Connector terminal

Abstract: A connector terminal for joining a round type electric wire with a flat type electric wire. The connector terminal comprises a first caulking portion for securing the round wire to a first end of the connector terminal, and a clasping portion for securing the flat wire to a second end of the connector terminal, the clasping portion comprising a first and second spring portion, a projecting portion projecting from the clasping portion toward the flat wire, and second caulking portion for compressing the flat electric wire between the first and second spring portion by securing the first spring portion to the second spring portion. The projecting portion may receive solder so that the flat type electric wire can be spot welded to the connector terminal. The resulting connection is extremely compact, reliable, and provides a stable electrical connection over time.

Description: BACKGROUND OF THE INVENTION The present invention relates to a connector terminal for connecting to a flat type electric wire (e.g., connecting a lead wire to a flat conductor), for use in internal wiring such as home equipment, industrial equipment, car equipment, etc. Conventionally, a round type electric wire has been joined with a flat type electric wire either by directly soldering the wires to a printed circuit board or by connecting the wires to individual connectors respectively, and mounting the connectors onto a printed circuit board. Such conventional joining techniques, however, have various problems. When a printed circuit board is used, the space for the joint portion cannot be reduced to a small size, making this joining technique unsuitable for small and high-density mounting. Soldering is necessary even when connectors are used. Accordingly, there is difficulty in maintaining sufficient reliability in electric stability and maintaining mechanical strength over a long time, particularly in the case where the joining technique is used for cars. Further, if the connection is made through soldering, when molding work or the like is performed on the joint portion in order to protect the joint portion, there is a possibility that the solder will flow due to the temperature of resin, thus risking a disconnection or short between adjacent circuits. There is also known from GB-A-1 268 770 a connector terminal for connecting a round type electric wire with a flat type electric wire by forming the connector terminal from a parallel length of metal strip. One end of the metal strip is formed as a ferrule into which the round electric wire is secured by crimping or soldering. The other end of the metal strip opposite the ferrule is bent back on its length to form a bottom plate and is then bent back on itself at the end adjacent the ferrule to form a top plate. On each side of the bottom plate extends a row of tongues or teeth. Thus, the flat electric wire is disposed between the bottom and top plates whereby the top plate is pressed below the top of the teeth to press down on the flat wire and the teeth are then bent in on the top plate and pressed down thereon in order to clamp the flat electric wire to obtain a mechanical and electrical connection. SUMMARY OF THE INVENTION An object of the present invention is to solve the problems in the prior art as described above and to provide an improved connector terminal for joining a round electric wire with a flat conductor, particularly suited for places where the space available is small which does not require soldering, and yet provides sufficient reliability, electric stability and mechanical strength over a long time. The present invention solves its task by a connector terminal comprising the features set out in claim 1. The connector according to the present invention comprises: a caulking portion formed at a first end of the connector terminal for fixing a round conductor of a round type electric wire by pressing with, for example, a crimping tool; a first spring portion formed at a second end of the connector terminal for sandwiching (e.g. compressing) a rectangular conductor of a flat type electric wire between the first spring portion and a second end of the connector terminal; a second caulking portion for caulking the spring portion to the second end of the conductor terminal and the rectangular conductor; and a projecting portion projecting from the connector terminal toward the rectangular conductor for making spot-welding with the rectangular conductor. The connector terminal of the present invention sandwiches the flat conductor and compresses it between the spring portion and the second end of the connector terminal. In a preferred embodiment of the invention, the second end of the connector terminal also comprises a spring portion whereby both spring portions are located by the second caulking portion together with a coated portion of the flat type electric wire so as to fix the rectangular conductor between the spring portions, and the projecting portion projecting from either spring portion is spot-welded on an exposed portion of the rectangular conductor. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of an embodiment of the connector terminal according to the present invention. Fig. 2 is a side view of a spring portion for describing a projecting portion. Fig. 3 is a perspective view showing the connection state of the connector terminal according to the present invention; and Fig. 4 is a perspective view of another embodiment of the connector terminal according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, embodiments of the connector terminal according to the present invention will be described. Fig. 1 is a perspective view showing an embodiment of the connector terminal according to the present invention. Connector terminal 10 comprises round conductor caulking portion 1 for caulking (e.g., crimping) a round type electric wire. Spring portions 2 and 2′ sandwich a flat conductor from its upper and lower sides. Spring-portion caulking portion 3 is provided for caulking spring portions 2 and 2′ so that spring portions 2 and 2′ sandwich the flat conductor. A projecting portion 4 is provided at a substantially central portion of spring portion 2. Connector terminal 10 includes base portion 12, to which round conductor caulking portion 1 and spring portion 2 are attached. Connector terminal 10 is integrally formed of a single sheet of plate as shown in the drawing, for example, tin-plated phosphor bronze plate (having a thickness of 0.25 mm). Fig. 2 is a side view of spring portion 2 for illustrating projecting portion 4. In Fig. 2, the same portions as those in Fig. 1 are correspondingly referenced. Projecting portion 4 is formed in a manner so that the central portion of spring portion 2 extends toward spring portion 2′. The top end of projecting portion 4 is made to abut on the rectangular conductor for the flat type electric wire in order to be spot-welded. The projecting portion 4 may be formed on either one of the spring portions (2 or 2′) or on both the spring portions (2 and 2′). Fig. 3 is a perspective view showing the connector terminal according to the present invention connecting a round electric wire 6 to flat conductor 7. The same portions as those in Fig. 1 are correspondingly referenced in Fig. 3. Flat conductor 5 has a thickness of 0.35 mm and comprises rectangular conductor 7, made for example of a tin-plated rolled copper foil which is 0.15 mm in thickness and 1.5 mm in width. Round electric wire 6 comprises round conductor 8 having a core electric wire of, for example, 0.5 mm. When the electric wires are connected to each other, round conductor 8 (e.g., the core electric wire) is made to abut on the round conductor caulking portion 1. Both ends of round conductor caulking portion 1 are then caulked together to connect the round type electric wire to the round conductor caulking portion 1, as shown in Fig. 3. The connection of flat conductor 5 is made as follows: flat type electric wire 5 is stripped at either one or both of its opposing coated surfaces (one surface in the illustrated case) at the end portion of the flat type electric wire 5, so that rectangular conductor 7 is exposed at that end portion. Each spring portion 2 and 2′ of connector terminal 10 has a width corresponding to that of one rectangular conductor 7. Flat type wire 5 is inserted between spring portions 2 and 2′ of connector terminal 10 in a manner so that the exposed portion of rectangular conductor 7 is sandwiched between spring portions 2 and 2′ and made to abut on projecting portion 4. In that position, force is applied to spring portions 2 and 2′ so that they approach each other. The coating of flat type electric wire 5 is thus broken by the spring-portion caulking portion 3, and the top end of spring-portion caulking portion 3 is bent so as to caulk spring portion 2 against spring portion 2′. Thus, connector terminal 10 is pressingly attached to the flat type electric wire 5 together with a part of the coating. At this time, spot welding is performed between the top end portion of the projecting portion 4 and rectangular conductor 7 so as to securely connect connector terminal 10 and rectangular conductor 7 together. When only one of the coated surfaces at the end portion of flat type electric wire 5 is stripped, projecting portion 4 need be provided only on one of the spring portions (spring portion 2 in the illustrated case) as shown in Fig. 1. In the case where both the coated surfaces of rectangular conductor are stripped (e.g., upper and lower surface), projecting portion 4 may be provided on each of the spring portions (2 and 2′) respectively so that both the projecting portions are spot-welded to the corresponding upper and lower surfaces of rectangular conductor 7. Although spring-portion caulking portion 3 is formed on spring portion 2, it may alternatively be formed on the other spring portion 2′. Fig. 4 is a perspective view showing another embodiment of the connector terminal of the present invention. In the drawing, the same portions as those in Fig. 3 are referenced correspondingly in Fig. 4. Round electric wire caulking portion 9 is provided further outside round conductor caulking portion 1 so as to pressingly fix the coated portion of round type electric wire 6. In this embodiment, round conductor 8 of the round electric wire 6 is pressingly fixed to connector terminal 10 not only by round conductor caulking portion 1 but also by round electric wire caulking portion 9, so that the holding force against any wire-pulling forces on connector terminal 10 can be greatly improved. As described above, the connector terminal according to the present invention is formed in a manner so that a round conductor caulking portion, spring pieces for pressingly fixing a rectangular conductor, and a projecting portion for making spot-welding between the rectangular conductor of the flat type electric wire and the connector terminal are integrally formed with each other. Accordingly, the connection between a round type electric wire and a flat type electric wire can be made extremely compact and highly reliable. The connector terminal according to the present invention has a further effect that reliable and stable connection can be maintained for a long time when the connector terminal is used for the connection of internal wiring in electronic equipment for home use or for industrial use in which round type electric wires and flat type electric wires coexist, particularly for use in cars.

Claims: A connector terminal for connecting a first round wire and a second flat wire comprising: a base portion (12) having first and second ends; a first caulking portion (1) for securing said first, round wire to said first end of said base portion; a clasping portion for connecting said second flat wire to said second end of said base portion, said clasping portion comprising: a first portion (2) disposed above said second end of said base portion, and a second caulking portion (3) for securing said first portion (2) to said second end of said base portion, said second flat wire being sandwiched between said first portion (2) and said second end of said base portion (12), in use of the terminal, characterised in that , said first portion (2) comprises of a spring portion; and by further comprising a projecting portion (4) projecting from said first portion and/or said second end toward said second flat wire for reliably connecting same together. A connector terminal as recited in claim 1, wherein said first caulking portion (1) and said clasping portions (2,3) are integrally formed with said base portion (12). A connector terminal as recited in claim 2, wherein said connector terminal is integrally formed of a single sheet of metal. A connector terminal as recited in claim 2, wherein said projecting portion (4) receives solder for spot welding said projecting portion to said second wire. A connector terminal as recited in claim 4, wherein said projecting portion (4) is disposed on said first spring portion. A connector terminal as recited in claim 4, wherein said projecting portion (4) is disposed on said second end of said base portion. A connector terminal as recited in claim 2, wherein said second end of said base portion comprises a second spring portion (2′), with said second caulking portion (3) securing said first spring portion to said second spring portion with said second wire being disposed therebetween. A connector terminal as recited in claim 7, wherein said second caulking portion (3) is disposed on said first spring portion (2). A connector terminal as recited in claim 7, wherein said second caulking portion (3) is disposed on said second spring portion (2′).

Inventors: SAEN HARUO, SUGAWARA KIYOTO, URUSHIBATA KENICHI, SAEN, HARUO, SUGAWARA, KIYOTO, URUSHIBATA, KENICHI
Applicants: SUMITOMO ELECTRIC INDUSTRIES, SUMITOMO ELECTRIC INDUSTRIES, LTD.
Application year: 1989
Main classification: H01R11
IPC codes: H01R11, H01R12, H01R4