Terminal fitting and method of forming it

A terminal fitting (T) has a tube (10) formed by at least one plate (12). A locking hole (19) is formed in the plate (12) and is engageable by a lock (52) of a connector housing (50). The plate (12) is deformed into the tube (10) adjacent the locking hole (19) to form a retaining portion (22) that enlarges an area of engagement with the lock (52) for holding the terminal fitting (T) more securely in the connector housing (50).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a terminal fitting and a method of forming it.

2. Description of the Related Art

U.S. Pat. No. 5,235,743 discloses a terminal fitting that has a rectangular tube formed by four plates. A locking hole is formed in a first of the plates of the rectangular tube. The terminal fitting is insertable into a cavity of a connector housing. A resiliently deformable lock is provided at an inner wall of the cavity and engages the locking hole of the terminal fitting to hold the terminal fitting in the cavity.

Consideration has been given to bending the first plate of the rectangular tube inward substantially at a right angle at an edge of a locking hole to form a locking wall. The locking wall could provide a larger engaging area than the edge of the plate at the locking hole, and hence the locking wall might provide more secure engagement with the resiliently deformable lock in the housing.

However, a curved surface is defined at the bend between the locking wall and the first plate of the rectangular tube. Thus, slippage occurs between the locking wall and the resiliently deformable lock of the housing when an external force acts on the terminal fitting in withdrawing direction. As a result, the lock may deform resiliently and disengage from the locking wall.

The present invention was developed in view of the above problem, and an object thereof is to improve the reliability of a retaining function by the engagement of a locking portion and a locking hole.

SUMMARY OF THE INVENTION

The invention relates to a terminal fitting to be inserted into a cavity of a connector housing and to be held therein by an engagement with a lock of the housing. The terminal fitting has a tube and a locking hole is formed in a wall of the tube. The wall that has the locking hole is deformed inwardly adjacent the locking hole so that an opening edge of the locking hole defines a retaining portion to be engaged with the lock.

The end surface of the plate at the opening edge of the locking hole can contact the lock to retain the terminal fitting. This end surface is displaced inwardly of the tube to define a larger engaging margin than a case where the engaging margin with the lock is defined merely by the thickness of the plate.

The portion of the wall of the terminal fitting that is deformed to define the retaining portion preferably is opposed to the lock. Accordingly, a boundary between the outer surface of the plate and the end surface at the locking hole is an angled edge. Thus, an external force acts on the terminal fitting in withdrawing direction is not likely to cause the lock to slip and disengage from the retaining portion, as in the case where the boundary between the outer surface of the plate and the end surface is curved.

A resilient contact preferably is accommodated in the tube. The resilient contact can contact the retaining portion to prevent deformation of the resilient contact beyond the deformation that occurs when the resilient contact is in contact with a tab. Accordingly, the shape of the terminal fitting can be simpler than if a separate excessive deformation preventing portion is provided.

The tab may be held resiliently between the resilient contact and a surface of the tube substantially opposite the surface with the locking hole.

The widthwise center of the resilient contact preferably substantially coincides with that of the retaining portion.

Two locking plates preferably are provided on a surface of the tube to prevent displacement of the resilient contact at an angle to the deforming direction when contacting the tab.

The widthwise center of resilient contact preferably is deviated from the widthwise center of the tube.

An area of the tube adjacent the locking hole is embossed or bent in to form an intrusion restricting portion in the opening area of the locking hole. The intrusion restricting portion preferably is outside a deformation space for the resilient contact with respect to a width direction.

These and other features of the invention will become more apparent upon reading of the following detailed description and accompanying drawings. It should be understood that even though embodiments are described separately, single features thereof may be combined.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Terminal fittings in accordance with the invention are identified by the letter T inFIGS. 1 to 12. The terminal fittings T are accommodated in a connector housing50made e.g. of a synthetic resin. Cavities51penetrate the housing50in forward and backward directions, and a lock52is cantilevered forward along the bottom wall of each cavity51. A retaining projection52ais formed on the surface of each lock52facing the cavity51. A front plate53is mounted on the front surface of the housing50, and tabs54of male terminal fittings mounted in an unillustrated mating connector are inserted from the front into the cavities51through tab insertion openings55in the front plate53.

Each terminal fitting T is made from a conductive metallic plate material Ta stamped or cut into a specified shape, as shown inFIG. 10, and then formed by bending, folding, pressing, embossing, etc. The terminal fitting T is narrow and long in forward and backward directions and has a substantially rectangular tube10formed at a front half and a wire connecting portion11at rear half. The wire connecting portion11is crimped, bent or folded into electrical connection, with an end of a wire W.

The rectangular tube10is substantially hollow in forward and backward directions and has a bottom plate12that is narrow and long in forward and backward directions. Side plates13L,13R project from front areas of the opposite left and right edges of the bottom plate12. A ceiling plate14extends from the entire upper edge of the left side plate13L towards the right side plate13R and is substantially parallel with the bottom plate12. Front, rear and middle parts of the extending right edge of the ceiling plate14contact the upper edge of the right side plate13R from above. Front and rear locking plates15F,15R extend down towards the resilient contact piece25along the inner surface of the right side plate13R. The locking plates15F,15R are formed in front and rear areas of the extending end of the ceiling plate14not in contact with the upper edge of the right side plate13R. The front locking plate15F is substantially rectangular and the bottom edge thereof is substantially in the middle of the rectangular tube10with respect to the height direction, and a rear notch16is formed at the rear end of the bottom edge. The rear locking plate15R is substantially rectangular, and the bottom edge thereof is at a low position near the bottom plate12in the rectangular tube10. A bottom notch17is formed substantially in the middle of the bottom edge with respect to forward and backward directions. On the other hand, a substantially rectangular front locking hole18F corresponding to the bottom edge of the front locking plate15F and a substantially rectangular rear locking hole18R corresponding to the bottom notch17of the rear locking plate15R penetrate the left side plate13L.

A substantially rectangular locking hole19is formed in the bottom plate12. The bottom edges of the left and right side plates13L,13R are cut up to a position slightly higher than the upper surface of the bottom plate12in areas corresponding to the locking hole19with respect to forward and backward directions, thereby transversely symmetrically forming side notches20. The side notches20create bottom edges for the left and right side plates13L,13R at location in an opening area of the locking hole19. An area of the bottom part of the right side plate13R aligned with the locking hole19is embossed inward towards the widthwise center to forming an intrusion restriction21. The intrusion restriction21is substantially rectangular in side view (see e.g.FIG. 3) and is trapezoidal in bottom view (see e.g.FIG. 4). It should be noted that the rear notch16of the front locking plate15F is formed to avoid interference with the top front corner of the intrusion restriction21.

The bottom plate12is stamped or embossed up and in adjacent the opening edge of the locking hole19to define a plastically deformed retaining portion22that is engageable with the retaining projection52aof the lock52. The retaining portion22includes a rearwardly facing edge12S on a portion of the bottom plate12defining the locking hole19. The edge12S is oriented to oppose the retaining projection52a. The retaining portion22is displaced laterally (e.g. to the left) along width direction relative to the rectangular tube10. Further, the upper or inner surface of the retaining portion22is a substantially flat surface located at substantially the same height as the bottom edges of the side notches20and the intrusion restriction21.

A resilient contact25is accommodated in the rectangular tube10. As shown inFIG. 5, the resilient contact25is long and narrow in forward and backward directions and is bent back from the front end of the bottom plate12. Additionally, the resilient contact25is comprised of a substantially semicircular bend26connected with the front end of the bottom plate12and an extending portion27extending back from the bend26. The extending portion27has a forwardly inclined section28F extending obliquely up and to the back from the upper end of the bend26and a backward inclined section28R extending obliquely down and out to the back from the rear end of the forwardly inclined section28F. In a free undeformed state, the resilient contact25is supported only at its front end and a free end25R at the rear of the backward inclined section28R is at a noncontact position spaced up from the bottom plate12. The resilient contact25is resiliently deformable up and down in a direction intersecting the forward and backward directions with the bend26as a supporting, while mainly deforming the bend26. The free end25R of the resilient contact25at rear of the backward inclined section28R contacts the upper surface of the bottom plate12when the resilient contact25is deformed down. Thus, the deformed resilient contact25is supported at both front and rear ends.

The bend26and the forward inclined section28F are located in an area before the locking hole19, and a substantially dome-shaped contact point29project up at the rear end (i.e. highest part) of the forward inclined section28F. The contact point29also is located before the locking hole19. The backward inclined section28R extends in an area from the front edge of the locking hole19to the bottom notch17of the rear locking plate15R, and the front end thereof is at a height substantially corresponding to the intrusion restriction21. Further, the widths of the bend26and the forward inclined section28F are substantially equal. The widths of the front and rear ends of the backward inclined section28R are substantially equal to the width of the forward inclined section28F; and an area of the backward inclined section28R except the front and rear ends thereof is narrower than the forward inclined section28F.

Front and rear projections30F,30R project out in the width direction from each of the left and right edges of the resilient contact25and are be substantially flush with the resilient contact25in the thickness direction. The left and right front projections30F are substantially symmetrical to each other and are near the front of the contact point29. The front projections30F are located to substantially correspond to the bottom edge of the front locking plate15F and the front locking hole18F with respect to forward and backward directions. In the free state where the resilient contact25is not deformed, the upper surface of the right front projection30F is slightly below the bottom edge of the front locking plate15F and is not in contact with this bottom edge, and the upper surface of the left front projection30F is slightly below the upper edge of the front locking hole18F and not in contact with this upper edge. On the other hand, the rear projections30R are transversely symmetrical and are close to the free rear end25R of the resilient contact25. The rear projections30R are located to correspond to the upper edge of the bottom notch17of the rear locking plate15R and the rear locking hole18R with respect to forward and backward directions. In the free state where the resilient contact25is not deformed, the upper surface of the right rear projection30R is slightly below the upper edge of the bottom notch17and does not contact this upper edge, and the upper surface of the left rear projection30R is slightly below the upper edge of the rear locking hole18R and does not contact this upper edge.

The resilient contact25is substantially transversely symmetrical and displaced to the left along the width direction relative to the rectangular tube10and the locking hole19. The widthwise center of the resilient contact25substantially coincides with that of the retaining portion22. When the locking hole19is viewed from below, a front-end area of the backward inclined section28R of the resilient contact25is exposed over substantially its entire width. The ceiling plate14includes a downwardly embossed tab receiving portion31with a widthwise center that substantially coincides with the widthwise center of the resilient contact25. A tab entrance space32is defined between the upper surface of the resilient contact25and the lower surface of the tab receiving portion31for receiving the tab54.

The terminal fitting T can be inserted into the cavity51of the housing50from behind. As a result, the bottom plate12of the rectangular tube10contacts with the retaining projection52ato deform the lock52down. The lock52is restored resiliently when the terminal fitting T is inserted to a proper position. Thus, the retaining projection52afits into the locking hole19, and the front surface of the retaining projection52aengages the retaining portion22of the locking hole19from behind. As a result, the terminal fitting T is held and cannot be withdrawn. A tab54can be inserted from the front through the tab insertion opening55in the front plate53and into the tab entrance space32. Thus, the tab54is held resiliently between the tab receiving portion31and the contact point29while resiliently deforming the resilient contact25. The tab54and the rectangular tube10are connected electrically by a resilient restoring force of the resilient contact25.

The edge12S of the retaining portion22at the opening edge of the locking hole19in the bottom plate12contacts the lock52to retain the terminal fitting T. The edge12S is displaced inwardly of the rectangular tube10. Thus, a larger engaging margin can be ensured as compared to a case where only the thickness of the plate defines an engaging margin.

The retaining portion22is displaced into the rectangular tube10and the edge12S of the bottom plate12is oriented to oppose the lock52. A boundary between the lower surface of the bottom plate12and the edge12S is well defined angled corner. Thus, even if an external force acts on the terminal fitting T in the withdrawing direction, there is no likelihood that the lock slips and disengages from the retaining portion as in the case where the boundary between the lower surface of the bottom plate and the end surface is a curve.

A portion of the resilient contact25corresponding to the contact point29engages the retaining portion22from above if a degree of downward deformation of the resilient contact25exceeds the deformation normally generated by the tab54, thereby preventing deformation of the resilient contact25beyond its resiliency limit. The retaining portion22for retaining the terminal fitting T also prevents excessive deformation of the resilient contact25. Thus, the shape of the terminal fitting T can be simplified as compared to a case where an excessive deformation preventing portion for exclusive use is provided in addition to the retaining portion.

External matter that intrudes through the locking hole19can push the resilient contact piece25up from below. However, the front projections30F contact the bottom edge of the front locking plate15F and the edge of the front locking hole18F from below. Additionally, the rear projections30R contact the bottom edge of the rear locking plate15R and the edge of the rear locking hole18R from below. Thus, the resilient contact25cannot be displaced up towards the tab entrance space32. Further, the locking plates15F,15R and the locking holes18F,18R are positioned before and behind the locking hole19. Thus, there is no likelihood that the resilient contact25is inclined forward and/or backward upon receiving a pushing force from external matter. This can prevent plastic deformation of the bent portion26, which is the supporting point of resilient deformation of the resilient contact25.

The front locking plate15F and the front locking hole18F are before the locking hole19and near the contact point29that contacts with the tab54. Thus, even if an area of the resilient contact25other than the bent portion26is deformed, there is no likelihood of changing the position of the contact point29. Therefore, the resilient contact25can contact with the tab54with a proper contact pressure.

The rear locking plate15R and the rear locking hole18R are behind the locking hole19and are near the free end25R of the resilient contact piece25. Thus, an interval along forward and backward directions between a front displacement preventing portion (front locking plate15F and/or front locking hole18F) and the rear displacement preventing portion (rear locking plate15R and/or rear locking hole18R) is long as compared to a case where the rear displacement preventing portion is closer to the supporting point of resilient deformation than to the free end. Accordingly, a degree of resilient deformation of the resilient contact25between the front and rear displacement preventing portions by being pressed by external matter can be suppressed, and the resilient contact25is unlikely to undergo a plastic deformation between the front and rear displacement preventing portions.

The bottom plate12has the locking hole19that exposes the resilient contact25to the outside of the rectangular tube10. However, the right side plate13R is formed with the intrusion restricting portion21close to the resilient contact25and at least partly within the opening area of the locking hole19. Thus, the intrusion of external matter through the locking hole19is restricted by the intrusion restricting portion21, which in turn prevents interference of external matter with the resilient contact25.

The intrusion restricting portion21is outside a deformation space for the resilient contact25with respect to the width direction. Thus, the interference of the resilient contact25and the intrusion restricting portion21can be avoided. Accordingly, the contact reliability of the tab54and the resilient contact25can be ensured without hindering the resilient deformation of the resilient contact25.

The widthwise center of resilient contact25is offset from that of the rectangular tube10. Thus a dead space exists between the resilient contact25and the side plate13R more distant from the resilient contact25. However, the intrusion restricting portion21is in this dead space, and space is used efficiently.

The locking hole19is formed over substantially the entire width of the rectangular tube10and the bottom end surfaces of the left and right side plates13L,13R of the rectangular tube10are exposed in the opening area of the locking hole19. The bottom end portion of the right side plate13R facing the locking hole19is embossed to project inward, thereby forming the intrusion restriction21. This embossing or stamping is easily workable as compared to cutting and bending. Therefore, a processing cost can be reduced.

The invention is not limited to the above described and illustrated embodiment. For example, the following embodiments are also embraced by the technical scope of the present invention as defined by the claims. Beside the following embodiments, various changes can be made without departing from the scope and spirit of the present invention as defined by the claims.

The retaining portion is embossed in the widthwise middle of the bottom plate in the foregoing embodiment. However, the left and/or right edges of the bottom plate may be embossed according to the invention.

Although the retaining portion is formed by embossing in the foregoing embodiment, it may be formed by making a cut in the bottom plate and bending this cut portion according to the present invention.

The widthwise center of the resilient contact is offset from that of the rectangular tube in the foregoing embodiment. However, the widthwise centers of resilient contacts and the rectangular tubes may coincide.

The retaining portion does not need to prevent excessive deformation of the resilient contact as in the foregoing embodiment.

Although the invention has been described with reference to a female terminal fitting, the invention is also applicable to a male terminal fitting.