EP1612889B1 - Terminal with leaf spring for reduced insertion force - Google Patents

Abstract

The device has a maintenance unit that maintains spring blades (1, 1`) remote from a conductive surface of a conductive terminal. The maintenance unit consists of an opening that is provided in one of lateral walls (7) of a cover (5). A lug passes from a lateral edge of a free end of the blade, so that the blade (1) is forced to take a position remote from the conductive terminal. An independent claim is also included for a modular electric apparatus including a conductor connecting device.

Description

The present invention relates to a device for connecting a conductor to an electrical terminal, of the type comprising at least one spring blade provided for pressing said conductor, when plugged into the device, against a conductive surface electrically connected to said terminal.

The invention aims to mitigate the driver's plugging efforts in the connection device. The invention also relates to a modular electrical appliance, for example of the type circuit breaker or differential switch, which is provided with such a connection device.

The devices which are particularly targeted by the invention are those which allow the plugging of a part of a fork or tongue bridging type electrical distribution system into a spring blade connection connector (s) ( s) for example a modular electrical device. Said blades must ensure a good electrical contact that does not deteriorate over time, and therefore develop a contact force sufficient to achieve it. However, the driver's insertion force, for example a tab of a bridging bar, is directly related to the contact force developed by the spring. (see the document EP-A-0687033 )

Currently, when it is at rest, the leaf spring of such a connector bears on the conductive surface of the terminal, and the displacement stroke of the spring is therefore equal to the thickness of the tongue which is inserted in the connection device.

By nature, the connection of a power distribution system of the type of bridging bar or tongues requires simultaneous or almost simultaneous insertion of several tongues in the connectors of a row of modular electrical devices arranged side by side. coast on the same standardized rail. This simultaneous insertion involves overcoming the resistance of several spring blades at the same time, which can be problematic because the contact forces that are imparted to each blade spring are far from negligible, and they are exerted at the same time. surplus approximately perpendicular to the insertion forces.

The problem consists in the occurrence of reducing the insertion force without altering the characteristics of the spring, and in particular the contact force that it can develop once the tongue of the bridging bar plugged against the terminal. Until now, when this type of problem arose, the remedy was to grease the plugging area and contact, without altering the connection device itself.

The present invention proposes to implement solutions in which the connection device was designed ab initio to respond to this problem.

Essentially, this device comprises means for maintaining at least one blade spring at a distance from the conductive surface.

This solution consists in fact in prepositioning one or more spring blades of the connection device in a position that can be described as ready for insertion. This prepositioning makes it possible to limit the stroke of the spring during the insertion of the bar, and thus to guarantee a progressivity of the effort. This progressivity gives the installer ease of insertion when implementing this type of device.

According to an alternative embodiment of the device of the invention, as mentioned in claim 1, at least one leaf spring has a lateral lug that can move in a window formed in a wall oriented parallel to the direction of deflection of the blade spring, said window being positioned and dimensioned so that when the pin, under the effect of the elastic forces, abuts against one of its edge, the blade is kept away from the conductive surface.

In fact, at least one of the blades is thus hooked at a distance from the conductive surface, the attachment level corresponding to a predefined passage height of the conductor to be connected which guarantees the reduction of the insertion force. When inserting the tongue of the bridging bar, each spring blade is released from its prepositioning level and can ensure all the contact force. The prepositioning keeps intact the contact force that is developed by the leaf spring.

According to one possibility, the wall in which the window is made is in one piece with a wall in which is produced and from which develops at least one spring blade of the device of the invention.

More precisely still, the wall comprising at least one spring blade is extended by two parallel side walls, at least one of which is provided with said window, these walls defining a volume in which the at least one leaf spring develops at least partially, said sidewalls being integral or integral with the conductive surface.

The connection device is then made without additional component compared to its predecessors. The solution is moreover standardizable, easy to implement, and it finally makes it possible to limit the contact stress at the time of insertion with a calibration margin which depends on the use that will be made subsequently. This calibration, carried out in the manufacturing phase of the device of the invention, makes it possible to adjust the insertion force according to the market requirements or the caliber of the product in which the device of the invention is integrated, for example a device modular type circuit breaker.

It consists in modulating the dimensions of the window according to the distance at which the spring blade is to be positioned relative to the conductive terminal, or not to provide a pin-window connection for all spring blades of the connection device.

Thus, according to one possibility, the device of the invention may comprise two parallel elastic blades leaving a space between them, a single blade having a lug cooperating with a window of the adjacent side wall.

As will be seen in more detail later, it is particularly the type of configuration that is used when two connectors are superimposed, for example a cage device and traditional screw surmounted by a cap incorporating the spring blade or blades. In this case, the space between the elastic blades allows the passage of the screw, whose head must be accessible from the front of the product.

Experience has shown that the plugging of the forked tabs bridging is greatly facilitated even if only one of the elastic blades is provided with the improvement of the invention, the progressivity of the plugging effort is already greatly improved.

According to an alternative to this first configuration, as mentioned in claim 5, the means for holding the blade away from the surface may consist of a crutch made from said blade, by cutting and folding a portion of the blade. ci, the free end of this folded portion bearing on the conductive surface.

This stand provides in fact an additional support that can raise the leaf spring or to put them in a position ready to plug. This support must of course be made outside the passage area of the inserted leaflet.

Preferably, the leg portion forming a crutch is cut and folded at the free end of the leaf spring.

This characteristic is particularly favorable in terms of industrial production, since it facilitates the cutting and folding operations.

This solution, like the previous one, does not require the use of additional components for the invention and it allows the user to overcome the use of grease or oil type products, etc. Depending on the shape or dimensions given to the stand, the calibration of the insertion force is also easy with this solution.

When the leaf spring has two parallel branches, providing a space between them, they are connected by a central stand, which is positioned after folding at the periphery of said space.

In the event that the device of the invention comprises two separate parallel spring blades, each having a crutch and also providing a space between them, the crutch portions are then disposed adjacent and always, after folding, on the periphery of this space.

In both cases, preferably, each stand is oriented substantially perpendicularly to the conductive surface. More preferably, the end of the stands in contact with the conductive surface is bent.

These configurational characteristics aim to optimize the use of this crutch, and to enable it to perform its function under the best conditions.

The means for holding the blade spring away from the conductive surface consist of a calibrated wedge held between the blade and the conductive surface by the elastic force exerted by said blade, said wedge being expelled upon introduction of the driver who hunt in front of him.

This requires the establishment of an intermediate piece housed between the spring blade and the conductive surface and calibrated at the discretion of the user. Its shape It must allow it to ensure the setting of the blade, but also to reduce the friction to determine, in the end, the insertion force that is necessary.

Compared to the previous solutions, this allows a calibration of the plugging force which is adjustable even when the apparatus for containing the connection device has already been manufactured.

It should be noted that in all the variants of the invention, the initial prestress which is imparted to the spring blade (s) maintained (s) at a distance from the conductive surface is controlled, and has no particular effect on the operation. subsequent connection device.

According to one possibility, the wedge profile is provided to give the spring blade an orientation enabling it to facilitate the insertion of the conductor, and it also has a concave front surface designed to receive the free end of the conductor in the course of insertion.

In addition to its main function of keeping the blade spring away from the conductive surface, the wedge therefore has a secondary function that can almost be described as guiding the introduction of conductors.

Preferably, this wedge is symmetrical with respect to a median plane parallel to the conductive surface, in order to optimize its use. In the case of a modular electrical appliance, this temporary removable wedge can also be put in place on the finished product, with packaging.

According to another alternative as mentioned in claim 11, the means for holding the blade away from the conductive surface consist of an extension of the free end of said blade resting near an edge of this surface so that when plugging the conductor, said free end is pushed out of the conductive surface and the blade elastically biased in contact with the conductor.

This is a kind of "guillotine" activated at the end of the race when inserting the tongue of the bridging bar. This variant, which allows to completely clear the plugging area, therefore limits the maximum insertion effort. This solution also makes it possible to optimize the contact force once the bar is plugged in, that is to say when the "guillotine" has been put into action.

According to a possible geometry, the end of the spring blade is for example extended by a loop open towards the conductive surface followed by a rectilinear portion oriented substantially vertically and whose end is in contact with said surface.

As has been mentioned before, the connection device of the invention may be composed of a cap having an upper wall of which develop two twin spring blades curved between two side walls to a flat portion of a conductive terminal parallel to the upper wall and to which are fixed said side walls.

This configuration is particularly suitable when the terminal cooperates with a cage disposed under the cap and with a screw clamping conductors in the cage whose rod passes between the twin spring blades and whose head is disposed above the upper wall of The hairdo.

This superposition is particularly applied to modular electrical devices of the type circuit breaker, differential switch, etc ... which also constitute the invention when equipped.

• la figure 1 est une vue en coupe longitudinale de la première variante de dispositif de connexion selon l'invention ;
• la figure 2 en montre une vue en perspective, avec une des deux lames ressort maintenue à distance de la borne conductrice ;
• la figure 3 est une vue en coupe longitudinale de la seconde variante ;
• la figure 4 représente une vue en perspective d'une coiffe reprenant la solution de la figure 3 ;
• la figure 5 montre une vue en coupe d'un exemple non revendiqué ; et
• la figure 6 est une vue en coupe de la dernière variante proposée.

The invention will now be described in more detail with reference to the appended figures for which:

• Figure 1 is a longitudinal sectional view of the first connection device variant according to the invention;
• Figure 2 shows a perspective view, with one of the two spring blades held away from the conductive terminal;
• Figure 3 is a longitudinal sectional view of the second variant;
• Figure 4 shows a perspective view of a cap showing the solution of Figure 3;
• Figure 5 shows a sectional view of an unclaimed example; and
• Figure 6 is a sectional view of the last proposed variant.

With reference to FIG. 1, the connection device of the invention mainly consists of a spring blade (1) resiliently biased towards the conductive surface of a terminal (2), so as to grip a conductor (no represent). This conductor is plugged in the direction shown by the arrow F. In the particular configuration shown in FIGS. 1 and 2, the connection device in fact overcomes a conventional cage terminal (3) and screw (4), and comprises essential title an upper wall (6) from which develop the leaf spring (1, 1 '), which are curved inwardly of the cap (5) thus formed, which is delimited by side walls (7 and 8) which are fixed on the terminal (2).

There already exist such connection structures comprising a traditional connector with cage and screw and a connector with superposed blades. The curved spring blades are such that their rounded lower portions (20) are in contact with the upper surface of the conductive terminal (2). The contribution of the invention lies at this level, since said spring blades (1, 1 ') undergo a additional prestressing to keep them away from said conductive terminal (2). In the version of the invention illustrated in FIGS. 1 and 2, the remote holding means consist on the one hand of an opening (9) made in one of the side walls (7) of the cap (5), opening (9) in which is housed a lug (10) protruding from a side edge of the free end of the leaf spring (1) (see Figure 2).

The leaf spring (1) is forced to take the position shown in Figure 1, away from the terminal (2). This configuration substantially decreases the effort of plugging the external conductor, in this case for example a fork of a bridge bar.

The configuration shown in Figures 3 and 4 is for the same purpose. In this case, the side walls (7, 8) of the cap (5) are not used. In this case, the free ends of each leaf spring (1, 1 ') are connected by a stand (11) obtained by cutting and folding a central section.

The central section is partially disengaged from the branches (1, 1 ') by longitudinal cuts over almost all of its length common with said branches (1, 1'). The central portion is then folded so as to make it on the one hand substantially perpendicular to the conductive surface of the terminal (2), and to curl on the other hand its end so that it rests on a rounded.

It should be noted that, in the configuration shown in FIGS. 3 and 4, the stand does not interfere, after folding, with the space in which the screw shank (4) must be inserted (not shown). . The distance between the conductive surface of the terminal (2) and the curved lower portion (20) of the leaf spring (1, 1 ') is substantially identical to that maintained in the configuration shown in Figures 1 and 2.

This distance is easy to vary, by changing the position of the lower curvature of the stand (11), or by lengthening the latter, etc. The same goes for the solution of FIGS. 1 and 2, in which the height of the window determines in fact the residual space maintained between the blade (1) and the conductive terminal (2).

It is also possible to cut the central stand (11) into two adjacent crutches. In this case, each blade spring (1, 1 ') has, on a portion at its free end, a width that allows it to be immediately adjacent to the other leaf spring (1', 1).

The two crutches (11, 11 ') resulting from this double operation are also located in the center of the cap, and do not interfere with the central passage space of the screw.

Figure 5 differs from the previous two in that it comprises a member (12) removable, a shim (12) which is inserted temporarily between the leaf spring (1) and the terminal (2). This wedge (12) is intended to be pushed by the end of the conductor (c) as it appears on the right of the figure. Thus, the wedge has a slightly rounded front surface (13) so as to "guide" the end of the conductor (c).

The shape of this wedge is symmetrical, so that it can be introduced, concave surface (13) obviously facing outwardly of the connecting device, in two different directions. In order for the wedge (12) to be wedged effectively, it comprises in particular two other concave curved surfaces, on its upper and lower lateral faces, which enable it to receive the lower surface (20) curved with the spring blade (1).

When the end of the conductor reaches the level of the surface (13), the user has not yet encountered any resistance, because the space between the rest of the leaf spring (1) and the conductive terminal (2) is at this point of dimension greater than the width or the diameter of the conductor. The end of the conductor (c) gradually pushes the shim (12) until the force of the blade is applied to the conductor: the shim (12) is then released, and can be housed in a housing provided for this effect, for example connected to the subassembly terminal / leaf spring, which ensures its position after plugging the driver.

The version shown in Figure 6 uses a principle similar to the solution of Figure 5, but without additional component, that is to say without wedge. Maintaining the curved lower surface (20) of the leaf spring (1) away from the conductive terminal (2) is here formed by an end section (13) of said blade (1), oriented substantially vertically so its free end is in contact with said terminal (2) for a distance between the latter and the curved lower surface (20) allowing the passage of the conductor (c). The section (13), rectilinear and substantially vertically oriented, is further disposed near a edge bordering the conductive terminal (2), as shown in solid lines. When the free end of the driver pushes this vertical portion (13), at the moment when the user proceeds to the plugging of said conductor (c), this portion is quickly found without support and is, because of the prestressing of the blade spring (1), pushed back down. The spring blade (1) then takes the form which appears in dashed line. In this case, the lower surface (20) curved of said blade (1) comes into contact with the driver (c) that it traps.

Claims (15)

1. Device for connecting a conductor to an electrical terminal (5), of the type including at least one leaf spring (6) which is provided to flatten the said conductor, when it is plugged into the device, against a conducting surface (2) which is connected electrically to the said terminal, and including means for keeping at least one leaf spring at a distance from the conducting surface, characterized in that at least one leaf spring (6) includes a lateral pin which can move in a window (9) which is made in a wall which is oriented parallel to the direction of deflection of the leaf spring, the said window (9) being positioned and dimensioned so that when the pin, by the effect of elastic stresses, is stopped against one of its edges, the leaf spring (6) is kept at a distance from the conducting surface (2).
2. Connecting device according to the preceding claim, characterized in that the wall in which the window is made is in one piece with a wall in which at least one leaf spring is implemented, and from which said leaf spring develops.
3. Connecting device according to the preceding claim, characterized in that the wall which includes at least one leaf spring is extended by two parallel lateral walls, at least one of which is equipped with the said window, these walls defining a volume in which the leaf spring(s) develop(s) at least partially, the said lateral walls being integral or in one piece with the conducting surface.
4. Connecting device according to the preceding claim, characterized in that it includes two parallel elastic leaves which make a space between them, only one leaf including a pin which co-operates with the window of the adjacent lateral wall.
5. Device for connecting a conductor to an electrical terminal (5), of the type including at least one leaf spring (6) which is provided to flatten the said conductor, when it is plugged into the device, against a conducting surface (2) which is connected electrically to the said terminal, and including means for keeping at least one leaf spring at a distance from the conducting surface, characterized in that the means of keeping the leaf spring (6) at a distance from the conducting surface (2) consists of a prop (11) which is implemented from the said leaf, by cutting and folding a portion of it, the free extremity of this folded portion being supported on the conducting surface.
6. Connecting device according to the preceding claim, characterized in that the portion of leaf forming the prop is cut and folded at the level of the free extremity of the leaf spring.
7. Connecting device according to the preceding claim, characterized in that the leaf spring includes two parallel branches which make a space between them, and connected by a central prop which, after folding, is located on the periphery of the said space.
8. Connecting device according to Claim 6, characterized in that it includes two parallel elastic leaves which are each equipped with a prop and which make a space between them, the props being arranged adjacently and, after folding, being located on the periphery of the said space.
9. Connecting device according to one of Claims 6 to 8, characterized in that each prop is oriented essentially perpendicularly to the conducting surface.
10. Connecting device according to one of Claims 6 to 9, characterized in that the free extremity of each prop at the contact with the conducting surface is curved.
11. Device for connecting a conductor (C) to an electrical terminal (5), of the type including at least one leaf spring (6) which is provided to flatten the said conductor (C), when it is plugged into the device, against a conducting surface (2) which is connected electrically to the said terminal, and including means for keeping at least one leaf spring at a distance from the conducting surface, characterized in that the means of keeping the leaf spring at a distance from the conducting surface consist of an extension of the free extremity (13) of the said leaf spring (6) resting near an edge of this surface (14), so that when the conductor is plugged in, the said free extremity (13) is pushed back out of the conducting surface (2), and the leaf is stressed elastically at the contact of the conductor (C).
12. Connecting device according to the preceding claim, characterized in that the extremity of the leaf spring is extended by an open loop towards the conducting surface, followed by a rectilinear portion which is oriented essentially vertically, and the end of which is at the contact of the said surface.
13. Connecting device according to one of the preceding claims, characterized in that it consists of a cap which includes an upper wall, from which two twin curved leaf springs develop between two lateral walls towards a plane portion of a conducting terminal which is parallel to the upper wall, and to which the said lateral walls are fixed.
14. Connecting device according to the preceding claim, characterized in that the terminal co-operates with a cage.
15. Modular electrical device of circuit breaker or differential switch type, characterized in that it is equipped with a connecting device according to Claim 13 or 14.

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