Electricity: conductors and insulators – Anti-inductive structures – Conductor transposition
Reexamination Certificate
2003-09-23
2004-11-09
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Anti-inductive structures
Conductor transposition
C174S068300, C439S098000, C439S939000
Reexamination Certificate
active
06815610
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a waterproof/oilproof electromagnetic shielding structure used at a portion where electric wires (cables) are connected respectively to input/output terminals of a motor of an electric car or an ordinary electronic/electric equipment.
Recently, small current circuits and electronic circuits have increasingly been used in automobiles, and installed wires have now had a large-current/high-voltage design, and under these circumstances, it has been required to provide effective and inexpensive electromagnetic shielding measures which protect the small current circuits liable to be affected by electromagnetic noises, and will not lower the detection precision of various sensors in the electronic circuits under the influence of electromagnetic noises.
In a related electromagnetic shielding structure, a plurality of pin terminals
3
are held by a terminal-holding retainer
2
provided within a cylindrical metal shell
1
, as shown in
FIG. 14
which is a side cross-sectional view. A shielded cable
4
, shown in
FIG. 14
, comprises a plurality of twisted insulated core wires
5
each having a conductor
5
a
covered with an insulator
5
b
, a metal braid
6
wound on the twisted core wires
5
, and an outermost sheath
7
covering this metal braid. The insulator is removed from an end portion of each insulated core wire
5
of the shielded cable
4
, and the exposed conductors
5
a
of the core wires
5
are connected to the pin terminals
3
, respectively.
The sheath
7
is removed from an end portion of the cable, thereby exposing the braid
6
, and a tubular metal net
8
is fitted on a skirt-like end portion of the braid
6
, and further a heat-shrinkable tube
9
is fitted on the metal net
8
. The heat-shrinkable tube
9
is heated to tighten the metal net
8
by its shrinking pressure, so that the metal net
8
is pressed against an outer peripheral surface of the metal shell
1
, and therefore is connected thereto, thereby electrically connecting the braid
6
to the metal shell
1
, thus achieving an electromagnetic shielding effect (see, for example, JP-UM-A-6-23179 (Page 2, FIG.
1
)).
One known electric connector, employing an electromagnetic shielding structure different from the above electromagnetic shielding structure, is shown in
FIG. 15
although such an electric connector is not clearly disclosed in any technical literature. Namely, in this case, a shielded wire (or shielded cable)
20
includes an insulator
22
covering a conductor
21
, an outermost sheath
23
covering the insulator
22
. A braid
24
, serving as a shielding layer, is embedded between the inner and outer layers, that is, the insulator
22
and the sheath
23
, and generated electromagnetic waves are absorbed by the braid
24
. A metal terminal
25
is press-fastened to the conductor
21
at a distal end of the wire, and this metal terminal
25
is connected to an input/output terminal of an equipment.
In this case, the sheath
23
is removed from the distal end portion of the shielded wire
20
, thereby exposing the braid
24
and the insulator
22
(which are disposed within this sheath), and an end portion of the exposed braid
24
is connected to a metal collar
26
and a mounting bracket
29
made of metal. The mounting bracket
29
is connected to a casing of the equipment connected to the ground. The braid
24
is connected to the equipment casing via the metal collar
26
and the mounting bracket
29
, thereby achieving a shielding conduction, and electromagnetic waves, generated from the shielded wire
20
, are absorbed by a shielding conduction path. Molten resins are injected to cover a shield connecting portion of the braid
24
, thereby forming an inner covering molded portion
28
A and an outer covering molded portion
28
B by a two-color molding method. In this manner, the electric connector, having the electromagnetic shielding structure, is formed.
The electromagnetic shielding structures of the electric connectors, shown respectively in Patent Literature 1 and
FIG. 15
, have the following problems.
First, in the case of the related structure of
FIG. 14
disclosed in Patent Literature 1, the metal net
8
(which is a cumbersome connecting member) is used to electrically connect the braid
6
to the metal shell
1
for shielding purposes, and this metal net
8
is pressed against the metal shell
1
by the use of the heat-shrinkable tube
9
. The number of the expensive component members, including the metal net
8
and the heat-shrinkable tube
9
, increases, and therefore this is disadvantageous from the viewpoint of the cost. And besides, the force for sufficiently pressing the metal net
8
against the metal shell
1
can not be obtained only by the heat-shrinking force of the heat-shrinkable tube
9
. Therefore, a shielding resistance is unstable, so that the effective electromagnetic shielding can not be effected, and therefore the reliability of the shielding-purpose connection of the braid
6
to the metal shell
1
is affected. In addition, if the heat-shrinkable tube should be damaged or ruptured, the metal net
8
is displaced out of position, and fails to serve to interconnect the metal shell
1
and the braid
6
, thus causing electrical disconnection, and this leads to a possibility that the intended electromagnetic shielding function is adversely affected.
In the case of the structure of
FIG. 15
, in order to connect the braid
24
of the shielded wire
20
to the equipment casing or the like, the metal collar
26
and the metal mounting bracket
29
are used as the relay members for the shielding-purpose connection. And besides, after the braid
24
is connected to the mounting bracket
29
, the inner and outer covering molded portions
28
A and
28
B are formed. Namely, the number of the component members is large, and besides the production process up to the molding step is very complicated, and naturally the production cost increases. In addition, the covering molded portions
28
A and
28
B adhere to the sheath
23
and insulator
22
of the shielded wire
20
which are molded of different resin materials, respectively, and further adhere to the metal collar
26
and the metal mounting bracket
29
. In view of physical properties, it is difficult to think that when a layer, adhering to resins of different natures or metals of different natures, is molded by the use of the same resin, a sufficient adhesion is obtained in an interface, and thus there is encountered a structural problem.
A further problem which is common to the structure of
FIG. 14
(disclosed in Patent Literature 1) and the structure of
FIG. 15
is that the conductor and the metal terminal are exposed, and a waterproof ability for preventing the intrusion of rain water from the exterior and an oil leakage prevention ability for preventing the leakage of oils (such as lubricating oil used in the equipment) to the exterior are not taken into consideration. Particularly in the case of the latter structure shown in
FIG. 15
, there is a fear that oil, such as lubricating oil used in the equipment, leaks to the exterior via the conductor
21
of the distal end portion of the shielded wire
20
and the metal terminal
25
, and adversely affects other equipment. In the case of the molded electric connector, the durability for a change of properties upon deposition of rain water is different from the durability for a change of properties upon deposition of oil, and the resin material of an ordinary nature, forming the covering molded portions
28
A and
28
B, can not meet such required characteristics for water and oil.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide an electromagnetic shielding structure with an oilproof and waterproof ability which achieves a satisfactory shielding performance particularly against electromagnetic waves from an installed large-current/high-voltage cable at low costs, and also has a required oilproof and waterproof performance against rain water and oils.
In order to achieve th
Fukushima Hirotaka
Kuboshima Hidehiko
Yagi Sakai
Oliva Carmelo
Reichard Dean A.
Yazaki -Corporation
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