WO2015166407A1

WO2015166407A1 - Electrical connector comprising a contact element of an aluminium based alloy

Info

Publication number: WO2015166407A1
Application number: PCT/IB2015/053083
Authority: WO
Inventors: Ennio Corrado; Luciano CHINETTI
Original assignee: Ennio Corrado; Chinetti Luciano
Priority date: 2014-04-28
Filing date: 2015-04-28
Publication date: 2015-11-05

Abstract

The present invention concerns an electrical connector comprising at least a contact element, said contact element being made of an alloy comprising aluminium, copper and at least one element selected from magnesium and zinc, said alloy having the following percentage composition by weight: - copper 1.5-7%, - magnesium 0.1-2.5 - zinc 0.1-2.5 - optionally silicon 0.1-2.5 - optionally manganese 0.1-2.5 - optionally tellurium 0.2-0.4 - aluminium balance to 100% Furthermore, the present invention concerns the use of said alloy as an electrical conductor.

Description

ELECTRICAL CONNECTOR COMPRISING A CONTACT ELEMENT OF AN ALUMINIUM BASED ALLOY

The present invention concerns an electrical connector comprising a contact element made of an aluminium based alloy. Furthermore, the present invention concerns the use of the aforementioned alloy as an electrical conductor.

The electrical connectors are connection elements that are used for reversibly joining two functional units of an electrical system so as to ensure the continuity of the transmission of electric energy between the units.

The functional units that can be connected by an electrical connector can be, for example, two electrical conductors (e.g. electrical cables) or an electrical conductor and a terminal of a device or electrical apparatus.

The electrical connectors are used for making electrical circuits in a very wide field of applications (for example motor vehicles, household appliances, lighting systems, etc.) .

The electrical connectors generally comprise one or more contact elements that are made of an electrical conductive material. Said contact elements are mechanically coupled with other contact elements, which are made of the same conductive material or of a different material, so that an electrical current can flow continuously between said two coupled elements. The coupling between the two elements is substantially made in a mechanical manner and without requiring welding operations. In the state of the art, the electrical conductive materials most commonly used to manufacture contact elements are brass (copper and zinc alloy) and copper.

Brass, in particular, is widely used because it is a good compromise in terms of electrical conductivity, workability of the material and cost.

The contact elements, typically made of brass, are coated on their surface with tin or nickel so as to increase their resistance to corrosion during use. In some fields of application (e.g. the field of electronics), the coating of the contact elements can also consist of a thin layer of highly pure gold. The gold coating, however, has a cost that is significantly higher than the tin or nickel coatings.

The application of tin or nickel coatings is based on processes of dipping in baths of metal in the liquid state or, more frequently, on processes of electrodeposition in acidic or basic aqueous solutions. In all cases, the processes of the state of the art used for applying corrosion resistant metal coatings are characterised by a high impact on the environment as well as poor health conditions of the working environment .

In the state of the art it is moreover known to use aluminium alloys, so called "light alloys", in numerous fields of structural engineering. Thanks to the advantageous relationship between mechanical and weight properties, these alloys are used, for example, in the aeronautic field for manufacturing frames and other structural elements, in the automotive industry for manufacturing components that are not exposed to high temperatures (e.g. rims and radiators) as well as for manufacturing bicycles frames, fixtures for buildings, etc .

The Applicants have now surprisingly found that an alloy comprising aluminium and copper and at least one other element selected from magnesium or zinc, can be advantageously used in the production of contact elements for electrical connectors.

Electrical connectors that comprise contact elements made of the aforementioned alloy indeed have different advantages with respect to the electrical connectors of the state of the art.

Firstly, the aforementioned alloy has a resistivity that is significantly lower than that of brass (around 50% of brass) and therefore higher conductivity.

Secondly, the aforementioned alloy has a specific weight that is lower than that of brass, therefore it is possible to make electrical connectors that are substantially lighter.

Moreover, in the presence of air, the aforementioned alloy is less subject to oxidisation with respect to brass.

Finally, the production cost of the aforementioned alloy is lower than that of brass, since it can also be produced starting from remelted aluminium.

A first aspect of the present invention is therefore an electrical connector comprising at least one contact element made of an alloy comprising aluminium, copper and at least one element selected from magnesium and zinc, said alloy having the following percentage composition by weight:

- copper 1.5-7%,

- magnesium 0.1-2.5%, - zinc 0.1-2.5%,

- optionally silicon 0.1-2.5%,

- optionally manganese 0.1-2.5%,

- optionally tellurium 0.2-0.4%,

- aluminium balance to 100%.

In accordance with a second aspect, the present invention concerns the use of the aforementioned alloy as electrical conductor.

In accordance with the present invention, the alloy is an aluminium-based metal composition comprising copper and at least another element selected from magnesium and zinc.

Copper is present in the alloy in a concentration in the range of 1.5-7% by weight, preferably in the range 2-5% by weight.

Magnesium is present in the alloy in a concentration in the range of 0.1-2.5% by weight, preferably in the range 0.2-2%.

Zinc, in addition to the magnesium or as a replacement thereof, is present in the alloy in a concentration in the range of 0.1-2.5% by weight, preferably in the range of 0.2-2% by weight.

The remaining and prevalent fraction of metal forming the alloy is made up of aluminium.

In accordance with the present invention, the alloy can also comprise silicon and/or manganese. Silicon improves the castability of the alloy and reduces its expansion coefficient. Manganese increases the mechanical resistance and corrosion resistance of the alloy.

When present, the concentration of each of said two elements is in the range of 0.2-0.4% by weight with respect to the weight of the alloy.

According to one preferred aspect, the alloy according to the present invention can moreover comprise one or more elements selected from the group of rare earth elements, preferably tellurium. When present, tellurium is preferably in a concentration of between 0.1-0.5% by weight with respect to the weight of the alloy. Advantageously, tellurium improves the conductivity of the alloy, also carrying out a protective effect against corrosion.

Other elements, such as iron or titanium, can also be present as impurities.

In one particularly preferred embodiment of the present invention, the metal alloy comprises aluminium, copper, magnesium and silicon in the following percentages by weight with respect to the weight of the alloy :

aluminium 96.5-97.45%;

copper 2.3-2.7%;

magnesium 0.2-0.4%;

silicon 0.05-0.4%.

According to a further preferred embodiment of the present invention, the metal alloy comprises aluminium, copper, magnesium, silicon and tellurium in the following percentages by weight with respect to the weight of the alloy:

aluminium 96-97.35;

copper 2.3-2.7%;

magnesium 0.2-0.4%:

silicon 0.05-0.4%;

tellurium 0.1-0.5. The alloy used for the purposes of the present invention for preparing electrical connectors has a resistivity value at 20°C that is equal to or lower than around 3.5 μΩ-cm. Such resistivity is substantially lower than that of brass which is equal to 7 μΩ-cm.

Secondly, the aforementioned alloy has a specific weight that is equal to or lower than 2.8 kg/dm³. Such a value is substantially lower than that of brass (8.4- 8.7 kg/dm³) . This represents an advantage in particular in the case of complex electrical apparatuses (e.g. electric systems of a motor vehicle, electrical apparatuses for medical use, etc.), in which the contribution to the overall weight of the apparatus due to the electrical systems can be considerable.

Moreover, the aluminium-based alloy according to the present invention has a production cost which is quite low and is therefore a valid alternative to brass .

The alloy according to the present invention can be prepared in accordance with the methods and with the apparatuses that are generally used in the field of production of aluminium alloys, in particular aluminium alloys that can be worked through plastic deformation or other manufacturing methods, such as, for example, pressure die-casting, press-extrusion, hot pressing, chilled casting.

In general, the alloy can be prepared by mixing, to the aluminium in the molten state, copper, at least one element from magnesium and zinc as well as the other optional elements in the amounts indicated above. The aluminium can also be remelted aluminium, i.e., aluminium coming from recycling and remelting of scrap aluminium.

In the preparation process, the aluminium based alloy is prepared in the form of semi-finished products, such as sheets, plates, continuous ribbons or bars having variable thickness according to the intended use.

From such semi-finished products, through lamination, stamping, embossing and other techniques, electrical contacts can be obtained in the most suitable shapes for use in manufacturing electrical connectors according to the present invention.

Preferably, the electrical connector according to the present invention has one of the following forms: electrical plug, electrical socket, jack plug, cable terminal, blade connector, spade connector, ring-tongue connector, etc.

The electrical connectors according to the present invention are substantially used in all the fields of the state of the art in which electrical systems are used containing two or more functional units to be connected to one another.

Some examples of the aforementioned electrical systems are: electrical systems for electrical devices for households (refrigerators, dishwashers, televisions, etc.), domestic and industrial electrical supply networks, electrical systems for motor vehicles, trains, aircrafts, electrical devices in the medical field .

Due to the chemical-physical properties of the alloy, in particular its melting point (500-550°C), the electrical connectors according to the present invention can be used in low voltage electrical systems and, in general, in applications in which the passage of current in the electrical system does not lead to a heating of the electrical contacts such as to damage it.

In one particularly preferred embodiment of the present invention, the contact element of the electrical connector comprises a film of surface coating comprising a polyurethane resin or an unsaturated polyester resin.

It has indeed been surprisingly observed that polyurethane resins and unsaturated polyester resins, applied in the form of a thin film, preferably with a thickness of 1-10 micrometres, more preferably 1-5 micrometres, provide the electrical contact with suitable corrosion resistance, without however substantially modifying electrical conductivity properties .

The resin is preferably applied in the form of a liquid composition (for example with a brush or roller) .

In the case of coating film comprising polyurethane resins, the liquid polyurethane composition is preferably a two-component composition.

The formation of the polyurethane polymer film is obtained by the reaction of at least one polyol component (monomer or oligomer comprising at least two OH groups) with at least one isocyanate component (also called hardener) .

The polyol component can be selected, for example, from polyether polyols (e.g. polypropylene glycol), polyester polyols and mixtures thereof. The isocyanate component can be selected for example from aliphatic, aromatic or cycloaromatic polyisocyanates , such as toluene diisocyanate, hexamethylene diisocyanate, etc.

The polyurethane composition can also contain one or more catalysts, like for example amine or organic metal compounds, solvents and additives (for example surfactants) .

In one preferred embodiment, the protective film is made up of a cross-linked polyurethane resin. For such a purpose, the liquid polyurethane composition can also contain a cross-linking agent, i.e. a compound that is OH-terminated or amine-terminated with a functionality that is equal to or greater than 3. Examples of such compounds are: glycerol, trimethylolpropane, triethanolamine, diethyltoluenediamine .

The unsaturated polyester resins can be obtained for example through a reaction of esterification of a saturated glycol with an unsaturated bivalent acid (e.g. maleic acid or fumaric acid) .

In the case of a coating film comprising polyester resins, the liquid composition applied is a two- component composition comprising, in addition the polyester resin (so called primary resin), a reactive monomer that generally acts also as a solvent (for example a monomer of the vinyl type (for example styrene) or allyl) . When being applied, to the liquid polyester composition a polymerization initiator is added (for example a peroxide compound) which triggers the radical polymerization between the primary resin and the reactive monomer with the formation of the protective film. The application of the protective films in accordance with the present invention is much easier and faster to be carried out with respect to the application processes of protective coatings of the prior art.

In particular, the use of polyester or polyurethane-based protective films makes it possible to avoid the application of tin or nickel-based protective layers, thus overcoming the drawbacks related to tin and nickel-plating processes of the prior art.

The polyurethane or polyester-based protective films, moreover, may be easily applied on the surfaces of interest only, thus reducing the consumption of polyurethane composition to the minimum possible.

The use of protective films in accordance with the present invention is moreover substantially definitely cheaper with respect to tin and nickel-plating processes .

As an example, but not for limiting purposes, some preferred embodiments of the present invention are described hereafter, with reference to the attached figures, in which:

- figure 1 shows a connector that can be used for electrically connecting an electric cable to a terminal of a source of electric energy (so called cable terminal ) ;

figure 2 shows an electrical connector in the form of an electrical plug.

In accordance with the embodiment according to figure 1, an electrical connector 1 is shown in the form of a cable terminal. The electrical connector 1 is provided with an electrical contact 2 made of an alloy in accordance with the present invention and shaped as a ring-tongue. The electrical contact 2 is coupled with an electrical cable 3 through an engagement portion 4 that is suitable for being crimped on an end of said electrical cable 3.

The cable terminal illustrated in figure 1 can be used for example to connect an electrical cable to one of the poles of a battery for supplying power to motor vehicles. For this specific application, the cable terminal is preferably coated with a polyester or polyurethane-based protective film. Considering the number of cable terminals typically used in the electrical system of a motor vehicle, the person skilled in the art will easily understand how the present invention allows to substantially reduce both the overall weight of the electrical system and the cost associated with the production of the cable terminals .

In accordance with the embodiment according to figure 2, an electrical connector 1 is shown in the form of an electrical plug. The electrical connector 1, is provided with at least one electrical contact 2 with a cylindrical shape that is cabled with an electrical cable 3. The electrical contact 2 is made of an alloy in accordance with the present invention. The electrical connector 1 also comprises an insulating body 5 that is intended to cover at least the cabled area of the electrical contact 2 with the electrical cable 3.

The electrical plug illustrated in figure 2 can be used for example as power supply terminal for connecting an electrical device to an electrical supply network .

Claims

1. Electrical connector comprising at least one contact element made of an alloy comprising aluminium, copper and at least one element selected among magnesium and zinc, said alloy having the following percentage composition by weight:

- copper 1.5-7%,

- magnesium 0.1-2.5%,

- zinc 0.1-2.5%,

- optionally silicon 0.1-2.5%,

- optionally manganese 0.1-2.5%,

- optionally tellurium 0.2-0.4%,

- aluminium balance to 100%.

2. Electrical connector according to claim 1, wherein copper is present in a percentage by weight between 2-5%.

3. Electrical connector according to any one of the previous claims, wherein magnesium is present in a percentage by weight between 0.2-2%.

4. Electrical connector according to any one of the previous claims, wherein zinc is present in a percentage by weight between 0.2-2%.

5. Electrical connector according to any one of the previous claims, wherein said alloy comprises silicon and/or manganese in a percentage by weight between 0.2-0.4.

6. Electrical connector according to claim 1, wherein said alloy has the following composition:

aluminium 96.5-97.45;

copper 2.3-2.7%;

magnesium 0.2-0.4%;

silicon 0.05-0.4%.

7. Electrical connector according to claim 1, wherein said alloy has the following composition:

copper 2.3-2.7%;

magnesium 0.2-0.4%:

silicon 0.05-0.4%;

tellurium 0.1-0.5;

aluminium balance to 100%.

8. Electrical connector according to claim 1, wherein said alloy has the following composition:

aluminium 96-97.35;

copper 2.3-2.7%;

magnesium 0.2-0.4%:

silicon 0.05-0.4%;

tellurium 0.1-0.5.

9. Electrical connector according to any one of the previous claims characterised in that said connector is selected among: electrical plug, electrical socket, jack plug, terminal, cable terminal, blade connector, spade connector, ring-tongue connector.

10. Electrical connector according to any one of the previous claims, wherein said contact element is coated with a protective film comprising a polyurethane resin or an unsaturated polyester resin.

11. Use, as electrical conductor, of an alloy comprising aluminium, copper and at least one element selected among magnesium and zinc, said alloy having the following percentage composition by weight:

- copper 1.5-7%,

- magnesium 0.1-2.5%,

- zinc 0.1-2.5%,

- optionally silicon 0.1-2.5%, - optionally manganese 0.1-2.5%,

- optionally tellurium 0.2-0.4%,

- aluminium balance to 100%.