• 专利附录
  • 专利说明
  • 权利要求
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    • 专利摘要:
    14 ABSTRACT A feed-through provides electromagnetic shielding where one or more signalleads pass through an enclosure. lt comprises a frame, having at least one opening,and an assembly comprising two or more joining parts, forming one or moreelongated waveguides. The joining parts are divisible along the length of thewaveguides, thereby being capable of surrounding a signal lead. The assembly isadapted to be attached to the frame such that one or more signal leads can passthrough an opening in the frame and through one of the waveguides. Installation isof the feed-through is made easier by the opening in the frame having a larger maximum extension than the maximum extension of a waveguide.
    公开号:SE1451594A1
    申请号:SE1451594
    申请日:2014-12-19
    公开日:2016-06-20
    发明作者:Johansson Hans-Erik
    申请人:Hans-Erik Johansson I Hagstad Ab；
    IPC主号:
    专利说明:

    FEED-THROUGH Technical fieldThe present invention relates to a feed-through for providing electro-magnetic shielding where one or more signal leads pass through a cabinet or other enclosure.
    Background Such a feed-through can be used to prevent emission of electromagneticwaves, for example to avoid electromagnetic interference or the leakage of criticalinformation from a network switch or server placed in a cabinet or enclosure. Forthe latter application, standards, usually referred to using the term ”TEIVIPEST”, areestablished that require attenuation up to the order of 100 dB at frequencies up to10 GHz at the feed-through.
    One example of such a feed-through, for optical cables, is described in US-7793415-B2, which shows a flat member with a number of openings. An enclosurecan be fitted around each cable to form a tube, and this tube can be attached to theflat member at an opening thereof. The flat member is in turn attached to anopening of a cabinet or other enclosure. This structure reduces electromagneticinterference to a desired level up to a frequency that is determined by the lengthand the inner diameter of the tube formed by the enclosure.
    One problem associated with such a feed-through is how to facilitateinstallation of, for example, optical cables in a cabinet or other enclosure where the feed-through is used.
    Summary One object of the present invention is therefore how to facilitate installationof, for example, optical cables in cabinets or other enclosures where the feed-through is used.
    This object is achieved by means of a feed-through as defined in claim 1.More specifically, such a feed through comprises a frame, having at least one opening, and an assembly comprising two or more joining parts, forming one or more elongated waveguides. The joining parts are divisible along the length of thewaveguides, thereby being capable of surrounding a signal lead. The assembly isadapted to be attached to the frame such that one or more signal leads can passthrough an opening in the frame and through one of the waveguides. Further, theopening in the frame then has a larger maximum extension than the maximum crosssection extension of a waveguide.
    With such a feed-through it is possible, while providing a reasonably shortwaveguide with a small diameter, to install, for example, a pre-terminated fiber-optic cable, i.e., one that has already been provided with a connector, which has aconsiderably greater cross section than a fiber-optic cable. The frame may beattached to a cabinet or other enclosure, and the user may stick the fiber-opticcable, or a bundle of cables, with a connector at its end, through the opening in theframe, which opening is large enough to allow this. The joining parts are then fittedaround the cable or cables such that the cables run in an elongated cavity in theinterior ofthe finished assembly. This can be achieved even in cases where thecavity is narrower than the connector. Means for attaching the parts together areprovided. The enclosing parts are then firmly connected to the frame. Thereby pre-terminated cables can be used, which makes any installation procedure considerablymore efficient.
    The number of cables that need to be fed through a cabinet wall may varygreatly between different applications. One way to achieve flexibility in the numberof cables possible to be fed though is to let the assembly consist of a variablenumber of parts, with a variable number of optional middle parts between two endparts. Installation is facilitated by the completed assembly forming one solid blockwithout extending and/or fragile parts.
    I/|achined parts allowing high precision may be used, making a tight fitbetween the parts possible, thus preventing the leakage of electromagneticradiation between the parts. The frame may be welded to the cabinet to preventleakage of radiation between the frame and the cabinet. A frame with a thicknesslarger than 10 mm may be used in order to facilitate welding. An electricallyconductive gasket, such as a copper-beryllium gasket, can be used to preventleakage of electromagnetic radiation between the assembly and the frame. The parts in the assembly may be made from steel, which has good conductive properties, resulting in a well-functioning waveguide. Tying the parts together usingnuts and bolts is one way to assure tight electric contact between them. ln general, the longer a waveguide is, the larger the attenuation will be. lnaddition, for a waveguide to be able to attenuate a given frequency, that frequencyneeds to be below the cut-off frequency of the waveguide. Standards as discussedabove mandate a certain minimum attenuation, leading to waveguides needing tohave a certain minimum length and maximum transversal extension. ln this case, thewaveguides may have length of at least 52 mm and/or a maximal transversalextension of at most 17.5 mm.
    On the connecting surfaces between joining parts, there may be recesses,the use of which may result in good electric and mechanical contact between theparts.
    Space is often tight in and around cabinets of the mentioned kind. Allowingthe waveguides to extend through the opening in the cabinet is one way of savingspace. ln particular, more space is often available outside of the cabinet. Aconfiguration wherein the feed-through extends further on the outside than on theinside ofthe cabinet will make better use of available space.
    The signal lead going through the feed-through is typically a fiber-optic cable.
    The object mentioned in the first paragraph may also be achieved by meansof a system, comprising the mentioned feed-through, a cabinet or enclosure, and one or more signal leads.
    Brief description of the drawings These and other aspects of the invention will now be described in moredetail, with reference to one embodiment of the invention.
    Fig 1 schematically illustrates a situation where a feed-through according tothe present disclosure can be used.
    Fig 2 schematically illustrates a waveguide below-cutoff.
    Fig 3 is a perspective drawing of an end part of an assembly.
    Fig 4 is a perspective drawing of a middle part of the assembly.
    Fig 5 is a perspective drawing showing how the parts of the assembly fit together.
    Fig 6 is a perspective drawing showing a view of a completed assembly andhow the assembly is attached to the frame.Fig 7 is a perspective drawing showing another view of a completedassembly.Fig 8 is a perspective drawing showing one side of an installed feed-through.Fig 9 is a perspective drawing showing another side of an installed feed- through.
    Detailed description Fig 1 illustrates a protected cabinet or other enclosure 1, which is a contextwhere a feed-through 11 according to the present disclosure can be used. Such acabinet or other enclosure can be used in a sensitive environment where processingdevices 3 in the cabinet 1, such as servers, electronically process unencryptedsensitive information. The cabinet 1, which may be made of thick sheet metal,functions as a Faraday cage, containing within its enclosure any electromagneticradiation from the processing devices 3, thereby preventing the leakage of sensitiveinformation. The processing devices 3 communicate with nodes 13 outside thecabinet 1 via optical fibers 5 which are terminated by means of connectors 7, 9 ateach end. The optical fibers may convey less sensitive information or theinformation carried by them may be encrypted. Furthermore, the conveyed opticalsignals as such usually give negligible leaked radiation, preventing interception ofsuch signals, unless the fibers are tampered with.
    The feed-through where the optical fibers extend out of the cabinet 1requires special attention so that electromagnetic radiation does not escape thecabinet, risking interception by a third party nearby. ln addition to the shielding situation described above, the feed-through maybe useful in other situations where considerable attenuation at a connection into aFaraday cage is needed. For instance, as the effect provided is more or less reci-procal, the feed-trough could protect sensitive equipment in a cabinet from externalelectromagnetic interference, such as electromagnetic pulses with high energy.Further, a shielded room used for sensitive measurements could be protected from external electromagnetic interference, etc.
    As is well known per se, an attenuating feed-through can be obtained bymeans of a waveguide below-cutoff, WBCO, ofwhich one example is schematicallyillustrated in Fig 2. ln this example the waveguide 12, made from a conductivematerial, has a cavity 14, open at both ends, with a circular cross section withdiameter D and a length l. The waveguide extends through a wall in a Faradaycage 1.
    Electromagnetic waves can propagate through a waveguide in a number ofdifferent modes, corresponding to different solutions to the Maxwell equations.These modes are distinguished by different configurations of the electric andmagnetic fields. Each of these modes has a cut-off frequency, below which nosubstantial propagation in that mode is possible. Below the lowest cut-off frequencyof all possible modes, no substantial propagation of electromagnetic waves ispossible at all. lnstead, signals suffer exponential attenuation. ln a circular wave-guide, the mode with the lowest cut-off frequency is the TE11(transverse electric)mode. The cut-off frequency fc of that mode can be shown to be, to three significant figures, 0.586 vc = T, where v is the propagation speed ofthe waveguide dielectric, i.e., the non-conductive material forming the bulk of the waveguide cavity. ln air, v is to a goodapproximation 3 >< 108 m/s. Below this cut-off frequency, over a distance l, anelectromagnetic wave with frequency f suffers a total attenuation of, again to three significant figures, lt can thus easily be realized that to maximize attenuation of signals of acertain frequency requires as high a cut-off frequency as possible, and thus as narrow a waveguide as possible, as well as a long a waveguide as possible.
    For a feed-though to function properly according to the strictest currentstandards, i.e. a dampening of 100 dB between frequencies 10 kHz and 10 GHz, thecross-section diameter of a waveguide should preferably be smaller than about 17.5mm. With an example cross-section diameter of 12 mm, a waveguide shouldpreferably be longer than about 52 mm.
    Fig 6 shows the parts of a complete feed-through. The feed-thoughcomprises a frame 43 and an assembly 41, the latter comprising two end parts 37and between them, optionally, one or more middle parts 31, 33. Fig 5 shows howthe parts of the assembly fit together. As the parts comprising the assembly arebrought together, waveguides 53 are formed from cut-outs on those parts. Aminimal configuration of the assembly 41 could consist of only two end parts 37.Any number of middle parts 31, 33 can then be placed between them according toneed. I/|iddle parts 31, 33 can be made slightly different, e.g. with 33 or without 31threads. I/|iddle parts with threads 33 are on the drawings marked ”C”, while thosewithout threads 31 are marked "X". This arrangement allows a tight fit between theparts. At the same time, the finished assembly is rugged without any extendingfragile parts and not likely to break apart during installation. The completedassembly 41 as shown in Fig 6 fits into an opening 51 of the frame 43. ln the embodiment described here, the parts ofthe assembly are made fromsteel, which material has good electric conducting properties, allowing for a well-functioning waveguide. Machined parts are used, which allows high precision,allowing for a tight fit between the parts. However, the skilled person realizes thatother fabrication methods and other materials with good electrical conductivity arealso possible.
    An electrically conducting gasket, such as a copper-beryllium gasket 49 maybe used to prevent leakage of electromagnetic radiation between the assembly 41and the frame 43. Copper-beryllium gaskets are rugged and easy to use.
    A person skilled in the art realizes that other arrangements, such as anarrangement of conductive gaskets made from, for example, silicone or rubbermixtures, lying flat on the frame 43 or running in one or more grooves in the frame,are conceivable as well.
    Figs 3 and 4 show different parts making up the assembly 41 (cf. Fig 6); an end part 37, and one example of a middle part 33. As mentioned above, there may be provided middle parts with holes 35 having threads, and middle parts 31 (cf. Fig5) with corresponding holes not having threads.
    An end part 37 comprises a flange portion 15 and a protruding section 17perpendicular to the flange. A middle part 31, 33 comprises two flange portions 15and one protruding section 17.
    The flanges 15 are devised to be attached to the frame 43 (cf. Fig 6). On eachmiddle part 31, 33, one flange portion 15 is located on each side of the protrudingportion. On the flanges 15, there are holes 19 in a direction perpendicular to theflanges 15, extending through the flanges. These holes 19 are suitable for attachingthe assembly 41 to the frame 43. ln the particular embodiment ofthe disclosuredescribed here, middle parts 31, 33 have one such hole 19 on each flange, while anend part 37 has four holes 19 on the edge ofthe flange facing away from theprotruding section 17 and two holes 19 on each ofthe two edges perpendicular tothe edge facing away from the protruding section 17. At the entrance to each hole19, there may be a recess 20 suitable for giving space for a nut.
    On the protruding section 17 on both end parts 37 and middle parts 31, 33,there are connecting surfaces 24 that will be in contact as the parts ofthe assemblyare brought together. On the middle parts 31, 33 there are such surfaces on eachside ofthe protruding section 17 and flanges, while on end parts 37, there are suchsurfaces only on a side of the protruding section 17 facing away from the flange 15.The peripheries of these surfaces may be raised, such that there is provided recesses26 there between, where holes 29, 35 for bolts are provided, in order to improvemechanical/galvanic contact between the surfaces of different parts by permittinghigher pressure at the contact surfaces 24. ln the embodiment described here, suchraised edges are present on the middle parts 31, 33, as well as on the end parts 37.
    At the connecting surfaces described above, there are cut-outs 21 that, whenmatched with corresponding middle 31, 33 or end parts 37, form the waveguides. lnthe embodiment described here, there are two such cut-outs at each connectingsurface. The cut-outs extend along the whole length of the parts 31, 33, 37. ln the embodiment described here, the cut-outs are semi-circular. However,a person skilled in the art realizes that cut-outs of other shapes, such as quadratic,rectangular, honeycomb or general polygon shaped are equally possible. A person skilled in the art would additionally recognize that it is equally possible to have a different number of cut-outs than two on the surfaces of the parts and to have cut-outs that for one waveguide have different cut-outs on the two different partsforming that waveguide.
    Additionally, on the connecting surfaces described above, there may be pins23 and ho|es 25 to aid alignment of end parts 37 and/or middle parts 31, 33attaching to each other. ln the embodiment described here, those pins 23 and ho|es25 are located on the flanges 15, near the end of the connecting surfaces. Justoutside of the pins 23 and ho|es 25, on the edge between the flange 15 and theconnecting surface, there may be smaller cut-outs 27, designed to aid disassembly, ifdesired, for example by inserting a screwdriver into the cut-out 27 and turning thescrewdriver and/or using it as a lever. ln the recesses at the connecting surfaces described above, there arethrough ho|es 29 extending perpendicularly to the surfaces, in the protrudingsections 17 and the flanges 15. ln the embodiment described here, on the middleparts 31, 33, there is one such hole 29 through each ofthe flanges 15. On end parts37, there is one such hole 29 though each side of the flange 15. On both end 27 andmiddle 31, 33 parts, there are three rows of ho|es 29 extending though the pro-truding section 17. One such row is located on one side ofthe two cuts-outs 21, onerow on the other side of the cut-outs 21 and one row between the cut-outs 21. Thenumber of ho|es 29 in each row depends on the length of the protruding section 17.ln the embodiment described here, each row has three ho|es 29. Needless to say,the hole configurations may be varied in a number of ways.
    On middle parts 31, 33, the ho|es described in the previous paragraph maybe threaded 33 or be without threads 31.
    Fig 5 shows how the assembly 41 is fitted together, here exemplified with anend part 37, a middle part 31without threads, and a middle part 33 with threadsbeing attached to each other using bolts 39, 40. The bolts may interact with thethreads 35 (cf. Fig 4) of middle parts 33 having such threads or with nuts if the boltspenetrate the entire assembly. Thereby the parts are compressed, bringing theconnecting surfaces described above into close contact. The skilled person willrecognize that other means for applying this pressure than bolts and optional nuts are possible.
    As already has been discussed, Fig 6 shows a completed assembly 41, theframe 43, and a wall ofthe cabinet 1. The frame 43 can have a rectangular crosssection and an opening 51, also rectangular in cross-section, where the narrowerpart of the assembly 41 fits, i.e., the part of the assembly comprised of the pro-truding sections 17 of the parts 31, 33, 37 making up the assembly. The frame mayfor example have been welded to the cabinet, although other ways of fitting theframe to the wall are conceivable. To be suitable for welding to the cabinet 1, it maybe beneficial for the frame 43 to have a thickness in a direction perpendicular to theplane of one side ofthe cabinet of at least 10 mm. ln the embodiment described here, the waveguides 53 formed by the joiningparts 31, 33, 37 are at a right angle to the plane ofthe frame 43 or of one side of thecabinet 1. However, it is equally possible for the waveguides 53 and the protrudingsections 17 of the joining parts 31, 33, 37 to be at an oblique angle to the flanges 15,resulting in a feed-though with signal leads 5 entering the cabinet 1 at an obliqueangle with respect to the plane ofthe frame 43 or of one side ofthe cabinet 1.Thismay have an advantage of saving space inside the cabinet.
    When the assembly has been put together, with leads in the waveguides, theassembly is fitted in the frame and firmly attached to the frame.
    Threaded bolts 47 attached to the frame 43 match holes in the flanges 15 ofthe parts comprising the assembly 41. These bolts may for example have been pressfitted into the frame. A set of holes 45, in the embodiment described two holesalong each short side ofthe opening 51 in the frame 43, extend through the frame43 and through the cabinet 1.
    Fig 7 shows another side of a completed assembly 41. Bolts 39, 40 attachingthe parts together are present both through the flanges and through the protrudingparts. Another set of bolts 42, hidden in fig 3, in the embodiment described twobolts 42 on each side, are attached to the end parts on the flange 15 close to theprotruding section 17. These bolts 42 match the holes 45 in the frame describedabove. Attaching the assembly with bolts from both sides of the cabinet 1 makes thefeed-though more tamper-resistant and make unauthorized access to the cabinetthough the feed-through more difficult.
    The assembly 41 as illustrated has contact surfaces 28 beneath the flanges.
    These contact surfaces 28 are devised to come into close contact with corresponding surfaces on the frame 43, optionally with an intervening gasket 49. These contactsurfaces as well may have recessed portions 30 as well, in order to leave space for agasket 49.
    Fig 8 shows one side of a complete feed-through, with the completedassembly 41 attached to the frame 43. Nuts 55 may attach to the bolts 47 attachedto the frame 43.
    Fig 9 shows the other side of a complete feed-through. Nuts 57 may attach tothe bolts 42 attached to the end parts.
    The present disclosure is not limited by the above example, and may be varied and altered in different way within the scope ofthe appended claims.
    权利要求:
    Claims (4)
    [1] 1. A feed-through for providing electromagnetic shielding where one or more signal leads pass through a cabinet or other enclosure (1), said feed-throughcomprising a frame (43), having at least one opening (51), and an assembly(41) comprising two or more joining parts (31, 33, 37), forming one or moreelongated waveguides (53), said joining parts (31, 33, 37) being divisiblealong the length of said waveguides (53), thereby being capable of surround-ing a signal lead, said assembly (41) being adapted to be attached to saidframe (43) such that one or more signal leads can pass through said at leastone opening (51) in the frame and through one of said waveguides (53),characterized by said opening (51) in the frame having a larger maximumtransversal extension than the maximum transversal extension of said waveguides (53). A feed-through according to claim 1, wherein the joining parts (31, 33, 37) form two or more elongated waveguides (53), one opening in the frame (43)providing access to more than one waveguide (53), such that signal leads canpass through said opening (51) in the frame (43) and through any of said two or more elongated waveguides (53). A feed-through according to any one ofthe preceding claims, wherein said waveguides have a length of at least 52 mm. A feed-through according to any one of the preceding claims, wherein said waveguides have a maximal transversal extension of at most 17.5 mm. A feed-through according to any one ofthe preceding claims, wherein, onthe connecting surfaces between said joining parts of said assembly, there are FeCeSSeS. 10. 11. 1
    [2] 2. 1
    [3] 3. 1
    [4] 4. 12 A feed-through according to any one ofthe preceding claims, wherein said waveguides (53) extend through said opening (51). A feed-through according to claim 6, wherein said waveguides (53) extend further on the outside of said cabinet (1) than on the inside of said cabinet (1)- A feed-through according to any one of the preceding claims, wherein saidframe (43) has a thickness perpendicular to the plane of one side of said cabinet (1) of at least 10 mm. A feed-through according to any one ofthe preceding claims, wherein said frame (43) is suitable for welding to said cabinet (1). A feed-through according to any one ofthe preceding claims, wherein said frame (43) and said assembly (41) are made from machined parts. A feed-through according to any one ofthe preceding claims, wherein said frame (43) and said assembly (41) are made of steel. A feed-through according to any one of the preceding claims, whereinelectric contact between said frame (43) and said assembly (41) is secured by a gasket (49) made from a conductive material, such as beryllium-copper. A feed-through according to any one ofthe preceding claims, wherein said signal lead is a fiber-optic cable. A feed-through according to any one of the preceding claims, wherein saidjoining parts (31, 33, 37) and/or said assembly (41) and said frame (43) are connected using bolts (39, 40) and optionally nuts. .A feed-though according to any one of the preceding claims, said frame (43) having a rectangular cross section in the plane of said cabinet, said one 16. 17. 13 opening in said frame (43) also being rectangular in cross section in the planeof one side of said cabinet (1), said joining parts of said assembly (41)comprising two end parts (37), and between said two end parts (37), one ormore middle parts (31, 33), said end parts (37) each having one flange (15)each fitting one the two edges along a first major axis of the frame (43) andat a right angle to said flange a protruding section (17) with one or more cut-outs (21), said middle parts (31, 33) having two flanges (15) fitting to the twoedges along a second major axis of the frame (43) and at a right angle to thetwo flanges (15) a protruding section (17), on both sides facing otherjoiningparts (31, 33, 37) having one or more cut-outs (21), said cutouts (21) forming said waveguides (53). A feed-through according to claim 15, wherein said middle parts (31, 33) areof two types, one type (33) having holes with threads fitting said bolts, theother type (31) having holes without threads. A system, comprising a feed-through according to any one of the precedingclaims, a cabinet or other enclosure (1) suitable for electromagnetic shielding and one or more signal leads.
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    同族专利:
    公开号 | 公开日
    SE538573C2|2016-09-27|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    SE1451594A|SE538573C2|2014-12-19|2014-12-19|Feed-through|SE1451594A| SE538573C2|2014-12-19|2014-12-19|Feed-through|
    PCT/EP2015/080208| WO2016097137A1|2014-12-19|2015-12-17|Feed-through|
    EP15819808.5A| EP3235357A1|2014-12-19|2015-12-17|Feed-through|
    US15/529,469| US10194566B2|2014-12-19|2015-12-17|Feed-through|
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