim 3, wherein the upper section and the lower cylindrical section of the outer contour merge, and wherein the merging is continuous and/or without forming an edge.

6. The protective tube according to claim 3, wherein the upper section of the outer contour has a length of 70 mm to 200 mm, a length of 95 mm to 120 mm, or a length of 100 mm.

7. The protective tube according to claim 3, wherein the upper section of the outer contour exhibits a cone angle of 1° to 7°, a cone angle of 2° to 6°, or a cone angle of 3° to 5° degrees relative to a central axis.

8. The protective tube according to claim 1, wherein the hollow body comprises a root formed at its upper end and a tip formed at its lower end, wherein the hollow body exhibits a diameter of 20 mm to 30 mm at its root or a diameter of 16 mm to 25 mm, or 19 mm at its tip.

9. The protective tube according to claim 3, wherein the upper section of the hollow body is devoid of the at least one helix structure and exhibits a length of 100 mm to 125 mm.

10. The protective tube according to claim 3, wherein a further section is arranged between the upper section of the hollow body and the lower section of the hollow body having the at least one helix structure, and wherein the further section is configured as a conical transitional section or transitional section with a diameter decreasing nonlinear.

11. The protective tube according to claim 1, wherein the at least one helix structure is interrupted at several places.

12. The protective tube according to claim 1, wherein the at least one helix structure is configured as a triple helix or a quadruple helix.

13. The protective tube according to claim 1, further comprising sections of multiple helices arranged vertically offset on the outer contour of the hollow body.

14. The protective tube according to claim 13, wherein the vertical offset of the helices equals a value of a pitch divided by a number of the helices.

15. The protective tube according to claim 1, wherein the at least one helix structure exhibits a cross section, wherein the cross section is: a round cross section, a box shaped cross section, wherein edges of the at least one helix structure not connected with the hollow body are deflashed or broken and have a radial transition formed between edges of the at least one helix structure adjoining the hollow body and the hollow body, a trapezoid cross section, or a triangular cross section.

16. The protective tube according to claim 1, further comprising at least one of: a flange that is one of connected to the hollow body's upper end, and part of the hollow body and affiliating to the upper end, wherein the hollow body is reinforced by a radius or a contour toward the flange; a radial reinforcement of the outer contour in an upper third of the hollow body; or a logarithmical tapering of the outer contour in a lower third of the hollow body.

17. The protective tube according to claim 1, wherein a material thickness of the at least one helix structure equals a 0.1-fold to 0.15-fold of a diameter of the hollow body present at a respective position of the helix structure or a diameter present at a different position of the hollow body.

18. The protective tube according to claim 1, configured with at least one of: a pitch of the at least one helix structure increasing toward an upper end of the hollow body; a material thickness of the at least one helix structure decreasing toward the upper end of the hollow body; or a height of the at least one helix structure increasing by half of a tapering of the hollow body toward the lower end of the hollow body.

19. The protective tube according to claim 1, wherein a tip of the hollow body is formed at the lower end of the hollow body, the tip comprising a flattened plane face.

20. The protective tube according to claim 1, wherein two helices run around the hollow body, wherein one of the helices has a positive pitch, wherein one of the helices has a negative pitch, and wherein a modulus of the pitch of both helices is substantially equal.

21. The protective tube according to claim 1, wherein the hollow body and the at least one helix structure are at least one of: encased by a plastic resistant to chemicals; lined with or made of a metallic alloy or a corrosion resistant nickel base alloy and Monel or a hard alloy on a cobalt chromium basis; or formed from a metal alloy with 13 weight-% to 20 weight-% chromium and 9 weight-% to 15 weight-% nickel and 1 weight-% to 4 weight-% molybdenum.

22. A gas sample collector for introduction into a process space having a flow directed in a direction, the gas sample collector comprising: a hollow body having an open lower end; an upper end having an opening for taking gas samples, wherein the hollow body has an outer contour and an inner surface, wherein the inner surface comprises a cylindrical shape, wherein the outer contour of the hollow body tapers toward the open lower end; and at least one helix structure, wherein the helix structure is arranged on the outer contour at least in sections or arranged in the outer contour at least in sections.

23. The gas sample collector according to claim 22, wherein the outer contour of the hollow body is conically shaped at least in sections or provided with a diameter decreasing at least in sections toward the open lower end in a nonlinear manner.

24. The gas sample collector according to claim 23 wherein the outer contour of the hollow body is concavely curved in an upper third of the hollow body.

25. The gas sample collector according to claim 22, wherein the outer contour of the hollow body has an upper section devoid of a helix structure and is conical or has a diameter decreasing toward the open lower end in a nonlinear manner, and wherein the outer contour of the hollow body has a lower section being cylindrical and comprises at least one helix structure, wherein the helix structure is arranged on the outer contour or arranged in the outer contour.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0058] FIG. 1 schematically shows an elongate body according to the state of the art,

[0059] FIG. 2 schematically shows a protective tube according to the state of the art,

[0060] FIG. 3A schematically shows a sectional view of a protective tube,

[0061] FIG. 3B schematically shows an enlarged detail of the sectional view according to FIG. 3A,

[0062] FIG. 4A schematically shows a partially transparent view of a protective tube,

[0063] FIG. 4B schematically shows a partially transparent view of a gas sample collector,

[0064] FIG. 4C schematically shows a partially transparent view of a protective tube,

[0065] FIG. 4D schematically shows a detail of a cross section of a protective tube,

[0066] FIGS. 4E to 4G schematically show cross sections of protective tubes,

[0067] FIGS. 5A to 5F schematically show details of longitudinal sections of a protective tube,

[0068] FIGS. 6A to 6E schematically show details of longitudinal sections of a protective tube,

[0069] FIGS. 6F to 6H schematically show enlarged details of longitudinal sections of a protective tube in the area of a helix structure,

[0070] FIG. 7 schematically shows a sectional view of a system having a process space and a protective tube protruding into the process space,

[0071] FIG. 8 schematically shows a perspective view of a gas sample collector,

[0072] FIGS. 9A to 9C schematically shows a protective tube,

[0073] FIG. 9D schematically shows a partially transparent view of a protective tube,

[0074] FIG. 9E schematically shows a partial section of a protective tube,

[0075] FIG. 9F schematically shows a cross section of the protective tube according to FIG. 9E,

[0076] FIG. 10A schematically shows a perspektive view of a detail of a gas sample collector,

[0077] FIG. 10B schematically shows a protective tube,

[0078] FIG. 10C schematically shows a detail of a protective tube,

[0079] FIG. 11A schematically shows a perspective view of a detail of a protective tube,

[0080] FIG. 11B to 11D schematically show cross sections of protective tubes, and

[0081] FIGS. 12A to 12D schematically show a cross section of a protective tube.

DETAILED DESCRIPTION

[0082] FIG. 1 shows an elongate body 1 according to the state of the art as in “R. D. Blevins: Flow-Induced Vibration; Krieger, Fla., 2001 (Fig. (a) Page 18)”. The body 1 comprises a cylindrical solid body 1.1 and three helix structures 1.2 to 1.4 surrounding the solid body 1.1 and arranged thereon, for example applied thereon.

[0083] FIG. 2 shows a protective tube 2 for a temperature sensor according to the state of the art as in U.S. Pat. No. 4,991,976 A.

[0084] The protective tube 2 is configured for sealed introduction into a process space P having a flow F shown in more detail in FIG. 7 and comprises a hollow body 2.1 which is closed at its lower end 2.2 and at its upper end 2.3 comprises an opening not shown in detail for introducing a temperature sensor. Furthermore, a contour 2.4, in the illustrated embodiment a flange, for sealing to the process space P is arranged at the upper end 2.3. In addition, the protective tube 2 comprises a helix structure 2.5 arranged on, e.g. applied on, an outer contour of the hollow body 2.1.

[0085] FIG. 3A shows a sectional view of an example embodiment of a protective tube 3 according to the invention. FIG. 3B shows an enlarged detail of the sectional view according to FIG. 3A.

[0086] The protective tube 3 is configured for sealed introduction into a process space P having a flow F shown in more detail in FIG. 7 and comprises a hollow body 3.1 which is closed at its lower end 3.2 and at its upper end 3.3 comprises an opening O for introducing a temperature sensor not shown.

[0087] Furthermore, a contour 3.4, in the illustrated embodiment a flange, for sealing to the process space P is arranged at the upper end 3.3. In this context, the contour 3.4 exhibits a diameter D.sub.F.

[0088] Additionally, the protective tube 3 comprises a helix structure 3.5 applied onto an outer contour AK of the hollow body 3.1 or integrally formed with the hollow body 3.1 and protruding therefrom. In this context, the helix structure 3.5 exhibits a square cross section.

[0089] The hollow body 3.1 is configured to be cylindrical inwardly. An outer contour of the hollow body 3.1 tapers toward the closed lower end 3.2. The tapering is for example conical. Likewise, the tapering may be realized by non-linear decrease of a diameter of the outer contour AK toward the closed lower end 3.2 at least in sections.

[0090] For example, the hollow body 3.1 exhibits a diameter D.sub.Q of approximately 20 mm to 50 mm, in particular 25 mm at its upper end 3.3, also referred to as the root of the protective tube 3, and exhibits a diameter D.sub.v of approximately 12 mm to 30 mm, in particular 16-19 mm, at its tip, i.e. the lower end 3.2.

[0091] In an example embodiment of the protective tube 3, an upper section A of the hollow body 3.1, also referred to as an upper retaining section, is configured without a structure, in particular devoid of the helix structure 3.5. For example, the upper section A exhibits a length L1 of approximately 50 mm to 250 mm or 90 mm to 125 mm, in particular 100 mm to 125 mm.

[0092] A lower section B which is provided with the helix structure 3.5, exhibits for example a length L2 of 200 mm to 300 mm or 500 mm or, if the protective tube 3 is applied in gas pipelines with large diameter, up to 1400 mm.

[0093] A length ration of the length L1 relative to the length L2 is for example 1:2 or 1:3 or is smaller for special applications.

[0094] The helix structure configured with a square cross section exhibits for example an edge length S of 2.5 mm.

[0095] In an example embodiment, the edge length S reduces starting from the root of the protective tube 3 toward its tip.

[0096] For example, the edge length S and thus a material thickness of the helix structure equals a 0.1-fold to 0.15-fold of a diameter of the hollow body 3.1 present at the respective position of the helix structure 3.5 according to:

S=0.1 . . . 0.15*D   (1)

[0097] with: D=diameter of the hollow body 3.1.

[0098] FIG. 4A shows a conically tapering protective tube 3.

[0099] FIG. 4B shows a gas sample collector 4, comprising a hollow body 4.1 which is open at its lower end 4.2 toward a gas sample collection point and which comprises an opening O at its upper end 4.3 for taking gas samples.

[0100] Furthermore, a contour 4.4, in the illustrated embodiment a flange, for sealing to the process space P is arranged at the upper end 4.3.

[0101] Additionally, the gas sample collector 4 comprises a helix structure 4.5 applied onto an outer contour AK of the hollow body 4.1 or integrally formed with the hollow body 4.1 and protruding therefrom.

[0102] The hollow body 4.1 is configured cylindrical inwardly. An outer contour of the hollow body 4.1 tapers toward the open lower end 4.2. The tapering is for example conical. Likewise, the tapering may be realized by non-linear decrease of a diameter of the outer contour AK toward the open lower end 4.2 at least in sections.

[0103] In addition, the hollow body 4.1 may comprise multiple openings O1 to On along an imaginary line toward a gas sample collection point. In this context the imaginary line runs starting from the lower end 4.2 to the upper end 4.3 of the gas sample collector 4 such that the protective tube 4.1 is designed similar to a recorder, i.e. its outer appearance resembles a recorder.

[0104] The further characteristics of the gas sample collector 4 correspond in an anlagous manner to the description referring to FIGS. 3A and 3B.

[0105] FIG. 4C shows a tapering protective tube 3, wherein the tapering occurs starting from the root of the protective tube 3 in a radius logarithmically increasing toward the tip. I.e. the tapering is realized by a non-linear decrease of a diameter of the outer contour AK toward the closed lower end 3.2.

[0106] FIG. 4D shows a detail of a cross section of a protective tube 3, wherein with a radius on a base of the helix structure 3.5 adjoining the hollow body 3.1 merges with the hollow body 3.1 and wherein upper edges facing away from the hollow body 3.1 are broken with a radius of, e.g. 0.1 mm.

[0107] Sharp edges have turned out to be advantageous in the flow test; however, injuries shall be prevented during assembly, hence the edges are for example removed in the range of 0.1 mm.

[0108] FIGS. 4E and 4F show cross sections of protective tubes 3. Other than in the embodiment shown in FIG. 3A, the helix structure 3.5 is configured as a triple helix (FIG. 4E) or a quadrule helix (FIG. 4F).

[0109] FIG. 4G shows a cross section of a protective tube 3 having a helix structure 3.5 configured as a triple helix having highly rounded upper edges.

[0110] Herein, a cylindrical inner section of the hollow body 3.1 exhibits a diameter D1, the outer contour AK of the hollow body 3.1 exhibits a diameter D2 and an imaginary cirle surrounding the helix structure 3.5 exhibits a diameter D3.

[0111] This enveloping diameter D3 results for example as:

D3=(2*0.12*D2)+D2   (2)

[0112] FIG. 5 shows a conically tapering protective tube 3 having a helix structure 3.5 in a half sectional view, wherein, starting from the tip of the protective tube 3, the edge length S, i.e. a material thickness of the helix structure 3.5, i.e. a height of the helix structure radially starting from the outer contour AK of the hollow body 3.1, decreases toward the root of the protective tube 3.

[0113] FIG. 5B shows a conically tapering protective tube 3 having a helix structure 3.5 in a half sectional view, wherein, as opposed to the protective tube 3 shown in FIG. 5A, a diameter D3 of the helix structure 3.5 is constant over the entire length of its layout.

[0114] In an exemplary embodiment of the protective tube 3, the tapered off upper section A, which is for example generated by producing the protective tube 3 on a turning machine, exhibits an outer diameter for mounting in a chuck and for welding in into a contour 3.4, which is for example configured as a flange, and is devoid of the helix structure 3.5. Herein, the section A exhibits a maximum diameter D.sub.v of a blank which simply remains unmachined and thus creates a thicker socket section.

[0115] FIG. 5C shows a conically tapering protective tube 3 having a helix structure 3.5 in a half sectional view, wherein, as opposed to the protective tube 3 shown in FIG. 5A, the edge length S, i.e. a material thickness of the helix structure 3.5, i.e. a height of the helix structure 3.5 radially starting from the outer contour AK of the hollow body 3.1, is constant over the entire length of its layout; however a distance d, d′ between individual helix windings of the helix structure 3.5 decreases toward the root of the protective tube 3.

[0116] In an exemplary embodiment of the protective tube 3, the tapered off upper section A, which is for example generated by producing the protective tube 3 on a turning machine, exhibits an outer diameter for mounting in a chuck and for welding in into a contour 3.4, which is for example configured as a flange, and is devoid of the helix structure 3.5.

[0117] FIG. 5D shows a conically tapering protective tube 3 in a half sectional view with a helix structure 3.5 having a uniformly round cross section and welded onto the outer contour AK of the hollow body as a round wire.

[0118] FIG. 5E shows a tapering protective tube 3 in a half sectional view, wherein the outer contour AK of the hollow body 3.1 exhibits an ascending curve progression with a radius decreasing toward the root of the protective tube 3 and wherein a section X is cylindrical or only marginally conical. Herein, the tapering occurs at least in sections by non-linear decrease of the diameter of the outer contour AK toward the closed loser end 3.2.

[0119] FIG. 5F shows a tapering protective tube 3 in a half sectional view having a logarithmically ascending curve progression toward the root of the protective tube 3, wherein the helix structure 3.5 exhibits a half-round cross section. I.e., the tapering occurs by non-linear decrease of the diameter of the outer contour AK toward the closed lower end 3.2.

[0120] The aforementioned embodiments assume that the protective tube 3 is formed from a solid body by shape cutting. Likewise, it is possible to produce at least the hollow body 3.1 together with the helix structure 3.5 in a deep drawing process or an impact extrusion process. Likewise, the contour 3.4 may be configured as a homogenous component with the hollow body 3.1 or may be subsequently attached thereon, e.g. by welding.

[0121] In the following embodiments of the protective tube 3, the hollow body 3.1 may likewise be formed from a solid body by shape cutting. It is possible to form the respective helix structure 3.5 in advance and to then apply it on the outer contour AK of the hollow body 3.1, e.g. by welding. Likewise, the contour 3.4 may be configured as a homogenous component with the hollow body 3.1 or may be subsequently attached thereon, e.g. by welding.

[0122] FIGS. 6A to 6E respectively show a half longitudinal section of a protective tube 3 with different implementations of a helix structure 3.5.

[0123] Herein, the protective tube 3 in FIG. 6A exhibits a helix structure 3.5 having a round cross section, the protective tube 3 in FIG. 6B exhibits a helix structure 3.5 having a square cross section, the protective tube 3 in FIG. 6C exhibits a helix structure 3.5 having a trapezoid cross section, the protective tube 3 in FIG. 6D exhibits a helix structure 3.5 having a triangular cross section, and the protective tube 3 in FIG. 6E exhibits a helix structure 3.5 having a rounded off cross section.

[0124] FIGS. 6F to 6H show enlarged details of longitudinal sections of a protective tube 3 in the area of a helix structure 3.5, wherein the protective tube 3 according to FIG. 6F exhibits a helix structure 3.5 having a half-round cross section, the protective tube 3 according to FIG. 6G exhibits a helix structure 3.5 having a highly rounded cross section, and the protective tube 3 according to FIG. 6H exhibits a helix structure 3.5 having a highly rounded cross section.

[0125] FIG. 7 shows a sectional view of a system 5 having a tubular process space P and a conically tapering protective tube 3 protruding into the process space P.

[0126] Herein, the protective tube 3 comprises a contour 3.4 configured as a flange, by means of which the protective tube 3 can be attached in a media tight manner on a flange socket 5.1 of the process space P.

[0127] The flange socket 5.1, also referred to as stand off or nozzle, exhibits a height h of 4″ to 8″, e.g. 6″ at a diameter D.sub.St of 1.5″ or 2″.

[0128] In this range of the height h the protective tube 3, i.e. the outer contour AK of the hollow body 3.1 on the length L1 in the section A, remains at least essentially or for the most part devoid of the helix structure 3.5 and protrudes with its lower section B, which has the helix structure 3.5, with a length L2 up into the middle third of the process space P which exhibits a diameter D.sub.i. Herein, the tip of the protective tube 3 protrudes preferably up into a middle or a middle third of the tubular process space P.

[0129] The diameter D.sub.Q at the root of the protective tube 3 is for example 1″, wherein the protective tube 3 exhibits a diameter D.sub.v of ¾″ at its lower end, i.e. at the tip. An internal bore for receiving the temperature sensor has for example a diameter D.sub.B of 0.26″.

[0130] FIG. 8 shows a tapering gas sample collector 4, also referred to as quill-style, in a perspektive view, wherein the helix structure 4.5 comprises multiple mutually overlapping helices. I.e., sections of multiple helices are arranged vertically offset on the outer contour AK of the hollow body 4.1.

[0131] FIGS. 9A to 9F show various embodiments of a protective tube 3.

[0132] Herein, the conical upper section A according to FIG. 9A merges with a step into the lower cylindrical section B.

[0133] According to FIG. 9B, a cylindrical upper section A merges by means of a conical section C configured as a transitional section into the lower cylindrical section B. Herein, the upper cylindrical section A is in particular a maximum diameter D.sub.v of a section of a blank which remains unmachined and thus creates an upper socket section.

[0134] According to FIG. 9C, the conical upper section A merges by means of a conical further section C configured as a transitional section into the lower cylindrical section B.

[0135] According to FIG. 9D a collar 3.6 is arranged in particular at the upper flange-shaped contour 3.4, wherein starting from the collar 3.6 a radius transition occurs onto the upper section A, whose tapering is configured by non-linear decrease of the diameter of the outer contour AK toward the closed lower end 3.2. A transition between the upper section A and the cylindrical lower section B is in particular continuous and without forming an edge as a smooth transition or with a radius transition in a way not shown in detail. In an example, the upper section A can be conical.

[0136] The inner bore for the temperature sensor is configured cylindrical or steplike cylindrical, wherein the inner bore may also be embodied with a step. Likewise, multiple steps are possible, in particular in the lower section, wherein the tip locates at the lower end 3.2 comprises a flattened plane face. Alternatively, the tip may also be a sphere tip according to FIGS. 9A to 9C or a different tip.

[0137] FIG. 9E schematically shows a partial section of an exemplary embodiment of a protective tube 3. FIG. 9F schematically shows a cross section of this protective tube 3.

[0138] The protective tube 3 comprises a hollow body 3.1 which is closed at its lower end 3.2 and comprises an opening O at its upper end 3.3 for introducing a temperature sensor and comprises a contour 3.4 configured as a flange at its upper end 3.3 for sealing to a process space P. The flange is for example integrally formed with the protective tube 3 or subsequently attached at the upper end, e.g. welded. In an exemplary embodiment, a closure element 3.7 is provided for closing the opening O.

[0139] Herein, the hollow body 3.1 is cylindrical inwardly and an outer contour AK of the hollow body 3.1 tapers toward the closed lower end 3.2. The hollow body 3.1 exhibits a diameter of 20 mm to 30 mm at its root formed at its upper end 3.3 and exhibits a diameter of 16 mm to 25 mm, in particular 19 mm, at its tip formed at its lower end 3.2.

[0140] Furthermore, a collar 3.6 is arranged at the upper flange-shaped contour 3.4, wherein starting from the collar 3.6 a radius transition occurs onto an upper section A of the hollow body 3.1. The radius transition exhibits for example a radius of 2.5 mm.

[0141] The upper section A of the outer contour AK of the hollow body 3.1 is conically formed and devoid of a structure, in particular devoid of the helix structure 3.5. Herein, the upper conical section A of the outer contour AK exhibits a cone angle of 1° to 7°, in particular 2° to 6°, in particular 3° to 5° degrees relative to a central axis.

[0142] A lower section B of the protective tube 3 is configured cylindrical, wherein a helix structure 3.5 is arranged on an outer contour AK of the hollow body 3.1 in the lower section B.

[0143] The helix structure 3.5 is configured as a so called triple helix, wherein individual windings, i.e. individual helices 3.5.1 to 3.5.3 of the helix structure 3.5 are offset by 120° relative to each other. Herein, the helices 3.5.1 to 3.5.3 exhibit a rectangular cross section with an edge length S.sub.H defining their height and an edge length S.sub.W defining their width.

[0144] At a base adjoining the hollow body 3.1 the helices 3.5.1 to 3.5.3 merge with a radius into the hollow body 3.1, and upper edges facing away from the hollow body 3.1 are broken with a radius of e.g. 0.1 mm.

[0145] A transition between the upper conical section A and the cylindrical lower section B is in particular continuous and without forming an edge as a smooth transition or with a radius transition in a way not shown in detail.

[0146] FIG. 10A shows a perspective view of a detail of a gas sample collector 4 having an interrupted helix structure 4.5. The helix structure 4.5 is for example realized by interrupting a continuous helix structure 3.5.

[0147] FIG. 10B shows a perspective view of a detail of a protective tube 3 having an interrupted helix structure 3.5. The helix structure 3.5 is for example realized by forming or arranging multiple helix elements on the outer contour AK.

[0148] FIG. 10C shows a perspective view of a detail of a protective tube 3 having an interrupted helix structure 3.5. The helix structure 3.5 is for example realized by interrupting a continuous helix structure 3.5.

[0149] FIG. 11A shows a detail of a protective tube 3 having a helix structure 3.5 configured as a triple helix. Other than in the protective tubes 3 or gas sample collectors 4 having the helix structures 3.5, 4.5 shown in the preceding figures, the helix structure 3.5 is presently neither applied onto the hollow body 3.1, 4.1 nor formed as an integral part thereof and protruding outward therefrom, but introduced into the outer contour AK of the hollow body 3.1.

[0150] Herein, the helix structure 3.1 exhibits a triangular cross section whose angle a may be variably chosen depending on a desired impact on the flow F according to FIGS. 11B to 11C.

[0151] Deviating from the shown triangular cross section of the helix structure 3.5, the helix structure 3.5 may exhibit different cross sections according to FIGS. 12A to 12D, e.g. a trapezoid cross section (FIG. 12A), a square cross section (FIG. 12B), a rounded cross section with a large opening (FIG. 12C) or a rounded cross section with a smaller opening (FIG. 12D).

[0152] Moreover, for further stabilizing or for increasing the stability of the protective tube 3 and the gas sample collector 4, introduction of material stress into the surface for improving vibration resistance is applicable for all illustrated embodiments of the protective tube 3 and the gas sample collector 4. For this purpose, the surface is compacted preferably in the upper section A by roll compacting, shot blasting or other smoothing or likewise by so called laser peening. This demonstrably serves for increasing the stability of the protective tube 3 or the gas sample collector 4. This compacting is demonstrable in an etched grinding pattern and also superficially visible by a modified structure.

[0153] In an example embodiment of the protective tube 3 and the gas sample collector 4, the hollow body 3.1 may, aside from the difference of the lower opening and the temperature sensor, exhibit the same features and advantages in an analogous way as described above in the possible embodiments of the gas sample collector 4 and the protective tube 3, respectively.

[0154] The invention is not limited to the preceding detailed embodiments. It may be modified within the scope of the subsequent claims. Likewise, individual aspects from the dependent claims may be combined with each other.