Electrical connectors – Metallic connector or contact also having securing part...
Reexamination Certificate
2001-09-21
2004-01-13
Bradley, P. Austin (Department: 2833)
Electrical connectors
Metallic connector or contact also having securing part...
C439S431000, C439S880000
Reexamination Certificate
active
06676458
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a structure and method for connecting a terminal and an electric wire, in which a wire connecting portion of the terminal can uniformly be press-connected to a core wire portion of the electric wire, reliable electric contact of the connected portion thereof is obtained, and an interlocking force thereof is improved.
The present application is based on Japanese Patent Applications Nos. 2000-286954, 2000-317982 and 2001-256720, which are incorporated herein by reference.
2. Description of the Related Art
According to a mode of a structure for connecting an electric wire to a terminal, as shown in
FIG. 1
, a core wire portion
45
at a peeled terminal end of an electric wire
44
is clamped by a pair of crimping pieces
42
which are provided on both sides of a bottom plate portion of a terminal
41
in such a manner as to erect therefrom for fixed press attachment, so that a contact between the core wire portion
45
and the crimping pieces
42
is obtained.
The terminal
41
has a circular plate-like electric contact portion
46
at one end, the pair of core wire crimping pieces
42
as an wire connecting portion at the other end thereof and a pair of coating crimping pieces
43
provided rearward of the pair of the core wire crimping pieces. The coating crimping pieces
43
are press attached fixedly to an insulating resin coating of the electric wire
44
, whereby the core wire portion
45
is prevented from being dislocated from the core wire crimping pieces
42
.
According to a crimping method shown in
FIG. 2
, the pair of crimping pieces
42
are crimped in a eyeglasses-like manner between an upper crimper
47
and a lower anvil
48
and respective strands of the core wire portion
45
are compressed between the pair of crimping pieces
42
and a bottom plate portion
49
.
However, while the connecting structure using the aforesaid solderless or crimping terminal
41
is effective for electric wires
44
of small diameters, for the electric wires of large diameters such as shield electric wires for conducting large current the connecting structure causes a problem that the contact area between the crimping pieces
42
and the core wire portion
45
becomes smaller, increasing electric resistance. In addition, since the crimping pieces
42
are strongly bent from the bottom plate portion
49
in the vicinity of where the crimper
47
is in contact with the anvil
48
, the connecting structure also causes a problem that stress concentrates in bent portions, and the mechanical strength of the terminal
41
is lowered depending upon ways in which the crimping pieces
42
are bent.
To cope with this, there has been used a terminal
51
of a type in which a core wire connecting portion is crimped circumferentially at equal intervals, as shown in FIG.
3
. This terminal
51
has a cylindrical electric contact portion
52
at one end and a cylindrical wire connecting portion
53
at the other end thereof, and the wire connecting portion
53
is crimped circumferentially at equal intervals into, for example, a hexagonal shape with a peeled core wire portion at a terminal end of an electric wire
54
being inserted into the wire connecting portion
53
. A coated portion
55
of the electric wire
44
is located rearward of the wire connecting portion
53
with a gap being provided therebetween. A mating male connector (not shown) is connected to the electric contact portion
52
located on the front side of the terminal
51
by inserting or screwing the former into the latter.
An embodiment of a connecting method (a connecting structure) of this type for connecting the terminal
51
and the electric wire
44
has been recited in Examined Japanese Utility Model Publication No. Sho. 50-43746, and will be described below with reference to FIG.
In this connecting method, an wire connecting portion
62
, initially formed into a cylindrical shape, is crimped into a hexagonal shape with a pair of upper and lower die halves
63
with a core wire portion
61
of the electric wire being inserted into the cylindrical wire connecting portion of the terminal so that the core wire portion
61
is caused to adhere to the wire connecting portion
62
from inside as well as to each other. In each die half
63
, as shown in
FIG. 5
, there are formed three pressing surfaces
64
, and an elongate projection
65
is formed on each pressing surface
64
. As shown in
FIG. 4
, the elongate projections
65
press against central portions of external surfaces of the hexagonal wire connecting portion
62
, respectively, in radial directions so that the contact qualities of the core wire portion
61
of the electric wire and the wire connecting portion
62
of the terminal are improved.
However, in the aforesaid connecting method and a connecting structure using the same method, as shown in
FIG. 4
, burrs
60
tend to be generated on both sides of the wire connecting portion between the upper and lower die halves
63
, and this causes a problem that many man-hours are disadvantageously required to remove the burrs
60
so generated. More over, when the wire connecting portion
62
of the terminal is crimped with the pair of upper and lower die halves
63
, as shown in
FIG. 6
, a crimping force (internal stress) P
1
directed toward the center of the core wire portion
61
tends to act largely, whereas crimping forces (internal stresses) P
2
applied to both sides of the core wire portion
61
tend to be reduced, and this tends to cause a problem that gaps are produced between strands of the core wire portion
61
, as well as between the core wire portion
61
and the wire connecting portion
62
on both the sides of the wire connecting portion
62
of the terminal. In case such gaps are produced, electric resistance is increased, and energizing efficiency is reduced. Moreover, there is caused a concern that the connecting portion is heated.
In addition, in a case where aluminum material is used for the core wire portion
61
, since an oxidized coating on the surface of the core wire portion
61
is thick, the coating needs to be broken, but the oxidized coating cannot be completely removed when the core wire portion
61
is clamped by the pair of crimping pieces
42
for connection or when the cylindrical wire connecting portion
53
is crimped into the hexagonal shape for connection, whereby there is also caused a problem that the electric resistance is increased, and the reliable electric connection is damaged.
In addition,
FIG. 7
shows the result of crimping an electric wire for connection using a similar method to that illustrated in FIG.
4
. Since elongate projections
65
formed on die halves
63
press against a core wire portion
61
′ at six positions thereon in radial directions as indicated by arrows F, the core wire portion
61
′ is deformed into a turtle-like shape in cross section, and stress concentration (chain lines
79
indicate an internal stress distribution) occurs in an wire connecting portion
62
′ of a terminal between respective recessed portions
77
produced by the respective elongate projections
65
(FIG.
5
), or at raised portions
78
, whereby the core wire portion
61
′ cannot be circumferentially uniformly crimped. This helps form easily gaps
70
in the interior of the core wire portion
61
′ (gaps between respective strands), as well as gaps
70
between the core wire portion
61
′ and the wire connecting portion
62
′ of the terminal, and cracks are also easily generated in the wire connecting portion
62
′ due to the stress concentration. Thus, there is caused a problem that the mechanical strength of the wire connecting portion is deteriorated. In case there are formed gaps
70
,
71
, as with the previous case, electric resistance is increased, thereby decreasing energizing efficiency. In addition, there are caused concerns that the wire connecting portion
62
′ is heated and that the core wire portion
61
′ is easil
Asakura Nobuyuki
Kuwayama Yasumichi
Onuma Masanori
Bradley P. Austin
León Edwin A.
Sughrue & Mion, PLLC
Yazaki -Corporation
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