Terminal assembly comprising a foam sealing material, electrical terminal and electrical conductor comprising a foamable sealing material as well as a method for sealing the connection between an electrical wire and an electrical terminal
A terminal assembly comprises a conductor and an electrical terminal having a connection area connected to the conductor. A seal of the terminal assembly seals the connection area in a fluid-tight manner. The seal is composed of a foamable sealing material which includes an activatable blowing agent.
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This application is a continuation of PCT International Application No. PCT/EP2016/074112, filed on Oct. 7, 2016, which claims priority under 35 U.S.C. § 119 to German Patent Application No. 102015219654.2, filed on Oct. 9, 2015.
FIELD OF THE INVENTIONThe present invention relates to a terminal assembly and, more particularly, to a terminal assembly having a seal which seals a connection between a conductor and an electrical terminal of the terminal assembly.
BACKGROUNDTerminal assemblies including electrical terminals and electrical wires connected to the electrical terminals are used in plug connectors and cable trees. The cable trees and the terminals in plug connectors are often produced from copper or a copper alloy. However, copper is very heavy and is relatively expensive. Cable trees and plug connectors are increasingly being miniaturized, in the automotive industry for example, to save weight and cost. Alternative conductor materials which are lighter and cheaper than copper are therefore increasingly considered; conductors made from base metals—metals which, in the electrochemical series, have a standard electrode potential smaller than the standard electrode potential of hydrogen—are lighter and cheaper than copper. The base metal may be, for example, aluminum or an aluminum alloy.
However, when connecting conductors which comprise a base metal to a terminal which comprises copper or another noble metal, it is difficult to produce a reliable mechanical and electrical connection between the conductor and the terminals. A mechanical connection of a conductor and a terminal which are composed of different metals or metal alloys is problematic as the connection is relatively weak and plug connectors in the automotive sector, for example, are exposed to large physical stresses and must therefore withstand high forces. Further, the connection of a terminal which comprises copper or a more noble metal to a conductor which comprises a base metal such as aluminum, for example, is electrochemically problematic because the point of contact between the noble and less noble metals is in danger of corroding. Due to the differing dissolution potentials of the different metals, galvanic corrosion can occur if the connection area comes into contact with an electrolyte, water, or moisture. The less noble metal becomes the anode and the more noble metal becomes the cathode, which leads to the dissolution of the anode. Such a corrosion thus weakens the mechanical connection. The corrosion may also impair the charge transfer if an oxidation layer is formed in the event of corrosion.
To prevent corrosion between the different materials of the terminal and the conductor, it is common to use a lubricant or a holt-melt adhesive to create a fluid-tight seal around the connection area. Lubricants, however, must be applied before the terminal is mechanically and electrically conductively connected to the conductor in the connection area, which negatively affects the mechanical stability of the connection. The same applies to the use of hot-melt adhesives as sealing materials. Sealing after the conductor and the terminal are already mechanically and electrically conductively connected to one another is complex and difficult to accomplish because the connection area can only be accessed with difficulty after connection, for example when it is inside a crimping sleeve. Conversely, the use of special seals is generally expensive and requires complex structural changes to the components of a terminal assembly in order to provide the seals with suitable sealing sites.
SUMMARYA terminal assembly comprises a conductor and an electrical terminal having a connection area connected to the conductor. A seal of the terminal assembly seals the connection area in a fluid-tight manner. The seal is composed of a foamable sealing material which includes an activatable blowing agent.
The invention will now be described by way of example with reference to the accompanying Figures, of which:
Exemplary embodiments of the present invention will be described hereinafter in detail with reference to the attached drawings, wherein like reference numerals refer to like elements. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete and will fully convey the concept of the disclosure to those skilled in the art.
An electrical terminal 1 according to an embodiment is shown in
As shown in
The terminal 1 comprises a seal 15. In the embodiment of
In the embodiment shown in
An electrical terminal 1′ according to another embodiment is shown in
In an embodiment, the foamable sealing material 19 is a thermoplastic, for example, a thermoplastic elastomer. Thermoplasts are deformed in a particular temperature range and thermoplastic elastomers are plastics which are dimensionally stable and elastically deformable at room temperature, and which plastically deform under the application of heat. The thermoplastic properties of the sealing material 19 make it possible to form the sealing 19 material easily into the shape desired, for example as a film 17, ring 17′, clip or sleeve, which facilitates assignment to the connection area 13. In an embodiment, the sealing material 19 is a polyolefin such as polyethylene, polypropylene or polyamides. In another embodiment, the sealing material 19 is a copolymer, for example, a copolymer comprising a vinyl acetate such as ethylene vinyl acetate, and a methyl acrylate such as ethylene methyl acrylate.
The sealing material 19, as shown in
An electrical wire 9 according to various embodiments is shown in
The conductor 7 comprises aluminum or an aluminum alloy and, in an embodiment, consists of aluminum or an electrically conductive aluminum alloy. In various embodiments, the conductor 7 has a conductor cross-sectional area of 0.1 to 3 mm2, 0.2 to 1.5 mm2, or 0.22 to 1 mm2. In an embodiment, the terminal 1 is made of a more noble metal than the conductor 7 and may comprise copper or a copper alloy.
In the embodiment shown in
The foamable sealing material 19 of
In the embodiment of the electrical wire 9 shown in
A terminal assembly 33 according to an embodiment is shown in
The foamable sealing material 19 is foamed by the activatable blowing agent 21 into the foamed sealing material 19a, as described below with reference to
The blowing agent 21 is activated to foam the foamable sealing material 19 and transform it into the foamed sealing material 19a. The blowing agent 21 can be activated, for example, by an increase in temperature; as soon as the temperature exceeds an activation temperature of the blowing agent 21, the blowing agent 21 expands, whereby the sealing material 19 is foamed, its volume is increased as a result, and it fills the free spaces in the connection area, for example the complete crimping sleeve 35. In other embodiments, the blowing agent 21 may be activated by the addition of a reactant, a change in pressure, or the application of radiation.
A melting point of the sealing material 19 is below the activation temperature of the blowing agent 21; the sealing material 19 can be thermoplastically deformable below the activation temperature. As a result, seals 15 in any desired form, for example films, rings or inserts, can be produced from the sealing material 19 using standard methods in plastics technology, without the blowing agent 21 being activated. The sealing material 19 can undergo primary molding below the activation temperature of the blowing agent 21. Primary molding includes manufacturing methods in which a solid body is produced from an amorphous substance. The amorphous substance can for example be a plastic or doughy state, such as a polymer melt, which can be formed into the desired shape for example by means of injection molding, extrusion blow molding or extrusion. The activation temperature is below the decomposition temperature of the sealing material 19 in order to preclude decomposition of the sealing material 19 in the event of activation. In an embodiment, the melting point of the sealing material 19 is below 170° C. and the sealing material 19 is capable of undergoing primary molding in a range between 90° C. and 170° C., or between 130° C. and 170° C. In an embodiment, the activation temperature is 180° C. to 210° C.
In an embodiment in which the cross-linking agent 31 is temperature-activated, the cross-linking temperature is above the melting point of the sealing material 19 and is at least as high as an activation temperature of the blowing agent 21. It is thus ensured that the sealing material 19 is not yet cross-linked while it is thermoplastic and capable of undergoing primary moulding and that the activation of the cross-linking agent 31 only occurs once the sealing material 19 is foamed.
An exemplary blowing agent 21 is schematically shown in
The blowing agent 21 shown in
When the activation temperature is exceeded, the expansion of the expansion substance 43 causes an increase in the internal pressure pI in the interior of the capsule 37, which expands due to the increasing internal pressure pI as shown in
In an exemplary method, in order to create the seal 15 at the terminal 1 and apply the sealing material 19, the sealing material 19 is first heated to approx. 170° C. using a heating device. The sealing material 19 comprises a plurality of microballoons which are plastically deformable at this temperature; the balloons are then pressed together in order to produce as thin a film 17 as possible therefrom. This film 17 is laid into the open crimp in the connection region 5 prior to the crimping process. Alternatively, small rings 17′ can be produced from the thin film. These are then slipped onto the isolated wire 9 into the connection region 5.
The seal 15 is thus located in the connection area 13 before the terminal 1 and the conductor 7 are crimped together. In this manner, the sealing material 19 is reliably arranged in or in sufficient proximity to the connection area 13, such that even a slight expansion and foaming of the sealing material 19 with a volume increase of, for example, at least 50%, is sufficient to accomplish a corrosion-resistant sealing of the connection area 13. After crimping, parts of the terminal assembly 33 are heated to over 200° C. in order to activate the blowing agent 21, which then presses the sealing material 19 into the free spaces and seals the connection area 13.
Claims
1. A terminal assembly, comprising:
- a conductor; and
- an electrical terminal having a connection area connected to the conductor and a seal that seals the connection area in a fluid-tight manner, the seal is composed of a foamable sealing material which includes an activatable blowing agent, the blowing agent is temperature-activatable and expands when an activation temperature is exceeded, the sealing material is a thermoplastic and a melting point of the sealing material is below the activation temperature of the blowing agent.
2. The terminal assembly of claim 1, wherein the blowing agent comprises a plurality of stretchable capsules each filled with an expandable substance.
3. The terminal assembly of claim 1, wherein the sealing material is capable of undergoing primary molding below the activation temperature of the blowing agent.
4. The terminal assembly of claim 1, wherein the sealing material includes a cross-linking agent.
5. The terminal assembly of claim 1, wherein the sealing material includes an adhesive agent.
6. An electrical terminal, comprising:
- a connection area connecting to a conductor; and
- a seal disposed at the connection area and composed of a foamable sealing material which includes an activatable blowing agent, the blowing agent is temperature-activatable and expands when an activation temperature is exceeded, the sealing material is a thermoplastic and a melting point of the sealing material is below the activation temperature of the blowing agent.
7. The electrical terminal of claim 6, wherein the connection area is covered at least in part by the sealing material.
8. An electrical wire, comprising:
- an insulating cover; and
- a conductor disposed in the insulating cover and having a connection section connecting to an electrical terminal, a seal composed of a foamable sealing material which includes an activatable blowing agent is disposed at the connection section, the blowing agent is temperature-activatable and expands when an activation temperature is exceeded, the sealing material is a thermoplastic and a melting point of the sealing material is below the activation temperature of the blowing agent.
9. The electrical wire of claim 8, wherein the seal is an elastic sealing ring disposed only over a portion of the conductor exposed in the connection section.
10. The electrical wire of claim 8, wherein the seal radially surrounds at least a portion of the insulating cover.
11. The electrical wire of claim 10, wherein the insulating cover is removed from the conductor in the connection section and the conductor is exposed in the connection section.
12. The electrical wire of claim 11, wherein the seal is arranged both in the connection section and at a portion of the insulating cover delimiting the connection section.
13. A method for sealing a connection between a conductor and a terminal, comprising:
- providing the conductor arranged in an insulating cover;
- connecting a connection section of the conductor to a connection area of the terminal;
- disposing a seal made of a foamable sealing material which includes an activatable blowing agent at the connection area and/or at the connection section;
- activating the blowing agent and foaming the sealing material by activation of the blowing agent to produce a foamed sealing material, the blowing agent is temperature-activatable and expands when an activation temperature is exceeded, the sealing material is a thermoplastic and a melting point of the sealing material is below the activation temperature of the blowing agent; and
- sealing the connection with the foamed sealing material in a fluid-tight manner.
14. The method of claim 13, wherein, before connecting the connection section of the conductor to the connection area of the terminal, and during the disposing step, the connection area of the terminal is at least partially covered with the sealing material.
15. The method of claim 13, wherein, before connecting the connection section of the conductor to the connection area of the terminal, and during the disposing step, at least a portion of the insulating cover is covered radially by the sealing material.
16. A sealing material for sealing a connection of a conductor to a connection area of an electrical terminal, comprising:
- a foamable sealing material including an activatable blowing agent distributed in the foamable sealing material and capable of foaming the foamable sealing material into a foamed sealing material upon activation, the activatable blowing agent is temperature-activatable and expands when an activation temperature is exceeded, the foamable sealing material is a thermoplastic and a melting point of the foamable sealing material is below the activation temperature of the activatable blowing agent.
17. The sealing material of claim 16, wherein the foamable sealing material includes a cross-linking agent having a cross-linking temperature greater than or equal to the activation temperature of the activatable blowing agent.
18. The electrical terminal of claim 6, wherein the sealing material is a polyolefin or a copolymer.
19. The electrical terminal of claim 6, wherein the sealing material includes a cross-linking agent having a cross-linking temperature greater than or equal to the activation temperature of the blowing agent.
20. The sealing material of claim 16, further comprising an adhesive agent integrated into the sealing material.
3955044 | May 4, 1976 | Hoffman et al. |
5118313 | June 2, 1992 | Delalle |
7390845 | June 24, 2008 | Lach, III |
7976750 | July 12, 2011 | Burmeister |
8247465 | August 21, 2012 | Inohara et al. |
8771015 | July 8, 2014 | Inoue |
9378867 | June 28, 2016 | Itou |
20050191882 | September 1, 2005 | Torii et al. |
20100206631 | August 19, 2010 | Peters et al. |
20130072074 | March 21, 2013 | Inoue et al. |
20160137912 | May 19, 2016 | Sherman |
101587848 | November 2009 | CN |
101827911 | September 2010 | CN |
102822263 | December 2012 | CN |
103004024 | March 2013 | CN |
103329380 | September 2013 | CN |
0037253 | November 1981 | EP |
0351982 | January 1990 | EP |
0701300 | March 1996 | EP |
2508561 | October 2012 | EP |
1468369 | February 1974 | GB |
S57-42939 | September 1982 | JP |
2005-261184 | September 2005 | JP |
2012-28152 | February 2012 | JP |
2014186989 | October 2014 | JP |
- The Fourth Office Action, National Intellectual Property Administration of the People's Republic of China and English translation, dated Nov. 17, 2020, 8 pages.
- Chinese Second Office Action and English translation, dated Dec. 20, 2019, 25 pages.
- European Patent Office Communication, dated Apr. 23, 2020, 6 pages.
- Chinese Third Office Action and English translation, dated Jul. 3, 2020, 26 pages.
- PCT Notification of Transmittal of the International Search Report and the Written Opinion of the International Searching Authority, or the Declaration, International Search Report and Written Opinion of the International Searching Authority, dated Nov. 21, 2016, 12 pages.
- Japanese Notice for Reasons for Refusal with English translation, dated Jun. 4, 2019, 15 pages.
Type: Grant
Filed: May 4, 2020
Date of Patent: Feb 8, 2022
Assignee: TE Connectivity Germany GmbH (Bensheim)
Inventors: Helge Schmidt (Speyer), Maryam Haghighi (Frankfurt am Main), Stefan Thoss (Worms)
Primary Examiner: Carlos N Lopez
Application Number: 16/866,084
International Classification: H01R 4/70 (20060101); H01R 4/18 (20060101); H01R 13/52 (20060101);