Electrical connection system having a terminal with contact ridges

An electrical connection system having a male terminal and female terminal configured to receive the male terminal. The female terminal has a resilient contact defining a ridge extending vertically from a top surface of the resilient contact and extends longitudinally along the resilient contact. The ridge is configured to provide a contact point between the female terminal and the male terminal. A leading edge of the ridge forms a ramp having an angle that is greater than 0 degrees and less than or equal to 30 degrees relative to the top surface of the resilient contact.

TECHNICAL FIELD OF THE INVENTION

The invention generally relates to electrical connection system, and more particularly relates to an electrical connection system having an electrical terminal with contact ridges that are configured to provide a reduced terminal engagement force.

BACKGROUND OF THE INVENTION

In electrical connection systems using stamped terminals, the female stamped terminal may include a ribbed contact surface to provide a concentrated contact point for the male terminal. In some applications, this contact surface in the female terminal is embossed and abruptly rises into the path of the male terminal as the connection system is being mated as illustrated inFIG. 1.

The reoccurring customer complaint with connection systems is that the engagement force of the two mating connectors is too high. While there are a number of methods that can be used to reduce the engage force, some changes are more efficient than others. Some connectors have used different materials for their stamped terminals that has a lower coefficient of friction while others have used lubricants such as grease or oil.

BRIEF SUMMARY OF THE INVENTION

According to a first embodiment, an electrical connection system is presented, The electrical connection system includes a male terminal and a female terminal configured to receive the male terminal. The female terminal has a resilient contact defining a ridge or a plurality of ridges extending vertically from the contact and longitudinally along the contact. The resilient contact may be characterized as a cantilever beam. The ridge is configured to provide a contact point between the female terminal and the male terminal. The resilient contact may have an arcuate shape that defines an apex and the ridge extends over the apex. A leading edge of the ridge forms an angle with the resilient contact that is greater than 0 degrees and less than or equal to 30 degrees. The angle may preferably be about 10 degrees. The leading edge may be substantially linear. The ridge may be formed by embossing the contact.

According to a second embodiment, a female electrical socket terminal configured to receive a corresponding male plug terminal is presented. The female electrical socket terminal includes a resilient contact configured to contact the male plug terminal and a longitudinal protrusion projecting from a top surface of the contact. The resilient contact may be characterized as a cantilever beam. The resilient contact may have an arcuate shape that defines an apex and the longitudinal protrusion extends over the apex. The longitudinal protrusion is configured to provide a point contact between the contact and the male plug terminal. The longitudinal protrusion may be formed in the contact by an embossing process. The female electrical socket terminal further includes a ramp on a forward edge of the longitudinal protrusion. The ramp has a second top surface that forms an angle relative to the first top surface that is greater than 0 degrees and less than or equal to 30 degrees. The angle may preferably be about 10 degrees. The ramp may be substantially linear.

Further features and advantages of the invention will appear more clearly on a reading of the following detailed description of the preferred embodiment of the invention, which is given by way of non-limiting example only and with reference to the accompanying drawings.

Corresponding features of the various examples presented herein have reference numbers that differ by 100, e.g. 10, 110, 210.

DETAILED DESCRIPTION OF THE INVENTION

The inventor has observed that the engagement force when one terminal is inserted into another follows a pattern: as the male terminal is inserted into the female terminal, the force required to overcome the frictional forces and reaction forces from the female terminal increases to a peak value and then is reduced and stabilizes to a relatively constant engagement force until the male terminal is fully inserted within the female terminal. In order to reduce customer complaints of high engagement force, the peak engagement force should be reduced as much as possible.

The connection system presented herein reduces the peak engagement force by increasing the lead-in angle on the stamped ribs on the female terminal. In most cases, the contact ribs are embossed into the metal and when the male interface is inserted, it stubs against this raised material until the force applied is great enough to slide up and over the embossed material. The proposed invention is a graduated emboss wherein a lead-in angle is applied to the embossed material such that upon insertion, the mating male interface gradually encounters the contact ribs and requires less force to overcome the raised material.

FIG. 1illustrates a non-limiting example of an electrical connection system10. The electrical connection system10includes a pair of molded dielectric connector housings12,14. A first connector housing12is a female connector housing12and a second connector housing14is a male connector housing14that mates with the female connector housing12. The connector housings12,14have a number of cavities16that are configured to retain an electrical terminal that is attached to an end of a wire cable18. The male connector housing14contains a number of male blade or plug type terminals20while the female connector housing contains a number of female or socket terminals22configured to receive the male terminals. The female terminal22is a box-type female terminal having a resilient contact designed to apply a contact force between the male and female terminal20,22in order to provide a reliable electrical connection therebetween. In this non-limiting example, the female terminal22is a dual contact beam terminal as described in U.S. Pat. No. 8,333,662 issued Dec. 18, 2012, the entire disclosure of which is hereby incorporated by reference.

FIG. 2illustrates a prior art female terminal122having a pair of longitudinal protrusions124or contact ridges124that are formed in the top surface126of a resilient contact arm128by an embossing process. As can be seen inFIG. 2, a leading edge130of the contact ridges124, i.e. the end of the contact ridge124closest to the terminal insertion end132, is blunt. This blunt leading edge130forms an angle θ relative to the top surface126of the contact arm128that is greater than 45 degrees.

FIG. 3illustrates a non-limiting example of a female terminal222incorporating the inventive features. The illustrated example includes a pair of longitudinal protrusions224or contact ridges224that are formed in a top surface226of a resilient contact arm228by an embossing process. As can be seen inFIG. 3, a leading edge230of the contact ridge224forms ramp234that defines an angle Φ relative to the top surface226of the contact arm228that is greater than 0 degrees and less than or equal to 30 degrees. This contact ridge224is foamed by an embossing process using specially designed tooling to obtain the desired ramp angle Φ.

FIG. 4illustrates a comparison of the leading edge130of the female terminal122shown in dotted outline versus the leading edge230of the female terminal222shown with a solid line. The ramp234in the illustrated example has an angle Φ of about 10 degrees. As used herein, about 10 degrees is in the range between 7.5 and 12.5 degrees. As can be seen, the ramp234on the leading edge230has a much less abrupt transition than the leading edge130. As can be further seen inFIG. 4, the heights of the ridges at the apex of each of the contact arm128,228, i.e. the point at which the contact arm interfaces with the male terminal, is the same in both female terminals122,222. The female terminal222therefore provides the same final contact force as the female terminal122.

FIG. 5shows a comparison the test results of engagement for the female terminal122and the female terminal222, wherein the female terminal222has a ramp angle Φ of about 10 degrees. As can be seen, the minimum236, maximum 238, and average 240 peak engagement force of female terminal222is reduced by about 37% compared to the minimum136, maximum 138, and average 140 peak engagement force of female terminal222while maintaining the same standard deviation242,142and while still providing the same final contact force.

While the illustrated embodiments include a pair of contacts ridges, alternative embodiments may be envisioned having a single contact ridge or more than two contact ridges. While the ramp in the illustrated example is formed during the embossing process, embodiments using other methods to form the ramp, such as grinding or material deposition. The ramp on the leading edge may also be applied to other terminal designs, including male bladed terminals in order to reduce peak engagement force.

Accordingly, an electrical connection system10having a female terminal222is provided. The ramps234formed on the leading edges of the contact ridges224of the female terminal222provide the benefit of a point contact between the male terminal and the female terminal222while reducing the peak engagement force236,238,240experienced by an operator when mating the female and male terminals.

While this invention has been described in terms of the preferred embodiments thereof, it is not intended to be so limited, but rather only to the extent set forth in the claims that follow. Moreover, the use of the terms first, second, etc. does not denote any order of importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items.