COMMUNICATION CABLE AND CABLE HARNESS

Abstract

A communication cable, in which an insulating coating covers the outer circumferences of a conductor pair and which can be firmly attached to an external substrate, and a cable bundle with such a communication cable are provided.A communication cable 1 comprises: a signal cable 10 with a pair of conductors 11 and an insulating coating 12 covering the outer circumferences of both conductors 11 together; and a sheath 20 covering the outer circumference of the signal cable 10, the signal cable 10 being obtained as a whole by twisting an arrangement with the pair of conductors 11 and the insulating coating 12 such that the two conductors 11 cross each other in a spiral, the insulating coating 12 being arranged between the two conductors 11, and an outer circumferential surface of the sheath 20 extending in an arrangement direction along which the two conductors 11 are arranged side by side, having a higher surface smoothness than an outer circumferential surface of the signal cable 10.

Description

TECHNICAL AREA

[0001] The present disclosure relates to a communication cable and a cable bundle. TECHNICAL BACKGROUND

[0002] To accommodate multiple cables while saving vertical space, or to achieve other purposes, cable harnesses can be configured in which the cables are attached to the surface of a plastic sheet or a sheet-like material made of nonwoven fabric. For example, patent document 1 discloses a configuration in which a cable harness, with cables attached to a sheet material by sewing or welding, is placed along a plate-shaped element that forms part of a vehicle's interior trim. It is also conceivable that, among various other types of cables, a communication cable could be integrated into the cable harness by attaching it to the sheet material.

[0003] A communication cable comprising a pair of conductors and used for transmitting differential signals can be a cable in which the pair of conductors is arranged in parallel and an insulating coating is provided on the outer circumferences of both conductors (two-core integrated cable). For example, patent documents 2 and 3 disclose two-core integrated cables of this type. As disclosed in these documents and patent document 4, there is also a configuration in which a two-core integrated cable, in which an insulating coating is provided around the outer circumferences of both conductors, is spirally twisted. PREVIOUSLY KNOWN DOCUMENTS PATENT DOCUMENTS Patent document 1: JP 2018 - 196 174 A Patent document 2: JP S60 - 123920 U Patent document 3: JP 2003 - 36739 A Patent document 4: JP 2015 - 191877 A OVERVIEW OF THE INVENTIONAL PROBLEM

[0004] It is conceivable to form a cable bundle by attaching a communication cable, as disclosed in patent documents 2 to 4 and consisting of a two-core integrated cable, to a substrate made of a non-woven fabric or the like, as in the configuration disclosed in patent document 1. However, in this case, the surface of the communication cable has an uneven structure due to the shape of the conductor pair, and therefore the communication cable may not be sufficiently firmly attached to the substrate. In particular, if a two-core integrated cable is spirally twisted, the attachment of the communication cable to the substrate tends to be incomplete, and the likelihood of adverse effects increases. For example, as in Fig.Figure 6, which schematically shows a cross-section of a state in which a two-core integrated cable 10 is attached to a substrate 30, shows cases in which an insulating coating 12 covering a pair of conductors 11 together can be firmly attached to the substrate 30 at a point near one of the conductors 11 (under the left conductor 11 in the figure), but cannot be firmly attached to the substrate 30 at a point near the other conductor 11.If the communication cable cannot be firmly attached to the substrate near the two conductors in this way, it is possible that not only will the cable strand fail to hold the communication cable stably to the substrate, but also that the transmission characteristics, such as the characteristic impedance, of the communication cable will become unstable and its noise resistance will deteriorate due to variations in the conductor spacing between the two conductors along the axial direction of the communication cable and a reduced symmetry between the two conductors.

[0005] Therefore, the task at hand is to provide a communication cable in which an insulating coating covers the outer circumferences of a conductor pair and which can be firmly attached to an external substrate, as well as a cable harness containing such a communication cable. SOLUTION TO THE PROBLEM

[0006] According to the present disclosure, a communication cable comprises: a signal cable with a pair of conductors and an insulating coating covering the outer circumferences of both conductors together; and a sheath covering an outer circumference of the signal cable, wherein the signal cable is obtained as a whole by twisting an arrangement with the pair of conductors and the insulating coating such that the two conductors cross in a spiral direction with the insulating coating arranged between them, and an outer circumferential surface of the sheath extending in an arrangement direction along which the two conductors are arranged side by side, having a higher surface smoothness than an outer circumferential surface of the signal cable.

[0007] According to the present disclosure, a cable string comprises: the communication cable described above; and a substrate, wherein the communication cable is attached to the substrate with a surface extending along the arrangement direction. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0008] The communication cable and cable harness according to the present disclosure provide a communication cable in which an insulating coating covers the outer circumferences of a conductor pair and which can be firmly attached to an external substrate, and a cable harness comprising such a communication cable. BRIEF DESCRIPTION OF THE FIGURES Fig. Figure 1 is a top view showing a communication cable according to one embodiment of the present disclosure. Fig.Figure 2 is a cross-sectional view showing a cross-section of the communication cable cut perpendicular to an axial direction. Fig. Figure 3 is a top view showing a two-core integrated parallel cable that serves as the starting material for the communication cable. Fig. Figure 4 is a top view showing a cable harness according to one embodiment of the present disclosure. Fig. Figure 5 is a cross-sectional view showing a point on the cable bundle where the communication cable is attached to a substrate. Fig. Figure 6 is a cross-sectional view showing a state in which a communication cable is attached to the substrate without any sheathing. Fig. 7A and Fig. Figure 7B shows models for estimating the fastening strength of the communication cable to the substrate, wherein Fig. 7A shows a case without sheathing and Fig.7B shows a case with a casing. EMBODIMENTS OF THE INVENTION Description of embodiments of the present disclosure

[0009] First, embodiments of the present disclosure are listed and described. The communication cable and cable harness according to the present disclosure can have the following configurations.

[0010] [1] A communication cable according to the present disclosure comprises: a signal cable with a pair of conductors and an insulating coating covering the outer circumferences of both conductors together; and a sheath covering an outer circumference of the signal cable, wherein the signal cable is obtained as a whole by twisting an arrangement with the pair of conductors and the insulating coating such that the two conductors cross in a spiral direction with the insulating coating arranged between them, and an outer circumferential surface of the sheath extending in an arrangement direction along which the two conductors are arranged side by side, having a higher surface smoothness than an outer circumferential surface of the signal cable.

[0011] Since the signal cable in the communication cable described above consists of a two-core integrated cable in which an insulating coating covers the outer circumferences of both conductors, and this two-core integrated cable is twisted, the communication cable achieves high stability in its transmission characteristics and high noise immunity. The sheathing is provided around the outer circumference of the signal cable, and the outer surface of the sheathing, extending in the direction of the conductors, has a higher degree of surface smoothness than the outer surface of the signal cable itself.By providing a sheath with a highly smooth outer surface, the communication cable is more easily brought into contact with and attached to the substrate surface when it is fastened, compared to cases where no sheath is provided. This allows the communication cable to be attached more securely to the substrate. Furthermore, the communication cable can be more easily brought into contact with and attached to the substrate surface, ensuring a high degree of symmetry between the two conductors.As a result, the communication cable is less likely to detach from the substrate when it is securely attached, and the twisted structure of the signal cable is maintained stably, ensuring high stability and symmetry in the conductor spacing between the two conductors. This allows the transmission characteristics of the communication cable, including its characteristic impedance, to be maintained stably. The noise immunity of the communication cable is also kept high.

[0012] [2] In the configuration described above in [1], an outer edge of the sheath in a cross-section of the communication cable cut perpendicular to an axial direction preferably has a side extending in the arrangement direction. This makes it easier to bring the outer circumferential surface of the communication cable sheath into contact with the substrate over a large area and to attach it particularly firmly to the substrate. Furthermore, since the communication cable can be attached to the substrate with high symmetry at the respective locations near the two conductors, the effect of maintaining high symmetry between the two conductors is excellent even when the communication cable is attached to the substrate.

[0013] [3] In the configuration described above in [2], the sheathing in a cross-section of the communication cable, cut perpendicular to the axial direction, preferably has a rectangular outer shape or an outer shape obtained by rounding the corners of a rectangle. Thus, when attaching the communication cable and other cables side by side to the surface of the substrate, the distances between the communication cable and the adjacent cables can be more easily defined based on the length of the sides of the rectangle in the cross-section.

[0014] [4] A cable assembly according to the present disclosure comprises: the communication cable according to any one of claims 1 to 3; and a substrate, wherein the communication cable is attached to the substrate with a surface extending along the arrangement direction.

[0015] Since the communication cable forming the cable bundle described above consists of a signal cable (obtained by twisting a two-core integrated cable) enclosed in a sheath with a smooth outer surface, and this sheath is attached to the substrate, the resulting cable bundle provides a more rigid connection between the communication cable and the substrate than a configuration without a sheath. Furthermore, because the communication cable is attached to the substrate with a high degree of symmetry between the two conductors, changes in the conductor spacing due to loosening of the twisted structure of the signal cable and a decrease in symmetry between the two conductors are less likely to occur.As a result, a cable harness is provided in which the transmission characteristics of the communication cable can be maintained stably over a long period of time and the communication cable has a high noise resistance.

[0016] [5] In the configuration described in [4] above, the substrate is preferably made of a nonwoven fabric and the communication cable is attached to the substrate by hot melt adhesive. Accordingly, the cable harness can maintain a high degree of flexibility even when the communication cable is rigidly attached to the substrate, which improves the handling characteristics of the cable harness. Furthermore, it is thus easier to achieve a secure attachment of the communication cable to the substrate.

[0017] [6] In the above configuration of [4] or [5], the substrate and the sheath preferably contain the same type of organic polymer and are fused together. As a result, it is possible for the substrate and the sheath to contain the same type of organic polymer, achieving a high bond strength at a hot melt joint between the substrate and the communication cable. Furthermore, migration of additives, such as plasticizers, through the hot melt joint between the sheath and the substrate is less likely, since identical or similar additives are typically added to the same type of organic polymer. DETAILED DESCRIPTION OF THE EXECUTION FORMS

[0018] A communication cable and a cable harness according to an embodiment of the present disclosure are described in detail below with reference to the drawings. A cable harness according to the embodiment of the present disclosure comprises a communication cable according to the embodiment of the present disclosure. In this description, terms such as "parallel," "straight line," and "rectangle," used to describe the shape or layout of components, encompass not only geometrically precise concepts but also tolerances, such as ±15% in length and ±15° in angle, which are generally accepted in communication cables and cable harnesses. Configuration of the communication cable

[0019] First, a communication cable according to an embodiment of the present disclosure is described. Fig.Figure 1 is a top view showing a communication cable 1 according to one embodiment of the present disclosure. Furthermore, it shows Fig. 2 a cross-section of the communication cable 1, cut perpendicular to its axial direction (longitudinal direction).

[0020] The communication cable 1 comprises a signal cable 10 and a sheath 20. The sheath 20 covers the outer circumference of the signal cable 10. Fig.In Figure 1, the sheathing 20 is removed at one end, so that the signal cable 10 is visible. The communication cable 1 may also have components other than the signal cable 10 and the sheathing 20, but with a view to improving the advantages of providing the sheathing 20 described later, preferably no further components are provided between the signal cable 10 and the sheathing 20 or on the outer circumference of the sheathing 20. In the following, "cross-section" in this description refers to a cross-section perpendicular to the axial direction of the communication cable 1. Furthermore, relative directions, such as "lateral direction" and "vertical direction," are defined such that they correspond to the cross-sectional view shown in Figure 1. Fig.The two directions shown correspond to this. That is, “lateral direction” refers to an arrangement direction along which a pair of conductors 11, which is described next, is arranged side by side, and “vertical direction” refers to a direction orthogonal to the lateral direction in the cross-section.

[0021] The signal cable 10 is an electrical cable for transmitting differential signals and comprises a conductor pair 11 and an insulating coating 12. The insulating coating 12 covers the outer circumferences of both conductors 11 together, so that the signal cable 10 is designed as a two-core integrated cable. That is, the insulating coating 12 has a structure in which it covers the outer circumferences of both conductors 11, and the sections covering the outer circumferences of both conductors 11 are continuous and formed as a single unit. The insulating coating 12 serves to insulate the two conductors of the conductor pair 11 from each other and from the external environment.

[0022] In the signal cable 10, the entire assembly, including the conductor pair 11 and the insulating coating 12 covering these conductors 11, is twisted such that the two conductors 11 cross each other in a spiral pattern, with the insulating coating 12 also positioned between the two conductors 11. In other words, the signal cable 10 has a structure in which the arrangement of conductor 11 and insulating coating 12 (in the top view of Fig.(3 shown) is configured as a two-core integrated parallel cable in which the insulating coating 12 is formed on the outer circumferences of the conductors 11, which are arranged parallel to each other, with the entire arrangement being twisted. It should be noted that, as described above, the “arrangement direction” (lateral direction) refers to a direction along which the two conductors 11 are arranged side by side, although, strictly speaking, the direction connecting the centers of gravity of the two conductors 11 changes along the axial direction due to the twisted structure of the two-core integrated cable. In a parallel cable without twisting (untwisted parallel cable), the direction connecting the centers of gravity of the two conductors 11 corresponds to the arrangement direction.Furthermore, in the twisted state, at each intermediate point between two adjacent intersections where the two conductors 11 cross, the direction connecting the centers of gravity of the two conductors 11 corresponds to an arrangement direction.

[0023] By using a signal cable 10 with a two-core integrated structure, in which a common insulating coating 12 coats the two conductors 11 together, it is possible to simplify the structure of the signal cable 10 and maintain a stable conductor spacing between the two conductors 11, thereby improving the stability of the transmission characteristics, such as the characteristic impedance. Furthermore, twisting the two-core integrated cable improves the symmetry of the two conductors 11 and suppresses common-mode noise, resulting in improved noise immunity of the signal cable 10. Additionally, the signal cable 10 exhibits improved bending resistance and is less susceptible to changes in transmission characteristics, such as the characteristic impedance, when bent.

[0024] The conductors 11 contained in the signal cable 10 can be made of any conductive material. Suitable examples include metallic materials such as copper, copper alloy, aluminum, and aluminum alloy. Alternatively, the conductors 11 can each consist of a solid cable. However, with regard to machinability during the twisting of a two-core integrated cable and the bending flexibility of the signal cable 10, the conductors 11 are preferably each formed as a twisted wire (strand) obtained by twisting several individual wires 11a together. In this case, after twisting the several individual wires 11a together, compression molding can be carried out to form a compressed twisted cable, as shown in [reference]. Fig.Figure 2 shows that the multiple individual wires 11a forming the conductor 11 can all be the same type of individual wire, or they can comprise two or more types of individual wires. There is no particular restriction regarding the size of the conductors 11, and this can be, for example, at least 0.01 mm in diameter, depending on their suitability as communication cables. 2 and up to 0.22 mm 2 be.

[0025] Furthermore, there are no particular restrictions regarding the material of which the insulating coating 12 is made, and various organic polymers can be used to form the insulating coating 12. Examples of organic polymers that form the insulating coating 12 include polyolefins, such as polyethylene and polypropylene; halogenated polymers, such as polyvinyl chloride; engineering plastics, such as polystyrene, polytetrafluoroethylene, and polyphenylene sulfide; various elastomers; and rubber. It is possible to use only one type of organic polymer, or two or more types of organic polymers can be combined by mixing, laminating, or other processes. The organic polymer can be cross-linked or foamed. The insulating coating 12 may optionally contain additives, such as a flame retardant, in addition to the organic polymer.

[0026] The thickness of the insulating coating 12 of the signal cable 10 is not subject to any particular restriction, but may, for example, be at least 0.1 mm and 0.3 mm or less at locations other than those between the conductors 11. The insulating coating 12 of the signal cable 10 has a section covering the outer circumference of one conductor 11 and a section covering the outer circumference of the other conductor 11. The insulating coating 12 can have any shape and be formed by any method, as long as its two sections are continuous with each other.For example, a two-core integrated cable can be formed by a method in which two insulated cables, each having an insulating coating that completely covers the outer circumference of a single conductor 11, are arranged side by side and brought into contact with each other, and the contact points of these two insulated cables are fused together. However, with regard to the structural stability of the signal cable 10, a configuration is preferred in which a coating material is integrally extruded to fill both the area between the two conductors of a conductor pair 11, which are arranged parallel to each other, and the outer circumference of the same, thus forming an insulating coating 12.

[0027] There is no particular restriction regarding the overall shape of the signal cable 10, but as shown in the cross-sectional view of Fig.As shown in Figure 2, it is preferable that the outer circumferential surface of the insulating coating 12 has a region that is substantially arcuate and reflects the shape of the conductors 11, which have a substantially circular cross-section. More precisely, it is preferable that, in cross-section, the outer edges of the insulating coating 12 are substantially arcuate, except in the positions between the two conductors 11, with the upper and lower outer edges of the insulating coating 12 having sections with an inwardly tapered shape (10a in the figure) at the point between the two conductors 11. The provision of these tapered sections 10a facilitates the twisting of the signal cable 10, which is configured as a two-core integrated cable.There is no particular restriction regarding the twist length of the signal cable 10, and this can be, for example, at least 5 mm and up to 50 mm with regard to its suitability as a communication cable.

[0028] The communication cable 1 further comprises a sheath 20, which serves as a covering element that covers the outer circumference of the signal cable 10. The sheath 20 covers the entire outer circumference of the signal cable 10. Preferably, the sheath 20 is in close contact (or surface contact) with the entire outer circumference of the signal cable 10, except for those points where gaps are unavoidably created between the signal cable 10 and the sheath 20.

[0029] There is no particular restriction regarding the material of which the sheathing 20 is made, and materials similar to those mentioned above for the insulating coating 12 of the signal cable 10 can be used. That is, the sheathing 20 can be made of an organic polymer, which includes, for example, polyolefins such as polyethylene and polypropylene, halogenated polymers such as polyvinyl chloride, engineering plastics such as polystyrene, polytetrafluoroethylene, and polyphenylene sulfide, various elastomers, and rubber. It is possible to use only one type of organic polymer, but two or more types of organic polymers can also be used together by mixing, laminating, or other processes. The organic polymers can be cross-linked or foamed. The sheathing 20 can optionally contain additives in addition to the organic polymer, such as…a flame retardant is included. As described above, preferably no further component is provided between the signal cable 10 and the sheathing 20. However, a configuration is also preferred in which a separating agent containing an inorganic powder material, such as talc, is arranged around the outer circumference of the signal cable 10 and forms the sheathing 20.

[0030] The outer circumferential surface of the sheathing 20 exhibits a high degree of smoothness. More precisely, among the various outer circumferential surface sections of the sheathing 20, a surface section extending in the arrangement direction (lateral direction) of the conductor pair 11 exhibits a higher degree of smoothness than the outer circumferential surface of the signal cable 10. That is, in cross-section, the smoothness of the upper and lower outer edges of the sheathing 20 is greater than the smoothness of the upper and lower outer edges of the signal cable 10 located within the sheathing 20. In other words, the height difference at the outer edges of the upper and lower outer edges of the sheathing 20 is less than that of the upper and lower outer edges of the signal cable 10. As described above, the narrowed sections 10a on the outer circumference of the signal cable 10 are formed at the points between the two conductors 11.The outer circumferential surface of the sheathing 20, however, does not exhibit any irregularity, such as a structure where the upper and lower edges are tapered inwards, or exhibits only irregularities that are shallower or smaller than those in the tapered sections 10a of the signal cable 10. There is no particular restriction regarding the specific degree of smoothness of the outer circumferential surface of the sheathing 20. However, it is desirable that the height differences in the upper and lower outer edges of the sheathing 20 in cross-section (i.e., the distance in the vertical direction between the outermost and innermost points of the outer edges) do not exceed 30% of the height differences in the upper and lower outer edges of the signal cable 10. Furthermore, the height differences in the upper and lower outer edges of the sheathing 20 in cross-section preferably do not exceed 10% of the height (dimension in the vertical direction) of the signal cable 10.The outer circumferential surface of the casing 20 is preferably as smooth as possible, and no particular lower limit is specified for it.

[0031] Due to the high smoothness of the upper and lower outer circumferential surfaces of the sheath 20, it is easier to ensure a larger contact area between the communication cable 1 and the surface of an external element, such as a substrate 30, than in cases where the sheath 20 is not provided around the signal cable 10 or where the smoothness of the outer circumferential surface of the sheath 20 is low, as will be described in detail later with regard to the cable bundle 3. Furthermore, when attaching the communication cable 1 to such an external element, it is possible to improve the strength and stability of the attachment at the contact points. Additionally, the communication cable 1 can be attached with high uniformity at the respective points near the two conductors 11, thus making it easier to maintain symmetry between the two conductors 11.Due to the strength, stability, and uniformity of the fastening, the twisted structure of the signal cable 10 is less likely to loosen, even when the communication cable 1 is attached to an external element. As a result, it is possible to maintain stable transmission characteristics, such as the characteristic impedance, of the communication cable 1 and to achieve high noise immunity. The presence of the sheath 20 around the signal cable 10 already suppresses loosening of the twisted structure of the signal cable 10, but since this sheath 20 has a smooth outer surface, loosening of the signal cable 10 is also very effectively suppressed when the communication cable 1 is attached to an external element.

[0032] As described above, there is no particular restriction regarding the specific thickness or shape of the sheathing 20, as long as the sheathing 20 has an outer circumferential shape in which its upper and lower outer circumferential surfaces are smoother than the upper and lower surfaces of the signal cable 10. However, considering the role of the sheathing 20, such as to achieve a smooth outer circumferential surface for the entire communication cable 1, the average thickness is preferably at least 0.1 mm. Conversely, to save space for the communication cable 1, the average thickness is preferably at most 0.5 mm.The shape of the sheathing 20 is preferably such that the outer edges of the sheathing 20 have sides in cross-section that extend in the arrangement direction; that is, the upper and lower outer edges of the sheathing 20, in particular the lower outer edge, extend linearly along the lateral direction. Furthermore, the upper and lower outer edges are preferably parallel to each other. Thus, the fact that the upper and lower outer edges of the sheathing 20 extend linearly in cross-section along the lateral direction means that the outer circumferential surface of the sheathing 20 has a surface that can be approximated as a flat plane along the arrangement direction of the conductors 11, thereby improving the effectiveness of the smoothness of the sheathing 20, such as improving its attachment to external elements. More precisely, the cross-sectional shape of the sheathing 20, as shown in [reference], has the following characteristics: Fig.Figure 2 shows, preferably a rectangular outer shape or an outer shape obtained by rounding the corners of a rectangle (i.e., a rounded outer shape). This makes it possible to clearly define the distance between adjacent cables by the length of the sides of the rectangle when arranging the communication cable 1 alongside other cables (including cables of the same type as the communication cable 1) in the cable bundle 3, which is described next. Cable harness configuration

[0033] The following describes a cable harness according to an embodiment of the present disclosure. Fig. Figure 4 shows a top view of a cable harness 3 according to an embodiment of the present disclosure. Furthermore, it shows Fig. 5 a point of the cable bundle 3 where the communication cable 1 is located, in a cross-section that is perpendicular to the axial direction of the communication cable 1. Furthermore, in Fig. 4, as in Fig. 1, the sheathing 20 of the communication cable 1 removed at one end.

[0034] The cable assembly 3 according to the present embodiment comprises the communication cable 1 described above according to the embodiment of the present disclosure, as well as a substrate 30. The communication cable 1 is attached to the substrate 30 with a surface extending in the arrangement direction (lateral direction) of the conductors 11, more precisely with its lower surface. The cable assembly 3 can comprise one or more communication cables 1 according to the embodiment of the present disclosure. In the Fig.In the configuration shown in Figure 4, the cable harness 3 comprises two communication cables 1. The cable harness 3 may also include other cables 5 in addition to the communication cable 1, according to the embodiment of this disclosure. If the cable harness 3 comprises several cables 1 and 5 that include the communication cable 1 of this disclosure, these cables 1 and 5 are preferably arranged parallel to the axial direction and attached to the common substrate 30.

[0035] There is no particular restriction regarding the type of substrate 30, as long as it is an element having a surface to which the communication cable 1 and, optionally, the other types of cables 5 can be guided and attached. However, with regard to the routing of the cable bundle 3, the substrate 30 preferably consists of a planar element, that is, a flexible flat or planar element. The planar element can be a textile material, such as a woven, nonwoven, or knitted fabric, a plastic sheet, or the like. There is no particular restriction regarding the method for attaching the cables 1 and 5, which comprise the communication cable 1, to the substrate 30, and examples of the method include hot melt bonding, sewing, bonding using adhesives or bonding agents, and fastening using a fastener, such as a clip.Among these methods, hot melt adhesive bonding is preferably used to fasten the communication cable 1, considering the reliability of the fastening, space saving, the minimal number of components required for fastening, and the like. If a nonwoven fabric is used for the substrate 30, the communication cable 1 can be easily and securely fastened by hot melt adhesive bonding. It should be noted that when the communication cable 1 is attached to the nonwoven fabric by hot melt adhesive bonding, the communication cable 1 can penetrate deep into the surface of the nonwoven fabric and come into contact with it during the melting process.However, in order to avoid impairing the properties of the substrate 30 and to increase the effect of improving the fastening strength using the sheathing 20, it is preferable to limit the contact depth, i.e. the length by which the contact between the communication cable 1 and the substrate 30 penetrates relative to the surrounding surface of the substrate 30, to a maximum of 10% of the thickness of the sheathing 20 or up to 0.02 mm.

[0036] There is no particular restriction regarding the material from which the substrate 30 is formed, but if hot melt adhesive bonding is used to attach the communication cable 1, the sheathing 20 of the communication cable 1 and the substrate 30 preferably contain the same type of organic polymers. Here, "containing the same type of organic polymers" means that the organic polymers contained in the respective materials comprise the same type of monomer units. Preferably, the organic polymer forming the substrate 30 is the same as the organic polymer forming the sheathing 20 of the communication cable 1. Thus, it is easier to improve the strength of the attachment between the communication cable 1 and the substrate 30 by hot melt adhesive bonding. Furthermore, migration of additives, such as...Plasticizers migrate between the substrate 30 and the sheath 20 of the communication cable 1 via the hot melt adhesive section because identical or similar additives are frequently used with the same type of organic polymer. Therefore, material degradation associated with such migration is less likely. A suitable example is a configuration in which polyvinyl chloride (PVC) is used for both the organic polymer forming the substrate 30 and the organic polymer forming the sheath 20 of the communication cable 1. In many cases, plasticizers are added to PVC, but when both the substrate 30 and the sheath 20 are made of PVC containing plasticizers, plasticizer migration through the hot melt adhesive section is less likely.

[0037] As described above, in the cable assembly 3 of the present embodiment, the communication cable 1, in which the sheathing 20, the lower surface of which has a higher degree of smoothness than that of the signal cable 10, is provided on the outer circumference of the signal cable 10, is brought into contact with the substrate 30 and attached to it. Since the lower surface of the sheathing 20 has a high degree of smoothness, the communication cable 1 is thus brought into contact with and attached to the substrate 30 over a larger area than in cases where a signal cable 10, whose outer circumference is not covered by the sheathing 20, is attached directly to the substrate 30 or where the smoothness of the lower surface of the sheathing 20 is lower.In particular, if the lower surface of the sheathing 20 is designed as a flat plane, the entire lower surface can be brought into contact with the surface of the substrate 30 and attached to it. This results in a cable harness 3 in which the signal cable 10 is firmly attached to the substrate 30 over a large area. Consequently, even if, for example, the cable harness 3 is bent and used, or used for an extended period of time, it is possible to maintain the stable condition in which the signal cable 10 is attached to the substrate 30.

[0038] If the signal cable 10 is attached directly to the substrate 30 without being covered by the sheath 20, it is difficult to ensure a large contact area between the signal cable 10 and the substrate 30, since a surface with low smoothness, exhibiting the narrowed section 10a, is exposed as the outer circumferential surface of the signal cable 10. This is due to the conductors 11 having an essentially circular cross-sectional shape, as described above. Consequently, if, for example, the cable is used in a bent form or for an extended period of time, the twisted structure of the signal cable 10 gradually loosens. Additionally, in a case such as in Fig.Figure 6 shows that the signal cable 10 is attached to the substrate 30 under only one of the two conductors 11 (the left conductor 11 in the figure), whereas the signal cable 10 is not attached to the substrate 30 under the other conductor 11 or is attached with a lesser fastening strength. In this case, at least one section of the communication cable is slightly exposed in the axial direction to a condition in which the fixed points and / or the fastening strengths are not uniform between the two conductors 11 relative to the respective conductor 11. When such a condition occurs, the twisted structure of the signal cable 10 gradually loosens. Furthermore, the symmetry between the two conductors 11 deteriorates slightly. As the twisted structure of the signal cable 10 loosens, the conductor spacing between the two conductors 11 can change, and the transmission characteristics, such as the characteristic impedance, of the signal cable 10 can become unstable.Furthermore, if the symmetry between the two conductors 11 deteriorates, the common-mode noise may increase and the noise immunity may decrease.

[0039] In contrast, in the cable assembly 3 according to the present embodiment, the communication cable 1 is formed by covering the outer circumference of the signal cable 10 with the sheathing 20, and the communication cable 1 is firmly attached to the substrate 30 using the smooth outer surface of the sheathing 20. Therefore, the twisted structure of the signal cable 10 is less likely to loosen, even if the cable assembly 3 is used in a bent position for an extended period. This ensures that the conductor spacing between the two conductors 11 remains stable, and the symmetry between the two conductors 11 is also maintained to a high degree.The signal cable 10 has a structure obtained by twisting a two-core integrated cable, and therefore the conductor spacing of the two conductors 11 and the symmetry between the two conductors 11 are advantageously maintained as characteristic properties of the signal cable 10 itself. By forming the sheath 20 and attaching it to the substrate 30 using the smooth surface of this sheath 20, the characteristic properties of the signal cable 10 can be effectively used as characteristic properties of the cable bundle 3. By stably maintaining the conductor spacing of the two conductors 11, it is possible to keep the transmission properties, such as the characteristic impedance, of the communication cable 1 stable.Furthermore, by maintaining a high level of symmetry between the two conductors 11, common-mode noise is less likely to occur, and high noise immunity can be achieved. Estimation of the fastening strength of the communication cable

[0040] The change in the fastening strength of the communication cables to the substrate 30 with and without the sheathing 20 is estimated by calculation. For this estimation, models were used whose cross-sectional views are shown in Fig. 7A and Fig.Figure 7B shows the signal cable 10 being obtained by arranging two conductors 11 with circular cross-sections and conductor cross-sectional areas of 0.05 mm² or 0.13 mm² side by side and providing an insulating coating 12 over the outer circumferences of the conductors 11. The distance between the conductors 11 was set to 0.35 mm, and the thickness of the insulating coating 12 was set to 0.2 mm in the areas outside the area between the conductors. In the model without the [missing information] Fig. In the sheathing shown in 7A, the signal cable 10 was used directly as a communication cable. In the model with a Fig.In contrast, in the sheathing shown in Figure 7B, the sheathing 20 was arranged on and under the signal cable 10, thus forming the communication cable. The sheathing 20 actually surrounds the entire outer circumference of the signal cable 10; however, here it is only arranged on and under the signal cable 10 to simplify the model. More precisely, a structure was used in which the narrowed sections on and under the signal cable 10 were filled with the sheathing 20, so that the outer edge of the sheathing 20 forms a tangent to the signal cable 10.

[0041] Models were created in which communication cables of the two types described above were each attached to the substrate 30 with their lower surface. That is, the substrate 30, which is assumed to be a nonwoven fabric, was positioned beneath the respective communication cable and brought into contact with it at a contact depth of 0.01 mm. Then, as indicated by the thick lines in the figures, the length of the contact points where the substrate 30 and the surface of the communication cable came into contact was geometrically calculated as the contact distance. The contact depth of 0.01 mm is close to the contact depths that were actually measured when conventional insulated cables with a substantially circular cross-section were fused to a nonwoven fabric.When calculating the contact distance, the contact points indicated by the thick lines in the figures were classified into straight and curved sections. The curved sections were approximated as elliptical arcs, and their lengths were calculated.

[0042] Furthermore, the bond strength between the communication cable and the substrate 30 was estimated for each model. The bond strength for the unshielded model with a conductor cross-sectional area of ​​0.05 mm² was set to 1, and the bond strength for each configuration was estimated to be proportional to the contact spacing. The fact that the contact spacing and the bond strength are proportional to each other was confirmed by tests in which the bond strength was actually measured by varying the conductor cross-sectional area in a configuration where conventional insulated cables with a substantially circular cross-section were fused to a nonwoven fabric.

[0043] The following Table 1 summarizes the conductor cross-sectional area and calculated values ​​of the contact spacing and the fastening thickness for both cases, i.e. the case where the communication cable is not provided with the sheathing 20 and the case where the communication cable is provided with the sheathing 20. [Table 1] Is there a casing? Conductor size (mm) 2 ) Contact gap (mm) fastening thickness Without casing 0,05 0,32 1,00 0,13 0,37 1,16 With sheathing 0,05 0,55 1,72 0,13 0,97 3,03

[0044] Table 1 confirms that providing the sheath 20 for all conductor cross-sectional areas increases the contact area between the communication cable and the substrate 30, as well as the fastening strength, compared to cases where the sheath 20 is not provided. Compared to the case where no sheath 20 is provided, the fastening strength when the sheath 20 is provided is [value missing] for a conductor cross-sectional area of ​​0.05 mm². 2 1.7 times larger and with a conductor cross-sectional area of ​​0.13 mm² 22.6 times larger. If the sheathing 20 is provided, the fastening strength increases the larger the conductor cross-sectional area.

[0045] The present invention is not limited to the embodiment described above, and various modifications are possible without departing from the idea of ​​the present invention. REFERENCE MARK LIST 1 communication cable 10 signal cables (two-core integrated cable) 10a Narrowed section 11 leaders 11a Single wire 12 Insulating coating 20 Sheathing 3 Cable harness 30 substrate 5 Other types of wire QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2018 - 196 174 A

[0003] JP S60 - 123920 U

[0003] JP 2003 - 36739 A

[0003] JP 2015 - 191877 A

[0003]

Claims

[1] Communication cable, comprising: a signal cable with a conductor pair and an insulating coating that covers the outer circumferences of both conductors of the conductor pair together; and a sheath that covers the outer circumference of the signal cable, wherein the signal cable is obtained by twisting an arrangement with the conductor pair and the insulating coating as a whole, such that the two conductors cross in a spiral shape, with the insulating coating arranged between them, and an outer circumferential surface of the sheathing, extending in an arrangement direction along which the two conductors are arranged side by side, has a higher surface smoothness than an outer circumferential surface of the signal cable. [2] Communication cable according to claim 1, wherein in a cross-section of the communication cable which is cut perpendicular to an axial direction, an outer edge of the sheathing has a side which extends in the arrangement direction. [3] Communication cable according to claim 2, wherein in a cross-section of the communication cable which is cut perpendicular to the axial direction, the sheathing has a rectangular outer shape or an outer shape obtained by rounding the corners of a rectangle. [4] Cable bundle, comprising: the communication cable according to one of claims 1 to 3; and a substrate, wherein the communication cable is attached to the substrate with a surface extending along the direction of arrangement. [5] Cable bundle according to claim 4, wherein the substrate is made of a nonwoven fabric and the communication cable is attached to the substrate by hot melt bonding. [6] Cable string according to claim 4, wherein the substrate and the sheathing contain the same type of organic polymer and are fused together.

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