An insulation-displacement terminal fitting

Abstract: [Object] To improve both a contact reliability with a core and a function of restricting a loose movement of a wire. [Solution] An insulation-displacement portion 16 is formed by a pair of plate portions 16F, 16R which are bent from a side wall 12 by bending a portion of the side wall 12 to project substantially in V-shape. A bending angle β between one plate portion 16R and the side wall 12 is set larger than a bending angle α between the other plate portion 16F and the side wall 12. Even if a pulling force acts on a wire W, the wire does not make a loose movement since the bending angle of the plate portion 16F located at the side behind with respect to a pulling direction to the side wall 12 is a right angle. Further, since the bending angle β between the plate portion 16R and the side wall 12 is set larger, an angle y between the plate portions 16F and 16R at the projecting end of the insulation-displacement portion 16 is sufficiently large to ensure a wide contact area with a core Wb. Thus, a high contact reliability can be secured.

Description: The present invention relates to an insulation-displacement terminal fitting. Japanese Examined Patent Publication No. 57-10550 discloses insulation-displacement terminal fitting in which portions of a pair of left and right side walls are bent to project inwardly in V-shape to form a pair of insulation-displacement portions, so that an insulation coating of a wire is cut open by projecting ends of the insulation-displacement portions and a core thereof is brought into contact with the projecting ends by pushing the wire in between the insulation-displacement portions in a direction normal to the longitudinal direction of the wire. In the case that the core is brought into contact with the projecting ends of the insulation-displacement portions projecting in V-shape as described above, a contact area with the core is increased and thus a contact reliability is better as an angle at the projecting ends of the V-shaped insulation-displacement portions increases. On the other hand, in the case that a pulling force acts on the wire in its longitudinal direction, a cut surface of a resin coating is more easily caught as an angle of plate portions forming the insulation-displacement portions becomes more closer to a right angle with respect to the pulling direction by decreasing the angle at the projecting ends of the V-shaped insulation-displacement portions. Therefore, a loose movement of the wire can be more effectively restricted. Thus, either one of the contact reliability with the core and the restriction of the loose movement of the wire has been conventionally fulfilled at the cost of the other in setting the angle of the V-shaped insulation-displacement portions. US 4512619 discloses a collapsible insulation displacement terminal comprising a metallic body with a pair of said portion positionable on opposite sides of an insulation covered wire. Each side portion includes the vacant intermediate region with an aperture defined therein. When the terminal is compressed by a force applied generally parallel to the length of the wire, the intermediate regions collapse inwardly of the terminal body toward one another. In the process, a contact edge defined by the apertures severs the insulation covering the wire and produces an electrical connection between the central core of the wire and the terminal. An object of the present invention is to improve both a contact reliability with a core and a function of restricting a loose movement of a wire. 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 having at least one pair of insulation-displacement portions provided to project inwardly substantially in V-shape from opposite side walls and bringable into contact with a wire at least partly inserted in a direction at an angle different from 0° or 180°, preferably in a direction substantially normal to the longitudinal axis of the terminal fitting, between the insulation-displacement portions, each insulation-displacement portion being formed by a pair of plate portions which are bent from the corresponding side wall by bending a portion of the side wall to project substantially inwardly, wherein the plate portions of at least one of the pair of insulation-displacement portions are formed such that a bending angle of a first plate portion thereof and the corresponding portion of the side wall is set larger than a bending angle between a second plate portion thereof and the corresponding portion of the side wall. According to a preferred embodiment of the invention, there is provided an insulation-displacement terminal fitting having one pair of insulation-displacement portions provided to project inwardly substantially in V-shape from opposite side walls, a resin coating of a wire being cut open by projecting ends of the insulation-displacement portions and a core thereof being brought into contact with the projecting ends of the insulation-displacement portion by pushing the wire oriented substantially parallel to the side walls in between each pair of insulation-displacement portions in a direction normal to the longitudinal axis of the wire, each insulation-displacement portion being formed by a pair of plate portions which are bent from the corresponding side wall by bending a portion of the side wall to project substantially in V-shape, wherein a bending angle between one of the pair of plate portions and the corresponding side wall is set larger than a bending angle between the other plate portion and the corresponding side wall. In the case that an external force which tries to loosely move the wire in its longitudinal direction acts on the wire, a high loose movement restricting function can be obtained by setting the bending angle of the plate portion located behind with respect to a direction of loose movement to the side wall at an angle close to a right angle. If the bending angle of the plate portion located before with respect to the direction of loose movement to the side wall is set at a large angle, i.e. an obtuse angle, a bending angle between the two plate portions at the projecting end of the insulation-displacement portion is large, thereby ensuring a wide contact area with the core. Preferably, the second plate portion of the pair of plate portions projects at a substantially right angle to the corresponding portion of the side wall. In other words, one of the pair of plate portions is at a right angle to the corresponding side wall. If the plate portion located behind with respect to the direction of loose movement acting on the wire is at a right angle to the side wall, it is engaged with a cut surface of the resin coating in a direction normal to the direction of loose movement. Thus, a high loose movement restricting effect can be obtained. Further preferably, the second plate portion of the pair of plate portions projects at an acute angle to the corresponding portion of the side wall. In other words, one of the pair of plate portions is at an acute angle to the corresponding side wall. If the plate portion located behind with respect to the direction of loose movement acting on the wire is at an acute angle to the side wall, it bites in the resin coating like a wedge. Thus, a high loose movement restricting effect can be obtained. Still further preferably, the second plate portion of the pair of plate portions projects at an obtuse angle to the corresponding portion of the side wall. Most preferably, the second plate portion is provided on a side of the insulation-displacement portion substantially opposed to an engaging portion of the insulation-displacement terminal fitting. According to a further preferred embodiment of the invention, the first plate portion is arranged at an obtuse angle with respect to the corresponding portion of the side wall. Preferably, the first plate portion is arranged on a side of the insulation-displacement portion substantially opposed to an engaging portion of the insulation-displacement terminal fitting. Most preferably, the pair of insulation-displacement portions being provided substantially facing each other is formed of two different types of insulation-displacement portions. 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 plan view of a first embodiment, FIG. 2 is a partial enlarged plan view of the first embodiment, FIG. 3 is a partial enlarged plan view of a second embodiment, FIG. 4 is a partial enlarged plan view of a third embodiment, FIG. 5 is a partial enlarged plan view of a fourth embodiment, and FIG. 6 is a partial enlarged plan view of a fifth embodiment. [First Embodiment] Hereinafter, a first embodiment of the present invention is described with ref erence to FIGS. 1 and 2. An insulation-displacement terminal fitting T according to this embodiment is produced by applying, e.g. bending to a conductive metallic plate material stamped 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 over its entire length. An engaging portion 13 preferably in the form of a substantially rectangular tube for the connection with a mating male terminal fitting (not shown) is formed at a substantially front half of the terminal fitting T, and 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. One or more insulation-displacement portions 15, 16 are formed before or adjacent to the crimping portion 14. The insulation-displacement portions 15, 16 are preferably formed in two positions space apart in forward and backward or longitudinal directions in each of a pair of side walls 12 standing from the opposite side edges of the bottom wall 11, i.e. a total of four insulation-displacement portions are preferably formed. Each pair of the insulation-displacement portions 15, 16 are transversely arranged or arranged at an angle different from 0° or 180°, preferably substantially normal to the longitudinal direction of the wire W as to hold the wire therebetween. Accordingly, the front or first and rear or second pairs of the insulation-displacement portions 15, 16 are provided in one insulation-displacement terminal fitting T. The respective insulation-displacement portions 15, 16 are formed by bending portions of the side walls 12 to project inwardly substantially in V-shape, so that projecting ends of a pair of substantially flat plate portions 15A or 16F and 16R obliquely extending from the side walls 12 are preferably substantially joined. The front (right in FIGS. 1 and 2) pair of the insulation-displacement portions 15 substantially have a shape of an isosceles triangle in which the pair of front and rear plate portions 15A forming the insulation-displacement portions 15 are symmetrical. Specifically, a bending angle between the side wall 12 and the front plate portion 15A is the same as the one between the side wall 12 and the rear plate portion 15A, about 120°, and accordingly an angle between the projecting ends of the two plate portions 15A is about 60°. Further, the pair of the insulation-displacement portions 15 are substantially symmetrical with respect to each other with respect to a center longitudinal axis of the terminal fitting T in plan view. The rear pair of the insulation-displacement portions 16 have a shape of a substantially right-angled triangle in which the pair of front or first and rear or second plate portions 16F, 16R forming the insulation-displacement portions 16 are asymmetrical. Specifically, a bending angle α between the front or first plate portion 16F and the side wall 12 is a substantially right angle, but a bending angle β between the rear or second plate portion 16R and the side wall 12 is an obtuse angle. An angle γ between the pair of the plate portions 16F, 16R is preferably about 45°. The rear pair of the insulation-displacement portions 16 are also symmetrical with respect to the center longitudinal axis of the terminal fitting T in plan view. Next, the action of this embodiment is described. The wire W having its longitudinal axis oriented in forward and backward directions (parallel to the longitudinal direction of the terminal fitting T and the side walls 12) is at least partly pushed 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 projecting ends of the substantially V-shaped insulation-displacement portions 15, 16 cut the resin coating Wa of the wire W open between the respective pairs of the insulation-displacement portions 15, 16, and bite in the cut-open sections of the resin coating Wa to be brought into (electric) contact with a core Wb, with the result that the wire W is connected with the respective insulation-displacement portions 15, 16 by insulation displacement. In a state where the wire W is connected by insulation displacement, wide contact areas are provided between the insulation-displacement portions 16 and the core Wb since the angle at the projecting ends of the rear insulation-displacement portions 16 is a relatively large angle of 45°, thereby securing a sufficient contact reliability. Further, the front plate portions 16F of the rear insulation-displacement portions 16 project substantially at a right angle to the side walls 12, and come into contact with cut surfaces Wc of the resin coating Wa of the wire W by engaging the corresponding surfaces substantially normal to the longitudinal axis of the wire W. Thus, even if a pulling force acting backward with respect to the longitudinal direction of the wire W is exerted on the wire W, a loose backward movement of the wire W can be securely prevented by the engagement of the plate portions 16F and the cut surfaces Wc. As described above, according to this embodiment, the bending angle α (substantially right angle) between the front plate portions 16F of the rear insulation-displacement portions 16 and the side walls 12 is set smaller than the bending angle β (obtuse angle) between the rear plate portions 16R and the side walls 12. Thus, a strong engagement to restrict the loose movement of the wire W in its longitudinal direction is secured by preferably making the front plate portions 16F substantially at a right angle to the side walls 12, whereas the angle γ between the plate portions 16F and 16F is increased by setting the angle between the rear plate portions 16F and the side walls 12 at an obtuse angle, thereby improving a contact reliability with the core Wb. [Second Embodiment] Next, a second embodiment of the present invention is described with reference to FIG. 3. According to the second embodiment, a front pair and a rear pair of insulation-displacement portions 16 are provided as in the first embodiment. Both pairs of the insulation-displacement portions 16 are similar or the same as the insulation-displacement portions 16 substantially in the form of a right-angled triangle located at the rear side of the first embodiment. Specifically, a pair of front and rear plate por tions 16F, 16R forming each insulation-displacement portion 16 are asymmetrical, and a bending angle α between the front plate portion 16F and the side wall 12 is a substantially right angle, but a bending angle β between the rear plate portion 16R and the side wall 12 is an obtuse angle. An angle γ between the pair of the plate portions 16F, 16R is preferably about 45°. No description is given on the structure, action and effects of the other construction by identifying it by the same reference numerals since it is similar or the same as the first embodiment. [Third Embodiment] Next, a third embodiment of the present invention is described with reference to FIG. 4. According to the third embodiment, a front pair and a rear pair of insulation-displacement portions 15, 16 are provided as in the first embodiment. The insulation-displacement portion 15 located at the right side (lower side in FIG. 4) of the insulation-displacement portions 15, 16 located at the front side and the insulation-displacement portion 15 located at the left side of the insulation-displacement portions 15, 16 located at the rear side are similar or the same as the insulation-displacement portions 15 located at the front side in the first embodiment, i.e. are in the form of an isosceles triangle in which a pair of front and rear plate portions 15A are substantially symmetrical. On the other hand, the insulation-displacement portion 16 located at the left side of the insulation-displacement portions 15, 16 located at the front side and the insulation-displacement portion 16 located at the right side of the insulation-displacement portions 15, 16 located at the rear side are similar or the same as the insulation-displacement portions 16 located at the rear side in the first embodiment, i.e. in the form of a right-angled triangle in which a pair of front and rear plate portions 16F, 16R are asymmetrical and the front plate portion 16F is at a right angle to the side wall 12 (longitudinal axis of the wire). In this way, the insulation-displacement portions 15 in the form of an isosceles triangle and the insulation-displacement portions 16 in the form of a right-angled triangle are offset to each other with respect to forward and backward or longitudinal directions and transverse direction (offset arrangement) in the third embodiment. [Fourth Embodiment] Next, a fourth embodiment of the present invention is described with reference to FIG. 5. An insulation-displacement portion 17 according to the fourth embodiment is such that a bending angle Xa between the front (right in FIG. 5) one of a pair of plate portions 17F, 17R forming the insulation-displacement portion 17 and the side wall 12 is an acute angle (smaller than 90°). A bending angle Ya between the rear plate portion 17R and the side wall 12 is an obtuse angle which is even larger than the obtuse bending angle β between the rear plate portion 16R of the insulation-displacement portion 16 in the form of a right-angled triangle in the first and second embodiments and the side wall 12. Consequently, an angle Za between the plate portions 17F and 17R is set at a relatively large angle (substantially equal to the angle γ between the plate portions 16F and 16R of the insulation-displacement portion 16 substantially in the form of a right-angled triangle). According to the fourth embodiment, when a backward pulling force acts on the wire W, the cut surface Wc of the resin coating Wa obliquely comes into contact with the front plate portion 17F which is at an acute angle to the side wall 12, and the front plate portion 17F bites in the core Wb like a wedge. Therefore, a higher loose movement restricting effect can be obtained. [Fifth Embodiment] Next, a fifth embodiment of the present invention is described with reference to FIG. 6. An insulation-displacement portion 18 according to the fifth embodiment is such that a pair of front and rear plate portions 18F, 18R forming the insulation-displacement portion 18 are both at an obtuse angle (larger than 90°) to the side wall 12, but a bending angle Xb between the front (right in FIG. 6) plate portions 18F and the side wall 12 is an angle relatively closer to 90° and a bending angle Yb between the rear plate portion 18R and the side wall 12 is larger than the bending angle Xb. With such an insulation-displacement portion 18, the plate portion 18F and the cut surface Wc of the resin coating Wa are engaged in a direction substantially normal to the longitudinal direction of the wire W when a pulling force acts on the wire W. Thus, an effect of restricting a loose movement of the wire W can be achieved. Further, a better contact reliability with the core Wb can be ensured since the front plate portion 18F is at an obtuse angle to the side wall 12 to thereby ensure a sufficiently large angle Zb between the front and rear plate portions 18F and 18R. The present invention is not limited to the above described and illustrated embodiment. For example, the following embodiment is also embraced by the technical scope of the present invention as defined in the claims. Beside the following embodiment, various changes can be made without departing the sprit of the present invention as defined in the claims. (1) In the foregoing embodiment, the plate portion which is at a small bending angle to the side wall is arranged at the side behind with respect to the pulling direction (front side) assuming that the wire is subjected to the pulling force to withdraw the wire backward from the insulation-displacement terminal fitting. However, according to the present invention, a plate portion having a small bending angle to the side wall may be provided at the side behind with respect to a pushing direction (rear side) assuming a case where the wire is conversely subjected to an external pushing force. LIST OF REFERENCE NUMERALS T insulation-displacement terminal fitting 12 side wall 16 insulation-displacement portion 16F plate portion 16R plate portion 17, 18 insulation-displacement portion 17F, 18F plate portion 17R, 18R plate portion W wire Wa resin coating Wb core α bending angle β bending angle Xa, Xb bending angle Ya, Yb bending angle

Claims: An insulation-displacement terminal fitting (T) having at least one pair of insulation-displacement portions (15; 16; 17; 18) provided to project inwardly substantially in V-shape from opposite side walls (12) and bringable into contact with a wire (W) at least partly inserted in a direction at an angle different from 0° or 180°, preferably in a direction substantially normal to the longitudinal axis of the terminal fitting (T), between the insulation-displacement portions (15, 16, 17, 18), each insulation-displacement portion (15; 16; 17; 18) being formed by a pair of plate portions (15A; 16F, 16R; 17F, 17R; 18F, 18R) which are bent from the corresponding side wall (12) by bending a portion of the side wall (12) to project substantially inwardly, characterized in that plate portions (16F, 16R; 17F, 17R; 18F, 18R) of at least one (16; 17; 18) of the pair of insulation-displacement portions (15; 16; 17; 18) are formed such that a bending angle (β; Ya; Yb) of a first plate portion (16R; 17R; 18F) thereof and the corresponding portion of the side wall (12) is set larger than a bending angle (α; Xa; Xb) between a second plate portion (16F; 17F; 18F) thereof and the corresponding portion of the side wall (12). An insulation-displacement terminal fitting according to claim 1, wherein the second plate portion (16F) of the pair of plate portions (16F, 16R; 17F, 17R; 18F, 18R) projects at a substantially right angle (α) to the corresponding portion of the side wall (12). An insulation-displacement terminal fitting according to one or more of the preceding claims, wherein the second plate portion (17F) of the pair of plate portions (16F, 16R; 17F, 17R; 18F, 18R) projects at an acute angle (Xa) to the corresponding portion of the side wall (12). An insulation-displacement terminal fitting according to one or more of the preceding claims, wherein the second plate portion (18F) of the pair of plate portions (16F, 16R; 17F, 17R; 18F, 18R) projects at an obtuse angle (Ya) to the corresponding portion of the side wall (12). An insulation-displacement terminal fitting according to one or more of the preceding claims, wherein the second plate portion (16F; 17F; 18F) is provided on a side of the insulation-displacement portion (16; 17; 18) substantially opposed to an engaging portion (13) of the insulation-displacement terminal fitting (T). An insulation-displacement terminal fitting according to one or more of the preceding claims, wherein the first plate portion (16R; 17R; 18R) is arranged at an obtuse angle (β) with respect to the corresponding portion of the side wall (12). An insulation-displacement terminal fitting according to one or more of the preceding claims, wherein the first plate portion (16R; 17R; 18R) is arranged on a side of the insulation-displacement portion (16; 17; 18) substantially opposed to an engaging portion (13) of the insulation-displacement terminal fitting (T). An insulation-displacement terminal fitting according to one or more of the preceding claims, wherein the pair of insulation-displacement portions (15; 16; 17; 18) being provided substantially facing each other is formed of two different types (FIG. 4) of insulation-displacement portions (15; 16; 17; 18).

Inventors: HIO MASAHIDE, KOJIMA EIJI, HIO, MASAHIDE, KOJIMA, EIJI, HIO, MASAHIDO
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 2001
Main classification: H01R4
IPC codes: H01R4