An insulation-displacement terminal fitting

Abstract: [Object] To restrict a loose movement of a wire in its longitudinal direction and securely cut a coating of the wire open. [Solution] Each insulation-displacement portion 17 to be connected with a wire W by insulation displacement is comprised of a pair of base portions 18 projecting inwardly in two positions of a corresponding side wall 12 spaced apart in the longitudinal direction of the wire W, and a blade portion 19 formed by folding and further projecting inwardly from the base portions 18. While the wire W is being pushed in between the insulation-displacement portions 17, a coating Wa can be securely cut open since the folded blade portions 19 are sharply brought into contact with the coating Wa. Even if a pushing or pulling force acts on the wire W in its longitudinal direction after the wire W is connected by insulation displacement, deformations of the insulation-displacement portions 17 in the longitudinal direction of the wire W are restricted by the base portions 18 projecting in two positions of each side wall 12. Therefore, a loose movement of the wire W in its longitudinal direction can be securely prevented.

Description: The present invention relates to an insulation-displacement terminal fitting. A known insulation-displacement terminal fitting is such that a wire extending along opposite side walls is pushed in between a pair of insulation-displacement portions projecting inwardly from opposite side walls in a direction normal to the longitudinal direction of the wire, a resin coating of the wire is cut open by the insulation-displacement portions and is brought into contact with a core of the wire while the wire is being pushed in as disclosed in Japanese Unexamined Patent Publication No. 8-241740. Since the insulation-displacement portions disclosed in the above publication are formed by bending or embossing portions of the side walls into V-shape (triangular shape) when viewed in a wire pushing direction, blade portions are not deformed when a pulling force act on the connected wire in its longitudinal direction. Thus, a loose movement of the wire in its longitudinal direction can be prevented. However, if the insulation-displacement portions are formed into V-shape, areas to be brought into contact with the coating are widened, making it difficult to cut the coating open as compared to insulation-displacement portions in the form of a single plate having a sharp cutting edge. If the coating is not cut open, the tom coating is hooked on the insulation-displacement portions and the core is inserted between the insulation-displacement portions while the hooked coating is elastically stretched. Thus, the core may be displaced in such a direction as to be withdrawn from a clearance between the insulation-displacement portions due to an elastic restoring force of the coating. If the coating is pushed in between the insulation-displacement portions together with the core without being torn, it causes a contact error between the core and the insulation-displacement portions. US-A-5934928 discloses a press-connecting terminal, having two pairs of press-connecting plate portions, which are cut-bent form the side walls in such a way as to extend in the direction perpendicular to each of the side walls above the bottom wall and substantially face each other. Each press connecting plate portion has a respective press-connecting blade portion, which is bent at a predetermined angle toward a contact portion side so that the portions situated outside of the respective edge faces of each press connecting blade form plated contact connecting faces, coming into a contact with and cutting the coated wire. An insulation - displacement terminal according to the preamble of claim 1 is disclosed in GB-A-1490197. In view of the above situation, an object of the present invention is to provide an insulation-displacement terminal fitting provided with insulation-displacement portions which can restrict a loose movement of a wire in its longitudinal direction and securely cut a coating of the wire open. This object is solved according to the invention, by an insulation-displacement terminal fitting according to claim 1. Preferred embodiments of the invention are subject of the dependent claims. According to the invention, there is provided an insulation-displacement terminal fitting in which a resin coating of a wire is or can be cut open by at least one pair of insulation-displacement portions projecting inwardly from a pair of side walls and a core of the wire is or can be brought into contact with the insulation-displacement portions by at least partly pushing or inserting or fitting the wire in between the insulation-displacement portions preferably in a direction substantially normal to its Iongitudinal direction, wherein each insulation-displacement portion comprises a pair of base portions formed by bending or embossing the corresponding side wall in two positions spaced apart in the longitudinal direction of the side wall or wire to project inwardly, and a blade portion formed by folding and projecting further inwardly from the base portions. The blade portion comprises two plates which are either spaced apart or in contact with each other. Since the blade portions formed by folding are sharply brought into contact with the coating while the wire is being pushed in between the insulation-displacement portions, the coating is securely cut open. Further, even if a pushing or pulling force acts on the wire in its longitudinal direction after the wire is connected by insulation displacement, deformations of the insulation-displacement portions in the longitudinal direction of the wire are restricted by the base portions projecting from the side walls in two positions, a loose movement of the wire in its longitudinal direction can be securely prevented. According to a preferred embodiment of the invention, only the blade portions of the insulation-displacement portions bite in the coating in a state where the wire is connected by insulation displacement. Since only the narrow blade portions formed by folding are sharply brought into contact with the coating while the wire is being pushed in between the insulation-displacement portions, a contact error resulting from the coating getting caught or hooked by the wide base portions can be avoided. Further preferably, at least one base portion of the insulation-displacement portion comprises a linear portion arranged at an angle comprised between 0° and 90° with respect to the corresponding portion of the side wall. Most preferably, both base portions of the insulation-displacement portion comprise linear portions arranged at an angle comprised between 0° and 90° with respect to the corresponding portions of the side wall so that the base portions form a substantially V-shape when viewed in a wire pushing direction. According to a further preferred embodiment of the invention, wherein at least one base portion of the insulation-displacement portion is substantially formed in L-shape when viewed in a wire pushing direction. Preferably, at least one base portion of the insulation-displacement portion comprises a portion substantially curved to be convex or concave inwardly or formed as quarter-circular arcs when viewed in a wire pushing direction. Most preferably, both base portions of one insulation-displacement portion comprise a portion substantially formed as quarter-circular arcs when viewed in a wire pushing direction, wherein the quarter-circular arcs are bulging either in directions toward each other or in directions opposite from each other. According to still a further preferred embodiment, the blade portion extends substantially normal to the corresponding side wall. The inventive terminal fitting may preferably take the following specific constructions. (1) The pairs of base portions substantially project in V-shape from the side walls when viewed in the wire pushing direction. (2) The base portions are L-shaped when viewed in the wire pushing direction. (3) The base portions are arcuate when viewed in the wire pushing direction. (4) Each pair of the base portions are so arcuate as to bulge in directions closer to each other. (5) Each pair of the base portions are so arcuate as to bulge in directions away from each other. These and other objects, features and advantages of the present invention will become more apparent upon reading of the following detailed description of preferred embodiments and accompanying drawings. It should be understood that even though embodiments are separately described, single features thereof may be combined to additional embodiments. FIG. 1 is a perspective view of a first embodiment, FIG. 2 is a side view of the first embodiment, FIG. 3 is a plan view of the first embodiment, FIGS. 4(A) and 4(B) are a lateral section and a partial plan view enlargedly showing insulation-displacement portions, respectively, FIGS. 5(A) and 5(B) are a lateral section and a partial plan view enlargedly showing insulation-displacement portions of a second embodiment, respectively, FIGS. 6(A) and 6(B) are a lateral section and a partial plan view enlargedly showing insulation-displacement portions of a third embodiment, respectively, and FIGS. 7(A) and 7(B) are a lateral section and a partial plan view enlargedly showing insulation-displacement portions of a fourth embodiment, respectively. Hereinafter, a first embodiment of the present invention is described with reference to FIGS. 1 to 4. An insulation-displacement terminal fitting T according to this embodiment is produced e.g. by applying bending and embossing to a conductive metallic plate material stamped or cut out into a specified shape. The insulation-displacement terminal fitting T is substantially narrow in forward and backward or longitudinal directions as a whole, and a pair of side walls 12 extend at an angle different from 0° or 180°, preferably substantially normal or upward from opposite side edges of a bottom wall 11 substantially over its entire length. An engaging portion 13 for the connection with a mating male terminal fitting (not shown) is formed at the front end of the terminal fitting T, a crimping portion 14 to be crimped or folded or bent into connection with a wire W is formed at the rear end of the terminal fitting T, and insulation-displacement portions 17 to be connected with the wire W by insulation displacement are formed before or adjacent the crimping portion 14. The engaging portion 13 is comprised of the bottom wall 11, the side walls 12 and ceiling walls 15 which extend inwardly from the upper edges of the side walls 12 while being at least partly placed substantially one over the other, and is in the form of a substantially rectangular tube extending in forward and backward or longitudinal directions as a whole. The crimping portion 14 is comprised of the rear end of the bottom wall 11, and a pair of crimping pieces 16 formed at the rear end of the side walls 12. The pair of crimping pieces 16 are preferably offset to each other with respect to forward and backward or longitudinal directions, and are crimped into connection with the wire W at least partly supplied or'inserted or fitted or placed between the side walls 12 while being arcuately deformed. It should be noted that this crimping step is performed simultaneously with or before or after a step of insulation displacement to be described later. Next, the insulation-displacement portions 17 are described. The insulation-displacement portions 17 are provided preferably in two positions spaced apart in forward and backward or longitudinal directions in each of the side walls 12, i.e. a total of preferably four insulation-displacement portions 17 are provided. Two insulation-displacement portions 17 transversely arranged to hold the wire W are paired, i.e. two front and rear pairs of the insulation-displacement portions 17 are formed in one insulation-displacement terminal fitting T. Each insulation-displacement portion 17 is formed by embossing the corresponding side wall 12 to project inwardly, and is comprised of a pair of base portions 18 projecting inwardly in two positions of this side wall 12 spaced apart in the longitudinal direction of the wire W (forward and backward directions), and a blade portion 19 formed by closely folding a portion further projecting inwardly from the projecting ends of the base portions 18. Preferably, the blade portion 19 comprises a coined or tapered portion 19A, which is coined or tapered inwardly so as to more efficiently bite or cut into the wire W. The pair of base portions 18 project from the side wall 12 substantially in V-shape when viewed in a direction in which the wire W is pushed in between the insulation-displacement portions 17 (wire pushing direction). It should be noted that the projecting ends of the base portions 18 are not directly connected with each other. In other words, the base portions 18 comprise or are preferably constituted by substantially linear portions extending at an angle different from 0° and 180°, preferably comprised between 0° and 90° with respect to corresponding portions of the side walls 12, wherein the base portions 18 of one insulation-displacement portion 17 come closer to each other so as to substantially indicate a triangular or V-shape but the leading ends of the base portions 18 preferably are spaced with respect to each other (i.e. the leading ends do not come into contact or touch each other). The blade portion 19 projects in I-shape from the projecting ends of the base portions 18 preferably in a direction substantially normal to the side wall 12 when viewed in the wire pushing direction. The blade portion 19 is formed by two halves or plates each projecting from the leading end of the respective base portion 18 and are preferably in contact by suitably connecting them. The insulation-displacement portion 17 thus formed is substantially symmetrical along forward and backward or longitudinal directions. Each pair of left and right insulation-displacement portions 17 are substantially symmetrically shaped and arranged, and two insulation-displacement portions 17 provided one after the other in the same side wall 12 are substantially symmetrically shaped and arranged. Accordingly, the blade portion 19 projects from distal ends of the base portions 18 under an angle different from 0° or 180°, so that the blade portion 19 preferably extends substantially at an angle normal to the respective side wall 12. A spacing Sb (FIG. 4B) between the projecting ends of the blade portions 19 of the pair of transversely arranged insulation-displacement portions 17 is set slightly smaller than the outer diameter of a core Wb of the wire W, and a spacing Sa between the base ends (boundaries with the projecting ends of the base portions 18) of the blade portions 19 is set equal to or slightly larger than the outer diameter of a resin coating Wa of the wire W. Next, the action of this embodiment is described. The wire W preferably having its longitudinal axis substantially oriented in forward and backward or longitudinal directions (substantially parallel to the longitudinal direction of the terminal fitting T and the side walls 12) is at least partly pushed or inserted or fitted in between the side walls 12 of the insulation-displacement terminal fitting T according to this embodiment in a direction at an angle different from 0° or 180°, preferably substantially normal to the longitudinal axis thereof. As the wire W is pushed in, the blade portions 19 cut the resin coating Wa of the wire W open between the respective pairs of the transversely arranged insulation-displacement portions 17 and bite in the cut-open sections of the resin coating Wa to be brought into contact with the core Wb. In this way, the wire W is connected with the insulation-displacement portions 17 by insulation displacement. Since the blade portions 19 made narrower than the V-shaped base portions 18 by folding shapely come into contact with the coating like a single blade while the wire W is being pushed in between the insulation-displacement portions 17, the resin coating Wa can be smoothly and securely cut open. Further, since the resin coating Wa is or can be brought into contact only with the narrow blade portions 19, but not with the base portions 18 at this time, there is no possibility of an erroneous insulation displacement resulting from the resin coating Wa getting hooked by the wider base portions 18. Even if a pushing or pulling force acts on the wire W in its longitudinal direction after the wire W is connected by insulation displacement, deformations of the insulation-displacement portions 17 in the longitudinal direction of the wire W are securely restricted since base ends 18A of the base portions 18 are continuous with the side walls 12 in two spaced-apart positions along the longitudinal direction of the wire W and the base portions 18 are substantially triangular. Therefore, a loose movement of the wire W in its longitudinal direction can be securely prevented. Next, a second embodiment of the present invention is described with reference to FIG. 5. Insulation-displacement portions 20 of the second embodiment differ from those of the first embodiment in their construction. Since the other construction is similar or same as in the first embodiment, no description is given on the structure, action and effects thereof by identifying it by the same reference numerals. Each insulation-displacement portion 20 of the second embodiment is such that base portions 21 thereof are substantially L-shaped when viewed in a wire pushing direction as shown in FIG. 5(B) and a blade portion 22 thereof extends in a direction substantially normal to the side wall 12. Each base portion 21 is formed in substantially L-shape by a base section 21A and a leading end 21B. The base sections 21A of the respective base portions 21 are continuous with the side wall 12 at substantially right angles, and the leading ends 21B of the base portions 21 substantially parallel with the side wall 12 are arranged substantially in flush with each other although not being directly coupled with each other. Next, a third embodiment of the present invention is described with reference to FIG. 6. Insulation-displacement portions 23 of the third embodiment differ from those of the first embodiment in their construction. Since the other construction is similar or same as in the first embodiment, no description is given on the structure, action and effects thereof by identifying it by the same reference numerals. Each insulation-displacement portion 23 of the third embodiment is such that base portions 24 thereof are in the form of substantially quarter-circular arcs when viewed in a wire pushing direction, and a blade portion 25 thereof extends in a direction substantially normal to the side wall 12. A pair of base portions 24 are in the form of concave arcs bulging in directions toward each other, and the base ends of the base portions 24 are smoothly tangent to the side wall 12 while the leading ends thereof are smoothly tangent to the blade portion 25. Next, a fourth embodiment of the present invention is described with reference to FIG. 7. Insulation-displacement portions 26 of the fourth embodiment differ from those of the first embodiment in their construction. Since the other construction is similar or same as in the first embodiment, no description is given on the structure, action and effects thereof by identifying it by the same reference numerals. Each insulation-displacement portion 26 of the fourth embodiment is such that, similar to the third embodiment, base portions 27 thereof are in the form of substantially quarter-circular arcs when viewed in a wire pushing direction, and a blade portion 28 thereof extends in a direction substantially normal to the side wall 12. A pair of base portions 27 are in the form of convex arcs bulging in directions away from each other, and the base ends of the base portions 24 are continuous with and at an angle different from 0° or 180° to the side wall 12 while the leading ends thereof are continuous with and at an angle to the blade portion 25. The present invention is not limited to the above described and illustrated embodiments. For example, the following embodiments are also embraced by the technical scope of the present invention as defined in the claims. Beside the following embodiments, various changes can be made without departing from the scope of the present invention as defined in the claims. (1) Although a pair of base portions are symmetrically shaped along the longitudinal direction of the wire in the respective foregoing embodiments, they may be asymmetrically shaped along the longitudinal direction of the wire according to the present invention. (2) Although a pair of base portions identical in shape are symmetrically arranged along the longitudinal direction of the wire in the respective foregoing embodiments, one and the other thereof may have different shapes when viewed in the wire pushing direction (e.g. the one base portion may be the base portion of the first embodiment while the other base portion may be the base portion of any of the second to fourth embodiments) according to the present invention. In other words, one insulation-displacement portion may be formed with a combination of two different base portions of any type 18, 21, 24, 27 described with reference to the first to fourth embodiments. (3) The projecting ends of a pair of plates forming the blade portion may be spaced apart and the two plates may be continuous with separate base portions or a blade portion formed by folding may be continuous with one base portion while being spaced apart from the other base portion according to the present invention. (4) Although the dimensions of the insulation-displacement portions are set such that only the blade portions of the insulation-displacement portions bite in the coating in the foregoing embodiments, they may be set such that both the entire blade portions and the projecting ends of the base portions bite in the coating when the wire is connected by insulation displacement according to the present invention. In such a case, if a pushing or pulling force acts on the wire in its longitudinal direction, such a force is received by not only the blade portions, but also the base portions. Therefore, a function of restricting a loose movement of the wire in its longitudinal direction becomes more reliable. (5) Insulation-displacement portions of opposite side walls 12 may be of different types 17, 20, 23, 26 as described with reference to the first to fourth embodiments, e.g. on one side wall 12 there may be an insulation-displacement portion 17 according to the first embodiment in a position substantially facing an insulation displacement portion 20 according to the second embodiment provided on the opposite side wall 12. LIST OF REFERENCE NUMERALS T insulation-displacement terminal fitting W wire Wa resin coating Wb core 12 side wall 17 insulation-displacement portion 18 base portion 19 blade portion 20,23,26 insulation-displacement portion 21,24,27 base portion 22,25,28 blade portion

Claims: An insulation-displacement terminal fitting (T) in which a resin coating (Wa) of a wire (W) can be cut open by at least one pair of insulation-displacement portions (17; 20; 23; 26) projecting inwardly from a pair of side walls (12) and a core (Wb) of the wire (W) can be brought into contact with the insulation-displacement portions (17; 20; 23; 26) by at least partly pushing the wire (W) in between the insulation-displacement portions (17; 20; 23; 26) preferably in a direction substantially normal to its longitudinal direction, each insulation-displacement portion (17; 20; 23; 26) comprising a pair of base portions (18; 21; 24; 27) formed by bending or embossing the corresponding side wall (12) in two positions spaced apart in the longitudinal direction of the side wall (12) to project inwardly to come closer to each other towards their leading ends and a blade portion (19; 22; 25; 28) comprising two plates each formed by folding and projecting further inwardly from the leading end of the base portions (18; 21; 24; 27), characterized in that the two plates are either spaced apart or in contact with each other by being suitably connected. An insulation-displacement terminal fitting according to claim 1, wherein only the blade portions (19; 22; 25; 28) of the insulation-displacement portions (17; 20; 23; 26) bite in the coating (Wa) in a state where the wire (W) is connected by insulation displacement. An insulation-displacement terminal fitting according to one or more of the preceding claims, wherein leading ends of the base portions (18; 21; 24; 27) of one insulation-displacement portion (17; 20; 23; 26) are not in contact with each other. An insulation-displacement terminal fitting according to one or more of the preceding claims, wherein at least one base portion (18) of the insulation-displacement portion (17) comprises a linear portion arranged at an angle comprised between 0° and 90° with respect to the corresponding portion of the side wall (12). An insulation-displacement terminal fitting according to claim 4, wherein both base portions (18) of the insulation-displacement portion (17) comprise linear portions arranged at an angle comprised between 0° and 90° with respect to the corresponding portions of the side wall (12) so that the base portions (18) form a substantially V-shape (FIG. 4B) when viewed in a wire pushing direction. An insulation-displacement terminal fitting according to one or more of the preceding claims, wherein at least one base portion (21) of the insulation-displacement portion (23) is substantially formed in L-shape (FIG. 5B) when viewed in a wire pushing direction. An insulation-displacement terminal fitting according to one or more of the preceding claims, wherein at least one base portion (24; 27) of the insulation-displacement portion (23; 26) comprises a portion substantially formed as quarter-circular arcs (FIG. 6B; 78) when viewed in a wire pushing direction. An insulation displacement terminal fitting according to claim 7, wherein both base portions (24; 27) of one insulation-displacement portion (23; 26) comprise a portion substantially curved to be concave (FIG. 6B) or convex (FIG: 7B) inwardly. An insulation-displacement terminal fitting according to one or more of the preceding claims, wherein the blade portion (19; 22; 25; 28) extends substantially normal to the corresponding side wall (12).

Inventors: AOYAMA MASAHIKO, KOJIMA EIJI, AOYAMA, MASAHIKO, KOJIMA, EIJI
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 2001
Main classification: H01R4
IPC codes: H01R4