Electrical connectors – Contact comprising cutter – Insulation cutter
Reexamination Certificate
2001-04-16
2002-07-09
Sircus, Brian (Department: 2839)
Electrical connectors
Contact comprising cutter
Insulation cutter
C439S406000
Reexamination Certificate
active
06416348
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an insulation-displacement terminal fitting with substantially V-shaped insulation-displacement portions.
2. Description of the Related Art
A known insulation-displacement terminal fitting with V-shaped insulation-displacement portions is disclosed in Japanese Examined Patent Publication No. 57-10550. This terminal fitting has a bottom wall and side walls that extend up from the bottom wall. Portions of the side walls extending from the bottom wall are deformed inward to define insulation-displacement portions that are V-shaped when viewed from above. A contact edge is defined at the projecting end or apex of each V-shaped insulation-displacement portion, This design enables a wire to be pushed down between the insulation-displacement portions. Movement of the wire causes an insulation coating of the wire to be caught by the upper ends of the contact edges and to be cut open. The contact edges then bite into the cut sections and contact a core of the wire.
FIG. 8
shows an insulation-displacement terminal fitting that catches and cuts an insulation coating
1
with V-shaped insulation-displacement portions
2
. The insulation-displacement portions
2
have contact edges
3
that are intended to contact the core
4
of the wire. However, as shown in
FIG. 8
, the insulation coating
1
may remain caught by the upper ends of contact edges
3
without being cut, and may be stretched and tom as the core
4
is pushed. In such a case, the stretched insulation coating will exert forces in a contracting direction, and those forces may lift the core
4
up in a direction to disengage from the insulation-displacement portions
2
. As a result, contact reliability between the core
4
and the insulation-displacement portions
2
may be reduced.
Further, the upper ends of the V-shaped insulation-displacement portions
2
are located only slightly lower than side walls
5
. Thus, the insulation coating
1
caught by the upper ends of the contact edges
3
of the insulation-displacement portions
2
may project above the side walls
5
. The insulation coating
1
that projects above the side walls
5
may be caught by a terminal insertion opening when the insulation-displacement terminal fitting is inserted into a housing (not shown), thereby hindering an inserting operation.
In view of the above problems, it is an object of the invention to provide an insulation-displacement terminal fitting which provides for improved operability and contact reliability.
SUMMARY OF THE INVENTION
The invention is directed to an insulation-displacement terminal fitting with opposed side walls and at least one pair of insulation-displacement portions projecting into the space between the side walls. The insulation displacement portions cut and open an insulation coating of a wire that is pushed along a direction normal to the longitudinal direction of the wire into the space between the insulation-displacement portions. A core of the wire then contacts the insulation-displacement portions.
The insulation-displacement portions comprise contact portions that project inwardly from side walls of the terminal fitting. The contact portions preferably are V-shaped and preferably are aligned along the pushing direction of the wire. The apex of each V-shaped contact portion defines a contact edge that contacts the core of the wire.
At least one blade projects from each side wall at a location before the contact portions with respect to the wire pushing direction. Each blade preferably is a single plate and has a cutting edge at its projecting end. An accommodation space is defined between opposed blades and has a width larger than the space between the corresponding pair of opposed contact edges. The cutting edges of the blades are located more toward the corresponding side walls than the contact edges when viewed in the wire pushing direction.
The plate-shaped blades make cuts in the insulation coating while the wire is being pushed in. Accordingly, the insulation coating is cut open more reliably by the V-shaped contact portions after the blades make the initial cut. The core then is pushed between the contact portions. The cut-open piece of the insulation coating caught by the contact portions is separated reliably from a portion of the insulation coating surrounding the core and is not stretched forcibly. Therefore, the insulation coating does not pull the core in a direction to be withdrawn from a clearance between the contact portions, and a high contact reliability can be secured between the core and the contact portions.
The cut-open piece of the insulation coating caught by the contact portions is located in the accommodation space between the blades, and hence is within a height range of the side walls.
Slanted guide surfaces are formed at the rear ends of the contact edges with respect to the wire pushing direction and guide the core between the contact edges. Thus the core can be guided between the contact edges by the guide surfaces without getting caught by the contact portions.
Each contact portion preferably comprises a shelf before the contact edges with respect to the wire pushing direction. The shelf preferably extends substantially normal to the wire pushing direction, and catches the insulation coating to prevent an entrance of insulation coating into the clearance between the contact edges. Therefore, a contact failure resulting from the insulation coating caught between the core and the contact edges can be prevented.
The accommodation space preferably communicates with the space outwardly from the contact portion via a clearance between the cutting blades. Additionally, the accommodation space extends sufficiently along the wire pushing direction to accommodate the entire cut-open portion of the wire.
These and other objects, features and advantages of the present invention will become apparent upon reading of the following detailed description of preferred embodiments and accompanying drawings.
REFERENCES:
patent: 3867005 (1975-02-01), Hoppe, Jr.
patent: 3895852 (1975-07-01), Wasserlein, Jr.
patent: 4040702 (1977-08-01), McKe et al.
patent: 4153324 (1979-05-01), Kukla
patent: 4427251 (1984-01-01), Mathe et al.
patent: 4940425 (1990-07-01), Hass et al.
patent: 5334058 (1994-08-01), Hotea
patent: 5549483 (1996-08-01), Hotea
patent: 5810616 (1998-09-01), Ivey
patent: 6012942 (2000-01-01), Volstorf
patent: 0 320 310 (1989-06-01), None
patent: 0 352 966 (1990-01-01), None
patent: 57-10550 (1982-02-01), None
patent: 09-274941 (1997-10-01), None
US 4,057,314, 11/1977, Mathe et al. (withdrawn)
Hio Masahide
Kojima Eiji
Casella Anthony J.
Hespos Gerald E.
Nguyen Son V.
Sircus Brian
Sumitomo Wiring Systems Ltd.
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