Electrical connectors – Including or for use with coaxial cable – Having crimpable metallic cable conductor grip
Reexamination Certificate
1999-11-19
2001-03-27
Sircus, Brian (Department: 2839)
Electrical connectors
Including or for use with coaxial cable
Having crimpable metallic cable conductor grip
C439S616000, C439S877000, C439S424000
Reexamination Certificate
active
06206727
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a terminal and to a method for crimping a terminal on a shielded cable, and particularly relates to a terminal to be connected with a shielded cable by crimping.
2. Description of the Related Art
A prior art terminal for crimped connection to a shielded cable is disclosed in Japanese Unexamined Utility Model Publication No. 5-27983 and is identified by the numeral
1
in FIG.
11
. The terminal
1
is provided with an inner conductor crimping portion
1
a,
an outer conductor crimping portion
1
b
and a sheath crimping portion
1
c
as shown in FIG.
11
.
The prior art terminal
1
is obliged to have a long length in view of the three crimping portions
1
a,
1
b
and
1
c
arranged along the terminal
1
for the connection with a shielded cable
2
. This long length stands as a hindrance to making the entire terminal smaller.
The inventors herein have considered using one crimping portion which serves both as the outer conductor crimping portion
1
b
and as a sheath crimping portion
1
c
. In such a case, the outer conductor of the cable is folded back over the sheath of the cable and crimping is applied to this folded portion in a manner that is designed not to damage the outer conductor. Alternatively, or additionally, it is desirable to apply a so-called “overlap crimping” to deal with a variation in cable diameter or for other purposes. This approach for addressing problems of the prior art is described in greater detail in copending application Ser. No. 09,442,289 filed Nov. 19, 1999.
Even with the above arrangements, it is necessary to increase a fastening force in the crimped portion to compensate for a reduction in the number of the crimped portions. This is also essential to ensure an electrical conduction with the outer conductor.
In view of the above problems, an object of the present invention is to provide a terminal and a method for crimping which can secure an electrical conductor.
SUMMARY OF THE INVENTION
The subject invention is directed to a terminal, comprising a crimping portion to be fastened to an end of a shielded cable. The shielded cable has an insulating element between inner and outer conductors, and the outer conductor has an outer surface covered by a sheath. The end of the cable is processed to expose portions of the inner and outer conductors, and the exposed portion of the outer conductor may be folded back over the sheath.
The crimping portion of the terminal can be fastened to the outer conductor. More particularly, the crimping portion comprises one or more crimping pieces which are to be crimped to wind at least partly on or around the outer conductor, and preferably around portions of the outer conductor that are folded back over the sheath. One or more projections are provided in positions on the inner surface of the crimping portion bite into and to hold the outer conductor, and preferably the portions of the outer conductor that are folded back over the sheath.
According to a preferred embodiment, the crimping portion can be fastened both to the sheath and to the outer conductor, preferably the portions of the outer conductor that are folded back over the sheath. Accordingly, a higher mechanical strength is provided and the connection is less sensitive to mechanical forces (such as pulling) on the shielded cable.
Preferably, the crimping pieces are to be or can be crimped to at least partly wind on or around the outer conductor with the end of a first crimping piece substantially placed or placeable on the end of a second crimping piece. Accordingly, an “overlap crimping” is advantageously possible.
According to a further preferred embodiment, there is provided a terminal, comprising a crimping portion to be fastened to an end of a shielded cable. The shielded cable has an insulating element between inner and outer conductors, and the outer surface of the outer conductor is covered by a sheath. The sheath is stripped to expose the outer conductor and the exposed outer conductor is folded back over the sheath so that the crimping portion can be fastened both to the sheath and to the outer conductor. The crimping portion comprises a pair of crimping pieces which are crimped to wind around the portion of the outer conductor that is folded back over the sheath, with the end of one crimping piece placed on that of the other crimping piece. At least a pair of projections are provided in positions of the inner surface of the crimping portion to bite into and hold the folded back portion of the outer conductor.
Accordingly, crimping is applied to a portion where the outer conductor is folded back over the sheath so that the terminal can be simultaneously fastened to the outer conductor and to the sheath. Hence, the entire length of the terminal is allowed to be shorter. In this case, the projections provided at the crimping portion hold the shielded cable by biting into portions of the outer conductor that are folded back over the sheath. Thus, the terminal can be fastened to the shielded cable with a sufficient force. Further, the terminal can be stably fastened to the shielded cable since the projections are arranged to hold the shielded cable firmly.
Preferably, the at least two crimping pieces extend from the bottom surface of the crimping portion while being spaced apart wider from each other toward the leading ends thereof. Further preferably, at least one projection is provided in a specified position on a bottom surface of the crimping portion and at least one projection is provided in a position at the leading end of the crimping piece, preferably the second crimping piece placeable below the first crimping piece after crimping. Accordingly, the projections are arranged in positions such that the projections and the shielded cable are unlikely to interfere with each other when the shielded cable is inserted into the terminal for crimping. Hence the shielded cable can be inserted smoothly.
Preferably, the projection provided at the leading end of the second or other crimping piece that is placed below or radially inwardly after crimping is spaced from the leading edge of the other crimping piece by a distance such that this projection can be located substantially right above the projection at the bottom surface when the outer diameter of the outer conductor is a reference value of its range of variation.
The outer diameter of the outer conductor at the folded portion may vary. In such a case, the position of the projection located at the leading end of the crimping piece after crimping is circumferentially displaced. As a result, the biting forces of this projection and the one at the bottom surface may not be balanced along vertical or diametrical direction. However, according to the above embodiment, if the terminal is fastened to the folded portion whose outer diameter is a reference value (about a middle value between the maximum and minimum diameters) of a range of predictable variation, the projection on the crimping piece can be located substantially right above the one on the bottom surface. When the folded portion whose outer diameter is the maximum or minimum value of the predictable variation range is fastened, the projection on the crimping piece is displaced only circumferentially from the diametrically opposite position by a small angle, which does not hinder the fastening in either case.
Most preferably, each projection has such a wedge-shape that its front surface extends at an angle different from 0° or 180°, preferably substantially normal to an insertion direction of the cable and its height is lowered toward the back. Accordingly, since each projection is wedge-shaped, the shielded cable can be inserted smoothly without the projection getting caught by the shielded cable, especially by the position of the outer conductor that is folded back over the sheath. Therefore, the cable can be inserted with an improved efficiency.
According to the invention, there is further provided a method for crimping a terminal onto a shielded cable
Aoyama Masahiko
Koide Takashi
Saito Masashi
Tanaka Masahiro
Casella Anthony J.
Hespos Gerald E.
Hyeon Hae Moon
Porco Michael J.
Sircus Brian
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