[0001] The object of the present invention is an electrical connector for connecting electrical
cables to electrical terminals.
DE102007005810A1 indicates a state of the art for such connectors. Furthermore,
WO 2004/047 227 A1 indicates a connector according to the preamble of claim 1.
[0002] Single piece electrical connectors made of copper are known, which form a cable connection
portion, for example a tubular or C-shaped seat suitable for receiving one end of
an electric cable and for being compressed around such an end so as to obtain, a press-fit
connection, as well as a terminal connection portion suitable for being connected
in pressing contact, for example through a bolt, against an electrical terminal of
a use.
[0003] This known type of electrical connector can be applied to make electrical contacts
in the civil, industrial and rail fields.
[0004] However, due to a considerable increase in the cost of copper and to the consequent
frequent theft of conductors made from such a metal, over the last years there has
been an increase in the use of conductors made from aluminium for transportation and
distribution of electrical energy.
[0005] The electric conductors made of aluminium must be connected to the pre-existing terminals
made of copper and also to the more common recently installed terminals which are
still now very frequently made of copper.
[0006] Therefore, a requirement has arisen of being able to have electrical connectors for
connecting cables made of aluminium to existing terminals made of copper.
[0007] Analogous requirements have arisen for connecting cables made of copper to terminals
made of aluminium, for connecting cables of steel to terminals made of copper and
vice versa, as well as for connecting cables made of steel to terminals made of aluminium and
vice versa.
[0008] There are connectors (so called cable terminal connectors) made of aluminium the
use of which however leads to a contact which is exposed to the environment between
metals with different galvanic potential, such as copper and aluminium, with consequent
risks of galvanic crevice corrosion in the contact area between the connector made
of aluminium and the terminal made of copper.
[0009] In order to avoid the problem of the galvanic corrosion which could occur in the
contact area between the aluminium and the copper, bi-metal connectors are currently
sold on the market having a cable seat in aluminium that is suitable for being compressed
onto the conductor, as well as a terminal connection portion made of copper that is
suitable for being connected in contact with a terminal, in which the cable seat and
the terminal connection portion are welded to one another.
[0010] Such a solution, although solving the problem of the crevice corrosion in a satisfactory
manner, is not without drawbacks.
[0011] The manufacturing process of the single parts made of aluminium and copper and their
subsequent joining through welding is, on one hand, complex and costly and, on the
other hand, is not able to obtain a copper-aluminium connection that is sufficiently
reliable and resistant for applications in which the connectors undergo vibrations.
One example of electrical connections exposed to the external environment and undergoing
vibrations and cyclical mechanical stress is the connection between electrical cables
and train rails.
[0012] The purpose of the present invention is therefore that of proposing an electrical
connector (so called cable terminal) for the connection of electrical cables made
of a first metal (for example aluminium) to terminals made of a second metal (for
example copper), having characteristics such as to withstand mechanical stress, in
particular vibrations, and avoid the phenomenon of galvanic crevice corrosion.
[0013] These and other purposes are achieved with a connector (cable terminal) according
to claim 1 for connecting an electric cable to a terminal, comprising a tubular body
that forms a cable connection portion that is suitable for receiving one end of an
electric cable and a terminal connection portion suitable for being connected in contact
with a terminal, in which the tubular body comprises one inner layer that is substantially
made of a first conductive metal that forms an inner surface of the tubular body and
one outer layer that is substantially made of a second conductive metal that is different
from the first conductive metal and that forms an outer surface of the tubular body,
in which the outer surface forms a terminal contact surface of the terminal connection
portion and the inner surface forms a cable contact surface of the cable connection
portion, in which said inner layer and said outer layer are metallurgically bonded.
The connection between the two layers can be made through melting of the material
in the transition area between the outer layer and the inner layer, for example through
the manufacture of the bi-layer or multi-layer tubular body through drawing or co-extrusion.
[0014] The cable terminal thus configured makes it possible to obtain the specific advantages
of a bi-metal cable terminal (no difference of galvanic potential in the area of contact
between the cable terminal and the terminal) with low costs and with mechanical resistance
that is suitable for applications undergoing vibrations.
[0015] Moreover, the use of a multi-layer tubular body manufactured through drawing or co-extrusion
allows a production of the connector on a large scale with low costs and with a close
and resistant joining between the layers themselves.
[0016] In the present description the terms "substantially made of a first metal" and "substantially
made of a second metal" or, more specifically "substantially made of copper" and "substantially
made of aluminium" do not exclude alloys of such metals as long as the metals indicated
form the main portion of the alloy itself. In the preferred embodiment, the expressions
"substantially made of copper" and "substantially made of aluminium" refer to the
two metals as usually found on the market and used as conductors for the electrical
and electro-technical industry.
[0017] In order to better understand the invention and to appreciate the advantages thereof,
in the following description we shall describe some of its embodiments given as an
example and not for limiting purposes, with reference to the attached figures, in
which:
figures 1A - 1E are side, front and rear views of a connector (cable terminal) for
connecting an electric cable to a terminal of a user, according to a first embodiment;
figure 1F is a longitudinal section view of the connector in figure 1A;
Figure 1G is a perspective view of the connector in figure 1A;
figures 2A - 2E are side, front and rear views of a connector (cable terminal) for
connecting an electric cable to a terminal of a user, according to a second embodiment;
figure 2F is a longitudinal section view of the connector in figure 2A;
figure 2G is a perspective view of the connector in figure 2A;
figure 3 illustrates the connector of figure 1 applied to an electric conductor;
figure 4 is a longitudinal section view of the conductor - connector group in figure
3;
figures 4A and 4B illustrate variant embodiments of the connector;
figure 5 is a cross-section view of the conductor - connector group in figure 3;
figure 6 illustrates an application of the connector for the electrical connection
of a cable to a train track;
figure 7 is a section view of the connection in figure 6.
[0018] With reference to the figures, a connector 1 (so called cable terminal) for connecting
an electric cable 2 to a terminal 3 comprises a tubular body 8 that forms a cable
connection portion 4 that is suitable for receiving an end of the electric cable 2
and a terminal connection portion 6 that is suitable for being connected in contact
with the terminal 3. The tubular body 8 comprises an inner layer 9 that is substantially
made of a first conductive metal (for example aluminium, alternatively steel, copper)
that forms an inner surface 17 of the tubular body 8 and an outer layer 10 substantially
made of a second conductive metal (for example copper, alternatively aluminium, steel)
that is different from the first conductive metal and that forms an outer surface
18 of the tubular body 8, in which the outer surface 18 forms a terminal contact surface
of the terminal connection portion 6 and the inner surface 17 forms a cable contact
surface of the cable connection portion 4.
[0019] The inner layer 9 and the outer layer 10 are connected to one another with continuity
of material substantially over the entire surface, for example through melting of
the material in the interface or transition area 19 between the outer layer and the
inner layer. Consequently the inner layer is to all effects welded to the outer layer.
This can be obtained for example through the manufacture of the bi-layer or multi-layer
tubular body 8 through drawing or co-extrusion.
[0020] According to one aspect of the invention, in the interface or transition area 19
between the two layers, the latter are metallurgically bonded. Such a metallurgical
bond between the two metal layers can be obtained for example through the manufacture
of the bi-layer or multi-layer tubular body through drawing. According to one embodiment
a bi-layer or multi-layer tube previously preassembled is equipped with an inner floating
mandrel and is cold drawn through one or a series of outer matrices so that the high
pressure between the tube layers generates the aforementioned metallurgical bond.
[0021] Alternatively, the metallurgical bond between the two metal layers can be obtained
by manufacturing the bi-layer or multi-layer tubular body through co-extrusion or,
in other words, through co-extrusion welding (CEW) in which the two different metals
are, for example, extruded simultaneously and together through the same matrix so
that the high pressure and the high temperature generate the metallurgical bond in
the transition area 19 between the two adjacent layers of the tube.
[0022] According to a further aspect of the invention, the metallurgical bond between the
two metal layers can be obtained through the manufacture of the bi-layer or multi-layer
tubular body through roll welding (ROW) in which the different metals are joined during
their forced passage between the lamination rollers so that the high pressure and,
if foreseen, the high temperature generate the metallurgical bond between the layers
of the tube.
[0023] In technical jargon the connection between the two layers thus obtained, that is
to say the metallurgical bond of the two different metal materials, is sometimes called
"metallurgical cladding". This connection is obtained through layers having preferably
uniform thicknesses and not too thin and provides, together with minimum thicknesses
of the metal layers involved of at least 0.5 mm, preferably from 0.5 mm to 10 mm,
the most favourable mechanical and galvanic characteristics for the electrical connector.
[0024] In accordance with one embodiment, the tubular body 8 is a two-layer tubular body
with the inner layer 9 made of aluminium and the outer layer 10 made of copper, in
which the inner layer 9 has a thickness ranging from 0.5 mm to 10 mm and the outer
layer 10 has a thickness ranging from 0.5 mm to 2 mm.
[0025] In the present invention by the term "metallurgical bond" we mean that the lattice
structure of the two metals is forced in mutual conformance with sharing of electrons
in the interface between the two layers which generates a bond at the atomic level.
[0026] Advantageously, in the interface (transition area 19) between the two layers, the
latter are metallurgically bonded and locally interpenetrated.
[0027] According to one aspect of the invention, the transition area 19 with metallurgical
bond extends continuously and uninterruptedly for the entire extension of the interface
between the two layers. Preferably, both metal layers (and also the interface between
them) substantially extend on the entire extension of the tubular body, the wall of
which is therefore multi-layer all over and substantially without monolayer portions.
[0028] The cable terminal thus configured makes it possible to obtain the specific advantages
of a bi-metal cable terminal (no difference of galvanic potential in the contact area
between the cable terminal and the terminal) with low costs and with mechanical resistance
that is suitable for applications undergoing vibration.
[0029] Moreover, the use of a multi-layer tubular body manufactured through drawing or co-extrusion
allows a production of the connector on a large scale at low costs and with a close
and resistant connection between the layers themselves.
[0030] In accordance with one embodiment, the terminal connection portion 5 is formed by
a flattened end, for example through cold plastic deformation, of the multi-layer
tubular body 8 and can be equipped with a through hole 11 that is suitable for receiving
a bolt 12 or a connection screw.
[0031] This facilitates making a connection in pressing contact through bolting down the
connector 1 to the terminal 3, for example to a terminal of a train rail 13 (Figures
6, 7).
[0032] In accordance with one embodiment, the cable connection portion 4 is formed by one
open end portion (tubular, for example cylindrical) of the tubular body 8, opposite
to the flattened end, and suitable for receiving an end of the electric cable 2 as
well as for being compressed around it so as to make a press-fit and shape connection
(Figures 3, 4).
[0033] In accordance with a further embodiment, at at least one or both the free ends 14,
15 of the tubular body 8 and, therefore, at the terminal connection portion 6 and/or
at the cable connection portion 4, the outer layer 10 extends beyond the inner layer
9, so that only the outer layer 10 is exposed to the external environment.
[0034] Such a configuration of the free edges of the tubular body 8 can be made for example
through boring or milling of the ends of the tubular body 8 so as to eliminate an
end section of the inner layer 9. The end section of the outer layer above the inner
layer can be folded towards the inside of the tubular body 8 to prevent exposure of
the inner layer to the environment.
[0035] This makes it possible to eliminate also the residual galvanic differential in the
free edges of the connector.
[0036] In the embodiment illustrated in figures 2A - 2G, the flattened terminal connection
portion is substantially symmetrical with respect to the cable connection portion.
[0037] Alternatively, in the embodiment illustrated in figures 1A - 1G, the flattened terminal
connection portion 6 defines a contact plane 16 that is substantially tangent to the
outer surface 18 of the cable connection portion 4 or radially outside of it or inclined
with respect to it, so that said contact plane 16 does not intersect the cable connection
portion 4.
[0038] This facilitates the connection of the connector 1 to extended flat terminals or
flat and extended surfaces in general.
[0039] From the description given, a man skilled in the art will appreciate how the connector
1 synergically reconciles the requirements of:
- an electrical connection between two different metals, such as for example aluminium
and copper, and the consequent problems of galvanic corrosion,
- a mechanical and electrical connection that can withstand vibrations and adverse weather
conditions,
- a simple structure that can be manufactured on a large scale and at low cost.
[0040] Of course, a person skilled in the art, with the purpose of satisfying contingent
and specific requirements, may carry out further modifications and variants to the
connector according to the present innovation, all moreover covered in the scope of
protection of the invention, as defined by the following claims.
1. Connector (1) for connecting an electric cable (2) to a terminal (3), said connector
(1), comprising a tubular body (8) that forms a cable connection portion (4) suitable
for receiving the electric cable (2) and a terminal connection portion (6) suitable
for being connected in contact with the terminal (3),
wherein the tubular body (8) is a multi-layer tubular body having an inner layer (9)
of a first conductive metal
that forms an inner surface (17) of the tubular body (8) and an outer layer (10) of a second conductive metal different from the first conductive
metal
and that forms an outer surface (18) of the tubular body (8),
in which the outer surface (18) forms a terminal contact surface of the terminal connection
portion (6) and the inner surface (17) forms a cable contact surface of The cable
connection portion (4)
characterized in that the tubular body (8) is a multi-layer tube selected from the group consisting of:
drawn multi-layer tubes,
coextruded multi-layer tubes,
laminated multi-layer tubes,
and said outer (10) and inner (9) layers are metallurgically bonded.
2. Connector (1) according to claim 1,
wherein the inner layer (9) and the outer layer (10) substantially extend on the entire
extension of the tubular body (8).
3. Connector (1) according to claim 1 or 2, wherein said outer layer (10) and said inner
layer (9) are metallurgically bonded and locally interpenetrated.
4. Connector (1) according to one of the previous claims, wherein the terminal connection
portion (5) is formed from a flattened end of the tubular body (8).
5. Connector (1) according to any one of the previous claims, wherein the terminal connection
portion (5) defines a through hole (11) suitable for receiving a bolt 12 or a connection
screw, said through hole (11) extending through both the outer and inner layers (10,
9,).
6. Connector (1) according to any one of the previous claims, wherein the cable connection
portion (4) is formed from an open end portion of the tubular body (8), opposite to
the flattened end, and suitable for receiving an end of the electric cable (2) as
well as for being compressed around it so as to make a press-fit connection.
7. Connector (1) according to any one of the previous claim, wherein at at least one
free end (14, 15) of the tubular body (8) the outer layer (10) extends beyond the
inner layer (9), so that only the outer layer (10) is exposed to the external environment.
8. Connector (1) according to the previous claim, wherein an end section of the outer
layer (10) above the inner layer is bent towards the inside of the tubular body (8).
9. Connector (1) according to any one of the previous claims, wherein the terminal connection
portion (6) is flattened and defines a contact plane (16) oriented so as not to intersect
the cable connection portion (4).
10. Connector (1) according to any one of the previous claims, wherein said first conductive
metal is selected from the group consisting of aluminium, copper, steel,
and said second conductive metal is selected from the group consisting of copper,
steel, aluminium.
11. Connector (1) according to any one of the previous claims, wherein the thickness of
the inner layer (9) is substantially uniform and equal to or greater than 0.5 mm.
and the thickness of the outer layer (10) is substantially uniform and equal to or
greater than 0.5 mm.
12. Connector (1) according to claim 12, wherein the tubular body (8) is a two-layer tubular
body with the inner layer 9 made of aluminium and the outer layer 10 made of copper,
wherein the inner layer 9 has a thickness ranging from 0.5 mm to 10 mm and the outer
layer 10 has a thickness ranging from 0.5 mm to 2 mm.
1. Verbinder (1) zum Verbinden eines elektrischen Kabels (2) mit einem Anschluss (3),
wobei der Verbinder (1) einen röhrenartigen Körper (8), der einen Kabelverbindungsbereich
(4) geeignet zur Aufnahme des elektrischen Kabels (2) ausbildet, und einen Anschlussverbindungsbereich
(6) umfasst, der geeignet ist, mit dem Anschluss (3) kontaktierend verbunden zu werden,
wobei der röhrenartige Körper (8) ein röhrenartiger Multischichtkörper ist, der eine
innere Schicht (9) aus einem ersten leitenden Metall, das eine innere Oberfläche (17)
des röhrenartigen Körpers (8) ausbildet, und eine äußere Schicht (10) aus einem zweiten
leitenden Metall aufweist, das von dem ersten leitenden Metall verschieden ist und
das eine äußere Oberfläche (18) des röhrenartigen Körpers (8) ausbildet,
wobei die äußere Oberfläche (18) eine Anschlusskontaktfläche des Anschlussverbindungsbereichs
(6) ausbildet und wobei die innere Oberfläche (17) eine Kabelkontaktfläche des Kabelkontaktbereichs
(4) ausbildet,
dadurch gekennzeichnet, dass der röhrenartige Körper (8) eine Multischichtröhre ist, die aus der Gruppe ausgewählt
ist, die besteht aus:
gezogenen Multischichtröhren,
coextrudierten Multischichtröhren,
laminierten Multischichtröhren,
und wobei die äußere (10) und innere (9) Schicht metallurgisch verbunden sind.
2. Verbinder (1) nach Anspruch 1, wobei die innere Schicht (9) und die äußere Schicht
(10) sich im wesentlichen über die gesamte Erstreckung des röhrenartigen Körpers (8)
erstrecken.
3. Verbinder (1) nach Anspruch 1 oder 2, wobei die äußere Schicht (10) und die innere
Schicht (9) metallurgisch verbunden sind und sich lokal gegenseitig durchdringen.
4. Verbinder (1) nach einem der vorhergehenden Ansprüche, wobei der Anschlussverbindungsbereich
(5) aus einem abgeflachten Ende des röhrenartigen Körpers (8) ausgebildet ist.
5. Verbinder (1) nach irgend einem der vorhergehenden Ansprüche, wobei der Anschlussverbindungsbereich
(5) ein Durchgangsloch (11) definiert, das geeignet ist zum Aufnehmen eines Bolzens
(12) oder einer Verbindungschraube, wobei sich das Durchgangsloch (11) sowohl durch
die äußere als auch die innere Schicht (10, 9) hindurch erstreckt.
6. Verbinder (1) nach irgend einem der vorhergehenden Ansprüche, wobei der Kabelverbindungsbereich
(4) aus einem offenen Endbereich des röhrenartigen Körpers (8) gegenüberliegend zu
dem abgeflachten Ende ausgebildet ist und geeignet ist zur Aufnahme eines Endes des
elektrischen Kabels (2) sowie auch zum darum herum komprimiert werden, um eine Presspassungsverbindung
herzustellen.
7. Verbinder (1) nach irgend einem der vorhergehenden Ansprüche, wobei an mindestens
einem freien Ende (14, 15) des röhrenartigen Körpers (8) sich die äußere Schicht (10)
über die innere Schicht (9) hinaus erstreckt, so dass nur die äußere Schicht (10)
der externen Umgebung ausgesetzt ist.
8. Verbinder (1) nach dem vorhergehenden Anspruch, wobei ein Endabschnitt der äußeren
Schicht (10) über der inneren Schicht hin zu dem Inneren des röhrenartigen Körpers
(8) gebogen ist.
9. Verbinder (1) nach irgend einem der vorhergehenden Ansprüche, wobei der Anschlussverbindungsbereich
(6) abgeflacht ist und eine Kontaktebene (16) definiert, die orientiert ist, so dass
sie nicht den Kabelverbindungsbereich (4) schneidet.
10. Verbinder (1) nach irgend einem der vorhergehenden Ansprüche, wobei das erste leitende
Metall aus der Gruppe ausgewählt ist, die besteht aus Aluminium, Kupfer, Stahl, und
wobei das zweite leitende Metall aus der Gruppe ausgewählt ist, die besteht aus Kupfer,
Stahl, Aluminium.
11. Verbinder (1) nach irgend einem der vorhergehenden Ansprüche, wobei die Dicke der
inneren Schicht (9) im Wesentlichen gleichförmig und gleich oder größer als 0,5 mm
ist und wobei die Dicke der äußeren Schicht (10) im Wesentlichen gleichförmig und
gleich oder größer als 0,5 mm ist.
12. Verbinder (1) nach Anspruch 11, wobei der röhrenartige Körper (8) ein röhrenartiger
Zwei-Schicht-Körper ist, wobei die innere Schicht (9) aus Aluminium gemacht ist und
die äußere Schicht (10) aus Kupfer gemacht ist, wobei die innere Schicht (9) eine
Dicke im Bereich von 0,5 mm bis 10 mm aufweist und die äußere Schicht (10) eine Dicke
im Bereich von 0,5 mm bis 2 mm aufweist.
1. Connecteur (1) pour connecter un câble électrique (2) à un terminal (3), ledit connecteur
(1) comprenant un corps tubulaire (8) qui forme une partie de connexion pour câble
(4) adaptée pour recevoir le câble électrique (2) et une partie de connexion pour
terminal (6) adaptée pour être connectée au terminal (3),
dans lequel le corps tubulaire (8) est un corps tubulaire multicouches ayant une couche
interne (9) d'un premier métal conducteur qui forme une surface interne (17) du corps
tubulaire (8) et une couche externe (10) d'un second métal conducteur différent du
premier métal conducteur et qui forme une surface externe (18) du corps tubulaire
(8),
dans lequel la surface externe (18) forme une surface de contact de terminal de la
partie de connexion au terminal (6) et la surface interne (17) forme une surface de
contact de câble de la partie de connexion au câble (4),
caractérisé en ce que le corps tubulaire (8) est un tube multicouches sélectionné dans le groupe constitué
par:
des tubes multicouches tréfilés,
des tubes multicouches co-extrudés,
des tubes multicouches laminés,
et lesdites couches externe (10) et interne (9) sont en liaison métallurgique.
2. Connecteur (1) selon la revendication 1, dans lequel la couche interne (9) et la couche
externe (10) s'étendent substantiellement sur la totalité du corps tubulaire (8).
3. Connecteur (1) selon la revendication 1 ou 2, dans lequel ladite couche externe (10)
et ladite couche interne (9) sont en liaison métallurgique et s'interpénètrent localement.
4. Connecteur (1) selon l'une des revendications précédentes, dans lequel la partie de
connexion au terminal (5) est formée à partir d'une extrémité aplatie du corps tubulaire
(8).
5. Connecteur (1) selon l'une quelconque des revendications précédentes, dans lequel
la partie de connexion au terminal (5) définit un trou traversant (11) adapté pour
recevoir un boulon (12) ou une vis de connexion, ledit trou traversant (11) s'étendant
à travers les couches externe et interne (10, 9).
6. Connecteur (1) selon l'une quelconque des revendications précédentes, dans lequel
la partie de connexion au câble (4) est formée à partir d'une extrémité ouverte du
corps tubulaire (8), à l'opposé de l'extrémité aplatie, et adaptée pour recevoir une
extrémité du câble électrique (2) ainsi que pour être compressée autour d'elle, de
manière à former un ajustement à pression.
7. Connecteur (1) selon l'une quelconque des revendications précédentes, dans lequel
au moins une extrémité libre (14, 15) du corps tubulaire (8) la couche externe (10)
s'étend au-delà de la couche interne (9), de sorte que seule la couche externe (10)
est exposée à l'environnement extérieur.
8. Connecteur (1) selon l'une quelconque des revendications précédentes, dans lequel
une section terminale de la couche externe (10) au-dessus de la couche interne est
recourbée vers l'intérieur du corps tubulaire (8).
9. Connecteur (1) selon l'une quelconque des revendications précédentes, dans lequel
la partie de connexion au terminal (6) est aplatie et définit un plan de contact (16)
orienté de manière à ne pas créer d'intersection avec la partie de connexion au câble
(4).
10. Connecteur (1) selon l'une quelconque des revendications précédentes, dans lequel
ledit premier métal conducteur est sélectionné dans le groupe constitué par l'aluminium,
le cuivre, l'acier, et ledit second métal conducteur est sélectionné dans le groupe
constitué par le cuivre, l'acier, l'aluminium.
11. Connecteur (1) selon l'une quelconque des revendications précédentes, dans lequel
l'épaisseur de la couche interne (9) est foncièrement uniforme et supérieure ou égale
à 0,5 mm et l'épaisseur de la couche externe (10) est foncièrement uniforme et supérieure
ou égale à 0,5 mm.
12. Connecteur (1) selon la revendication 11, dans lequel le corps tubulaire (8) est un
corps tubulaire à deux couches, la couche interne (9) étant faite d'aluminium et la
couche externe (10) étant faite de cuivre, dans lequel la couche interne (9) a une
épaisseur allant de 0,5 mm à 10 mm et la couche externe (10) a une épaisseur allant
de 0,5 mm à 2 mm.