Terminal structure

Abstract: A terminal structure is disclosed, wherein a metal plate is turnable at one end thereof with respect to a metal terminal, and a torsion coil spring 23 has one end normally pressing the metal plate so that the metal plate may be turned away from the metal terminal when the terminal structure is operated to insert an electrically conductive wire thereinto and so that the metal plate may be turned towards the metal terminal when a force is applied to the electrically conductive wire to pull out the same from the terminal structure, thereby to press the electrically conductive wire against the metal terminal with a stronger force of the torsion coil spring, thus securing the electric conduction between the metal terminal and the electrically conductive wire while allowing the electrically conductive wire to be connected and disconnected to and from the terminal structure with a light operating action.

Description: The present invention relates to a terminal structure and more particularly relates to a terminal structure wherein a metal plate is turned away from a metal terminal against the spring action of a torsion coil spring while an electrically conductive wire is inserted. If action is applied to the electrically conductive wire in a direction to pull it out from the structure, the metal plate is turned towards the metal terminal thereby to press the electrically conductive wire against the metal terminal with a stronger force and secure electric conduction between the metal terminal and the wire. A torsion coil spring of a specific elasticity normally gives such pressure as to hold the electrically conductive wire and the metal terminal in an electrically stabilized conductive condition. Further, the electrically conductive wire may be attached and detached with a one-touch light operating action. So far various terminal structures have been proposed wherein an electrically conductive wire may be easily connected to the structure with a one-touch operating action. For example, the terminal structure 1 as shown in Fig. 10 is composed of an electrically isolated case 2 of synthetic resin. The terminal structure has a metal terminal 3 secured to the case 2 therewithin with a pair of extensions 3a protruding out of the case. A metal plate 4, that is a substantially U-shaped plate spring, has a centre portion 4a mounted on a pin 2a formed on the case 2 and has one end 4b engaging an inner surface 2b and has the opposite end 4c pressed against the metal terminal 3. Further, an operating pin 5 is slidably inserted into a guide hole 2c formed within the case 2. If the operating pin 5 is pressed from the outside of the case 2, the inner end 5a of the operating pin 5 presses the end 4c of the metal plate 4 against the spring action thereof in a direction away from the terminal 3. Thus the electrically conductive wire (not shown) may be inserted in between the metal terminal 3 and the metal plate 4 through a wire guide hole 2d formed within the case 2. Upon freeing the operating pin 5, the metal plate 4 returns with its elasticity to press the electrically conductive wire against the metal plate 3, thereby to secure the electric conduction between the electrically conductive wire and the metal plate 3. However, according to the conventional terminal structure 1 having the plate spring 4 used to give a pressure to the electrically conductive wire, the user is required to press a small operating pin 5 against the strong spring action of the plate spring in order to insert the electrically conductive wire into the structure 1 or to pull out the same therefrom. Therefore, the operation of the operating pin 5 will give a pain to the finger of the user and the operativity is extremely bad. As the result, the user often fails to press the operating pin 5 deep enough, allowing the electrically conductive wire to be forcibly pulled out of the case with resultant damage to the terminal structure 1. Another conventional terminal structure 10 as shown in Fig. 11 is composed of an electrically isolated case 11 of synthetic resin. The terminal structure has a U-shaped metal terminal 12 secured to the case 11 therewithin with a pair of extensions protruding out of the case. A metal plate 13 has one end formed in a ring 13a and has an opposite flat end 13b. The metal plate 13 is, at the ring 13a, turnably mounted on a support pin 11a formed on the case 11 so that the metal plate 13 may be turnable with respect to the metal terminal 12. A compression coil spring 14 is provided between the case 11 and the metal plate 13 so that the compression coil spring 14 may press the flat end 13b of the metal plate 13 against the metal terminal 12. Further, an operating pin 15 is slidably inserted into a guide hole 11b formed within the case 11. According to the conventional terminal structure 10, especially having the compression coil spring 14 used in such a way that one end of the compression coil spring 14 is simply pressed against the metal plate 13, the end of the compression coil spring 14 is actually liable to slide with respect to the metal plate 13. It therefore often happens that the position where the compression coil spring 14 gives pressure to the metal plate 13 will change each time the operating pin 15 is pressingly operated. As a result, it becomes difficult to hold the electrically conductive wire with a constantly stabilized pressure. DE-B-12 13 024 discloses a terminal structure contained in a case for detachably holding an electrically conductive wire for electrical conduction therewith, the terminal structure comprising: a metal terminal having a support; a metal plate having one end tumably mounted on the support of the metal terminal so that the metal plate may be turnable around the support; and a torsion coil spring having a coil portion turnably mounted on the support of the metal terminal and having one end thereof engaging the metal terminal, the torsion spring giving a pressure to the metal plate so that the metal plate may press the electrically conductive wire against the metal terminal to establish electric conduction between the electrically conductive wire and the metal terminal, the torsion coil spring allowing the metal plate to be turned around the support in the direction away from the metal terminal against the spring action of the torsion spring when the electrically conductive wire is inserted into the case, the torsion coil spring turning the metal plate around the support in the direction towards the metal terminal when a force is applied to the electrically conductive wire to pull the same outwardly of the case, thereby to increase the pressure for holding the electrically conductive wire between the metal plate and the metal terminal. According to the present invention, there is provided a terminal structure for detachably holding an electrically conductive wire for electrical conduction, said terminal structure comprising: a metal terminal having an upper side wall and a lower side wall having a contact surface, said metal terminal having a support provided between said upper side wall and said lower side wall; an elongate metal plate having one end and an opposite free end, said one end being formed with two rings forked with a space provided therebetween and being turnably mounted on said support so that said metal plate may be turned around said support with respect to said metal terminal; and a torsion coil spring having a central coil portion turnably mounted on said support and positioned in said space between said two rings of said metal plate, said torsion coil spring having one end inserted into a hole provided at said upper side wall of said metal terminal and having an opposite end engaging a hole provided at said metal plate between the opposite ends thereof, so that said free end of said metal plate may be normally pressed towards said contact surface of said metal terminal. The contact surface may have been treated by a knurling process so that the contact surface may effectively hold an electrically conductive wire in co-operation with the free end of the metal plate. The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:- Fig. 1 is a perspective view of a terminal structure according to an embodiment of the invention; Fig. 2 is an exploded perspective view of the terminal structure; Fig. 3 is a plan elevational view of the terminal structure shown in lateral section; Fig. 4 is a front elevational view of the terminal structure; Fig. 5 is a perspective view of the terminal structure partly broken away to show the essential parts thereof; Fig. 6 is a perspective view of three terminal structures arranged side by side within a case shown partly broken away; Fig. 7 is a front elevational view of the terminal structure shown in vertical section to show an electrically conductive wire being inserted into the terminal structure; Fig. 8 is a front elevational view of the terminal structure shown in vertical section to show the electrically conductive wire pressed against a metal terminal by a metal plate and made electrically conductive with the metal terminal; Fig. 9 is a front elevational view of the terminal structure shown in vertical section to show the electrically conductive wire being pulled out of the case; Fig. 10 is a front elevational view of a conventional terminal structure shown in vertical section to show a metal plate formed as a plate spring; and Fig. 11 is a front elevational view of another conventional terminal structure shown in vertical section to show a metal plate pressed by a compression coil spring. In Figs. 1 to 6, a terminal structure 20 of an embodiment of the invention is substantially composed of a metal terminal 21, elongate plate 22 and a torsion coil spring 23. The metal terminal 21 is provided to take out the electric conduction through the terminal structure 20, and is formed with a plate of metal such as iron plated with an electrically favourable conductive material. The plate is, as shown, bent into a sidewise U-shape having opposite upper and lower side walls 21d, 21f. The metal terminal 21 has an extension 2a provided on one side lengthwise of the side walls and having an opening 21b formed at the end thereof so that an electrically conductive wire 24 may be inserted therethrough and soldered to the end. Further, the metal terminal 21 has another extension of a reduced width provided opposite to the extension 21a and bent at a right angle in the same direction with the side walls 21d, 21f so as to form a support 21c. The side wall 21d has an upper face providing a contact surface 21e which has been roughly treated by a knurling process so as to securely hold electrically conductive wire 24 pressed thereagainst. The other side wall 21f has an opening 21g through which one end of the torsion coil spring 23 is inserted. The metal plate 22 is provided to press the electrically conductive wire 24 against the contact surface 21e of the metal terminal 21. The metal plate 22 has one end formed with rings 22a forked with a space 22c provided therebetween and has a slightly curved flat part extended from the forked rings 22a and forming a pressing part 22b. The flat part has a hole 22d formed therein into which the other end of the torsion coil spring 23 is inserted. The space 22c between the rings 22a is provided to accommodate therein a coil portion 23a of the torsion coil spring 23. The torsion coil spring 23 is provided to apply a pressure to the metal plate 22. The opposite ends 23b, 23c of the spring are inserted into the opening 21g of the metal terminal 21 and into the hole 22d of the metal plate 22 respectively. With the coil portion 23a of the torsion coil spring 23 inserted into the space 22c between the rings 22a of the metal plate 22 while the rings 22a and the coil portion 23a are supported on the support 21c, the opposite ends 23b, 23c are inserted into the opening 21g and the hole 22d respectively. With reference to Fig. 6, a plurality of terminal structures 20, each of which is constructed as mentioned above, are contained in a case 25 of a material such as synthetic resin or the like which is electrically isolated. The case 25 has an operating pin 26 slidably provided therein. The pin 26 may be pressed from the outside to apply a pressure to the pressing part 22b of the metal plate 22 thereby to turn the metal plate 22 in the direction 2 where the metal plate 22 is spaced from the metal terminal 21. The embodiment as shown in Fig. 6 shows three terminal structures 20 arranged side by side in the case 25 so that three electrically conductive wires 24 may be connected to the terminal structures 20 respectively. With reference to Figs. 7 to 9, in order to connect the electrically conductive wire 24 to the terminal structure 20, the electrically conductive wire 24 is inserted into the hole 25a of the case 25 while the operating pin 26 is pressed in the direction as indicated by the arrow A. With the pressing operating of the operating pin 26, the metal plate 22 is turned around the support pin 21c in the direction as indicated by the arrow C against the spring action of the torsion coil spring 23. The metal plate 22 is therefore moved away from the contact surface 21e of the metal terminal 21 while the electrically conductive wire 24 is inserted deep into the case 25 in the direction of arrow B. Subsequently, when the operating pin 26 is freed, the metal plate 22 is turned by the spring action of the torsion spring 23 in the direction opposite to the direction indicated by the arrow C. Thus, the metal plate 22 will press the electrically conductive wire 24 against the contact surface 21e of the metal terminal 21 thereby to establish an electrically conductive relation between the metal terminal 21 and the electrically conductive wire 24. Simultaneously, the operating pin 26 is returned in the direction as indicated by the arrow D to the initial inoperative position by the action of the spring action of the torsion coil spring 23. In order to remove the electrically conductive wire 24 from the terminal structure 20, the operating pin 26 is, as shown in Fig. 9, again pressed in the direction as indicated by the arrow A thereby to turn the metal plate 22 around the support pin 21c in the direction as indicated by the arrow C against the spring action of the torsion spring 23. In the meantime, the electrically conductive wire 24 may be pulled out of the terminal structure 20 in the direction as indicated by the arrow E with an extremely light operation force of the operating pin 26. In contrast to a plate spring, the torsion coil spring may, due to the property thereof, be initially set to have a small spring force. Precisely, concerning the torsion coil spring, the increasing amount of spring force (spring constant) per unit deformation amount may be set to a considerably small value compared with a plate spring.

Claims: A terminal structure (20) for detachably holding an electrically conductive wire (24) for electrical conduction, said terminal structure (20) comprising: a metal terminal (21) having an upper side wall (21f) and a lower side wall (21d) having a contact surface (21e), said metal terminal (21) having a support (21c) provided between said upper side wall (21f) and said lower side wall (21d); an elongate metal plate (22) having one end (22a) and an opposite free end (22b), characterised in that said one end is formed with two rings (22a) forked with a space (22c) provided therebetween and is turnably mounted on said support (21c) so that said metal plate (22) may be turned around said support (21c) with respect to said metal terminal (21); said terminal structure further comprising a torsion coil spring (23) having a central coil portion (23a) turnably mounted on said support (21c) and positioned in said space (22c) between said two rings (22a) of said metal plate (22), said torsion coil spring (23) having one end (23b) inserted into a hole (21g) provided at said upper side wall (21f) of said metal terminal (21) and having an opposite end (23c) engaging a hole (22d) provided at said metal plate (22) between the opposite ends (22a, 22b) thereof, so that said free end (22b) of said metal plate (22) may be normally pressed towards said contact surface (21e) of said metal terminal (21). A terminal structure (20) according to claim 1, wherein said contact surface (21e) has been treated by a knurling process so that said contact surface (21e) may effectively hold an electrically conductive wire (24) in co-operation with said free end (22b) of said metal plate (22).

Inventors: OSADA YUTAKA, OSADA, YUTAKA
Applicants: OSADA CO LTD, OSADA CO., LTD.
Application year: 1997
Main classification: H01R4
IPC codes: H01R4, H01R9