This application claims the benefit of the filing date under 35 U.S.C. §119(a)-(d) of European Patent Application No. 14 290 059.6, filed Mar. 10, 2014.
The invention generally relates to an electrical connector terminal, and, more specifically, to an electrical connector terminal having a crimp barrel.
Crimped electrical connector terminals are conventionally known, and often fabricated using the same conducting material for the crimp barrel and the conductors of the wire. Commonly, the conducting material is copper, due to its good electrical conductivity and mechanical strength. However, copper has nevertheless some drawbacks. Firstly, the price for copper has risen sharply in recent years. Secondly, copper is relatively dense, making it a heavy material. There is an increased industrial effort to both reduce the cost, and the weight of automobiles. Such efforts would benefit greatly by exchanging the rather heavy copper with more lightweight materials.
Given aluminium's good electrical conductivity, in combination with light weight and low cost, aluminium has been identified as a suitable material to reduce the use of copper conductors. It has long been proposed to produce electrical terminals with aluminium conductors that are crimped to a copper connector. Such a combination would thereby combine the light weight of aluminium conductors with the good spring characteristics of copper. However, the use of aluminium in combination with copper is challenging. In the presence of moisture, a difference in potential between copper and aluminium will result in the dissolution of aluminium at the points of contact between aluminium and copper, thereby negatively effecting the electrical connection between the two materials. To overcome this problem, measures have to be taken to prevent the presence of moisture in the contact area.
One such approach is disclosed in International Patent Publication No. WO 2012/054072, which discloses an electrical terminal using a copper-aluminium combination. The electrical terminal uses an F-crimp that extends from the stripped conductors of the wire up until a segment of the wire where the conductors are surrounded with an insulation layer. The crimp barrel has a front sealing portion for closing gaps at the extremity of the stripped conductor. Thus, moisture may be prevented from reaching the contact between the aluminium conductor and the copper crimp barrel. However, such a design presents sever disadvantages.
First, since the additional front seal segment is also crimped with an F-crimp, just like the other segments of the crimp barrel, the entire electrical terminal is longer in length than conventional terminals using only copper for both the wire and the crimp barrel. The extra length may result in an incompatibility with existing copper-based cable harnesses having copper terminals, when the copper-based cable harnesses are exchanged with an aluminium cable harness having the copper-aluminium terminals.
Furthermore, due to the lower conductivity of the aluminium with respect to copper, the diameter of the conductors of an aluminium wire has to be larger than the diameter of an equivalent copper wire. To avoid increasing the total diameter of the wire, the thickness of the insulation layer is typically made smaller. This, however, leads to an increased risk of moisture penetrating to the contact areas in regions where the insulation layer around the conductors is accidently cut during the crimping process. Thus, there is a higher risk that the aluminium conductors may become exposed to moisture in contact areas with copper, negatively effecting the lifetime of the connector.
In another approach, detailed in U.S. Pat. No. 4,641,911, an electrical terminal has a crimp barrel positioned such that both the stripped conductors and the insulation is crimped. A funnel shape is formed in the axial direction by partially overlapping the sidewalls of the crimp barrel. However, the crimp barrel is not suited for copper-aluminium connectors, as in the transition region between the stripped conductors and the insulation layer of the wire, the crimp barrel is not closed so that moisture can easily penetrate to the contact area.
Therefore, there is a need for an electrical terminal with an improved crimp barrel to reduce the risk of exposure of the contact area to moisture, where the electrical terminal has a reduced length so as to be compatible with conventional copper-based electrical terminals.
An electrical terminal has a crimp barrel. The crimp barrel has a base; and opposing side walls extending from the base and each has an opposing end region. The opposing side walls have a conductor receiving region in which the sidewalls have an F-crimp when crimped to stripped conductors of a wire; a wire insulation receiving region for receiving an insulation covered portion of the wire; and a transition region positioned between the conductor receiving region, and the wire insulation receiving region. The opposing end regions in the transition region are overlapped in the circumferential direction when crimped to surround the wire.
The invention will now be described by way of example, with reference to the accompanying Figures, of which:
In a first embodiment, shown in
The crimping portion 5 has a conductor receiving region 9 for receiving stripped conductors of a wire and a wire insulation receiving region 11 for receiving a wire part with insulation. The crimping portion 5 furthermore includes a transition region 13 between the conductor receiving region 9 and the wire insulation receiving region 11.
At the extremity opposite to the contacting portion 3, the electrical terminal 1 has an electrical pin or socket contact element in a terminating region 15.
When folded around a wire, the regions 9, 11, 13 of the crimping portion 5 form the crimp barrel.
The crimping portion 5 has a continuous base 17 that extends longitudinally from the contacting portion 3 to the terminating region 15. The conductor receiving region 9 has opposing sidewalls 19a and 19b extending from the base 17. The wire insulation receiving region 11 has opposing sidewalls 21a and 21b extending from the base 17. The transition region 13 has opposing sidewalls 23a and 23b extending from the base 17.
The sidewalls 19a, 19b of the conductor receiving region 7 each have a front cover end 25a and 25b at their extremity towards the contacting portion 3.
In the embodiments of
The sidewalls of the conductor receiving region 9, the transition region 13 and the wire insulation receiving region 11 are folded around the wire 33 during the crimp process, as shown in
As shown in an embodiment of
As can be seen in
In another embodiment having aluminium conductors 35 and the copper crimping portion 5, the conductor receiving region 9 includes one or more serrations 43 (in dotted lines in
As an alternative or in addition to the serrations 43, the non-conducting surface layers on the surface of the aluminium conductors 35 can also be cracked using a higher level of compression during crimping compared to a copper-copper crimp.
In an embodiment of
As seen in the embodiment of
In an embodiment of
In an embodiment shown in
The dimensions of the sidewalls 23a and 23b and the length of the cuts 51a and 51b are chosen such that a funnel shape 57 is obtained in the transition region 13 along the longitudinal axis 55. A smaller diameter of the funnel 57 corresponds to the diameter of the bare stripped conductors 35 and a larger diameter of the funnel 57 corresponds to the wire 33 and its insulation 37.
In an embodiment of
In an embodiment of
At the interface between the transition region 13 with the overlapping end regions 45a,45b and the wire insulation receiving region 11, a cut 65 is present in the end region 45a of the sidewall 23a. The cut 65 extends substantially perpendicular to the edge of the end region 45a and enables the transition from the overlapping crimp to the ring shaped crimp. Additionally, the sidewalls 23a,23b have bevelled or rounded edges 66a,66b to facilitate the overlapping. The shapes of these bevelled edges can vary depending on the desired final shape.
In an embodiment of
In order to keep the total length of the connector 1 comparable to a conventional copper crimp connector, the front cover ends 25a and 25b are bent around an axis 69 perpendicular to the longitudinal axis 55, such that the sidewalls 19a, 19b, 21a, 21b, 23a and 23b are all bent circumferentially around the direction parallel to the longitudinal axis 55.
In a second embodiment of
The second embodiment has a modified conductor receiving region 73 in the crimping portion 5 compared to the connector in the first embodiment. As shown in
Similar to the first embodiment, two front covers 79a and 79b are used to close the opening of the tunnel created by the folded sidewalls 77a and 77b of the conductor receiving region 73, in the crimped state. The sidewall 77a is longer by a distance Δ, essentially corresponding to the thickness d of the front cover 79b. As shown in
In an embodiment, voids inside the tunnel along the conductor receiving region 9 or 73 and the transition region 13 or 75 are filled with a corrosion protection material, such as grease or other similar moisture repellent or inhibitor, to even further reduce the risk of an exposure of the contact area to moisture.
In
In a first step 81, a wire 33 is placed on the electrical terminal 1 or 71. The bare, stripped conductors 35 are positioned in the conductor receiving region 9 or 73 and the portion of the wire 33 having the insulation 37 is positioned in the wire insulation receiving region 11 so that the transition between the two parts of the wire 33 is positioned in the transition region 13 or 75.
In a second step 83, a corrosion preventing material is provided, such as grease, in the conductor receiving region 9 or 73 and the transition region 13 or 75.
In a third step 85, the sidewalls 19a/b, 21a/b, 23a/b in the conductor receiving region 9 or 75, the transition region 13 or 75 and the wire insulation receiving regions 11 are crimped to thereby enclose the wire 33 in the electrical terminal 1 or 711. Crimping in the conductor receiving region 9 is performed such that an F-crimp is achieved. Crimping of the transition region 13 or 75 is performed such that the end portions 45a,45b of the sidewalls 23a,23b are overlapping in the circumferential direction 47. Crimping of the wire insulation receiving region 11 is carried out such that the sidewalls are enveloping the insulation 37 without, however, having the overlapping ends.
Finally, according to step 87, the front covers 25a,25b are folded along the axis 69 perpendicular to the longitudinal axis 55 to close the tunnel formed by the crimped sidewalls.
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2012054072 | Apr 2012 | WO |
Number | Date | Country | |
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