WO2014052325A1 - Coaxial cable connector, such as for use with leaky feeder communications systems, and methods therefor - Google Patents

Description

COAXIAL CABLE CONNECTOR, SUCH AS FOR USE WITH LEAKY FEEDER COMMUNICATIONS SYSTEMS, AND METHODS THEREFOR

BACKGROUND

[0001] Coaxial cable, or coax, has an inner conductor surrounded by a flexible, tubular insulating layer, surrounded by a conducting shield. The term coaxial comes from the inner conductor and the outer shield sharing a geometric axis. The ends of coaxial cables usually terminate with connectors. Coaxial connectors are designed to maintain a coaxial form across the connection and have the same well-defined impedance as the attached cable. Traditional coaxial connectors include multiple parts that are assembled and/or crimped onto the conductor and shield of the cable. The cable must first be prepared by stripping the layers of insulation in a particular fashion. Once the cable is prepared, the connector components are assembled to the cable often with small screws, seals, rings, and the like. Accordingly, installing such a connector is a tedious and error prone task.

[0002] Traditional coax connectors are particularly problematic in certain field applications. For example, a leaky feeder is a communications system used in underground mining and other tunnel environments. It consists of a coaxial cable run along tunnels which emits and receives radio waves, functioning as an extended antenna. The cable is "leaky" in that it has gaps or slots in its outer conductor to allow the radio signal to leak into or out of the cable along its entire length. Because of this leakage of signal, line amplifiers are required to be inserted at regular intervals, typically every 350 to 500 meters, to boost the signal back up to acceptable levels. Furthermore, because the cable is deployed in a mine tunnel, the cable is susceptible to damage and may require further splicing to effect repair of the leaky feeder system.

[0003] As can be appreciated a mining environment is not conducive to handling multiple small parts and trying to keep a cable clean while meticulously stripping a length of coaxial cable. Accordingly, there is a need for a coaxial connector with few parts and with minimal cable preparation requirements that is more suitable to field applications.

[0004] The need exists for a system that overcomes the above problems, as well as one that provides additional benefits. Overall, the examples herein of some prior or related systems and their associated limitations are intended to be illustrative and not exclusive. Other limitations of existing or prior systems will become apparent to those of skill in the art upon reading the following Detailed Description. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Non-limiting and non-exhaustive embodiments of the coaxial cable connector, including the preferred embodiment, are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various view unless otherwise specified.

[0006] FIG. 1 is an exploded perspective view of a coaxial connector according to a first exemplary embodiment;

[0007] FIG. 2 is an exploded side view of the coaxial connector shown in FIG. 1 ;

[0008] FIG. 3 is a side view in elevation of the coaxial connector shown in FIGS. 1 and 2;

[0009] FIG. 4 is a side view in cross section of the coaxial connector taken about line 4-4 in FIG. 3;

[0010] FIG. 5 is a side view in cross section of the coaxial connector shown in FIGS. 1-4 with a coaxial cable installed;

[0011] FIG. 6 is a side view in cross section of the coaxial connector illustrating the installation of a cable with a smaller conductor;

[0012] FIG. 7 is a flow chart illustrating the use of the coaxial connector as described herein;

[0013] FIG. 8 is an exploded side view of a coaxial connector according to an second exemplary embodiment;

[0014] FIG. 9 is a partial exploded side view of the coaxial connector shown in FIG. 8;

[0015] FIG. 10 is a partial exploded side view of the coaxial connector shown in FIGS. 8 and 9;

[0016] FIG. 1 1 is an end view of the double-ended collet shown in FIG. 8 as viewed from the insertion end;

[0017] FIG. 12 is an end view of the double-ended collet shown in FIG. 8 as viewed from the shoulder end; and

[0018] FIG. 13 is a top view of a portion of coaxial cable configured for insertion into a coaxial connector. [0019] Sizes of various depicted elements are not necessarily drawn to scale.

DETAILED DESCRIPTION

[0020] Various examples of the invention will now be described. The following description provides certain specific details for a thorough understanding and enabling description of these examples. One skilled in the relevant technology will understand, however, that the invention may be practiced without many of these details. Likewise, one skilled in the relevant technology will also understand that the invention may include many other obvious features not described in detail herein. Additionally, some well-known structures or functions may not be shown or described in detail below, to avoid unnecessarily obscuring the relevant descriptions of the various examples.

[0021] The terminology used below is to be interpreted in its broadest reasonable manner, even though it is being used in conjunction with a detailed description of certain specific examples of the invention. Indeed, certain terms may even be emphasized below; however, any terminology intended to be interpreted in any restricted manner will be overtly and specifically defined as such in this Detailed Description section.

[0022] With initial reference to FIGS. 1 and 2, the coaxial connector 20 is designed to quickly and efficiently connect with coaxial cable 10 and conductively interface with its center core conductor 8 and shield 4. In this case, coaxial connector 20 is used with a leaky feeder communications system 100. Coaxial connector 20 includes a connector fitting 40, clamping nut 30, and an adaptor assembly 50. Connector fitting 40 includes a mounting portion 42 with a shield collet 44 extending therefrom. The mounting portion 42 receives the adaptor assembly 50 that interfaces with the conductor ferrule 80.

[0023] With further reference to FIG. 3, it can be appreciated that the clamping nut 30 assembles onto the mounting portion 42 and over shield collet 44. Clamping nut 30 is sealed to the connector fitting 40 by an o-ring 24 which is inserted in o-ring groove 48 formed around the connector fitting 40. Clamping nut 30 is also sealed against the shield collet 44 by a compression seal 70 which also seals against the outer insulation 2 of coaxial cable 10. Washer 22 is disposed between compression seal 70 and clamping nut 30 in order to facilitate rotation of the clamping nut during installation. The o-ring 24 may be made of any suitable o-ring material depending on the application, such as for example, Buna-N or other elastomeric material. Compression seal 70 may be formed of a resilient material such as rubber or a suitable o-ring type material. [0024] Mounting portion 42 of the connector fitting 40 includes a bulk head fitting flange 402 and a corresponding threaded portion 408. Accordingly, the threaded portion 408 may be inserted into an enclosure 45, for example, and retained thereto with a nut 26. In this case, enclosure 45 may house a component of leaky feeder system 100. Mounting portion 42 may also include internal male threads 422 in order to facilitate the connection of conduit.

[0025] As shown in FIG. 4, connector fitting 40 includes a mounting portion 42 with a shield collet 44 extending therefrom. Shield collet 44 includes a pair of kerfs 46 cut into the collet to facilitate clamping the coaxial cable. Shield collet 44 includes a conical surface 410 configured to interface with a ramped surface 36 on clamping nut 30. Connector fitting 40 may comprise, for example, nickel plated brass, silver plated brass, or other conductive material. While shown in the figures as having two segments defined by kerfs 46, shield collet 44 may include additional kerfs and corresponding segments.

[0026] Clamping nut 30 includes ramped interior surface 36 which extends up to an annulus 38. Clamping nut 30 includes female threads 306 which are mateable with male threads 406 disposed on the mounting portion 42 of the connector fitting 40. It can be appreciated from the figure that as clamping nut 30 is threaded onto mounting portion 42, ramped interior surface 36 compresses conical surface 410 thereby causing the collet to squeeze against the components of coaxial cable 10. Shield collet 44 includes an interface region 420 which conductively interfaces with the shield 4 of the coaxial cable 10. Shield collet 44 also includes an interior barb 412 which is adapted to grasp the outer insulation 2 of the coaxial cable 10 as clamping nut 30 squeezes the collet. In order to facilitate installation of the nut it may be sized for easy grasping as shown. However, the nut may be shortened to approximately 2.25 inches, for example, to provide a more compact connector.

[0027] Shield collet 44 includes a secondary conical surface 414 which mates against secondary ramped surface 37 of clamping nut 30. Accordingly, as the clamping nut 30 is installed onto the shield collet 44 the barb 412 is urged against the coaxial cable insulation 2. Shield collet 44 also includes a compression taper 416 which is operative to engage a mating frustoconical surface 72 on the compression seal 70. Thus, as the clamping nut 30 is installed onto the connector fitting the compression taper 416 squeezes the compression seal 70 against the outer insulation 2 of the coaxial cable 10. Clamping nut 30 includes a shoulder 304 which abuts washer 22 thereby providing a clamping force against the components of the coaxial connector 20.

[0028] Coaxial cable 10 may be inserted into the coaxial connector 20 through cable aperture 32, which leads into an interior 34 of the connector. Annulus 38 is bounded axially by shoulder 302 formed in clamping nut 30 and shoulder 418 formed around the outside of shield collet 44. It can be appreciated that once initially installed onto the shield collet 44 the clamping nut 30 is thereafter retained on the connector fitting 40 by the interference between shoulders 302 and 418. Clamping nut 30 may be formed of plastic or metal, such as aluminum, steel, brass, or the like.

[0029] Mounting portion 42 is configured to receive insulator member 60. Insulator member 60 is in turn configured to receive the conductor ferrule 80 which connects to the adapter assembly 50. Insulation member 60 may be formed from a dielectric material such as PTFE, Nylon or Teflon. Spacer 23 is disposed between insulator member 60 and the adaptor assembly 50. Spacer 23 may be formed of plastic such as nylon. Conductor ferrule 80 includes a receptacle 82 with a conductor pin 84 extending therefrom (see FIG. 2). Receptacle 82 includes a pair of kerfs 86 to facilitate the insertion of the center core conductor 8 of the coaxial cable 10. In this case, the diameter of receptacle 82 is just slightly smaller than the center core conductor 8. The kerfs 86 allow receptacle 82 to flex to provide a friction fit between the receptacle 82 and the center core conductor 8. Conductor ferrule 80 may be formed of, for example, gold plated brass, silver plated brass, or other conductive material.

[0030] Conductor pin 84 extends through insulator member 60 and attaches to the adaptor assembly 50. Adaptor assembly 50 includes a printed circuit board (PCB) to which is attached a pigtail 52 and an optional miniaturized connector 54. Conductor pin 84 is conductively connected to the PCB 56. Conductor ferrule 80, insulator 60, and spacer 23 are retained in the mounting portion 42 by an internal retaining ring, or circlip 28. While one form of adaptor assembly 50 is shown and described, other possible connectors or plugs may be used to mechanically and electrically connect the coaxial cable 10 to another component via the coaxial connector 20.

[0031] With reference to FIG. 5, a description of the installation of coaxial cable 10 may be understood. As seen in the figure, cable 10 has been prepared for insertion into coaxial connector 20 by removing a portion of the cable such that approximately one quarter inch of the center core conductor 8 is exposed. The outer insulation 2 of cable 10 has also been stripped to expose approximately one half inch of the shielding 4. In order to expose the center core conductor 8 the outer insulation 2, shielding 4, and inner insulation 6 is removed. A suitable tool (not shown) can perform such as stripping. Although shown being fully tightened in FIG. 5, the clamping nut 30 would initially be loosened such that shoulders 302 and 418 are in close confronting relation. While shown as employing threads, connector fitting 40, and clamping nut 30 of the coaxial connector 20 may use other mechanical elements to allow a user to efficiently connect the coaxial connector to an end of a coaxial cable. Thus, while referred to as a clamping "nut" 30, the clamping nut may be more appropriated referred to as a clamping member, which may be manually and mechanically secured to the connector fitting 40.

[0032] With the connector 20 in the loosened state, cable 10 is inserted through aperture 34 and into connector 20. As coaxial cable 10 is inserted into the connector, center core conductor 8 is seated in receptacle 82, shielding 4 is received into the interface region 420, and outer insulation 2 is inserted through the interior barb 412 as well as through the compression seal 70. Once the cable is inserted, the clamping nut 30 is tightened such that the conductive region 420 interfaces with shielding 4, interior barb 412 grasps the outer insulation 2, and compression seal 70 expands onto outer insulation 2.

[0033] FIG. 6 illustrates that the coaxial connector 20 may be used on different sized coaxial cable. For example, in this case the cable 1 10 is a 75 ohm cable whereas cable 10 is a 50 ohm cable. While many of the components of the coaxial connector 20 may be used across different sized coaxial cables, the insulator member 160 as well as conductor ferrule 180, for example, may be scaled or resized in order to accommodate a different size conductor core 108 and corresponding insulation.

[0034] With reference to FIG. 7, a process 900 represents a method for installing a coaxial connector according to the technology described herein. At step 910 the coaxial connector 20 may be installed into an enclosure. For example, the mounting portion 42 may be inserted into a hole formed in an enclosure and secured thereto with nut 26. At step 912 the coaxial cable 10 is prepared for insertion into the coaxial connector 20. Accordingly, the center core conductor 8 is exposed by removing outer insulation 2 shielding 4 and inner insulation 6. In this example, approximately one quarter of an inch of conductor is exposed. Next at step 914 the shielding or ground is exposed by removing the outer insulation 2 an additional half inch, approximately. (Steps 912 and 914 may be performed concurrently, such as by using an appropriate coaxial cable stripping tool, not shown.) Once the cable has been prepared, the cable is inserted into the connector at step 916. At step 918 the center core conductor 8 is seated into the conductor ferrule 80 and at step 920 the shield is inserted into the shield collet 44 adjacent the interface region 420. At step 922 clamping nut 30 is tightened or secured, thereby clamping the shield and insulation. And, at step 924 the adaptor assembly 50 may be connected to a mating device located inside the enclosure to thereby provide electrical connection between the coaxial cable 10 and electronics (not shown). [0035] FIGS. 8-12 illustrate a coaxial connector 220 according to a second exemplary embodiment. In this embodiment, connector 220 includes a clamping nut 230, a mounting fitting 242, a double-ended shield collet 244, and a collet ring 240. Seal ring 270 provides a seal between the clamping nut 230 and outer insulation 2. Washer 305 provides an interface between clamping nut 230 and seal ring 70. In this case, seal ring 270 may be comprised of rubber and washer 305 may be comprised of aluminum, for example. As in the first embodiment above, the conductive components of the connector may formed of, for example, gold plated brass, silver plated brass, or other conductive material.

[0036] With reference to FIGS. 9 and 10, for example, it can be appreciated that the mounting fitting 242 and double-ended shield collet 244 are separate pieces. This is in contrast to the embodiment described above with respect to FIGS. 1-7, where the mounting portion 42 and shield collet 44 are of unitary construction. In this case, the double ended collet 244 is clamped on both ends (430, 432).

[0037] As perhaps best shown in FIG. 9, insertion end 430 is configured to receive the prepared portion of cable 10. Insertion end 430 may also be referred to herein as a first collet end. Insertion end 430 includes a ramped surface 415 and associated kerfs 246 that allow insertion end 430 to contract as collet ring 240 is urged toward collet 244. In this case collet ring 240 includes a conical, or ramped, surface 237 that compresses insertion end 430 such that interior surface 413 clamps onto outer insulation 2.

[0038] On the opposite end of double-ended shield collet 244 is a shoulder end 432, which may also be referred to as a second collet end. Shoulder end 432 includes a ramped surface 417 and associated kerfs 247 that allow shoulder end 432 to contract as mounting fitting 242 is urged toward collet 244. The mounting fitting 242 includes a conical, or ramped, surface (not shown) similar to that of collet ring 240 that compresses shoulder end 432 such that interior surface 413 clamps onto shielding wires 4. It should be understood that clamping nut 230 is operative to urge the components of coaxial connector 220 together in order to contract or compress the first and second collet ends. Coaxial connector 220 interfaces with the center core conductor 8 in a similar fashion to that described above with respect to the first exemplary embodiment.

[0039] With reference to FIGS. 1 1 and 12, it can be appreciated that the prepared portion of coaxial cable 10 is inserted into insertion end 430 of double-ended collet 244. The cable is inserted until the shielding 4 abuts shoulder 425. With further reference to FIG. 13, it should be understood that cable 10 is prepared in an alternate configuration. In this configuration the shielding wires 4 are bent back onto the outer insulation. In this case, the outer insulation includes a primary layer 2 and a secondary layer 3. In this example, the primary layer 2 is striped off and the shield 4 is bent back onto secondary layer 3. It can also be appreciated from the figures that the interior surface 413 both clamps outer insulation 2 and interfaces with shielding 4. Accordingly, interior surface 413 includes an insulation clamping region 434 adjacent insertion end 430, and a shield interface region 436 adjacent shoulder 425. In this case, the clamping region 434 and shield interface region 436 are substantially the same diameter; however, the diameter of the two regions may vary depending on the construction of the coaxial cable used.

[0040] It should be appreciated that while the coaxial connector has been described herein with respect to leaky feeder systems other systems using coaxial cable may benefit from the use of the disclosed connector. Accordingly, the disclosure should not be construed as being limited to any particular coaxial cable system. In addition, while the adaptor assembly 50 has been described with particular connectors and wiring other adaptors may be used.

[0041] Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise," "comprising," and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to." As used herein, the terms "connected," "coupled," or any variant thereof means any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between the elements can be physical, logical, or a combination thereof. Additionally, the words "herein," "above," "below," and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word "or," in reference to a list of two or more items, covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.

[0042] The above Detailed Description of examples of the invention is not intended to be exhaustive or to limit the invention to the precise form disclosed above. While specific examples for the invention are described above for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. Further any specific numbers noted herein are only examples: alternative implementations may employ differing values or ranges. [0043] The teachings of the invention provided herein can be applied to other systems, not necessarily the system described above. The elements and acts of the various examples described above can be combined to provide further implementations of the invention. Some alternative implementations of the invention may include not only additional elements to those implementations noted above, but also may include fewer elements.

[0044] These and other changes can be made to the invention in light of the above Detailed Description. While the above description describes certain examples of the invention, and describes the best mode contemplated, no matter how detailed the above appears in text, the invention can be practiced in many ways. Details of the system may vary considerably in its specific implementation, while still being encompassed by the invention disclosed herein. As noted above, particular terminology used when describing certain features or aspects of the invention should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the invention with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the invention to the specific examples disclosed in the specification, unless the above Detailed Description section explicitly defines such terms. Accordingly, the actual scope of the invention encompasses not only the disclosed examples, but also all equivalent ways of practicing or implementing the invention under the claims.

Claims

CLAIMS What is claimed is:

1. An apparatus substantially as shown and described above and equivalents thereof.

2. A method substantially as shown and described above and equivalents thereof.

3. A connector, comprising:

a connector fitting including a mounting portion and a shield collet extending therefrom, wherein the shield collet is adapted to receive a portion of coaxial cable therein; and

a clamping nut including a ramped interior surface operative to engage an outer surface of the shield collet, whereby urging the clamping nut toward the mounting portion causes the shield collet to conductively interface with the coaxial cable.

4. The connector according to claim 3, further comprising a conductor ferrule housed in the mounting portion and configured to receive a center core conductor of the coaxial cable.

5. The connector according to claim 4, further comprising an adapter assembly inserted into the mounting portion and connected to the conductor ferrule.

6. The connector according to claim 3, wherein the shield collet includes an interior barb operative to grasp an outer insulation of the coaxial cable when the clamping nut is urged toward the mounting portion.

7. The connector according to claim 3, wherein the connector fitting is configured to conductively and mechanically couple with a component of a leaky feeder communications system.

8. The connector according to claim 1 , wherein the connector fitting comprises silver plated brass.

9. A method of connecting to coaxial cable having a center core conductor, inner insulation, shielding, and outer insulation, the method comprising:

providing a coaxial connector having a mounting fitting, a shield collet, and a clamping nut;

preparing a length of coaxial cable for insertion through the clamping nut and into the shield collet, including:

removing a portion of outer insulation and a portion of inner insulation to expose a length of center core conductor and a length of shielding, and

bending the length of shield back onto the outer insulation;

inserting the prepared length of coaxial cable through the clamping nut and into the shield collet; and

installing the clamping nut onto the mounting fitting.