HK1151128A - Multilayer cable jacket - Google Patents

Description

Multi-layer cable sheath

Background

Communication cables typically include an outer protective jacket to protect the cable internals from external contamination and/or forces. For example, a typical coaxial cable includes a center conductor surrounded by an insulator, an outer conductor, and an outer protective jacket. Some protective jackets are made of a relatively rigid material to protect the internal components of the cable. Cables with rigid protective jackets are very useful when the cable is installed outdoors, either in the air or underground, because such jackets can provide additional protection.

Unfortunately, the rigidity of the outer sheath causes a number of problems. For example, coaxial cables with rigid jackets are difficult to terminate with typical cable connectors. Typical cable connectors use a post (or similar structure) that must slide under the sheath and thereby expand the sheath to ensure its proper installation. Rigid sheaths require a significant insertion force to fully and properly insert the post beneath the sheath. Further, because the plastic becomes more rigid when exposed to low temperatures, the required insertion force values increase with any decrease in the cable's ambient temperature. Therefore, it is very difficult, if not impossible, to mount a typical cable connector on a cable including a rigid sheath at low temperatures.

Disclosure of Invention

In general, exemplary embodiments of the present invention relate to a multi-layer cable jacket for protecting cable internals. Moreover, the disclosed embodiments provide a multi-layer cable jacket that can reduce the insertion force values required to fully insert the posts of a typical cable connector under the jacket, even when the cable is exposed to low temperature environments.

In one exemplary embodiment, the cable includes one or more inner members, a multi-layer jacket surrounding the one or more inner members. The one or more internal components include at least one electrical conductor configured for propagating a signal. However, other multi-layer constructions may be utilized, and in the disclosed embodiments the multi-layer jacket includes an inner layer surrounded by an outer layer. The inner layer is composed of a material or combination of materials, the material of the inner layer having a relatively low stiffness compared to the material of the outer layer. The advantages of using a multilayer jacket are present in many respects. In particular, the ability to provide a jacket with a less rigid inner layer provides a jacket that easily accommodates the posts of a cable connector, thereby reducing the insertion force values required to install the connector, even in low temperature environments. At the same time, the outer layer having the greater rigidity may provide sufficient protection for the inner components of the cable.

In another exemplary embodiment, a method of making a cable having one or more internal components is disclosed. First, one or more inner components are surrounded with an inner jacket layer. The one or more internal components include at least one electrical conductor configured for propagating a signal. The inner jacket layer is then surrounded by an outer jacket layer. The inner jacket layer is made of one or more materials that have a relatively low stiffness compared to the material used to construct the outer jacket layer.

In yet another exemplary embodiment, a method of manufacturing a coaxial cable is disclosed. In the disclosed embodiment, the center conductor is surrounded by an insulator. The center conductor is configured for propagating a signal; next, the insulator is surrounded by an outer conductor. The inner jacket layer is then extruded onto the outer conductor. Finally, the outer jacket layer is extruded onto the inner jacket layer. Also, the inner jacket layer is constructed of one or more materials, and the material of the inner jacket layer has a relatively low stiffness compared to the material used to make the outer jacket layer.

The disclosed embodiments each have a number of potential advantages. For example, each of the disclosed embodiments provides an outer jacket to protect the inner components of the cable from external contamination and forces. In addition, the disclosed embodiments address key issues in the prior art, including providing the ability to make a cable connector (or similar component) easier to install due to a reduced force required to fully insert the post (even in low temperature environments).

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential characteristics of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. Additionally, it is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

Drawings

Aspects of the exemplary embodiments of the present invention will become apparent by consideration of the following detailed description of the exemplary embodiments in conjunction with the accompanying drawings.

FIG. 1A is a perspective view of an exemplary coaxial cable terminated with two exemplary connectors;

FIG. 1B is a cross-sectional view of the exemplary coaxial cable of FIG. 1A;

FIG. 1C is a partial perspective view of the coaxial cable of FIG. 1A, with portions of each layer broken away;

FIG. 1D is a further cross-sectional view of the exemplary coaxial cable of FIG. 1A and a cross-sectional view of the exemplary connector;

fig. 2 is a flow chart of an example method of making the example coaxial cable of fig. 1A.

Detailed Description

Exemplary embodiments of the present invention relate to a multi-layer cable jacket. In the following detailed description of some exemplary embodiments, reference will now be made in detail to specific embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and structural, logical, and electrical changes may be made without departing from the scope of the present invention. In addition, it is to be understood that the various embodiments of the invention, although different, are not necessarily mutually exclusive. For example, a particular feature, structure, or characteristic described in connection with one embodiment may be included within other embodiments. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled.

Ⅰ.Exemplary coaxial Cable

Referring initially to fig. 1A, an exemplary coaxial cable 100 is disclosed. The exemplary coaxial cable 100 may be any type of coaxial cable including, but not limited to, 50 ohm and 75 ohm coaxial cables. As shown in fig. 1A, exemplary coaxial cable 100 is terminated to either end of connector 150. Although connector 150 shown in fig. 1A is an F-type female connector, it should be understood that cable 100 may also be terminated with other types of female and/or male connectors (not shown). Further, while the exemplary embodiments are described in the context of coaxial cables and connectors, it should be understood that other types of cables and/or cable components may be employed.

Referring to fig. 1B and 1C, a coaxial cable generally includes a center conductor 102 surrounded by an insulator 104, an outer conductor 106 surrounding the insulator, and a multi-layer jacket 108 surrounding the outer conductor 106. As shown in fig. 1B and 1C, the multi-layer jacket 108 generally includes an inner layer 110 surrounded by an outer layer 112. As used herein, the phrase "enclosed" refers to an inner layer substantially surrounded by an outer layer. However, it should be understood that the inner layer may be "surrounded" by the outer layer, but the inner layer is not directly adjacent to the outer layer. Thus, the term "enclosed" allows for the possibility of an intervening layer. Each of these components of the exemplary coaxial cable 100 will now be described in turn.

The center conductor 102 is disposed in the center of the exemplary coaxial cable 100. The center conductor 102 is configured to carry a range of currents (amps) and to carry RF/electronic digital signals. In certain exemplary embodiments, the center conductor 102 is made of solid copper, Copper Clad Aluminum (CCA), Copper Clad Steel (CCS), or silver plated copper clad steel (SCCCS), although other conductive materials are possible. For example, the center conductor 102 may be made of any conductive metal or alloy. Additionally, the center conductor 102 may be, for example, solid, hollow, stranded, corrugated, plated, or clad.

Insulator 104 surrounds center conductor 102 and generally serves to support and isolate center conductor 102 and outer conductor 106. Although not shown in the drawings, an adhesive, such as a polymer, may be used to bond the insulator 104 to the center conductor 102. In certain exemplary embodiments, the insulator 104 may be tape-like, solid or foamed polymer or fluoropolymer, but is not so limited. For example, the insulator 104 may be foamed Polyethylene (PE).

The outer conductor 106 surrounds the insulator 104 and generally serves to minimize Radio Frequency (RF) signals entering the center conductor 102 or emanating from the center conductor 102. Although the outer conductor 106 shown in fig. 1B and 1C constitutes a tape layer and a braid, it should be understood that the outer conductor 106 may in fact consist of only one layer or more than two layers.

For example, the outer conductor 106 may include one or more layers of tape that shield high frequency RF signals and may also include one or more braids for shielding low frequency RF signals. The tape layer may include, but is not limited to, the following layers: for example, aluminum/polymer/binder, aluminum/polymer/aluminum/binder, aluminum/polymer, or aluminum/polymer/aluminum. However, it should be understood that the belts described herein are not limited to belts having any particular combination of layers. The braid may be comprised of, for example, interwoven, fine gauge aluminum or copper wires, such as 34 American Wire Gauge (AWG). However, it should be understood that the braid discussed herein is not limited to braids made from any particular type or size of wire. Each of the tape layers and/or braid may enhance the shielding of the outer conductor 106 from high or low frequency RF signals.

The multi-layer jacket 108 surrounds the insulator 104 and generally serves to protect the internal components of the coaxial cable 100 from external contaminants such as dust, moisture, and oil. In a typical embodiment, the jacket 108 may also serve to limit the bend radius of the cable to prevent kinking, while serving to protect the cable (and its internal components) from crushing or other deformation caused by external forces. As noted elsewhere herein, the example multi-layer jacket 108 generally includes an inner layer 110 surrounded by an outer layer 112. In addition, inner layer 110 is made of a material that is relatively less rigid than the material comprising outer layer 112.

For example, the outer layer 112 may be made of a relatively rigid material, such as, but not limited to: polyethylene (PE), High Density Polyethylene (HDPE), Low Density Polyethylene (LDPE), or Linear Low Density Polyethylene (LLDPE), or some combination thereof. The actual materials used may depend on the particular application/environment. For example, the relatively high stiffness and hardness of PE suggests that the material can be used in coaxial cables laid underground or outdoors in the air because of its tensile strength, impact resistance, crush resistance, compression resistance, abrasion resistance, and relatively low cost. These characteristics of PE make the material used as the jacket superior in performance to softer materials such as rubber polyvinyl chloride (PVC). However, as previously mentioned, sheaths made entirely of rigid, substantially incompressible material (e.g., PE) often require significant insertion force values to allow the post of a cable connector (or the like) to be fully inserted beneath the sheath.

For this reason, the inner layer 112 is made of a relatively less rigid and more flexible material, such as, but not limited to: foamed PE, polyvinyl chloride (PVC) or Polyurethane (PU), or some combination thereof. The relative flexibility of the inner layer 110 as compared to the outer layer 112 may reduce the amount of insertion force required to fully insert the post of the cable connector under the multi-layer jacket 108.

Referring now to fig. 1D, an end of a coaxial cable 100 terminated with a cable connector 150 is disclosed. As shown in fig. 1D, during installation, the post 152 of the cable connector 150 slides under the multi-layer jacket 108. It should be appreciated that the post 152 is slid further below the outer conductor 106 as shown in fig. 1D. Alternatively, the post 152 may be slid under one or more layers of the multi-layer outer conductor, such as the braid, instead of sliding onto one or more layers of the multi-layer outer conductor, such as the tape layer.

The relatively soft inner layer 110 causes the inner layer 110 to compress and thereby accommodate the shape of the post 152. In this manner, the post 152 may be fully inserted under the multi-layer sheath 108 with less insertion force than would be used to fully insert the post 152 under a single layer sheath made entirely of substantially the same material as the substantially incompressible material of the rigid outer layer 112.

Further, the relatively soft inner layer 110 is particularly advantageous in a low temperature environment. For example, although it may be difficult or impossible to mount the cable connector 150 to a rigid single-layer jacketed cable at low temperatures, the insertion force required is greatly reduced by the adaptable, compressible inner layer 110, such that the cable connector 150 may be relatively easily mounted to the exemplary coaxial cable 100 at low temperatures. Thus, the cable connector 150 can be installed onto the exemplary coaxial cable 100 at cryogenic temperatures, which was previously very difficult or even impossible with coaxial cables having only a rigid single layer jacket. At the same time, the relatively rigid outer layer 112 provides the necessary protection for the inner components of the coaxial cable 100.

One advantage of the design of the multi-layer jacketed cable 100 can be seen below by comparing the estimate of the required connector insertion force for a rigid single-layer jacketed cable with the estimate of the required connector insertion force for the exemplary multi-layer jacketed cable 100. The connector insertion force of the cable can be estimated by the tensile strength of the jacket and the area of material that will attempt to displace the jacket material. For example, area A of braided wires in a rigid single layer jacketed cable or in the outer conductor 106 of the example cable 100_BIt can be calculated as follows:

similarly, the area a of the connector post 152 of the cable connector 150_CPIt can be calculated as follows:

then the two areas a_BAnd A_CPInsertion force F that may be used to attach connector post 152 to a rigid single layer LDPE jacket cable_IEAThe estimation is carried out as follows:

F_IEA＝T_J×(A_B+A_CP) 2000 x (0.0021+0.0400) 84.2 lbs (3)

Similarly, the insertion force F required to attach the connector post 152 to the exemplary multi-layer jacketed cable 100 may be estimated as follows_IPAThe multi-layer jacketed cable 100 has a relatively soft inner layer 110 made of foamed LDPE:

F_IPA＝T_FJ×(A_B+A_CP) 757 x (0.0021+0.0400) 31.9 lbs (4)

The above calculations and estimations are based on the following assumptions:

T_JLDPE sheath tensile strength of 2,000 pounds per square inch

T_FJTensile strength of 757 pounds per square inch for foamed LDPE

D_B0.0063 inch diameter of braided wire

B_NENumber of braided ends per cable 68

D_CPConnector terminal diameter of 0.225 inch

Thus, in at least one exemplary embodiment, the insertion force F required to attach the connector post 152 to the exemplary cable 100_IPA(31.9 lbs.) of insertion force F required to attach the same connecting stud 152 to a rigid single layer jacketed cable_IEA(84.2 lbs.) 52.3 lbs. It is due to the multi-layer design of the relatively soft inner layer 110 and the relatively rigid outer layer 112 of the example cable 100 that the insertion force required is reduced.

Although the multi-layer jacket 108 described herein generally includes a single inner layer 110 surrounded by a single outer layer 112, it should be understood that the multi-layer jacket 108 may in fact be comprised of more than two layers, so long as the multi-layer jacket 108 includes at least one relatively soft inner layer and one relatively rigid outer layer.

Ⅱ.Device for manufacturing coaxial cableExample method

With continuing reference to fig. 1B, 1C, and 2, an example method 200 of making an example coaxial cable is disclosed.

In step 202, the center conductor 102 is surrounded by an insulator 104. For example, the center conductor 102 may be conveyed through a first extruder where a pre-coat of an adhesive, such as a polymer, is applied. The precoated center conductor 102 may then be conveyed through a second extruder where an insulator 104 is applied to surround the center conductor 102. Alternatively, step 202 may be omitted entirely, wherein the center conductor 102 is already surrounded by the insulator 104 prior to performing the example method 200.

Next, in step 204, the insulator 104 is surrounded by the outer conductor 106. As previously described, the outer conductor 106 may be made of alternating layers of tape and/or braid. For example, the insulator 104 and the one or more components it surrounds may be conveyed through one or more winding operations, each winding operation winding a layer of tape around the insulator 104. Similarly, for example, each layer of tape may be conveyed through one or more braiding operations, each braiding operation braiding, or wrapping a layer of braid around each layer of tape. Alternatively, this step 204 may be omitted entirely, wherein the insulator 104 is already surrounded by the outer conductor 106 prior to performing the exemplary method 200.

[0034] Next, in step 206, the outer conductor 106 is surrounded by the inner layer 110 of the multi-layer jacket 108. For example, the outer conductor 106 and the components it surrounds may be conveyed through a third extruder where the inner layer 110 of the multi-layer jacket 108 is applied to surround the outer conductor 106.

Finally, in step 208, the inner layer 110 of the multi-layer jacket 108 is surrounded by the outer layer 112 of the multi-layer jacket 108. For example, the inner layer 110 and the components it surrounds may be conveyed through a fourth extruder where an outer layer 112 having a multi-layer jacket 108 is applied to surround the inner layer 110.

Thus, the example method 200 may be used to manufacture the example coaxial cable 100. As disclosed elsewhere herein, the positioning of the relatively soft inner layer 110 relative to the relatively rigid outer layer 112 makes termination of the coaxial cable 100 with the cable connector 150 easier, particularly in low temperature environments where the cable connector 150 is installed.

Ⅲ.Alternative embodiments

Although the exemplary embodiment is described in the context of a standard coaxial cable, it should be understood that other configurations of cables may likewise benefit from the multilayer jacket 108 described herein. For example, flooded (flooded) coaxial cables and/or self-supporting coaxial cables may also be configured to include a multilayer jacket. Additionally, while the example cable connector 150 described herein is configured as a standard F-type female connector, other connectors or cable components that include posts (or similar structures) that must slide under or otherwise mate with a cable jacket may similarly benefit from the multi-layer jacket 108 described herein.

Still further, while the discussion herein generally refers to coaxial cables, it is understood that other types of cables, such as other communications types of cables, may be constructed to include a multi-layer jacket incorporating the inventive concepts herein. Although the inner members of the exemplary coaxial cable 100 include a center conductor 102, an insulator 104, and an outer conductor 106, it should be understood that cables having other types of inner members may similarly benefit from the multi-layer jacket types claimed herein. In general, any cable having any combination of internal components that may be terminated with a connector (or similar component) that includes a post that must be slid under or otherwise mated with a cable jacket may similarly benefit from the inventive concepts described herein.

The exemplary embodiments described herein may be embodied in other specific forms. The exemplary embodiments described herein are to be considered in all respects only as illustrative and not restrictive.

Claims (20)

1. An electrical cable, comprising:

one or more internal components including at least one electrical conductor configured for propagating a signal; and

a multilayer sheath surrounding the one or more inner components, the multilayer sheath comprising an inner sheath layer surrounded by an outer sheath layer, wherein the inner sheath layer has a stiffness less than a stiffness of the outer sheath layer.

2. The cable of claim 1, wherein the at least one electrical conductor comprises a center conductor, and wherein the one or more inner members further comprise: an insulator surrounding the center conductor; and an outer conductor surrounding the insulator.

3. The cable of claim 1, wherein the outer jacket layer comprises Polyethylene (PE).

4. The cable of claim 1, wherein the outer jacket layer comprises High Density Polyethylene (HDPE), Low Density Polyethylene (LDPE), or Linear Low Density Polyethylene (LLDPE), or any combination thereof.

5. The cable of claim 1, wherein the inner jacket layer comprises foamed polyethylene.

6. The cable of claim 1, wherein the inner jacket layer comprises polyvinyl chloride (PVC).

7. The cable of claim 1, wherein the inner jacket layer comprises Polyurethane (PU).

8. A method of manufacturing a cable having one or more internal components, the method comprising the steps of:

surrounding one or more inner components with an inner jacket layer, the one or more inner components comprising at least one electrical conductor configured for propagating a signal; and

surrounding the inner jacket layer with an outer jacket layer, wherein the inner jacket layer has a stiffness less than a stiffness of the outer jacket layer.

9. The method of claim 8, wherein the at least one electrical conductor comprises a center conductor, and wherein the one or more inner members further comprise: an insulator surrounding the center conductor; and an outer conductor surrounding the insulator.

10. The method of claim 9, wherein the step of surrounding one or more inner components with an inner jacket layer comprises applying the inner jacket layer over the outer conductor with a first extruder.

11. The method of claim 10, wherein the step of surrounding one or more inner components with an outer jacket layer comprises applying the outer jacket layer over the inner jacket layer with a second extruder.

12. The method of claim 8, wherein the outer jacket layer comprises polyethylene.

13. The method of claim 8, wherein the outer jacket layer comprises high density polyethylene, low density polyethylene, or linear low density polyethylene, or any combination thereof.

14. The method of claim 8, wherein the inner jacket layer comprises foamed polyethylene.

15. The method of claim 8, wherein the inner jacket layer comprises polyvinyl chloride.

16. The method of claim 8, wherein the inner jacket layer comprises polyurethane.

17. A method of manufacturing a coaxial cable, the method comprising the steps of:

surrounding a center conductor with an insulator, the center conductor configured to propagate a signal;

surrounding the insulator with a tape layer;

surrounding the tape layer with a woven layer;

extruding an inner sheath layer on the woven layer; and

extruding an outer jacket layer over the inner jacket layer, wherein a rigidity of the inner jacket layer is less than a rigidity of the outer jacket layer.

18. The method of claim 17, wherein the outer jacket layer comprises polyethylene, high density polyethylene, low density polyethylene, or linear low density polyethylene, or any combination thereof.

19. The method of claim 17, wherein the inner jacket layer comprises foamed polyethylene, polyvinyl chloride, or a combination thereof.

20. The method of claim 17, wherein the outer jacket layer comprises polyethylene and the inner jacket layer comprises foamed polyethylene.