Patent Publication Number: US-8109786-B2

Title: Connector for coaxial cable

Description:
CROSS REFERENCE TO PRIOR APPLICATION 
     The present application claims priority under 35 U.S.C. 119 to Korean Patent Application No. 10-2009-0002694 (filed on Jan. 13, 2009), which is hereby incorporated by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a connector for a coaxial cable, and more particularly, to a connector for a coaxial cable that secures a high-reliability electrical contact although there are changes in an inner diameter of a hollow inner conductor of the coaxial cable. 
     2. Description of the Related Art 
     A coaxial cable comprises an inner conductor that is a medium of signal transmission, an insulator surrounding the inner conductor, an outer conductor surrounding the insulator, and a sheath surrounding the outer conductor. The coaxial cable is more strongly resistant to interference of external electromagnetic waves than other cables, and thus, it is currently used in many industrial fields. 
     The inner conductor of the coaxial cable may have a shape of a solid cylinder or a hollow cylinder. Generally, the solid cylinder-shaped inner conductor is used to a coaxial cable having a relatively smaller diameter, and the hollow cylinder-shaped inner conductor is used to a coaxial cable having a relatively larger diameter. And, the outer conductor of the coaxial cable may have a flat type and a corrugated type. A coaxial cable with the flat type outer conductor allows easy manufacturing and small diameter, and a coaxial cable with the corrugated type outer conductor allows relatively better properties of signal attenuation and cable bending. 
     For a special purpose of use, the coaxial cable needs to be electrically connected with other coaxial cables or electrical equipments such as a measuring equipment, an operating equipment, a control equipment and so on. For example, the coaxial cable may be connected with another coaxial cable for extending the length of a signal transmission line. The coaxial cable may be connected with a measuring equipment for quality test. The coaxial cable may be electrically connected with an operating equipment and a control equipment for signal transmission therebetween. 
     A connector is used to connect the coaxial cable with another coaxial cable or an electrical equipment. The connector comprises a pin, a housing, and an insulator. The pin connects an inner conductor of a coaxial cable with an inner conductor of another coaxial cable or an inner conductor of a coaxial cable with a signal receiving/transmitting unit of an electrical equipment. The housing connects an outer conductor of a coaxial cable with an outer conductor of another coaxial cable or an outer conductor of a coaxial cable with a ground of an electric equipment. The insulator insulates the pin from the housing. 
     In the case that the inner conductor is a hollow inner conductor, the pin of the connector is inserted into a hollow of the inner conductor. The pin inserted into the hollow of the inner conductor is contacted with the inner surface of the inner conductor. In this way, the coaxial cable is electrically coupled with the connector. At this time, if a contact between the pin of the connector and the inner conductor of the coaxial cable is incomplete, a signal flowing toward the inner conductor may be distorted or attenuated while passing through the connector. For this reason, a complete contact should be guaranteed between the pin of the connector and the inner conductor of the coaxial cable. 
     However, a pin of a conventional connector has a fixed diameter. Thus, when the pin is inserted into an inner conductor having a larger inner diameter than a diameter of the pin, a contact between the pin and the inner conductor is not guaranteed to be complete. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a connector for a coaxial cable applicable to coaxial cables of different inner diameters without any design change. 
     In order to achieve the object, the present invention provides a connector for a coaxial cable that allows a physical and electrical connection between a coaxial cable and various kinds of electric members. The coaxial cable includes a hollow inner conductor and a corrugated outer conductor. The connector for a coaxial cable according to the present invention comprises a carrier terminal inserted into and contacted with the hollow inner conductor to transmit an electrical signal of the coaxial cable to the electric member; a conductive housing for receiving the conductive carrier terminal therein and for electrically interfacing the coaxial cable with the electric member and coupling the coaxial cable to a ground; and an insulator interposed between the carrier terminal and the housing and for insulating the carrier terminal from the housing, wherein the conductive carrier terminal has a conductive elastic assembly with an adjustable diameter such that a size of a part of the conductive carrier terminal inserted into the inner conductor corresponds to an inner diameter of the inner conductor, thereby forming a close electrical contact with the conductive carrier terminal irrespective of the inner diameter of the inner conductor. 
     The conductive carrier terminal includes a conductive pin having a shape of an elongated bar; and a conductive elastic carrier member attached to a part of the conductive pin inserted into the inner conductor and having an adjustable size to the inner diameter of the inner conductor. And, the elastic carrier member has a plurality of curved elastic bars arranged in a circumferential direction and combined to form a circle, and each curved elastic bar is bent convexly to form a conductive elastic carrier member of a circular shape having a larger size than the inner diameter of the inner conductor. The curved elastic bar includes a fixed end fixed to the pin; and a contact body extending from the fixed end and forming an electrical elastic contact with an inner surface of the inner conductor, wherein the contact body is bent convexly with regard to a vertex, so that when the contact body is inserted into the inner conductor, the contact body is pressed down and elastically deformed by an external force, and when the external force disappear, the contact body is elastically restored to its original state. 
     The connector for a coaxial cable according to the present invention further comprises a coupling member for electrically coupling the outer conductor with the housing. The coupling member includes a conductive pipe inserted and fixed in the housing; and a conductive wing assembly installed in the conductive pipe for electrically coupling the outer conductor with the housing. 
     The conductive wing assembly has a plurality of conductive wings arranged in a circumferential direction and combined to form a circle. The conductive wing includes a nipper connected with the outer conductor; and a protrusion coupled with the housing, wherein the nipper is inserted and secured in a corrugation of the corrugated outer conductor of the coaxial cable, and the protrusion is surface-contacted with the housing. 
     Advantageous Effects 
     The present invention secures a high-reliability electrical contact with various kinds of coaxial cables having different inner diameters, and thus prevents signal distortion or excessive attenuation. 
     And, the present invention secures easy insertion/drawing of a carrier terminal of a connector into/from an inner conductor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of an example of a connector for a coaxial cable according to a present invention. 
         FIG. 2  is a cross-sectional view of the connector of the coaxial cable of  FIG. 1 . 
         FIG. 3  is a perspective view of a carrier terminal according to the present invention, comprising a pin and an elastic carrier member attached to the pin. 
         FIG. 4  is an enlarged cross-sectional view of a curved elastic bar according to the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Hereinafter, preferred embodiments of a connector for a coaxial cable according to the present invention will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is an exploded perspective view of an example of a connector for a coaxial cable according to a present invention.  FIG. 2  is a cross-sectional view of the connector of the coaxial cable of  FIG. 1 .  FIG. 3  is a perspective view of a carrier terminal according to the present invention, comprising a pin and an elastic carrier member attached to the pin.  FIG. 4  is an enlarged cross-sectional view of a curved elastic bar according to the present invention. 
     As shown in  FIGS. 1 and 2 , a connector  100  for a coaxial cable according to a present invention comprises a carrier terminal  110  electrically connected with an inner conductor  12  of a coaxial cable  10 , a housing  130  serving as a ground of the connector  100 , an insulator  150  for insulating the carrier terminal  110  from the housing  130 , and a coupling member  190  for electrically interfacing an outer conductor  14  of the coaxial cable  10  with the housing  130 . 
     The carrier terminal  110  is a medium for electrically coupling the hollow inner conductor  12  of the coaxial cable  10  with a connection part  32  of a specific electric member  30 . Here, the specific electric member  30  may include a connector of another coaxial cable, a measuring equipment, an operating equipment, a control equipment and so on. 
     When the connector  100  and the coaxial cable  10  are physically connected with each other, one end of the carrier terminal  110  of the connector  100  is fitted into a hollow of the inner conductor  12  of the coaxial cable  10 . And, when the connector  100  and the electric member  30  are physically connected with each other, the other end of the carrier terminal  110  of the connector  100  is electrically connected with the connection part  32  of the electric member  30 . 
     Referring to  FIG. 3 , the carrier terminal  110  has a pin  112  and an elastic carrier member  114 . Each of the pin  112  and the elastic carrier member  114  is made of a conductive material. The elastic carrier member  114  is a conductive elastic assembly having a plurality of curved elastic bars  114 ′ arranged in a circumferential direction and combined to a circle. Referring to  FIG. 4 , each of the curved elastic bars  114 ′ has a fixed end  114 ′ a  fixed and joined to the pin  112 , and a contact body  114 ′ b  inserted into the inner conductor  12  of the coaxial cable  10  and contacted with the inner surface of the inner conductor  12 . The contact body  114 ′ b  has the degree of freedom in the radial (arrow A) and longitudinal (arrow B) directions with regard to the fixed end  114 ′ a . The contact body  114 ′ b  has a shape bent at a predetermined angle (for example, an obtuse angle of 120 degrees or more) relative to a vertex  114 ′ c  such that its maximum height before elastic deformation is at least larger than the height of the inner conductor  12  of the coaxial cable  10 . 
     And, the curved elastic bars  114 ′ have elastic retention. Thus, when an external force is applied to the curved elastic bars  114 ′, the curved elastic bars  114 ′ are deformed as indicated by a dotted line in  FIG. 4 . When the external force disappears, the curved elastic bars  114 ′ are restored to their original state as indicated by a solid line in  FIG. 4 . That is, when the carrier terminal  110  is inserted into the inner conductor  12  of the coaxial cable  10  by a physical connection of the coaxial cable  10  and the connector  100 , the curved elastic bars  114 ′ of the carrier terminal  110  are elastically deformed as indicated by the dotted line in  FIG. 4 . When the connection of the coaxial cable  10  and the connector  100  is released, the curved elastic bars  114 ′ are restored to their original shape as indicated by the solid line in  FIG. 4 . 
     As mentioned above, if the carrier terminal  110  is press-fit engaged with the inner conductor  12  of the coaxial cable  10 , the curved elastic bars  114 ′ of the carrier terminal  110  are elastically deformed as indicated by the dotted line in  FIG. 4 , so that an electrical contact is formed between the curved elastic bars  114 ′ and the inner surface of the inner conductor  12 . At this time, because the curved elastic bars  114 ′ are bent at a predetermined angle relative to the vertex  114 ′ c , it is easy to insert/draw the carrier terminal  110  into/from the inner conductor  12  of the coaxial cable  10 . Accordingly, the connector  100  of the present invention can flexibly establish an electrical connection with coaxial cables having different inner diameters of inner conductors, thereby providing a reliable connecting environment. 
     Meanwhile, the insulator  150  is located between the carrier terminal  110  and the housing  130 , and electrically insulates the carrier terminal  110  from the housing  130 . 
     And, the housing  130  is made of a conductive material to electrically interface the outer conductor  14  of the coaxial cable  10  with a ground  34  of the electric member  30 . The housing  130  receives the carrier terminal  110  and the insulator  150  therein. 
     First, the housing  130  and the ground  34  of the insulator  30  are electrically connected with each other by a bolt-nut connection. The bolt-nut connection is established by inserting the bolt  34  into a space  172  between the housing  130  and the nut  170  and rotating the nut  170 . And, the housing  130  has a flange  132  for preventing the nut  170  from moving away from the housing  130 . Meanwhile, the locations of the nut  170  and the bolt  34  may be reversed. That is, modification may be made such that a bolt is formed at one end of the housing  130  and a nut is formed at the ground  34  of the electric member  30 . 
     And, the housing  130  and the outer conductor  14  of the coaxial cable  10  are electrically connected with each other by the coupling member  190 . The coupling member  190  has a conductive pipe  192  and a conductive wing assembly  194  connected with the inner surface of the conductive pipe  192 . The conductive pipe  192  has a male screw  196  formed along the outer periphery thereof. The male screw  196  is engaged with a female screw  134  formed along the inner periphery of the housing  130 . 
     The conductive wing assembly  194  has a plurality of conductive wings  198  arranged in the circumferential direction and combined to form a circle. Each of the conductive wings  198  has a nipper  198   a  coupled with the outer conductor  14  of the coaxial cable  10 , and a protrusion  198   b  coupled with the housing  130  of the connector  100 . The nipper  198   a  is inserted and secured into a corrugation of the corrugated outer conductor  14  of the coaxial cable  10 , and the protrusion  198   b  is surface-contacted with the housing  130 . In this way, the outer conductor  14  is physically and electrically connected with the housing  130  through the coupling member  190 . 
     Hereinafter, description is made on a process for physically and electrically connecting the coaxial cable  10  with various kinds of electric members  30  using the connector  100  of the above-mentioned configuration according to the present invention. 
     The sheath of the coaxial cable  10  to be connected is striped off. As shown in  FIG. 2 , the outer conductor  14  is inserted into the coupling member  190  of the connector  100  with the outer conductor  14  exposed outward. Then, the outer conductor  14  is physically and electrically connected with the conductive pipe  192  while the nipper  198   a  of the conductive wing assembly  194  of the coupling member  190  is interposed therebetween. The conductive wing assembly  194  is physically and electrically connected with the conductive pipe  192  and the housing  130  through the protrusion  198   b . Meanwhile, the connector  100  is physically and electrically connected with the electric member  30  by connection of the nut  170  of the housing  130  of the connector  100  and the bolt  34  of the electric member  30 . 
     And, as the coaxial cable  10  is inserted in the housing  130  through the coupling member  190 , the carrier terminal  110  is inserted into a hollow of the inner conductor  12  of the coaxial cable  10  to form an electrical contact, so that an electrical connection is established between the coaxial cable  10  and the electric member  30 . At this time, although the inner diameter of the inner conductor  12  is larger than the diameter of the pin  112  of the carrier terminal  110 , because the pin  112  has the elastic carrier member  114  attached thereto, a high reliability-electrical contact can be formed between the inner conductor  12  and the pin  112  through an elastic mechanism shown in  FIG. 4 .