Female terminal fitting

Abstract: A pair of resilient contacts 12 facing each other are made into a C shape. The base end of each contact 12 connects to a tubular member 11. In this manner, the contact 12 has a strengthening wall 13 formed along the direction of bending. Thus when a male terminal fitting C is inserted between the contacts 12, the strengthening walls 13 bend in a direction that is parallel to the wall face and consequently an increased clamping force can be provided notwithstanding that the thickness of the terminal material is not great. Miniaturization of the terminal is facilitated.

Description: TECHNICAL FIELD The present invention relates to a female electrical connector. BACKGROUND TO THE INVENTION Female terminal fittings of the type shown in Figures 7 and 8 of this specification are well known. This type of female terminal fitting comprises a main body 1 formed by bending from a thin electrically conducting metal plate, and a stainless steel protecting cover 2 that covers the main body 1. The main body 1 is formed so as to have an insertion aperture 3 into which a corresponding male terminal fitting (not shown) is inserted, the insertion aperture 3 being connected to a barrel member 4 which is located posteriorly to the insertion aperture 3 and which allows the connection of an electric wire terminal thereto. The insertion aperture 3 has a pair of resilient contacts 6 formed by extending longitudinal side walls 5 in an anterior direction, the side walls 5 being provided so as to face each other on the left and right sides (the upper and lower sides in Figure 7). The male terminal fitting is inserted between the resilient contacts 6 and forces them apart. However, the resilient force of the contacts is determined by the plate thickness of the portion connecting with the side walls, and in the case where this portion is thin, it is not possible to maintain a sufficient contact pressure with respect to the male terminal fitting. In particular, along with the increased desirability of miniaturization of the connector, it becomes necessary to reduce this portion's thickness in correspondence with the plate material thickness of the female terminal fitting. For this reason, it becomes very difficult to maintain a sufficient contact pressure with respect to the male terminal fitting. EP-A-0700124 discloses an electrical terminal having a resilient contact divided into two longitudinally extending portions, each portion having a supporting wall protruding in the direction of parting of the contacts and connecting the free end of the contacts to a supporting member at the base of the contacts. The present invention has been developed after taking the above problem into consideration, and aims to provide a female terminal fitting wherein a pair of resilient contacts provided thereon give an increased contact pressure. SUMMARY OF THE INVENTION According to the invention there is provided a female terminal fitting having opposed resilient contacts adapted to part resiliently from a rest position at a distal end, to grip a male terminal fitting inserted therebetween, and a supporting member at a proximal end supporting the base of each of said contacts, wherein said contacts each further include a supporting wall connected to said supporting member, and protruding in the direction of parting of said contacts, said supporting member being tubular, and wherein said contacts are 'U' shaped in section, the edge portions of the contacts facing each other and constituting said supporting walls, and the mid-portions of the contacts having contacting members protruding therefrom, characterized in that each of said contacts has one of said supporting walls on either side thereof, at the distal extremity said supporting walls being positioned for mutual contact in opposed pairs in the rest position, said supporting walls being connected at one respective end to the base and at the other respective end to the distal ends of said contacting members, and said terminal fitting further including a tubular protecting cover for enclosing said contacts, said cover surrounding said terminal fitting on all sides and having a through hole in the distal end thereof to allow entry of a male terminal fitting, said cover being internally slightly larger than said supporting member so as to fit closely therewith, and having protruding members at the proximal end thereof adapted to fold over a proximal portion of said terminal fitting to retain said cover thereon. These supporting walls stiffen the contacts in the direction of parting or bending and thus have the effect of increasing the contact pressure on an inserted male terminal. Advantageously the walls can be bent out of the sheet material from which the terminal fitting is made, and thus contributes to miniaturization of the terminal and the use of the minimum sheet thickness commensurate with function. The contact may bend at the region of attachment to the supporting member, and thus in one embodiment the contacts are stiffened in this area only, for example by one or more slits in the supporting member itself. In this way the contact is partially constituted by the slit region of the supporting member. A tubular supporting member is preferred for reasons of strength and integrity. The contacts may be further stiffened by indentations pressed in the surface thereof, preferably adjacent the root or base of each contact. The contacts may themselves have contacting members pressed in or sheared out of one face thereof, and in the preferred embodiment these contacting members are constituted by opposite substantially parallel slits. A protective cover is provided to add strength to the terminal and to protect the relatively deformable contacts from accidental damage. The cover is tubular so as to surround the terminal on all sides. BRIEF DESCRIPTION OF THE DRAWINGS Other features of the invention will be apparent from the accompanying description of a preferred embodiment shown by way of example only in the accompanying drawings, in which: Figure 1 is a diagonal view of a disassembled first embodiment of the invention; Figure 2 is a diagonal view of the first embodiment with the protecting cover attached; Figure 3 is a cross-sectional view through the first embodiment; Figure 4 is a partially enlarged diagonal view showing an elastic contact of the first embodiment; Figure 5 is a partially enlarged cross-sectional view showing a male terminal fitting in an inserted state in the first embodiment; Figure 6 is a cross-sectional view from the side showing the first embodiment in an attached state in a connector housing; Figure 7 is a cross-sectional view from the side of a prior art female terminal fitting; Figure 8 is a plane cross-sectional view through the prior art female terminal fitting. DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention is explained hereinbelow, with reference to Figures 1 to 6. As shown in Figure 1, a female terminal fitting comprises a terminal main body A made from electrically conducting sheet metal (for example, a thin copper alloy) that has been bent, and a protecting cover B that covers the terminal main body A; the protecting cover is for example of a stronger material, such as stainless steel. The main body A is configured so as to be provided with an insertion member 10 into which a corresponding male terminal fitting C (see Figure 5) is inserted, and a barrel member 20 connected to the insertion member 10 via a connecting member 30, the terminal of an electric wire being connected by crimping thereto. The barrel member 20 comprises a wire barrel 21 that crimps a core wire of an electric wire, and an insulation barrel 22 connecting to the posterior side of the wire barrel 21 that crimps a covered portion of the core wire. The barrels 21 and 22 have a conventional shape whereby they protrude upwards as crimping members 21a and 22a. The insertion member 10 has an angled tubular shape that narrows off towards the anterior end, and, as shown in Figure 3, the insertion member 10 has a partition extending from the anterior end towards the posterior end, the partition dividing the aperture 10 into an upper and lower part. Thus, the posterior end has a tubular member 11 forming an angled tubular shape, and the anterior end has resilient contacts 12 which are channel-shaped when seen cross-sectionally. The contacts 12 are formed so as to be connected and to face each other in an up-down direction. This tubular member 11 constitutes a supporting member of the present invention, and, the left and right edge members of the contacts 12 comprise resilient strengthening walls 13. As shown in Figure 3, a slit 14 is provided between the strengthening walls 13 located above and below, the slit 14 extending from approximately the centre with respect to the lengthwise direction up to the tubular member 11, and gradually widening as it proceeds towards the tubular member 11 where its posterior end has a rounded shape. In the roof face and the base face of the insertion member 10, a contacting member 15 is formed so as to protrude inwards. As shown in Figure 4, the contacting members 15 are cut away in a parallel manner along the longitudinal direction of the left and right sides of roof face and the base face, the inner side of the contacting member 15 protruding towards the interior of the insertion member 10 by being bent inwards. The location of the protrusion is closer to the anterior side of the contacting member 15. The connecting member 30 is in the form of a groove facing side walls 31 on the left and right sides having a pair of stabilizers 32 protruding in an upward direction. As shown in the left side of Figure 1, the protecting cover B is formed by bending a stainless steel thin metal plate into an angular tubular shape, its lengthwise dimension being slightly larger than the length of the insertion member 10, and its inner diameter being slightly larger than the outer diameter of the tubular member 11. In other words, the protecting cover B has a bending space provided to allow the bending of the elastic contacts 12 with respect to the insertion member 10 and is insertable from the anterior end so as to cover the space. The upper face of the protecting cover B has a lance 41 formed by cutting away so as to extend outwards from the anterior end. The right side wall of the protecting cover B (the more proximately located side wall in Figure 1) protrudes slightly higher than the upper face, thereby constituting a protecting wall 44. The bending space of the lance 41 is within the protecting wall 44. At the anterior end of the protecting cover B an opening edge is bent inwards, and a through hole 42 formed for allowing the male terminal fitting C to pass through. The posterior end of the protecting cover B has a pair of fixed members 43 protruding therefrom. When the protecting cover B is over the insertion member 10, these fixed members 43 overlap the side walls 31 of the connecting member 30 from the exterior. By bending the fixed members 43 inwards, the protecting cover B is retained (see Figure 2). Figure 6 shows the female terminal fitting attached to a connector housing 50. This connector housing 50 has cavities 51 aligned in the sideways direction thereof. The posterior end of each cavity 51 has a terminal attachment hole 51a for attaching the female terminal fitting, and the anterior end thereof has a terminal insertion hole 51b for inserting the male terminal fitting C. Furthermore, stopping members 52 are formed by cutting away inner wall faces on the outer side of the cavities 51. A lance 41 of the female terminal fitting fits with the stopping member 52 when the female terminal fitting is attached to the cavity 51 via the terminal attachment hole 51a. Thus, the female terminal fittings are attached with their bases facing each other. Next, the operation of the present embodiment is explained. After each of the terminal fittings is attached to the connector housing 50, the male and female connectors are fitted together and the male terminal fitting C is inserted into the through hole 42 of the protecting cover B via the terminal insertion hole 51b of the connector housing 50, and furthermore is inserted into the insertion member 10 of the terminal main body A. The male terminal fitting C which has entered the insertion member 10 enters between the contacts 12 and parts the contacting members 15. Along with this, the contacts 12 widen by changing shape so as to bend in an up-down direction from the root portion (see Figure 5). At this stage, the contacts 12 force the bending of those portions of the elastic strengthening walls 13 which connect with the tubular members 11, the bending occurring along the direction of the wall face (the up-down direction in Figure 5). Consequently, a resilient force corresponding to that of the strengthening wall 13 applies on the portion having the wall 13 provided thereon, thereby resulting in an increase in the force applying to the contacts 12. The male terminal fitting C is thus strongly clamped by the contacts 12. In this manner, in the present embodiment, the following results are achieved by connecting the strengthening wall 13 extending from the base ends of the elastic contacts 12 to the tubular member 11. (1) By providing the strengthening wall 13, the resilient force of the contacts 12 increases, and accordingly, the contacting force with respect to the male terminal fitting C can be increased. (2) Since the supporting member (the tubular member 11), which connects with the base end of the strengthening wall 13, is made into a tubular shape, it is difficult for this portion to change shape and bend in accompaniment with the change in shape of the wall 13; thus the contact pressure can be increased with certainty. (3) As a result, since the contacting force with respect to the male terminal fitting C can be increased without increasing the thickness of the plate material, this configuration is particularly effective in the case where the terminal fitting is to be miniaturized. (4) Since the contacting members 15 protrude from the facing faces in the contacts 12, the male terminal fitting C makes contact with certainty with the contacts 12, thereby maintaining a conducting state with certainty. Moreover, since the contacting members 15 have been formed by shearing and bending, the contacting members 15 make a more certain contact with the male terminal fitting C. (5) The force applying on the contact 12 by the insertion of the male terminal fitting C can be distributed to the base portion of the contact 12 and the strengthening wall 13, thereby reducing the malformation of the contacts 12 due to prolonged use, the life thereof thus increasing. (6) Since the protecting cover B is attached into the insertion member 10, an accidental change in shape of the contacts 12 due to an external forces can be prevented. Furthermore, the present invention is not limited to the embodiments described above with the aid of figures. For example, the possibilities described below also lie within the technical range of the present invention. (1) In the above embodiments, the protecting cover B is formed to be separate and is arranged to be attached to the insertion member 10. However, it may equally be arranged so that the protecting cover is formed in a unified manner with the insertion member. Moreover, the configuration may equally be such that the protecting cover is not attached at all. (2) In the embodiment described above, the contacts 12 are made to be facing each other in an up-down direction, but they may equally be arranged to face each other in a sideways direction. Furthermore, the contacts may equally be four in number and may be arranged to face each other in up-down and left-right directions. (3) In the first embodiment, although it was arranged so that the contacting member 15 is cut away from the facing faces of the contacts 12, it may equally be arranged so that the contacting member is formed by pressing in or the like.

Claims: A female terminal fitting (A) having opposed resilient contacts (12) adapted to part resiliently from a rest position at a distal end, to grip a male terminal fitting inserted therebetween, and a supporting member (11) at a proximal end supporting the base of each of said contacts (12), wherein said contacts (12) each further include a supporting wall (13) connected to said supporting member (11), and protruding in the direction of parting of said contacts (12), said supporting member (11) being tubular, and wherein said contacts (12) are 'U' shaped in section, the edge portions of the contacts facing each other and constituting said supporting walls (13), and the mid-portions of the contacts (12) having contacting members (15) protruding therefrom, characterized in that each of said contacts (12) has one of said supporting walls (13) on either side thereof, at the distal extremity said supporting walls (13) being positioned for mutual contact in opposed pairs in the rest position, said supporting walls (13) being connected at one respective end to the base and at the other respective end to the distal ends of said contacting members (15), and said terminal fitting further including a tubular protecting cover (B) for enclosing said contacts (12), said cover (B) surrounding said terminal fitting (A) on all sides and having a through hole (42) in the distal end thereof to allow entry of a male terminal fitting, said cover (B) being internally slightly larger than said supporting member (11) so as to fit closely therewith, and having protruding members (43) at the proximal end thereof adapted to fold over a proximal portion of said terminal fitting (A) to retain said cover (B) thereon. A terminal according to claim 1 characterized in that the contacting members (15) are sheared out of said mid-portions. A terminal according to claim 2 wherein said contacting members (15) have inward bulges adjacent the distal ends thereof.

Inventors: CHISHIMA MASAMITSU, OKA HIROYUKI, OKAMURA KENJI, SEKO SATOMI, YOSHIMASA WADA, CHISHIMA, MASAMITSU, OKA, HIROYUKI, OKAMURA, KENJI, SEKO, SATOMI, YOSHIMASA, WADA
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1997
Main classification: H01R13
IPC codes: H01R13