Terminal for fixing wires

Abstract: Two or more core wires (8,8′) are inserted into an approximately U-shaped barrel (23) of a terminal (20) and fixed to the terminal and each other. The terminal comprises a tab (21) having serrations (25,26), formed on the upper and lower surfaces thereof, disposed along the boundary between the core wires so that the serrations shear an oxide film formed on the core wires in contact with the upper and lower surfaces of the tab and remove the oxide film from the core wires, whereby the core wires are electrically connected with each other via the tab. The tab is integral or unintegral with a connector terminal or an inter-connecting terminal. The drawing to be published with the abstract is Fig. 2.

Description: The present invention relates to a connector terminal and an inter-connecting terminal and more particularly to a terminal provided a core wire-fixing barrel in which two or more electric wires are inserted and pressured on the wires to contact with the wires and fix them, and for reducing the contact resistance between electric wires in fixing two or more electric wires thereto by a barrel and between the wires and the terminal. A connector terminal to be used to connect electric wires of a wire harness of an automobile or an electric office automation equipments has a construction as shown in Fig. 10. An inter-connector terminal or an intermediate joint terminal for connecting electric wires without the intermediary of a connector has a construction as shown in Fig. 13. That is, the connector terminal 1 which is solid comprises an electrical contact portion 3 disposed in the front of a bottom 2 and a core wire-fixing barrel 4 and a coating film-fixing barrel 5 both disposed in the rear of the bottom 2. The inter-connecting terminal 6 U-shaped in its sectional configuration consists of only a core wire-fixing barrel 7. W-type fixing method, C-type fixing method or F-type fixing method, soldering or welding is used to connect the electric wires to the connector terminal 1 or the interconnecting terminal 6. F-type fixing method is most widely used because this method is most efficient of these methods. As shown in Figs. 15 and 16, according to F-type fixing method, in fixing two electric wires W1 and W2 to the inter-connecting terminal 6, the inter-connecting terminal 6 is placed on an anvil 11 of a presser 10. The core wire 8 of the electric wire W1 and the core wire 8' of electric wire W2 are inserted into the core wire-fixing barrel 4 with the core wire 8 held in a higher space and the core wire 8' held in a lower space. Then, a crimper 12 is moved downward to deform the barrel 7 and fix the core wires 8 and 8' to the interconnecting terminal 6. In fixing the electric wires W1 and W2 to the connector terminal 1, the core wire 8 of the electric wire W1 and the core wire 8' of the electric wire W2 are inserted into the core wire-fixing barrel 4 and the coating film 9 of the electric wire W1 and the coating film 9' of the electric wire W2 are inserted into the coating film-fixing barrel 5. Then, the crimper 12 is moved downward to deform the barrels 4 and 5 and fix the core wires 8 and 8' to the core wire-fixing barrel 4 and coating films 9 and 9' to the coating film-fixing barrel 5. As a result, the core wire 8 and the core wire 8' are connected with the connector terminal 1 or the interconnecting terminal 6, respectively. The conventional connector terminal 1 or the inter-connecting terminal 6 has a problem that oxide film formed on the surface of the core wires 8 and 8' acts as a contact resistance in connecting the core wires 8 and 8' with the connector terminal 1 or the inter-connecting terminal 6. In order to solve this problem, as shown in Figs. 11 and 13, a plurality of serrations 13 is formed on the inner surface of the bottom of the core wire-fixing barrels 4 and 7 and that of the side walls thereof so as to shear and remove the oxide film from the core wires 8 and 8' by means of edges 13a of the serrations 13. This construction is disclosed in examined Japanese Utility Model Publication No. 34-11265. However, as shown in Figs. 12 and 14, the above-described construction is not effective for removing the oxide film from the core wires in fixing two or more core wires to the barrels 4 and 7. That is, as shown in Fig. 17, the core wire 8' disposed in the lower space of each of the barrels 4 and 7 contacts the serrations 13 formed on the bottom thereof in a large area, but the core wire 8 mainly contacts the serrations 13 formed on upper portions of the side walls of the barrels 4 and 7. Therefore, the core wire 8 contacts the serrations 13 in a small area. In addition, the core wires 8 and 8' disposed along the boundary (X) between the electric wires W1 and W2 do not contact the serrations 13. Accordingly, the oxide film is not removed therefrom along the boundary (X). That is, there is a possibility that the core wires 8 and 8' are not connected electrically. As apparent from the above description, according to the above-described construction, the electric wires W1 and W2 are not electrically connected with each other because of the above-described reason. In recent years, the operation of an automobile has been electronically controlled and hence micro-current circuits have been increasingly used and large current circuits generate a great amount of heat due to the use of a large capacity synchronous generator. In this situation, there are strong demands for the drop of the contact resistance between the core wires and the terminal and between the wires. It is an object of the present invention to provide a terminal for fixing two or more core wires thereto with the contact resistance between the core wires reduced to electrically connect the core wires therewith by dropping the contact resistance between the core wires and the terminal. In accomplishing these and other objects of the present invention, there is provided a terminal including a core wire-fixing barrel which is approximately U-shaped so as to have side walls and is crimped on two or more core wires inserted thereinto, said terminal comprising: a tab having upper and lower surfaces with serrations formed thereon, said tab being disposed along a boundary between said core wires so that said serrations shear an oxide film formed on said core wires in contact with said upper and lower surfaces of said tab and remove said oxide film from said core wires, whereby said core wires are electrically connected with each other via said tab; characterised in that said tab is integral with the core wire-fixing barrel; and said tab consists of a pair of tabs projecting horizontally inwardly from and being integral with inner surfaces of both side walls of the core wire-fixing barrel so that the tabs are positioned in a middle portion of the core wire-fixing barrel in a vertical direction thereof. According to the above-described construction, the tab having the serrations formed thereon is interposed between the core wires of the electric wires. Accordingly, the serrations remove the oxide film formed on the core wires disposed on the boundary between the core wires. As a result, the core wires can be connected with each other via the tab. That is, the core wires in contact with the terminal are connected therewith via the peripheral surface of the core wires, and the core wires not in contact with the terminal are connected therewith via the tabs between the core wires. Thus, the electrical connection between the core wires 8 and 8' and the terminal 20 can be reliably accomplished. The serrations to be formed on the upper and lower surface of the tab at regular intervals may be arranged horizontally or diagonally. The serrations may be circular, rectangular, cross or in any desired configurations so long as the serrations shear and remove the oxide film of the core wires. These and other objects and features of the present invention will become clear from the following description taken in conjunction with the preferred embodiments thereof with reference to the accompanying drawings, in which: Fig. 4 is a perspective view showing a terminal according to an embodiment of the present invention; Fig. 5 is a sectional view taken along a line V-V of Fig. 4; Figs. 6A and 6B are perspective views showing modifications of the embodiment of the present invention, respectively; Figs. 8B and 8C are perspective views showing a terminal according to a second embodiment of the present invention, respectively; Fig. 9A through 9F are views showing an example of a serration, respectively; Fig. 10 is an exploded view showing a conventional connector terminal and electric wires; Fig. 11 is a sectional view showing a serration of Fig. 10; Fig. 12 is a perspective view showing the state in which the electric wires are fixed to the connector terminal of Fig. 10; Fig. 13 is an exploded view showing a conventional inter-connecting terminal and electric wires; Fig. 14 is a perspective view showing the process of fixing the electric wires to the inter-connecting terminal; Fig. 15 is a view showing the process of fixing electric wires to a terminal; Fig. 16 is a view showing the process of fixing the electric wires to the terminal; and Fig. 17 is a section view showing a problem of a conventional art. Before the description of the present invention proceeds, it is to be noted that like parts are designated by like reference numerals throughout the accompanying drawings. The embodiment of the present invention will be described below with reference to the drawings. A connector terminal 20 according to an embodiment of the present invention will be described below with reference to Figs. 4 and 5. In this embodiment, the tab 21 is integral with the terminals 20. That is, a pair of tabs 21a' and 21b' project horizontally inward from the inner surfaces of both side walls of the core wire-fixing barrel 23 so that the tabs 21a' and 21b' are positioned in the middle of the core wire-fixing barrel 23 in the vertical direction thereof. The interval between the tabs 21a' and 21b' is slight, thus partitioning the space surrounded with the bottom of the core wire-fixing barrel 23 and the side walls thereof into an upper space and a lower space. The tabs 21a' and 21b' have serrations 25 and 26 in the form of circular grooves which are formed on the upper and lower surfaces thereof similarly to the first embodiment. Two electric wires are inserted into contact with the tabs 21a' and 21b' as follows: One core wire is inserted into the lower space and the other core wire is inserted into the upper space. Thus, the electric wires can be reliably and easily inserted into the core wire-fixing barrel 23. The operation in fixing the electric wires to the terminal 20 and the connection state thereof are as follows: The core wire 8' of the electric wire is inserted into the core wire-fixing barrel 23 and then the tab 21 is placed on the upper side of the core wire 8' and thereafter, the core wire 8 of the electric wire W1 is placed on the upper surface of the tab 21. The core wires 8 and 8' are fixed to the core wire-fixing barrel 23 and the electric wires W1 and W2 are fixed to the coating film-fixing barrel 24 by the method previously described. Modifications of this embodiment are described below with reference to Figs. 6A and 6B. As shown in Fig. 6A, a pair of the tabs 21a' and 21b' is formed by partly cutting a middle portion of the core wire-fixing barrel 23 and projecting the cut portion horizontally inward from both side walls of the core wire-fixing barrel 23. As shown in Fig. 6B, a pair of the tabs 21a' and 21b' is formed by bending a middle portion of the core wire-fixing barrel 23 so as to project horizontally inward from both side walls thereof. An inter-connecting terminal according to a second embodiment will be described below with reference to Figs. 8B and 8C. In the second embodiment, the tab is also integral with the inter-connecting terminal 30. As shown in Fig. 8B, a pair of tabs 31a' and 31b' projects inward from the inner surface of both side walls of the barrel. The inter-connecting terminal according to this example corresponds to the first embodiment. As shown in Fig. 8C, a tab 31a" is formed by bending inward a part of the barrel projecting from the front of the lower portion of one side wall and a tab 31b" is formed by bending inward a part of the barrel projection from the rear of the lower portion of the other side wall. The configurations and arrangement of the serrations 25, 26, 32 and 33 formed on the tab and those of the serrations 23a and 34 formed on the core wire-fixing barrel according to the above described embodiments may be modified as shown in Figs. 9A through 9F. That is, the serrations may be arranged at regular intervals horizontally as shown in Fig. 9A or diagonally as shown in Fig. 9B. The configuration thereof may be circular as shown in Fig. 9C; rectangular as shown in Fig. 9D; or cruciform as shown in Fig. 9F. In addition, the serrations may consist of narrow cuts and arranged at random as shown in Fig. 9E. Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom.

Claims: A terminal (20,30) including a core wire-fixing barrel (23) which is approximately U-shaped so as to have side walls and is crimped on two or more core wires (8,8') inserted thereinto, said terminal comprising: a tab having upper and lower surfaces with serrations (25,26) formed thereon, said tab being disposed along a boundary between said core wires so that said serrations shear an oxide film formed on said core wires in contact with said upper and lower surfaces of said tab and remove said oxide film from said core wires, whereby said core wires are electrically connected with each other via said tab; characterised in that said tab is integral with the core wire-fixing barrel; and said tab consists of a pair of tabs (21a',21b';31a',31b';31a'',31b'') projecting horizontally inwardly from and being integral with inner surfaces of both side walls of the core wire-fixing barrel so that the tabs are positioned in a middle portion of the core wire-fixing barrel in a vertical direction thereof. A terminal as claimed in claim 1, in which said terminal is a connector terminal (30) comprising said core wire-fixing barrel, a coat film-fixing barrel and an electrical contact portion. A terminal as claimed in claim 1, in which said terminal is an inter-connecting terminal or an intermediate joint terminal comprising only said core wire-fixing barrel. A terminal as claimed in claim 3, in which a slight gap exists between the ends of said pair of tabs and some of the core wires are inserted between the tabs and a bottom wall of the terminal, and other core wires are inserted above the tab, so that the serrations shear an oxide film formed on said core wires in contact with said upper and lower surfaces of the tabs. A terminal as claimed in claim 1, in which said serrations are grooves spaced at certain intervals on the upper and lower surfaces thereof. A terminal as claimed in claim 5, in which said grooves of the tab are circular, rectangular or cruciform.

Inventors: ITO AKIRA, ITO, AKIRA, ITO, AKIRA, C/O SUMITOMO WIRING SYSTEMS LTD.
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1992
Main classification: H01R4
IPC codes: H01R4