Abstract:
A coaxial cable connector suitable for assembly with one of a series of coaxial cables having one same specification and different wire outer diameters is disclosed to use a plastic bushing for compressing by a barrel to wrap about the coaxial cable and compress an inner tube against the aluminum foil and insulation spacer of the coaxial cable, protecting the coaxial cable against weather and extending the lifespan. A short distance is left between the aluminum foil insertion hole on the left end of the inner tube and the left orifice of the barrel, facilitating insertion of the insulation spacer and aluminum foil of the coaxial cable without causing damage.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is coaxial cable connectors and more particularly to such a coaxial cable connector that fits a series of coaxial cables having one same specification and different wire outer diameters. 
     2. Description of the Related Art 
     In current television market, cable TV is the mainstream. Cable TV signal is transmitted to a television of a subscriber through a coaxial cable. Coaxial cable is not limited to cable TV application, it can also be used in any of a variety of other fields for signal transmission. For two-way high-frequency transmission, a coaxial cable is extended from an outdoor place to the inside of a house and then connected to a TV or TV splitter through a coaxial cable connector. This coaxial cable connector is adapted for connecting a coaxial cable to a mating connector at the TV or TV splitter. 
     To fit different signal transmission quality requirements, the braided outer conductor of a coaxial cable can have a standard, tri-shield or quad-shield design. In consequence, the wire outer diameter is relatively changed. Further, a coaxial cable further comprises an aluminum foil surrounding the insulation spacer within the braided outer conductor to provide a shielding effect. 
     Many coaxial cable connectors are commercially available for assembly with one of a series of coaxial cables having different wire outer diameters.  FIG. 1  illustrates a cable end connector A fastened to one end of a coaxial cable B. This cable end connector A consists of a screw nut A 1 , a plastic body shell A 2 , an inner tube A 3  and a metal barrel A 4 . 
     The screw nut A 1  is disposed at the front side, having an inner thread for threading onto a mating connector. The plastic body shell A 2  is connected to the screw nut A 1 . A gasket ring A 21  is set in between the plastic body shell A 2  and the screw nut A 1 . The inner tube A 3  is inserted into the inside of the plastic body shell A 2 . The metal barrel A 4  is sleeved onto one end of the plastic body shell A 2  adjacent to the coaxial cable B. 
     During installation, as shown in  FIG. 1 , the protective plastic covering of the coaxial cable B is properly stripped off, and then the center conductor B 1  of the coaxial cable B is inserted through the metal barrel A 4  into the inner tube A 3 , and then a crimping tool is operated to crimp the cable end connector A, forcing the metal barrel A 4  along the plastic body shell A 2  toward the screw nut A 1 , thereby finishing the installation, as shown in  FIG. 1A . At this time, a sufficient space is left between the outer edge of the barbed end portion A 31  of the inner tube A 3  and the inner end edge A 23  of the plastic body shell A 2  for receiving one of a series of coaxial cables having one same specification and different wire outer diameters. By means of the elastically deformable property of a specially configured packing portion A 22  of the plastic body shell A 2 , a coaxial cable B having a different wire outer diameter can be tightly sealed in this cable end connector A. With respect to the details of this cable end connector, please refer to U.S. Pat. No. 6,848,939, entitled “Coaxial cable connector with integral grip bushing for cables of varying thickness”. 
     However, when the aforesaid cable end connector A is assembled with a coaxial cable B, the plastic body shell A 2  is partially exposed to the weather (see  FIG. 1A ) and will become aged and oxidized soon. Therefore, the application of this design of cable end connector is limited. In actual application, this design of cable end connector still has drawbacks as follows: 
     1. The plastic body shell A 2  is partially exposed to the outside between the screw nut A 1  and the metal barrel A 4 . When the cable end connector A is used outdoor, the plastic body shell A 2  will become aged and oxidized soon under the effect of the sun, rain and wind, and rainwater may leak in between the cable end connector A and the coaxial cable B, affecting signal transmission stability and quality. If a metal body shell is used to substitute for the plastic body shell A 2 , the crimping operation during installation of the cable end connector will become difficult. Therefore, this design of cable end connector is not well invited in the market.
 
2. A long distance is left between the aluminum foil insertion hole A 32  on the left end of the inner tube A 3  and the left orifice A 41  of the metal barrel A 4 . This distance is approximately equal to the length of the bare aluminum foil B 31  of the coaxial cable B (or even longer), as shown in  FIG. 1 . Thus, it is difficult to insert the insulation spacer B 2  and aluminum foil B 3  of the coaxial cable B into the cable end connector A, and the insulation spacer B 2  and aluminum foil B 3  of the coaxial cable B may be damaged during insertion, affecting signal transmission quality and stability. To avoid this problem, it is necessary to shorten the distance between the aluminum foil insertion hole A 32  on the left end of the inner tube A 3  and the left orifice A 41  of the metal barrel A 4  to about ⅔ of the length of the bare aluminum foil B 31  of the coaxial cable B. In this case, the inner diameter of the inner end edge A 23  of the plastic body shell A 2  will be reduced due to engagement between of the clamping portion A 22  of the plastic body shell A 2  and the beveled clamping surface A 42  of the metal barrel A 4 , interfering with the insertion of the coaxial cable B.
 
       FIG. 2  illustrates another structure of connector D according to the prior art, which consists of a screw nut D 1 , an inner tube D 2 , a body shell D 3 , a barrel D 4  and a plastic bushing D 5 . Unlike the prior art design shown in  FIG. 1 , the plastic bushing D 5  is mounted in the body shell D 3  and the barrel D 4  and kept from sight. 
     The screw nut D 1  is connected with one end of the inner tube D 2  for the passing of the center conductor B 1  of the coaxial cable B. The body shell D 3  surrounds the inner tube D 2 . The inner tube D 2  has a barbed portion D 21  disposed at one end thereof and extending out of one end of the clamping portion D 31  of the body shell D 3 . The barrel D 4  is sleeved onto the clamping portion D 31  of the body shell D 3 . The plastic bushing D 5  is set in the barrel D 4 . 
     A large space is left between the outer edge D 211  of the barbed portion D 21  of the body inner tube D 2  and an inner end edge D 51  of the plastic bushing D 5  for receiving a different thickness of braided outer conductor of a coaxial cable of one same specification. By means of the elastically deformable property of the plastic bushing D 5 , the connector fits cables of varying thickness. 
     In the aforesaid cable end connector D, the body shell D 3  is a metal member, and a crimping tool must be used to crimp the clamping portion D 31  of the body shell D 3  and the barrel D 4  during installation of the cable end connector D. Because the crimping distance D 32  has a certain length, much crimping pressure must be applied to the crimping tool to move he barrel D 4  relative to the clamping portion D 31  subject to the crimping distance D 32 . Thus, much effort is necessary to complete the crimping operation. Further, a long distance is left between the aluminum foil insertion hole D 2  on the left end of the inner tube D 2  and the left orifice D 41  of the metal barrel D 4 . This distance is greater than the length of the bare aluminum foil B 31  of the coaxial cable B. Thus, it is difficult to insert the insulation spacer B 2  and aluminum foil B 3  of the coaxial cable B into the cable end connector D, and the insulation spacer B 2  and aluminum foil B 3  of the coaxial cable B may be damaged during insertion. During a high-frequency two-way signal transmission operation, this aluminum foil damage causes an increase in the reflective loss, affecting signal transmission quality and stability. To avoid this problem, it is necessary to shorten the distance between the aluminum foil insertion hole D 2  on the left end of the inner tube D 2  and the left orifice D 41  of the metal barrel D 4  to about ⅔ of the length of the bare aluminum foil B 31  of the coaxial cable B. In this case, the inner diameter of the inner end edge D 51  of the plastic bushing D 5  will be reduced due to engagement between of the clamping portion D 52  of the plastic bushing D 5  and the beveled clamping surface D 33  of the body shell D 3 , interfering with the insertion of the coaxial cable B. 
     SUMMARY OF THE INVENTION 
     The present invention has been accomplished under the circumstances in view. It is therefore the main object of the present invention to provide a coaxial cable connector assembled with a coaxial cable consisting of a center conductor, surrounded by an insulation spacer, surrounded by an aluminum foil, surrounded by a braided outer conductor, surrounded by a protective plastic covering. The protective plastic covering of the coaxial cable been stripped off subject to a predetermined length to expose the braided outer conductor, the exposed braided outer conductor been turned backwardly onto the protective plastic covering to expose the insulation spacer and the aluminum foil and to leave a predetermined length of the bare aluminum foil outside the protective plastic covering for installation in the coaxial cable connector. The coaxial cable connector comprises a screw nut having an inner thread for threading onto an outer thread of a mating member; an inner tube mounted in one end of the screw nut, the inner tube comprising a barbed unit extending around the periphery of a left end thereof remote from the screw nut and a foil insertion hole defined in the left end; a body shell surrounding the inner tube, the body shell comprising an axial hole, a clamping portion surrounding the axial hole and a stop flange extending around the periphery at one end of the clamping portion; a barrel sleeved onto one end of the body shell beyond the clamping portion and defining with the body shell a crimping distance before installation of the coaxial cable in the coaxial cable connector, the barrel comprising a left orifice for entrance of the coaxial cable connector, a packing hole defined therein and a tapered inner surface formed in a right side of the packing hole; and a plastic bushing set in the barrel to leave a large gap in between an inner end edge of a left end thereof and an outer end edge of the barbed unit of the inner tube for receiving the braided outer conductor of the coaxial cable, the plastic bushing been crimped and clamped on the protective plastic covering of the coaxial cable against the barbed unit of the inner tube after stoppage of a right end thereof against the stop flange of the body shell, the plastic bushing comprising an inner end edge at a left end thereof, the inner end edge of the plastic bushing defining an inner diameter fitting the packing hole of the barrel, a tapered inside wall gradually reducing in direction from a hole in a right end thereof toward the inner end edge of the left end thereof, and a beveled retaining surface extending around the periphery corresponding to the tapered inside wall and sloping leftwards. The crimping distance is about ⅔ of the predetermined length of the bare aluminum foil of the coaxial cable facilitating crimping. The distance between the aluminum foil insertion hole of the inner tube and the left orifice of the barrel is about ⅔ of the predetermined length of the bare aluminum foil of the coaxial cable; the beveled retaining surface of the plastic bushing is press-fitted into the tapered inner surface of the barrel to prohibit the plastic bushing from escaping from the packing hole of the barrel. The hole in the right end of the plastic bushing is greater than the packing hole of the barrel, capable for receiving a different thickness of braided outer conductor of a coaxial cable of one same specification. 
     Thus, the coaxial cable connector of the invention has connector that has advantages and features as follows: 
     1. The crimping distance between the coaxial cable and the coaxial cable is about ⅔ of the predetermined length of bare aluminum foil of the coaxial cable, facilitating crimping. 
     2. A short distance, about ⅔ of the predetermined length of bare aluminum foil of the coaxial cable is left between the aluminum foil insertion hole  2  on the left end of the inner tube and the left orifice of the barrel, facilitating insertion of the insulation spacer and aluminum foil of the coaxial cable without causing damage. 
     3. The plastic bushing has a beveled retaining surface press-fitted into the tapered inner surface of the barrel so that the plastic bushing will not escape from the packing hole of the barrel. 
     4. The hole in the right end of the plastic bushing is greater than the packing hole of the barrel, capable for receiving a different thickness of braided outer conductor of a coaxial cable of one same specification. 
     5. By means of the elastically deformable feature of the hole in the right end of the plastic bushing to compress the barbed portions of the inner tube, the part of the coaxial cable outside the barbed portions of the inner tube well wrapped, achieving a watertight seal. 
     6. The inner diameter of the inner end edge of the left end of the plastic bushing fits the packing hole of the barrel for guiding in the coaxial cable. 
     7. The plastic bushing further has a tapered inside wall gradually reducing in direction from the hole in the right end toward the inner end edge of the left end. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view of a coaxial cable connector before installation of a coaxial cable according to the prior art. 
         FIG. 1A  is similar to  FIG. 1 , illustrating a coaxial cable installed in the coaxial cable connector. 
         FIG. 2  is a sectional view of another structure of coaxial cable according to the prior art. 
         FIG. 3  is an elevational assembly view of a coaxial cable connector in accordance with the present invention. 
         FIG. 4  is an exploded view of the coaxial cable connector in accordance with the present invention. 
         FIG. 5  is a sectional view of the coaxial cable connector in accordance with the present invention. 
         FIGS. 6˜9  illustrate the assembly process of the coaxial cable connector with a coaxial cable according to the present invention. 
         FIG. 10  is a sectional view of an alternate form of the coaxial cable connector in accordance with the present invention. 
         FIG. 11  is a sectional view of another alternate form of the coaxial cable connector in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIGS. 3˜5 , a coaxial cable connector  100  in accordance with the present invention is shown comprising a screw nut  1 , an inner tube  2 , a body shell  3 , a barrel  4  and a plastic bushing  5 . 
     The coaxial cable connector  100  is assembled with a coaxial cable B consisting of a center conductor B 1 , surrounded by an insulation spacer B 2 , surrounded by an aluminum foil B 3 , surrounded by a braided outer conductor B 4 , surrounded by a protective plastic covering B 5 . The braided outer conductor B 4  can be a standard, tri-shield or quad-shield design. 
     Referring to  FIG. 5  again, the screw nut  1  has an inner thread  11  for threading onto an outer thread of a mating member (not shown); the inner tube  2  is mounted in one end of the screw nut  1 ; the body shell  3  surrounds the inner tube  2 , having a clamping portion  31  and a stop flange  30  extending around the periphery at one end of the clamping portion  31 ; the inner tube  2  has a barbed unit formed of at least one, for example, three barbed portions  21  (as shown in  FIG. 5 ) suspending outside the body shell  3 . Further, a gasket ring  12  is mounted in between the screw nut  1  and the body shell  3 . 
     The barrel  4  is sleeved onto one end of the body shell  3  beyond the clamping portion  31 . The plastic bushing  5  is set in the barrel  4 , leaving a large gap in between the inner end edge  51  of the left end  52  of the plastic bushing  5  and the outer end edge  211  of the barbed portions  21  of the inner tube  2  for receiving the braided outer conductor B 4  (of standard, tri-shield or quad-shield design) of the coaxial cable B, see also  FIG. 9 . By means of the elastically deformable material property, the protective plastic covering B 5  cab be positively surrounded by the plastic bushing  5  to compress the barbed portions  21  of the inner tube  2 , enhancing engagement between the barbed portions  21  of the inner tube  2  and the braided outer conductor B 4  of the coaxial cable B and sealing the gap against outside moisture. 
     Referring to  FIGS. 4 and 5  again, the inner end edge  51  of the left end  52  of the plastic bushing  5  has a diameter fitting the inner diameter of the packing hole, referenced by  42 , of the barrel  4 . The inner end edge  51  of the left end  52  of the plastic bushing  5  has an inner diameter fitting the packing hole  42  of the barrel  4 . The plastic bushing  5  further has a tapered inside wall  56  gradually reducing in direction from the hole  55  in the right end  53  toward the inner end edge  51  of the left end  52 , and a beveled retaining surface  54  extending around the periphery corresponding to the tapered inside wall  56  and sloping leftwards. Further, a crimping distance  32  is defined between the body shell  3  and the barrel  4 , i.e., between an inner end edge  40  of the barrel  4  and the stop flange  30  of the .body shell  3 . 
       FIGS. 6˜9  illustrate the assembly process of the coaxial cable B and the coaxial cable connector  100 . 
     At first, as shown in  FIG. 6 , strip off the protective plastic covering B 5  of the coaxial cable B properly, and then turn the exposed braided outer conductor B 4  backwardly onto the protective plastic covering B 5  to expose the insulation spacer B 2  and the aluminum foil B 3 , leaving a predetermined length of bare aluminum foil B 31  outside the protective plastic covering B 5 . Normally, the predetermined length of bare aluminum foil B 31  is ¼ inches (6.4 mm). At this time, the crimping distance  32  defined between the body shell  3  and the barrel  4  is maintained. The crimping distance  32  is ⅔ of the predetermined length of bare aluminum foil B 31 . 
     Thereafter, as shown in  FIG. 7 , insert the coaxial cable B into the coaxial connector  100 . At this time, the coaxial cable B and the coaxial connector  100  are not crimped by a crimping tool. As illustrated, the center conductor B 1  of the coaxial cable B passes through the barrel  4  and the plastic bushing  5  into the inner tube  2  and extends out of the screw nut  1 , the insulation spacer B 2  and aluminum foil B 3  of the coaxial cable B are inserted into the inside of the inner tube  2 , and the inner tube  2  is inserted in between the aluminum foil B 3  and the braided outer conductor B 4  of the coaxial cable B. 
     Thereafter, as shown in  FIG. 8 , after insertion of the coaxial cable B into the coaxial cable connector  100 , a crimping tool is used to crimp the coaxial cable connector  100 . When the crimping distance  32  is reduced to ½ distance  33  during crimping, the inner end edge  51  of the left end  52  of the plastic bushing  5  will be forced to compress the coaxial cable B and to guide the barrel  4  toward the screw nut  1  (see the arrowhead direction), causing the left end  52  of the plastic bushing  5  to enter the packing hole  42  of the barrel  4  subject to the guidance of a tapered inner surface  43  in the barrel  4 , and to force the beveled retaining surface  54  of the left end  52  of the plastic bushing  5  into engagement with the tapered inner surface  43  of the barrel  4 . 
     When the crimping tool is crimped to the extent, the crimping distance  32  is disappeared, as shown in  FIG. 9 . At this time, the inner end edge  40  of the barrel  4  is stopped against the stop flange  30  of the .body shell  3 , and the right end  53  of the plastic bushing  5  is tightly engaged in the axial hole  34  of the body shell  3 .  FIG. 9  illustrates the coaxial cable B inserted into the coaxial cable connector  100  and crimped. 
     In the aforesaid coaxial cable connector  100 , the body shell  3  is made of a metal material (plastics can also be used). Because both the body shell  3  and the barrel  4  are metal members, the crimping distance  32  can be relatively shorter so that less effort is necessary when crimping the clamping portion  31  of the body shell  3  and the barrel  4  by the crimping tool. The crimping distance  32  is preferably about ⅔ of the predetermined length of bare aluminum foil B 31  of the coaxial cable B. 
     Further, a short distance L is left between the aluminum foil insertion hole  22  in the left end of the inner tube  2  and the left orifice  41  of the barrel  4  (see  FIG. 5 ). This short distance L is about ⅔ of the predetermined length of bare aluminum foil B 31  of the coaxial cable B. This short distance L facilitates insertion of the insulation spacer B 2  and aluminum foil B 3  of the coaxial cable B without causing damage. When used for high-frequency two-way signal transmission application, the reflective loss is minimized, enhancing transmission quality and stability. 
     In conclusion, the invention provides a coaxial cable connector that has advantages and features as follows: 
     1. The crimping distance  32  between the coaxial cable B and the coaxial cable  100  is about ⅔ of the predetermined length of bare aluminum foil B 31  of the coaxial cable B, facilitating crimping. 
     2. A short distance, about ⅔ of the predetermined length of bare aluminum foil B 31  of the coaxial cable B is left between the aluminum foil insertion hole  22  on the left end of the inner tube  2  and the left orifice  41  of the barrel  4 , facilitating insertion of the insulation spacer B 2  and aluminum foil B 3  of the coaxial cable B without causing damage. 
     3. The plastic bushing  5  has a beveled retaining surface  54  press-fitted into the tapered inner surface  43  of the barrel  4  so that the plastic bushing  5  will not escape from the packing hole  42  of the barrel  4 . 
     4. The hole  55  in the right end  53  of the plastic bushing  5  is greater than the packing hole  42  of the barrel  4 , capable for receiving a different thickness of braided outer conductor B 4  of a coaxial cable B of one same specification. 
     5. By means of the elastically deformable feature of the hole  55  in the right end  53  of the plastic bushing  5  to compress the barbed portions  21  of the inner tube  2 , the part of the coaxial cable B outside the barbed portions  21  of the inner tube  2  is well wrapped, achieving a watertight seal. 
     6. The inner diameter of the inner end edge  51  of the left end  52  of the plastic bushing  5  fits the packing hole  42  of the barrel  4  for guiding in the coaxial cable B. 
     7. The plastic bushing  5  further has a tapered inside wall  56  gradually reducing in direction from the hole  55  in the right end  53  toward the inner end edge  51  of the left end  52 . 
       FIG. 10  illustrates an alternate form of the coaxial cable connector in accordance with the present invention. Similarly, this alternate form comprises a screw nut  1 , an inner tube  2 , a body shell  3 , a barrel  4  and a plastic bushing  5 . According to this alternate form, the plastic bushing  5  further comprises a barbed portion  57  extending around the tapered inside wall  56  for retaining the inserted coaxial cable B tightly; the screw nut  1  further has a constructed end portion  13 , enhancing the shielding effect of the coaxial cable connector. 
       FIG. 11  illustrates another alternate form of the coaxial cable connector in accordance with the present invention. Similarly, this alternate form comprises a screw nut  1 , an inner tube  2 , a body shell  3 , a barrel  4  and a plastic bushing  5 . According to this alternate form, the body shell  3  is a plastic member; the barrel  4  has an inner thread  44  forced into engagement with the periphery of the body shell  3  to enhance connection between the body shell  3  and the barrel  4  and to prohibit the body shell  3  from escaping from the barrel  4 ; the inner tube  2  further comprises a barbed portion  23  for stopping against a constructed inner part of the body shell  3  to prohibit the body shell  3  from escaping from the inner tube  2 . 
     Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.