EP1453154A1

EP1453154A1 - Electric connection terminal

Info

Publication number: EP1453154A1
Application number: EP03425135A
Authority: EP
Inventors: Antonio Coppola
Original assignee: Signal Lux MDS Srl
Current assignee: Signal Lux MDS Srl
Priority date: 2003-02-28
Filing date: 2003-02-28
Publication date: 2004-09-01
Anticipated expiration: 2023-02-28
Also published as: DE60300651D1; ES2238670T3; ATE295621T1; DE60300651T2; EP1453154B1

Abstract

A low-voltage electric connection terminal, in particular for signal lights, comprises an outlet connector provided with a plate-like element having a through hole, and a plug connector having an elongated prismatic lead-in wire for engagement with said plate-like element. Said connectors are mutually coupled by fitting along a fitting direction which is inclined with respect to the outlet connector axis and with respect to the slipping-off direction which is also inclined with respect to the outlet connector axis. In a coupled condition said elongated prismatic lead-in wire passes through the through hole formed in said plate-like element.

Description

The present invention relates to a low-voltage electric connection terminal and more particularly to a terminal for signal lights of common use mounted on household appliances, electric apparatus, machine-tools and vehicle of every kind.
Electric connection terminals for low-voltage users generally comprise a casing for supporting the bulb or other signal lights, externally shaped in a specific manner or provided with appropriate means for insertion in the apparatus to be controlled; this casing generally comprises an outlet connector usually known as female connector which is coupled by forced fitting with a plug connector usually known as male connector, in a fitting direction defined by the sliding surfaces along which mutual contact between said connectors takes place.
These terminals must substantially meet two main requirements and more specifically great facility in mutual coupling of the connectors and high reliability of said coupling against accidental slipping off of the connectors themselves, in addition to a very low cost.
An imperfect coupling of the connectors may in fact cause slipping off of same both during the apparatus mounting step at the factory and subsequently during operation, due to possible vibrations and different movements.
Slipping off of the connectors causing switching off of the signal light could bring to a wrong conclusion in terms of malfunction of the apparatus, which will bring about important economical damages due to stopping of the apparatus for inspection of same, search of a possible failure and control of the operating cycle; not to be excluded are also possible risks for the operators who may be brought to think that a switched off signal light ensures lack of electric voltage in the apparatus.
Terminals of the above type are already known in the art, however all of them have serious limits and drawbacks.
A first type of known terminal comprises an outlet connector provided with a lead-in wire that, in addition to a portion for cramping an electric wire, has a pipe-shaped coupling portion, and a plug connector provided with a lead-in wire that, in addition to a portion for cramping the electric wire with which it is to be connected, also has a cylinder-shaped coupling portion. During mutual coupling, the cylinder portion enters the tubular portion: contact between the inner surface of the tubular portion and the outer surface of the cylindrical portion ensures the electric contact between the two portions and a friction force sufficient for maintenance of the coupling. The problem arises because the friction force opposing slipping off between the two connectors also opposes fitting of same so that coupling becomes hard.
Another type of known terminal has an outlet connector comprising a clip consisting of a first flat portion against which a second flat portion elastically acts and a plug connector comprising a cylinder-shaped coupling portion to be fitted in said clip. Insertion of the plug connector into the outlet connector is very easy but the friction force opposing slipping off is very weak and therefore coupling is substantially unreliable.
In a third type of known terminal being the object of the European patent No. 782,217 for example, the outlet connector has a flattened tubular portion and the plug connector has a laminar portion engaging in the tubular portion over an area thereof substantially corresponding to the surface of the opposite side edges of the laminar portion. The insertion force is weak and therefore the resistance to slipping off is weak as well; for this reason reliability of the coupling does no longer rely on friction between the surfaces in contact with each other but on additional devices which make the terminal structure more complicated and increase cost of the terminal.
Incidentally, it is to be noted that in this type of terminal the usual positions of the connectors are reversed: the terminal contains the male connector that must be coupled with a separated female connector.
In conclusion, the mating connectors of the known art when they involve a wide mutual-contact surface to simultaneously ensure the electric contact and the resistance to slipping off, transfer the difficulty of the connectors to slip off to the insertion step as well, thereby increasing the efforts of the operators and reducing the speed in carrying out wiring. When, on the contrary, they are selected so as to minimize the insertion effort, they offer a low connection reliability or slipping off is therein counteracted by transferring this task from the connectors to other devices, which will give rise to an unacceptable increase in the cost of the terminal.
The Applicant has now become aware of the fact that the above problems could be solved by a new way of carrying out insertion and locking of the connector against slipping off and has found a new terminal capable' of operating following the above method, while at the same time ensuring functional qualities, reliability and low cost. In particular, the Applicant has perceived that the solution could be found in differentiating the fitting direction from the slipping off direction in the two connectors.
In a first aspect the invention relates to a,low-voltage electric connection terminal comprising an outlet connector, having a laminar portion provided with a through hole, and a plug connector having an elongated prismatic coupling portion, in which said elongated prismatic portion in a coupled relationship with said laminar portion, passes through said through hole.
In a second aspect the invention relates to an outlet connector for low-voltage electric connection terminals comprising the features set out in the characterizing portion of claim 6 and in the claims depending thereon.
In a further aspect the invention relates to a method of connecting and locking an outlet connector and a plug connector to each other, which connectors are part of a low-voltage electric connection terminal and are adapted to be mutually coupled by fitting of said plug connector into said outlet connector in a predetermined direction, according to which said insertion is carried out along an inclined direction with respect to the axis of said outlet connector.
Further features and advantages of the invention will become more apparent from the detailed description of a preferred but not exclusive embodiment of a terminal in accordance with the present invention. This description will be set out hereinafter with reference to the accompanying drawings, given by way of non-limiting example; in which:

Fig. 1 shows a plug connector of a terminal in accordance with the invention in a step of inserting it into the corresponding outlet connector;
Fig. 2 shows the connectors of the terminal in Fig. 1 coupled with each other, in use;
Fig. 3 shows the connectors of the terminal in Fig. 1 mutually locked with each other under the effect of a tractive effort tending to cause slipping off of same from one another.

Fig. 1 shows a low-voltage electric connection terminal, in particular for signal lights, which is generally denoted at 1.
The terminal comprises a casing 2 at one end of which a signal light not shown is mounted which is selected from those known in the art.
For example, it consists of the usual small bulb made of glass, known since long, internally provided with an incandescent filament. At the other end of the casing an outlet connector 3 is present, which is preferably formed in the body of said casing. In use this outlet connector is coupled with a plug connector 4 so as to establish the electric contact therebetween and give rise to a mechanical coupling adapted to resist a possible tractile effort acting on the connectors and capable of causing mutual separation of the latter.
Fig. 1 shows a pair alone of corresponding outlet/plug (female/male) connectors but it is apparent that the terminal will be provided with two pairs of corresponding connectors in order to be able to connect the two conductors coming out of the signal light. On the other hand, one of the conductors could be embodied by the body of the outlet connector thereby avoiding the necessity of a second pair of connectors. At all events, the accompanying figures only show a pair of outlet connectors and plug connectors, being easy to apply the teachings relating to this pair to a double pair of connectors.
In accordance with the invention, the outlet connector 3 comprises a substantially axial tubular cavity 5 for insertion of the corresponding plug connector 4, which cavity has an axially internal first stretch 6 followed by an axially external second stretch 7.
The first stretch 6 has a predetermined maximum width "L" in a plane p-p orthogonal to the axis x-x of said casing; fastened to the inner wall of this first stretch, preferably on the side surface thereof, is an anchoring end portion of a plate-like element 9, the residual laminar portion 9b of which extends lengthwise in the direction of said maximum dimension "L". Said laminar portion 9b has a length greater than width "L", is elastically movable with respect to the anchoring portion 9a, in the axial plane containing said dimension "L", is inclined to the second stretch 7 of the cavity and is provided with a through hole 10. The through hole 10 can have any shape but preferably it is in the form of a drop the bulging portion of which faces the anchoring portion 9a of the plate-like element.
Preferably, said drop-shaped hole is produced by joining two circular holes of different diameter with each other, which holes are disposed side by side in the longitudinal direction of the plate-like element, the hole of greater diameter constituting the bulging portion of the through hole 10. Due to its larger length as compared with dimension "L", the laminar portion 9b may bend around the junction line with the anchoring portion 9a, away from the second cavity stretch but it cannot reach the position at which its lying plane is perpendicular to the axis x-x of the cavity. This feature restrains the laminar portion 9a from rotating until going beyond such a position, towards the end of stretch 6 opposite to stretch 7.
The second stretch 7 has the outwardly-open end of the connector preferably funnel-like tapered to guide fitting of the plug connector; in the interface plane f-f with the first stretch 6 orthogonal to the axis of said casing, said second stretch has a maximum width "D", in the same direction as said maximum predetermined width "L", preferably smaller than "L".
The distance "H" between said interface and the junction line between the anchoring portion of the plate-like element linked to the wall of the first stretch and the free laminar portion is preferably at least as large as the length of said free laminar portion and more preferably larger than this length.
At said interface, for the reasons to be better clarified in the following, the inner wall of the outlet connector has a relief projecting from the side surface of said first and second stretches radially towards axis x-x-. The position of this relief is preferably close to plate-like element 9, in the axial plane containing said dimension "L"; its width, parallel to the cavity wall, in the plane f-f, preferably does not exceed that of the plate-like element 9.
The stretches 6 and 7 of the just described outlet connector can have any shape, in particular a flattened tubular or elliptic shape; preferably they are of cylindrical shape. In this case obviously, dimensions "L" and "D" coincide with the diameters of the corresponding stretches. Preferably, the axis y-y of the second stretch 7 is parallel to, but not coaxial with the axis x-x of the first stretch 6.
The corresponding plug connector 4 comprises a portion 12 consisting of the end portion of the conductor to be connected with the signal light for example, from which an elongated prismatic coupling portion 13 axially emerges, which coupling portion when it is in a coupled relationship with the corresponding laminar portion of the outlet connector, passes through the through hole 10.
Said elongated prismatic portion comprises a lead-in wire cramped to the end of conductor 12 and having a right section of any convenient shape but preferably of a shape complementary to that of hole 10. The term "complementary" means that the right section of the lead-in wire has a very small play with respect to the right section of the hole so that it can freely run in the hole when the two sections, of the lead-in wire and the hole, lie in substantially parallel planes but the more the lying planes of said sections diverge from each other, the more this sliding is strongly hindered. In a convenient accomplishment of the invention, particularly in connection with a hole having the preferred drop-like shape described above, the lead-in wire 13 preferably has a cylindrical either solid, or alternatively, tubular shape of an outer diameter substantially corresponding to that of the hole portion of greater diameter.
In an alternative embodiment of the invention only shown in Fig. 1, conductor 12 is a coaxial conductor having a central core 14 and a coaxial crown 15 electrically insulated from each other. In turn, the coaxial crown 15 is protected from the outside in a quite known manner by an insulating and mechanically resistant sheath 4a. In this case the surface of the inner wall of the second stretch 7 is made at least partly conductive and is connected (in a manner not illustrated because it can be easily envisaged by a person skilled in the art) to one of the conductors of the signal light so that the terminal of the invention may comprise a single outlet connector with a single laminar portion, i.e. a single plate-like element 9. In use, in fact, the plug connector 12 will have a crown portion 15a of the conductor adjacent to the lead-in wire 13 devoid of the protective coating 4a and therefore electrically connected with said conductive portion of the wall of the second stretch 7.
After the above description, it is now possible to understand the new method of coupling the terminal in accordance with the invention.
In accordance with this method, the plug connector 4 provided with the lead-in wire 13, is inserted (Fig. 1) into the opening of the outlet connector 3 and progressively pushed to the inside along axis y-y of the stretch 7 of the outlet connector cavity.
When the lead-in wire 13 reaches the interface f-f separating the second stretch 7 from the first stretch 6 the relief 11 interferes with the end of the lead-in wire and modifies the advance direction of same inclining it with respect to the axis of the outlet connector, preferably along dimension "L", in a new direction "i". The value of angle "v" between direction "i" and axis y-y is preferably included between 5° and 15°.
Going on in its advance movement in the direction "i", the lead-in wire encounters the laminar portion 9b at hole 10, in particular at the portion of smaller diameter, and bends it towards the opposite end of the connector. Insertion in hole 10 is in fact hindered by the interference between the head of the lead-in wire and the hole edge, in particular due to the angle existing between the advance direction of the lead-in wire and the lying plane of the plate-like element measured from angle "w" between direction "i" and direction "L".
However, said bending of the plate-like element promotes insertion of same because it modifies angle "w" between said directions reducing value of same, and shifts the position of hole 10 bringing the portion of greater diameter close to the head of the lead-in wire; in conclusion the lead-in wire, by effect of a thrust of weak value, passes through the hole (Fig. 2) and stops against the inner wall of stretch 6. The electric conduction is ensured by the slightly forced contact between the side surface of the lead-in wire and that of the hole edge, extension of which depends on the plate-like element thickness.
Preferably, the value of angle "w" ranges between 130° and 155°.
On the contrary, as regards slipping off of the plug connector from the outlet connector, locking of the connectors' coupling is achieved due to the fact that a traction of said plug connector away from said outlet connector extends along a slipping-off direction "s" which has an inclination, in the axis of said outlet connector, different from that of said insertion direction "i".
In other words, each time an accidental or intentional traction is exerted on the plug connector, the lead-in wire 13 moving out of the first stretch 6 bends the plate-like element 9b towards the second stretch 7 modifying value of angle "w" and making it wider. Preferably, the relief 11 is such shaped that it also enables straightening of the lead-in wire 13 which, as a result, will reduce value of angle "v" between the direction "s" (former "i") and axis y-y.
Preferably, the value of angle "v" between the direction "s" and axis y-y is smaller than 5°.
By effect of the angular variation of the lying plane of the plate-like element, the lead-in wire is forced towards the portion of the hole of smaller diameter (Fig. 3) increasing the value of the interference between its side surface and the hole edge. Slipping off of the lead-in wire from the hole is particularly hindered due to friction produced in two diametrically opposite regions A and B of the lead-in wire, along the direction of the longitudinal extension of the plate-like element generating a torque opposing said slipping off.
In normal operation the electric contact between the plate-like element 9 and the coupling portion 13 of the conductor 12 is ensured by the interconnecting forces generated by bending of the plate-like element 9 itself.
The invention has many important advantages.
Coupling between the connectors is of easy execution and needs a thrust of very reduced value that is not tiresome the operator and enables a quick execution of said coupling.
The obtained coupling is very solid and makes slipping off of the coupled connectors substantially impossible; in fact, application of a force tending to separate the connectors gives rise by itself an equal force in the opposite direction counteracting said separation.
In conclusion, the terminal being the object of the invention has a very low cost, lower than that of the known terminals having greater reliability, which however have the above mentioned defects.
In the present specification usually all possible structural and kinematic alternatives to the specifically described embodiments of the invention are possible. However the same are intended also included within the protection scope of the present invention, said alternatives being easily identifiable from the above description of the relation existing between each embodiment and the result that the invention wishes to obtain.

Claims

A low-voltage electric connection terminal, in particular for signal lights, comprising an outlet connector (3), having a laminar portion (9b) provided with a through hole (10), and a plug connector (4) having an elongated prismatic coupling portion (13), to be engaged in said laminar portion (9b), said connectors (3, 4) being adapted to be mutually coupled by fitting along a fitting direction ("i") in a manner suitable to establish the electric contact between said portions (9b, 13), characterized in that said elongated prismatic portion (13) in a coupled relationship with said laminar portion (9b), passes through said through hole (10).
A terminal as claimed in claim 1, characterized in that said laminar portion (9b) is inclined to the axis (x-x) of said outlet connector (3).
A terminal as claimed in claim 1, characterized in that said elongated prismatic portion (13), in a coupled relationship with said laminar portion (9b), is inclined to the axis (x-x) of said outlet connector (3).
A terminal as claimed in claim 1, characterized in that said laminar portion (9b) and elongated prismatic portion (13), in a condition of mutual coupling, are inclined to one another.
A terminal as claimed in claim 1, characterized in that said laminar portion (9b) and elongated prismatic portion (13) are in mutual contact along the perimetric extension of said hole (10).
An outlet connector for low-voltage electric connection terminals, in particular for signal lights, comprising a casing (2) supporting said signal light at one end and provided, at the opposite end, with an axial tubular cavity (5) for insertion of a corresponding plug connector (4), characterized in that said cavity comprises:

a first axially-internal stretch (6) having a predetermined maximum dimension (L) in a plane (p-p) orthogonal to the axis (x-x) of said casing (2);

a second axially-external stretch (7) smaller that said predetermined maximum dimension (L) in a plane (f-f) orthogonal to the axis (x-x) of said casing (2) and in the same direction as said predetermined maximum dimension (L);

a plate-like element (9) having an anchoring portion (9a) anchored to the inner side surface of said first stretch (6), and a laminar portion (9b) longitudinally extending in the direction of said predetermined maximum dimension (L) having a greater length than said maximum dimension (L), elastically movable relative to the anchoring portion (9a) in the axial plane containing said predetermined dimension, inclined to said second stretch (7) of the cavity and provided with a through hole (10).
A connector as claimed in claim 6, characterized in that said through hole (10) has the shape of a drop.
A connector as claimed in claim 6, characterized in that said second stretch (7) is parallel and offset with respect to the axis (x-x) of said casing.
A method of connecting and locking an outlet connector (3) and a plug connector (4) to each other, which connectors (3, 4) are part of a low-voltage electric connection terminal (1), in particular for signal lights, and are adapted to be mutually coupled by fitting of said plug connector (4) into said outlet connector (3) in a predetermined direction, according to which said insertion is carried out along a fitting direction ("i") which is inclined with respect to the axis of said outlet connector.
A method as claimed in claim 9, wherein locking between said outlet connector (3) and plug connector (4), interconnected with each other, is carried out by exerting a traction action on said plug connector (4) away from said outlet connector (3) along a slipping-off direction ("s") the inclination of which, in the axis (x-x) of said outlet connector (3), is different from the inclination of said fitting direction ("i").
A method as claimed in claim 9, wherein the inclination angle ("v"), in the axis (x-x) of said outlet connector (3), of said slipping-off direction ("s") is smaller than the corresponding angle of said fitting direction ("i").