EP0488896B1 - Double insulated electrical plug - Google Patents

Description

The present invention relates to an electrical plug for connecting two elements of an electrical cable with two pins each having a connection means, said pins being fitted in two housings provided in an insulating insert, and said plug being electrically insulated by an external overmolding.

The invention finds a particularly advantageous application in the general field of connectors, and in particular in that of bipolar and bipolar + earth plugs when a high degree of insulation is sought.

An electrical plug conforming to the preamble in which the insulating insert is a substantially flat piece of plastic is known from the prior art. The pins are fitted into housings, essentially constituted by the thickness of the insert, and the stripped strands of the elements of the cable are crimped, for example, into barrels for connecting the pins to the outlet of said barrels on the face of the insert intended to receive the isolation overmolding. This same face is provided with hook-shaped retaining means in which the elements are arranged so as to offer a tensile strength when the cable is pulled abruptly.

However, this type of known electrical plug has the disadvantage of an insufficient electrical insulation with respect in particular to flying strands which could escape from the connection drums and thus come into contact with the overmolding and even be flush with it. particularly long flying strands, which is not acceptable for safety reasons.

To resolve this drawback, German patent application DE-A-3 807 309 proposes to provide the electrical plug of the preamble with an intermediate insulating shell covering the insert and intended to receive said external overmolding. Thus, the insulating shell, placed intermediate between the insert and the overmolding, prevents any flying strand, whatever its length, from coming into contact with the overmolding. On the other hand, because of the enveloping nature of the shell on the insulating insert, very long flying strands cannot, at worst, leave the plug only through the front part of the plug, i.e. on the side of the pins, a location which is not accessible when the electrical plug is connected.

It should be noted that in the electrical plug described above, the placement of the shell on the insert requires that one end of the cable be introduced through a hole in the shell, which can only be done manually. , excluding any possibility of automatic assembly of the assembly.

Document DE-B-1 020 078 teaches an electrical plug which includes a shell intended to be placed on an insert carrying the pins connected to the cable. This shell has two lateral openings which, when the shell is positioned on the insert, allows the flying strands to exit so that they can then come into contact with the overmolding and present a danger when the plug is connected.

In addition, according to this document, the lateral openings of the shell, for introduction onto the electric cable, are closed in the upper part. The shell is therefore placed on the insert in a single vertical movement, the upper wall of the lateral openings coming to bear on the cable so that it bends to pass through it.

Also, the technical problem to be solved by the object of the present invention is to produce an electrical plug for connecting two elements of an electrical cable with two pins each having a connection means, said pins being fitted in two housings arranged in a insulating insert, and said plug comprising an intermediate insulating shell covering said insert and intended to receive an external overmolding of insulation, electrical plug which would allow very easy mechanization of the assembly of all the parts constituting it, and in particular which would allow the automatic installation of the insulating shell on the insert, without exerting any constraint on the cable, in particular without bending it.

The solution to the technical problem posed consists, according to the present invention, in that said shell comprises means for lateral introduction of the shell onto said cable constituted by a lateral groove open at its two ends so as to allow the establishment of the insulating shell on the insert in a lateral movement and then bring it in a vertical movement on said insert.

Thus, it is possible to set up the insulating shell by a simple lateral feed movement, instead of having to introduce it beforehand on the cable through a through hole.

Advantageously, said lateral groove provides walls forming means for immobilizing the elements of the cable in the electrical plug.

In this way, the lateral groove performs a double function, that of passing the cable through the shell and that of retaining the elements of the cable.

It is also expected that said insulating shell includes lateral ribs for stiffening said overmolding. Compared to the known plug in which said ribs are made with the insert, this advantageous arrangement reduces the cost of the electrical plug object of the invention since the material constituting the shell, polypropylene for example, can be significantly cheaper (about 3 times) than that constituting the insulating insert (polyamide for example) .

The description which follows with reference to the appended drawings, given by way of nonlimiting examples, will make it clear what the invention consists of and how it can be implemented.

Figure 1 is a perspective view of an insert and a shell of a bipolar electrical plug according to the invention.

FIG. 2 is a perspective view, in the direction of arrow F1, of the shell of FIG. 1.

FIG. 3 is a perspective view of the assembly formed by the insert and the shell of FIG. 1.

Figure 4 is a perspective view of the electrical plug of Figure 1 after overmolding.

Figure 5 is a sectional view of the insert of a bipolar electrical plug + earth according to the invention.

Figure 6 is a bottom view of the plug of Figure 5.

Figure 7 is a sectional view along line II-II of the sheet of Figure 5.

FIG. 1 shows, in perspective, an electrical plug of the bipolar type for connecting two elements 101, 102, the neutral and the phase for example of an electric cable 100, with two pins 201, 202 each having a connection means which, in the embodiment of Figure 1, is, without limitation, a barrel 211, 212 of connection intended to receive strands 111, 112 stripped of the element 101, 102 corresponding. The fixing of said strands 111, 112 in the drums 211, 212, of connection is obtained, in the case of FIG. 1, by crimping through the slots 311, 312.

The pins 201, 202, which can be made of brass, are fitted by ultrasound, overmolding, or any other means, into two housings 301, 302 arranged in an insulating insert 300 made of molded polyamide for example.

As shown in FIG. 1, the electrical plug comprises an insulating shell 400 intended to cover said insert 300 and to receive an overmolding 500, shown in FIG. 4, which makes it possible to ensure the external insulation of said plug. The shell 400, thus placed in the intermediate position between the insert 300 and the isolation overmolding 500, provides maximum electrical insulation of the plug, in particular against the flying strands which could escape from the connection drums 211, 212. As can be seen in Figure 3, the enveloping nature of the shell 400 has the advantage of forcing particularly long flying strands out of the plug on the side of the pins, in a place where, given overmolding, they do not present any danger when the plug is connected.

On the other hand, as can be seen in FIGS. 1, 2 and 3, the insulating shell 400 has lateral ribs 401, 402 for stiffening the isolation overmolding, which makes it possible to reduce the cost price of the plug. , the material constituting the shell, polypropylene for example, being in fact less expensive than the polyamide of the insert in which said stiffening ribs are usually made.

Figure 1 also shows that the insulating insert 300 has a recess 320 limited by two side partitions 331, 332 and inside which are housed the elements 101, 102 of the cable 100 in their part between the cable and the drums. connection. Furthermore, the insulating shell 400 has walls 421, 422 which bear against said lateral partitions 331, 332 when the shell is placed on the insert. Thus, the walls 421, 422, acting as immobilization means, form with the recess 320 retaining means in baffle with respect to the elements 101, 102. This baffle system makes it possible to completely preserve the connections ensuring the immobilization of the elements during a brutal pull of the cable.

It can be noted in FIGS. 1 and 2 that the shell 400 comprises means for lateral introduction of said shell onto said cable 100. In the example shown, said lateral introduction means consist of a lateral groove formed by the two walls 421, 422 and one third wall 423. The shell can then be put in place very easily, it suffices for this to present it on the cable in a lateral movement illustrated by the arrow F1 in FIG. 1, then to bring it, according to arrow F2, on insert 300 to its final position.

Thus, using two very simple movements, it is possible at the same time to place the shell on the insert, to pass the cable through the shell and to immobilize the elements of the cable. This results in very easy automation of the assembly of the electrical plug.

It should be noted that the lateral groove provides both the means for introducing the shell onto the cable and the walls of the immobilization means.

After having been put in place on the insert 300, the insulating shell 400 is held in place using fixing means which are constituted by two fixing lugs 330 arranged on either side of the insert 300, one of said pins cooperating with a slot 410 which, as shown in Figure 2, is arranged in said shell on the wall 423 of the lateral groove. The introduction of said lug into the slot 410 is carried out by elastic deformation of the shell, the latter resuming its initial shape when the lug 330 is engaged in said slot. The presence of two pins, only one of which is actually used, makes it possible to introduce the shell onto the insert in any direction, thereby increasing the ease of assembly of the plug.

Figures 5 and 6 show an alternative embodiment of the electrical plug described above with reference to Figures 1 to 4, for the connection of a cable 100 comprising, in addition to the phase and the neutral 101, 102, an element 103 for setting To the earth. In accordance with FIG. 5, the insulating insert 300 also comprises a third housing 303 in which is disposed a means 350 of electrical contact in the form of a barrel, opening to the outside of the insert by a fixing means 360, a rivet for example, to a ground rail 600. The strand 113 of the grounding element 103 is crimped into the barrel 350, through a light (not shown), equivalent to the lights 311, 312 of FIG. 1. It is understood that, in the case of FIG. 5, the insert 300 includes two separate recesses 321, 322 intended to house the elements 101 and 102 respectively.

The bottom view, shown in Figure 6, shows the arrangement of the earth rail 600 with respect to the insert 300 and the overmolding 500 when the electrical plug is completely assembled.

According to an advantageous characteristic of the invention, it is provided that the three elements 101, 102, 103, phase, neutral and earthed, have an identical length so that during assembly, due to the sliding of the hull on the insert and blocking of the phase and neutral elements by said baffles, the grounding element 103 has an extra length, or soft strand, of safety, as illustrated in FIG. 7. A brutal pull on the cable 100 induces the rupture of at least one of the phase or neutral elements before the earthing element.

Finally, in order to facilitate the mounting of the plug, and as shown in FIGS. 1 and 5, the insulating insert 300 comprises introduction means, constituted by cones 341, 342, 343, making it possible to introduce the elements 101, 102, 103 of the cable 100 with respect respectively to the means 301, 302 for connection and to the means 350 for electrical contact.

Claims (12)

1. An electrical plug for connecting two cores (101, 102) of an electrical cable (100) to two pins (201, 202) each having respective connection means (211, 212), said pins being received in two housings (301, 302) formed in an insulating insert (300), and said plug also including an intermediate insulating shell (400) covering said insert (300) and designed to receive an external molding of insulation (500), said insulating shell (400) being suitable for preventing any loose strand, whatever its length, from coming into contact with the outer molding (500) and for constraining at least any loose strands of great length to exit the plug at the pin end at a location where, given the outer molding, they do not present any danger when the plug is plugged in, characterized in that said shell includes means for engaging the shell (400) laterally onto said cable (100), which means are constituted by a lateral groove (421, 422, 423) that is open at both ends so as to enable the insulating shell (400) to be placed on the insert (300) by being moved laterally and then to be brought longitudinally against said insert (300).
2. An electrical plug according to claim 1, characterized in that said insulating shell (400) includes lateral ribs (401, 402) for stiffening said outer molding (500).
3. An electrical plug according to claim 1 or 2, characterized in that said insulating insert (300) includes at least one recess (320, 321, 322) defined by two lateral partitions (331, 332) and within which there are received those portions of the cable cores (101, 102) that extend between said cable (100) and said connection means (211, 212), and in that the insulating shell (400) has locking means (421, 422) co-operating with said recess (320, 321, 322) to form zigzag retaining means for said elements.
4. An electrical plug according to claim 3, characterized in that said locking means are walls (421, 422) bearing against said lateral partitions (331, 332) of the recess (320, 321, 322) when the shell (400) is put into place on said insert (300).
5. An electrical plug according to any one of claims 1 to 4, characterized in that said insulating insert (300) includes two means (341, 342) for inserting cable cores relative to the connection means (211. 212).
6. An electrical plug according to claims 3 and 4, characterized in that said lateral groove provides said walls (421, 422) forming said locking means.
7. An electrical plug according to any one of claims 1 to 6, characterized in that the shell (400) is held on the insert (300) by complementary fixing means (330, 410) provided respectively on the shell and on the insert.
8. An electrical plug according to any one of claims 2 to 7, characterized in that said complementary fixing means are constituted by at least one fixing projection (330) disposed on the insulating insert (300) and co-operating with a slot (410) formed in said shell (400).
9. An electrical plug according to any one of claims 1 to 8, characterized in that the cable (100) has an "earth" third core (103), said insert (300) also including a third housing (303) containing electrical contact means (350), opening to the outside of the insert (300) via earth rail fixing means (360) for fixing to an earth rail (600), and having said earth core (103) connected thereto.
10. An electrical plug according to claim 9, characterized in that said insulating insert (300) includes third means (343) for inserting the earth core 103 facing the electrical contact means (350).
11. An electrical plug according to claim 9 or 10, characterized in that the cores (101, 102, 103) are of identical length so that, on assembly, the earth core (103) has extra length or slack for safety purposes.
12. An electrical plug according to claim 5 and any one of claims 1, 6, 7, 8, 10, 11, and 12, characterized in that said insertion means are insertion cones (341, 342, 343).

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