EP0148056B1 - Universal clamp that cannot be lost for the realisation of electrical clamping connections between two conducting elements - Google Patents

Abstract

A loss proof general purpose terminal for forming electric connections by clamping between two conducting elements, comprising a connection area disposed at the bottom of a recess formed in an insulating material body and having a central tapped bore, a clamping screw for screwing into said bore and a stirrup portion mounted so as not to be lost under the head of the screw. It further comprises, guided inside the recess a stirrup-plate having a threaded bore through which said screw is screwed. This stirrup-plate comprises two diametrically opposite lateral projections extending at right angles and whose ends are bent back inwardly and extend partially into the passage zone of said stirrup portion.

Description

The present invention relates to a universal captive terminal intended to make electrical connections by clamping between two conductive elements such as, for example, an electrical wire and a connection pad of an electrical appliance.

In general, it is known that according to the current state of the art, there are at least two main types of terminals used to make such connections.

The first type of terminals, generally called clamp terminals, does not require any special preparation of the end of the electric wire where the connection must be made, if not a simple stripping, in the case where the electric wire is found covered with an insulation sheath. According to this first type of terminal, the connection area is located at the bottom of a cell made in an insulating body and constituting a guide cage, and has a tapped hole (or even a smooth hole to the right of which is arranged a nut), into which is screwed a clamping screw fitted with a bracket. Usually, this stirrup, of width substantially equal to that of the cell, is mounted captively under the head of the screw (between head and thread). Thus, to make a connection with an electric wire, the screw is unscrewed and then the end of the wire, if bare, is introduced into the free space between the connection pad and the bracket. The screw is then screwed until the end of the wire is properly compressed between the stirrup and the connection plate. To prevent the assembly formed by the screw and its stirrup from being lost, the cell comprises, preferably at the opening through which the screwing is practiced, a narrowing, either made in one piece or constituted by an element reported such as a hood.

Thus, at the end of the unscrewing of the screw, the stirrup stops against the narrowing of the cell and is blocked, so that it cannot get lost.

The second type of terminal, generally called cage terminals, involves a clamping cage open at least at one of its ends to allow the passage of the terminal or possibly the end of a wire and a face provided with '' a threaded hole into which a screw is screwed. As previously, this cage is mounted inside a cell made in a body of insulating material. To ensure the captivity of the screw, this cell has, at the opening through which the screwing takes place, a narrowing in which abuts, at the end of unscrewing, the. screw head.

It is noted that these two types of terminals are not suitable for the connection of wires fitted with closed lugs, the use of which is imposed by certain regulations and which have a hole through which the clamping screw must pass.

Indeed, in the case of a clamp terminal, it would be necessary, to mount the terminal, to remove the screw-clamp assembly beforehand, which is incompatible with the imperdability of this assembly.

Furthermore, the drawback of cage terminals comes from the fact that due to the stresses exerted during the tightening of the screw, the cage must necessarily have relatively thick walls. Consequently, the width of the internal volume of the terminal and therefore the width of the terminal used will be much less than the width of the cell, which is usually imposed for reasons of space, in particular in the case where several identical terminals are juxtaposed. It is clear that the use of closed terminals in such terminals would be contrary to the spirit of the regulations which impose the use of closed terminals, because in the event of incorrect tightening, there is no maintenance of the connection.

Furthermore, from patent DE 1 225 727 there is also known a terminal comprising a connection pad disposed at the bottom of a cell formed in a body of insulating material and having a central bore associated with first screwing means, a screw clamp intended to pass through the bore and to be screwed into the first screwing means, a stirrup through which said screw passes and a movable assembly comprising a stirrup plate equipped with second screwing means into which the screw is screwed and retaining means provided with at least one part forming a stop for said stirrup.

However, this solution has the same drawbacks as those previously mentioned with regard to the clamp terminals. The invention therefore aims to eliminate these drawbacks. It more particularly relates to a universal connection terminal which can receive all kinds of conductors, both electric wires without special preparation, as wires equipped with open or closed terminals of maximum width, this terminal being furthermore equipped with means ensuring the of its components.

• l'étrier est monté, de façon imperdable, sous la tête de la vis,
• l'ensemble mobile est guidé à l'intérieur de l'alvéole,
• les seconds moyens de vissage consistent en un perçage taraudé formé dans la plaquette-étrier,
• les moyens de retenue s'étendent du côté de la plaquette-étrier opposé à ladite plage de raccordement et sont agencés de manière à ce qu'à l'issue du dévissage de la vis de la plage de raccordement, l'étrier vienne porter sur les moyens de retenue et assure en combinaison avec le guidage de l'ensemble mobile à l'intérieur de l'alvéole, un maintien de la vis dans l'axe du perçage de la plage de raccordement quelle que soit la position dudit ensemble mobile à l'intérieur de l'alvéole.

To achieve these results, the terminal according to the invention firstly comprises, in a manner analogous to that described in patent DE A 1 225 727, a connection pad disposed at the bottom of a cell formed in a body. in insulating material, and having a central bore associated with first screwing means, a clamping screw intended to pass through said bore and to be screwed into the first screwing means, a stirrup through which said screw passes, and a mobile assembly comprising a stirrup plate fitted with second screwing means into which the screw is screwed and retaining means provided with at least one part forming a stop for said stirrup. This terminal is more particularly characterized in that:

• the stirrup is mounted, captively, under the head of the screw,
• the mobile assembly is guided inside the cell,
• the second screwing means consist of a tapped hole formed in the stirrup plate,
• the retaining means extend from the side of the stirrup plate opposite said connection pad and are arranged so that, after unscrewing the screw of the connection pad, the stirrup comes to bear on the retaining means and ensures, in combination with the guidance of the mobile assembly inside the cell, that the screw is held in the axis of the bore of the connection pad regardless of the position of said mobile assembly at inside the cell.

In this last position, the screw which is still screwed by its end into the threaded bore of the caliper plate can no longer be released due to the stop which prevents any further unscrewing.

Furthermore, the aforesaid cell comprises a narrowed opening so as to prevent the mobile assembly, formed by the screw, the stirrup, the stirrup plate and the retaining means, from escaping.

The terminal previously described presents multiple possibilities of use. It is suitable for the connection of closed lugs which, in the unscrewed position of the screw, can engage between the connection pad and the stirrup plate, then be tightened by screwing the screw, the latter then passing through the piercing the terminal. It can also receive, in a similar way, one or more electric wires without any particular preparation.

According to another mode of use, the electrical wires can be introduced between the stirrup and the stirrup plate, then be clamped between these two parts. This solution facilitates the introduction of the wires thanks to the mobility inside the cell of the assembly formed by the screw, the stirrup and the stirrup plate in the closed position of the screw.

The retaining means associated with the stirrup plate can be very varied.

They may for example consist of at least one lateral extension of the stirrup plate, which rises substantially at right angles and comprises at its end a return extending in the passage volume of the stirrup and / or of the head of the screw, so as to limit its axial travel at the end of unscrewing when the screw is released from the threads of the connection pad.

According to an advantageous embodiment of the invention, the stirrup plate comprises two diametrically opposite lateral extensions and therefore has a U-shape whose two ends are folded inwards and extend partially in the passage area of the stirrup and / or the head of the screw.

• Les figures 1 et 2 représentent, en perspective, l'extrémité de deux fils électriques, à savoir, un fil électrique simplement dénudé (figure 1) et un fil équipé d'une cosse fermée (figure 2) ;
• Les figures 3 et 4 représentent, en vue de côté (figure 3) et en vue de dessus (figure 4), les éléments constitutifs d'une borne universelle imperdable selon l'invention ;
• La figure 5 est une vue en perspective des éléments représentés figures 3 et 4 logés à l'intérieur d'un alvéole ;
• Les figures 6 à 9 sont des coupes schématiques d'une borne du type de celle représentée figures 3 à 5, permettant d'illustrer le principe de fonctionnement de cette borne, notamment dans son application à la connexion d'une cosse fermée ;
• La figure 10 est une vue de côté de l'ensemble représenté figures 3 et 4, cette vue permettant d'illustrer un autre type d'application de la borne ;
• Les figures 11, 12 et 13 représentent, en perspective, trois variantes d'exécution des moyens de retenue utilisables dans une borne selon l'invention.

Embodiments of the invention will be described below, by way of nonlimiting examples, with reference to the appended drawings in which:

• Figures 1 and 2 show, in perspective, the end of two electric wires, namely, a simply stripped electric wire (Figure 1) and a wire equipped with a closed terminal (Figure 2);
• Figures 3 and 4 show, in side view (Figure 3) and in top view (Figure 4), the components of a captive universal terminal according to the invention;
• Figure 5 is a perspective view of the elements shown in Figures 3 and 4 housed inside a cell;
• Figures 6 to 9 are schematic sections of a terminal of the type shown in Figures 3 to 5, to illustrate the operating principle of this terminal, especially in its application to the connection of a closed terminal;
• Figure 10 is a side view of the assembly shown in Figures 3 and 4, this view to illustrate another type of application of the terminal;
• Figures 11, 12 and 13 show, in perspective, three alternative embodiments of the retaining means usable in a terminal according to the invention.

As previously mentioned, the terminal according to the invention applies to the connection of conductive elements of various shapes and types. Among these, it has simply been shown, in FIGS. 1 and 2, that the conductors which are most useful for understanding the operation of the terminal and the advantages which it provides.

Thus, Figure 1 shows an electric wire 1 with stranded conductors 2 wrapped in an electrically insulating sheath 3 and the end of which has been stripped for connection. FIG. 2 represents an electric wire 4 of a type similar to the previous one, but equipped with a closed terminal 5 comprising a flat connection pane 6 of substantially rectangular shape provided with a central bore 7 and a fixing collar 8 by clamping on the stripped part of the electric wire 4.

As shown in FIGS. 3 to 5, the connection terminal firstly comprises a connection pad 9, of rectangular shape, which is fixed for example by force engagement or by any other means in the bottom of a cell. 10 practiced in a body 11 of insulating material. This connection pad 9, connected to the electrical circuit of an appliance, comprises a central threaded hole 12 into which the clamping screw 13 of the terminal can be screwed. As previously mentioned, this central bore 12 could be smooth and arranged in line with a tapped hole provided in the body 11 or produced by a nut secured to the body 11. In both cases, the length of the tapping must be sufficient for the number of threads in engagement allows effective tightening of connections.

Furthermore, the clamping screw 13 is equipped with an elastic stirrup 14 and of curved shape, mounted captively under the head 15 of the screw 13 (between head 15 and thread 16).

This screw 13 is also screwed before its engagement in the connection area 9 in the threaded bore 18 of a stirrup plate 19 of rectangular shape, made of a thin and slightly elastic sheet.

In the example shown, the means for retaining the assembly constituted by the screw 13 and the stirrup 14 consist of two tongues 20, 21 extending, at right angles, the stirrup plate 19 in two diametrically opposite locations, adjacent to two opposite angles of said stirrup plate 19. These two tabs 20, 21 comprise at their end, at a determined distance from the stirrup plate 19, a part 22, 23 folded at right angles which extends in the direction of the screw 13, as far as the passage volume of the stirrup 14. The ends of these two tongues 22, 23 are cut in a circle 24 coaxial with the threaded bore 18 and which has a radius slightly greater than that of the head 15 of the screw 13.

The cell 10 further comprises, at its opening, a narrowing formed as a whole or constituted by an attached element such as a terminal cover cap 26. This narrowing makes it possible to maintain the assembly formed by the screw 13, the stirrup 14, the plate 19 and the tongues 20, 21 inside the cell 10 while allowing it a predetermined axial play j.

Figures 6 to 9 illustrate the operation of the terminal previously described. Thus, in the example shown in Figure 6, the screw in the released position is released from the thread 12 of the connection pad 9, but is however engaged in the caliper plate 19. In this position, the caliper 14 comes in abutment against the folded parts at right angles 22, 23 of the tongues 20, 21, so that the screw 13 is immobilized. To achieve this result, the height of the thread of the screw 13 must be substantially equal to the distance separating the stirrup plate 19 from the folded parts at right angles 22, 23.

In this position, the terminal is in the loose state, a state in which it is possible to engage the conductors either in the interval between the stirrup plate 19 and the stirrup 14 or in the interval between the caliper plate 19 and the connection pad 9. Thus, an appreciable advantage of the invention consists in that it is possible to deliver the terminals in this loose state, so as to avoid the user an additional operation. Indeed, until now, to avoid losing the screws, the terminals were always delivered in the tightened state.

FIG. 7 illustrates the clearance j which the assembly formed by the screw 13, the stirrup 14, the stirrup plate 19 and the tongues 20, 21 possesses, when the terminal is in the loose state.

Thanks to this play, it is possible to engage, between the stirrup plate 19 disposed in the raised position and the connection pad 9, one or more closed lugs 6, as shown in FIG. 8, a capacity of two can be advantageously provided. pods inserted head to tail. Likewise, the introduction of electrical wires between the stirrup 14 and the stirrup plate 19 as illustrated in FIG. 10 is considerably facilitated. Note that the width of the closed terminal 6 used in Figure 8 is substantially equal to the width of the cell 10, unlike a conventional cage mounting, the thickness of the cage not involved.

Once the lug (s) 6 are engaged, the thrust necessarily exerted during screwing on the head of the screw by the screwdriver, plate, via the stirrup plate 19, the lug (s) 6 on the connection pad 9 to reach the position shown in FIG. 8. Next, the screw 13 is screwed, screwing during which the screw 13 passes through the bore 7 of the terminal 6 and is screwed into the threaded bore 12 of the connection pad 9. Note that this screwing takes place without difficulty because the screw 13 which is guided by the stirrup plate 19, is rigorously in the axis of the threaded bore 12 of the connection pad 9. During all the screwing, the relative distance between plate 19 and track 9 remains constant and equal to the thickness of the terminals 6. At the end of screwing, the caliper plate 19 emerges from the thread (under-head part 15 of the screw 13) and the tightening is provided between the connection pad 9 and the captive clip 14, the plate ette-caliper 19 playing only a role of force distribution washer (position shown in Figure 9). When unscrewing, the elasticity of the caliper plate 19 and of the caliper 14 exerts on the screw 13 a tensile force allowing the threading of the caliper plate 19 to be re-engaged on the wash thread 13. To achieve this result , it is necessary to ensure that the useful height h of clearance under the head of the threads of the screw 13 is hardly greater than the thickness of the stirrup plate 19.

The use of the terminal described above for tightening wires without preparation is obvious, as shown in FIG. 10. As previously mentioned, the introduction of the ends of the wires 30, 31 between the stirrup 14 and the stirrup plate 19 is facilitated, on the one hand, due to the fact that the screw is originally in the released position and, on the other hand, due to the play of the mobile assembly 13, 14, 19, 20, 21 , 22, 23 in the socket 10. Here again, the preparatory effort for screwing presses the stirrup plate 19 on the connection pad 9. At the end of the screwing, the tightening reaction between the stirrup 14 and the pad connection 9 only causes the sets of threads to be taken up between the caliper plate 19 and the screw 13.

Of course, the invention is not limited to the embodiments previously described. It will be noted in particular that the retaining means associated with the stirrup plate can have different shapes.

They may consist, for example, as shown in FIG. 11, in a single lateral tab 33, extending, at right angles, the stirrup plate 19 and provided with a return 34 extending in the passage volume of the stirrup . In the example shown in this figure, the tongue 33 is adjacent to an angle of the stirrup plate 19. It is clear however that this tongue could just as easily extend from a central zone on one side of the stirrup plate.

In the example shown in FIG. 12, the retaining means comprise two tongues 35, 36 each provided with a return 37, 38 extending in the passage volume of the stirrup 14. These two tongues 35, 36 are perpendicular to the stirrup plate 19 and are respectively adjoining two central zones on two opposite sides of said stirrup plate 19. In this example, the stirrup 14 comprises, projecting from its upper face, two pairs of bosses 40, 41 , 42, 43 ensuring its lateral retention when it is in abutment on the returns 37, 38 of the tongues 35, 36.

The retaining means may further comprise, as shown in FIG. 13, two diametrically opposed tongues 44, 45, adjacent to two opposite angles of the stirrup plate 19 and perpendicular thereto, the ends of which have two returns 46, 47, for example obtained by cutting, which extend in the plane of the tongues 44, 45, parallel to the stirrup plate 19. In this case, the captive stirrup 14 has a rectangular shape of width substantially equal to the distance separating the outer faces of the two tongues 44, 45 and is provided with two diametrically opposite rectangular cutouts 48, 49 for the passage of said tongues 44, 45. This arrangement makes it possible at the same time to guide the stirrup 14 along the tongues 44, 45.

Claims (7)

1. A loss proof general purpose terminal for formning electric connections by clamping between two conducting elements, this terminal comprising a connection area (9) disposed at the bottom of a recess (10) formed in an insulating material body, and having a central bore (12) associated with first screwing means, a clamping screw (13) intended to pass through said bore (12) and to be screwed into said first screwing means, a stirrup portion (14) through which passes said screw (13) and a mobile assembly comprising a stirrup-plate (19) equipped with second screwing means into which screw (13) is screwed and retention means comprising at least one portion (22, 23) forming an abutment for said stirrup portion (14), characterized in that :

the stirrup portion (14) is mounted so that it cannot be lost, under the head (15) of said screw (13),

the mobile assembly is guided inside said recess (10),

the second screwing means consist of a tapped bore (18) formed in said stirrup-plate (19),

the retention means extend on the side of the stirrup-plate (19) which is opposite said connection area (9) and are arranged so that, when the screw (13) is screwed out of the connection area (9), the stirrup portion (14) bears on the retention means and, while also guiding the mobile assembly inside said recess (10), maintains the screw (13) in the axis of the.bore (12) of the connection area (9) whatever the position of said mobile assembly inside said recess (10).

2. The terminal as claimed in claim 1, characterized in that said recess (10) comprises a narrowed opening for preventing the mobile assembly formed by said screw (13), said stirrup-plate (19) and said retention means from escaping.

3. The loss proof terminal as claimed in claim 1, characterized in that said clamping screw (13) has a clearance height between head and screw thread in which, at the end of screwing up, the stirrup-plate (19) frees itself from the threads of said screw (13) and said stirrup-plate (19) has a resilience so that at the beginning of screwing out, this resilience exerts on said screw (13) a traction force for reengaging the internal thread of the stirrup-plate (19) on the thread of said screw (13).

4. The terminal as claimed in one of the preceding claims, characterized in that the useful under- head clearance height h of the threads of the screw (13) is slightly greater than the thickness of said stirrup-plate (19).

5. The terminal as claimed in one of the preceding claims, characterized in that said retention means associated with said stirrup-plate (19), consist of at least one lateral projection (20, 21) from said stirrup-plate (19) which extends substantially at right angles and comprises at its end, a bent back portion (22, 23) extending into the passage volume of said stirrup portion (14), so as to limit its axial travel, at the end of screwing out, when said screw (13) is freed from the threads of the connection area (9).

6. The terminal as claimed in one of the preceding claims, characterized in that said stirrup-plate (19) comprises two diametrically opposed lateral projections (20, 21) extending at right angles so as to form a U shape whose two ends are bent back inwardly and extend partially into the passage zone of said stirrup portion (14).

7. The terminal as claimed in one of claims 1 to 5, characterized in that said stirrup-plate (19) comprises two diametrically opposite tongues (44, 45) extending perpendicularly to said stirrup-plate (19) and whose ends comprise two bent portions (46, 47) extending into the plane of the tongues (44, 45) parallel to said stirrup-plate (19) and said stirrup portion (14) has two corresponding diametrically opposite cut outs for allowing said tongues (44, 45) to pass therethrough.

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