Patent Application
20120129388
1. Field of the Invention
This invention relates to electrical cable connectors. More particularly, the invention relates to a coaxial cable connector interconnectable via laser welding.
2. Description of Related Art
Coaxial cable connectors are used, for example, in communication systems requiring a high level of precision and reliability.
To create a secure mechanical and optimized electrical interconnection between the cable and the connector, it is desirable to have generally uniform, circumferential contact between a leading edge of the coaxial cable outer conductor and the connector body. A flared end of the outer conductor may be clamped against an annular wedge surface of the connector body via a coupling body. Representative of this technology is commonly owned U.S. Pat. No. 6,793,529 issued Sep. 21, 2004 to Buenz. Although this type of connector is typically removable/re-useable, manufacturing and installation is complicated by the multiple separate internal elements required, interconnecting threads and related environmental seals.
Connectors configured for permanent interconnection via solder and/or adhesive interconnection are also well known in the art. Representative of this technology is commonly owned U.S. Pat. No. 5,802,710 issued Sep. 8, 1998 to Bufanda et al.
However, solder and/or adhesive interconnections may be difficult to apply with high levels of quality control, resulting in interconnections that may be less than satisfactory, for example when exposed to vibration and/or corrosion over time.
Competition in the coaxial cable connector market has focused attention on improving electrical performance and long term reliability of the cable to connector interconnection. Further, reduction of overall costs, including materials, training and installation costs, is a significant factor for commercial success.
Therefore, it is an object of the invention to provide a coaxial connector and method of interconnection that overcomes deficiencies in the prior art.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, where like reference numbers in the drawing figures refer to the same feature or element and may not be described in detail for every drawing figure in which they appear and, together with a general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the invention.
Aluminum has been applied as a cost-effective alternative to copper for the conductors in coaxial cables. However, aluminum oxide surface coatings quickly form upon air-exposed aluminum surfaces. These aluminum oxide surface coatings may degrade traditional mechanical, solder and/or conductive adhesive interconnections.
The inventors have recognized that increasing acceptance of coaxial cable with solid outer conductors of aluminum and/or aluminum alloy enables connectors configured for interconnection via laser welding between the outer conductor and a connector body which may also be cost effectively provided, for example, formed from aluminum and/or aluminum alloy.
An exemplary embodiment of a laser weldable coaxial connector 2 is demonstrated in
One skilled in the art will appreciate that connector end 18 and cable end 12 are applied herein as identifiers for respective ends of both the coaxial connector 2 and also of discrete elements of the coaxial connector 2 described herein, to identify the same and their respective interconnecting surfaces according to their alignment along a longitudinal axis of the coaxial connector 2 between a connector end 18 and a cable end 12.
Where the diameter of the bore 6 is selected with respect to the diameter of the outer conductor 8 to be a close tolerance fit, laser welding interconnection of the outer conductor 8 and the connector body 2 may be performed without the addition of further material, such as welding rod or wire. The high level of localized heating from the laser, applied to the seam 16 between the outer conductor 8 and the connector body 2, may be applied as a pulse directed to a target spot, with successive pulses applied to an overlapping spot portion to form a continuous weld between adjacent portions of the outer conductor 8 and the connector body 2.
Prior to interconnection via laser welding, the end of the cable 9 may be prepared, as best shown in
Where applicable, the cable end preparation may also include the step of straightening the cable end portion, for example to eliminate any bending in the cable resulting from bulk cable delivery of the cable wound in spools, so that when inserted into the bore 6, the cable end is coaxial with the bore 6 along its length and the inner conductor 24 projects from the connector end 18 parallel to the longitudinal axis of the bore 6. Thereby, the seam between the bore sidewall 20 and the outer diameter of the outer conductor 8 will be uniform around the circumference of the outer conductor 8, increasing the uniformity of the resulting laser weld.
Because the localized heat of the laser welding process can disrupt aluminum oxide surface coatings in the immediate weld area, no additional care may be required with respect to removing or otherwise managing the presence of aluminum oxide on the interconnection surfaces.
An overbody 30, as shown for example in
Depending upon the applied connection interface 14, demonstrated in the exemplary embodiments herein as a standard 7/16 DIN interface, the overbody 30 may be provided with an overbody flange 32 and longitudinal support ridges 34 for a coupling nut 36. The coupling nut 36 is retained upon the support ridges 34 at the connector end 18 by an overbody flange 32 and at the cable end 12 by a retention spur 38 provided on at least one of the support ridges 34. The retention spur 38 may be angled toward the connector end 18, allowing the coupling nut 36 to be placed over the cable 9 initially spaced away from the coaxial connector 2 during interconnection (see
The overbody 30 may also extend from the connector end 18 of the connector body 4 to provide portions of the selected connection interface 14, such as an alignment cylinder 39 of the 7/16 DIN interface, further reducing metal material requirements of the connector body 4.
The overbody flange 32 may be securely keyed to a connector body flange 40 of the connector body 4 and thereby with the connector body 4 via one or more interlock apertures 42 such as holes, longitudinal knurls 43, grooves, notches 45 or the like provided in the connector body flange 40 and/or outer diameter of the connector body 4, as demonstrated in
As best shown in
The inner conductor 24 extending from the prepared end of the coaxial cable 9 may be selected to pass through to the connector end 18 as a portion of the selected connection interface 14, for example as shown in
Although a direct pass through inner conductor 24 advantageously eliminates interconnections, for example with the spring basket of a traditional coaxial connector inner contact, such may introduce electrical performance degradation such as PIM. Where the inner conductor 24 is also aluminum material some applications may require a non-aluminum material connection point at the inner contact/inner conductor of the connection interface 14. As shown for example in
Laser welding apparatus may be provided with a fiber optic laser head extension which may be adjusted to aim the laser beam B at each target location along the seam 16. Alternatively, the coaxial connector 2, upon which the target location resides, may be maneuvered to align the target location with respect to the laser head 54. A laser head 54 typically includes a collimator 56 and a focus lens 58 which focuses the laser beam B upon a focal point F at the target location. As shown in
Prior to and once beyond the focal point F, the laser beam B has an increasing diameter, progressively diminishing the effective power of the beam at longitudinal locations other than the focal point F. To maximize heat generation for welding, the laser head 54 may be positioned with respect to the seam 16, such that the focal point F is below the seam 16 outer face, for example as shown in
In further embodiments, for example as shown in
In addition to increased adjustment requirements for the laser beam to follow the inner circumference of the seam 16, the present embodiment also requires removal of additional dielectric material 26, which may generate impedance discontinuity issues addressable by the addition of further impedance tuning features, such as dielectric spacers or the like.
One skilled in the art will appreciate that the connector and interconnection method disclosed has significant material cost efficiencies and provides a permanently sealed interconnection with reduced size and/or weight requirements.
Where in the foregoing description reference has been made to materials, ratios, integers or components having known equivalents then such equivalents are herein incorporated as if individually set forth.
While the present invention has been illustrated by the description of the embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus, methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the spirit or scope of applicant's general inventive concept. Further, it is to be appreciated that improvements and/or modifications may be made thereto without departing from the scope or spirit of the present invention as defined by the following claims.
