EP0383661B1 - Device for electrically connecting a cable, in particular one for ignition, with a terminal - Google Patents

Description

The invention relates to an electrical connection device of the type comprising a conductive part, also called a terminal, having an end for receiving an electric cable and an end suitable for connection on a stud.

Devices of this type are already known in which the connection end consists of a split ring, elastically deformable, of a shape adapted to that of the stud, and suitable for being disposed in the axial extension of the cable.

Such devices are used in particular in the ignition systems of internal combustion engines to ensure the connection of an ignition cable to a stud, or terminal, forming part of an ignition member, such as a candle, a reel or distributor.

In this application to the ignition cables, a cap is also provided which surrounds the cable and the conductive part and which is suitable for sealing with the cable and with the stud or the member which carries the stud, to ensure the electrical insulation.

These connection devices must make it possible to ensure, in all circumstances, excellent radial tightening of the split ring on the stud to obtain perfect electrical contact, even after several connection and disconnection operations.

It is also necessary that these connection and disconnection operations can be carried out manually without the effort required to put the split ring on the stud, or remove it from the stud, exceeds the established standards.

With known connection devices of this kind, it frequently happens, in particular under the effect of vibrations or significant accelerations, that the radial tightening force of the ring weakens and thus adversely affects the electrical connection between the ring split and the stud. This then results in micro-cuts which lead to poor ignition and therefore poor combustion of the engine, with emission of harmful gases and unburnt gases in the exhaust.

To overcome this drawback, it has been proposed to strengthen the split ring so that it provides higher radial tightening and therefore better electrical contact with the stud.

Unfortunately, this solution has the disadvantage that the effort required for the establishment of the ring on the pad or for its extraction from the pad is thus increased. Consequently, the increase in the clamping force of the split ring comes at the expense of connection and disconnection facilities, which is not acceptable due to the standards imposed.

We also know, from US-A-2,567,727, a connector suitable for connecting the respective ends of two electric cables and comprising two sockets, one male and the other female, fitted to the ends of the cables and clean to adapt to each other.

This connector includes a locking sleeve which surrounds the male plug and which is capable of sliding axially to prevent the radial expansion of the female plug after the male plug has been inserted into the latter.

Such a connector cannot be suitable for the connection of a split ring on a stud of an ignition member because it would either be necessary to provide a specific ignition member already equipped with a locking sleeve, or to provide a specific adapter on the ignition member, which is not acceptable in practice.

In addition, the connector of document US-A-2,567,727 requires two sealing sheaths respectively surrounding the male plug including the locking sleeve and the female plug, which complicates the structure of the connector.

The need to use two sealing sheaths makes, here again, such a connector unsuitable for the connection of a split ring on an ignition member stud, in particular a spark plug.

It is therefore an object of the invention to provide an electrical connection device of the type defined in the introduction which makes it possible to strengthen the radial tightening and therefore the electrical contact of the split ring on the stud.

It is also an object of the invention to provide a connection device of this kind in which the force necessary for the installation of the split ring on the stud or its removal from the stud is of the same order of magnitude, or even even weaker, than in the case of the devices of the prior art.

It is also an object of the invention to provide such a connection device, in which the radial tightening force of the ring is not affected, even after several connection and disconnection operations.

It is also an object of the invention to provide such a connection device, which is intended especially for cables of the ignition systems of internal combustion engines.

The invention also aims to provide a connection device, especially for ignition cables, which ensures a perfect seal between the cable and the stud or a member which carries the stud.

It also aims to provide a connection device of this kind which makes it possible to carry out operations of connection and disconnection under conditions very close to those of known devices.

Also one of the objects of the invention is to provide such a connection device which adapts to standard studs, in particular of ignition members.

• un manchon rigide isolant propre à coulisser axialement autour du câble et de la pièce conductrice entre une première position dégagée de la bague pour sa mise en place sur le plot ou son extraction du plot et une seconde position engagée sur la bague pour le serrage de la bague sur le plot ; et
• un capuchon en matériau souple et isolant, solidaire du manchon et possédant un premier embout d'extrémité propre à être serré à étanchéité autour du câble et un second embout d'extrémité propre à s'adapter à étanchéité autour du plot et/ou d'un organe supportant le plot, le capuchon étant déformable axialement pour autoriser son déplacement par rapport à la bague fendue et faire passer le manchon de l'une à l'autre de ses deux positions.

The invention relates more precisely to an electrical connection device of the type defined in the introduction, which is characterized in that it comprises:

• a rigid insulating sleeve suitable for sliding axially around the cable and the conductive part between a first position released from the ring for its positioning on the stud or its extraction from the stud and a second position engaged on the ring for tightening the ring on the stud; and
• a cap made of flexible and insulating material, integral with the sleeve and having a first end fitting capable of being tightly sealed around the cable and a second end fitting capable of adapting to sealing around the stud and / or a member supporting the stud, the cap being axially deformable to allow its displacement relative to the split ring and to pass the sleeve from one to the other of its two positions.

Thus, when the sleeve is in the disengaged position of the ring, one can put the ring on the stud and then move the sleeve to its engaged position on the ring, which ensures the tightening of the ring on the stud and makes thus the practically unbreakable ring of the stud.

If you want to separate the split ring from the stud, it is first necessary to move the sleeve from its position engaged on the ring to its position released from the ring, then then to extract the ring from the stud.

Therefore, the establishment of the split ring on the stud or its extraction from the stud requires an effort of the same order of magnitude, or even less, than that which must be exerted with the devices of the prior art, fact that it is not necessary to provide a tightening of the split ring tightening.

In a preferred embodiment of the invention, the sleeve is cylindrical in shape and comprises, at one end, a frustoconical internal wall flared in the direction of this end to facilitate engagement of the sleeve on the split ring.

Advantageously, this frustoconical wall opens onto an intermediate cylindrical internal wall suitable for ensuring the radial tightening of the split ring and opening out on the other end of the sleeve by a slightly flared frustoconical wall.

The intermediate internal wall constitutes the active part of the sleeve which prevents, in the position engaged on the ring, the radial expansion of this ring. The slightly flared tapered wall is intended to facilitate the axial sliding of the sleeve along the electric cable, when this sleeve is moved from one to the other of its two extreme positions.

In a first alternative embodiment, the cap is in one piece and has a body which completely encloses the sleeve, this body being connected at one end to the clamping end piece on the cable by a tight and deformable bellows, and forming at its other end the sealing tip.

In another alternative embodiment, the cap is formed from two parts, namely a first part having a body which surrounds one end of the sleeve and which is connected to the clamping end piece on the cable by a tight and deformable bellows and a second part having a body that surrounds the other end of the sleeve and which forms the sealing tip.

In the two aforementioned variant embodiments, the waterproof and deformable bellows allows the sleeve to slide from one of its two extreme positions to the other, the bellows being compressed in the released position of the ring and, on the contrary, being expanded in the position engaged on the ring.

Advantageously, the waterproof and deformable bellows is compressed in its natural position, or position at rest, which keeps the sleeve in its position released from the split ring.

In the position where the split ring is engaged on the stud and the sleeve in its position engaged on the ring, the cap then ensures continuity between the electric cable and the stud or the body carrying the stud.

According to another aspect, the invention relates to an electric cable, in particular for an ignition system, equipped at at least one of its ends with a connection device as defined above.

• la figure 1 est une vue en coupe d'un dispositif de connexion équipant l'extrémité d'un câble d'allumage, avant mise en place sur le plot d'une bougie, le manchon étant dans sa position dégagée ;
• la figure 2 est une vue analogue à celle de la figure 1, dans laquelle la bague fendue est mise en place sur le plot, le manchon étant toujours dans sa position dégagée ;
• la figure 3 est une vue analogue à celle de la figure 2 dans laquelle la bague fendue est mise en place sur le plot, le manchon étant dans sa position engagée sur la bague ;
• la figure 4 est une vue en coupe analogue à celle de la figure 3, dans une variante de réalisation ; et
• la figure 5 est une vue en coupe d'un manchon muni d'un capuchon isolant en deux parties.

In the description which follows, given by way of example, reference is made to the appended drawings, in which:

• Figure 1 is a sectional view of a connection device fitted to the end of an ignition cable, before installation on the stud of a spark plug, the sleeve being in its released position;
• Figure 2 is a view similar to that of Figure 1, in which the split ring is placed on the stud, the sleeve being always in its released position;
• Figure 3 is a view similar to that of Figure 2 in which the split ring is placed on the stud, the sleeve being in its position engaged on the ring;
• Figure 4 is a sectional view similar to that of Figure 3, in an alternative embodiment; and
• Figure 5 is a sectional view of a sleeve provided with an insulating cap in two parts.

Reference is first made to FIG. 1 which shows an ignition cable 10 provided, at one of its ends, with a connection device 12 according to the invention. This device is intended to ensure an electrical connection between the conductive core 14 of the cable and a stud 16, also called "olive", carried by an insulating body 18, or "porcelain", of a spark plug 20 partially shown.

The stud 16 has a general shape of revolution and comprises, in a manner known per se, a front part 22 having entry and retaining chamfers and attached to a rear part 24 by a cylindrical part 26, of smaller diameter, forming a peripheral annular groove.

The connection member 12 comprises a one-piece conductive part 28, also called a "terminal", having an end 30 for receiving the cable 10 and an end 32 suitable for connection to the stud 16.

The receiving end 30, of generally cylindrical shape, has two tabs 34 and 36 suitable for holding by clamping the end of the cable 10 which should be connected to the stud 16. The connection end 32 is constituted by a ring cylindrical split elastically deformable, of a shape adapted to that of the stud, and disposed in the axial extension of the cable 10. This ring defines a slot 38 parallel to the axis of the conductive part.

The connection end 32 further comprises at least two tabs 40 folded radially towards the inside of the conductive part 28 and capable of coming into abutment against the front face 42 of the stud 16 during the positioning of the split ring on this stud.

The connection end 32 further comprises at least two bosses 44 projecting towards the inside of the split ring and capable of being positioned in the annular groove of the stud 16, when the tabs 40 are supported on the front face 42 of the stud.

The electrical contact between the conductive part 28 and the core conductive 14 of the cable 10 is provided, in a manner known per se, by a conductive metal clip (not shown) comprising two parallel branches joined together by an elbow. One of the branches of the clip is inserted between the core and the cable sheath, while its other branch is inserted between the end 30 of the part 28 and the outside of the cable sheath.

The connection device 12 further comprises a rigid insulating sleeve 46, for example formed of a thermosetting resin, of generally cylindrical shape, capable of sliding axially around the cable 10 and around the conductive part 28 located in the axial extension of the cable . The sleeve 46 comprises a generally cylindrical external wall 48 extending from its front end 50 to its rear end 52. At its front end 50, the sleeve 46 comprises a frustoconical internal wall 54 flared in the direction of this end. The frustoconical wall 54 opens onto an intermediate cylindrical wall 56 suitable for ensuring, as will be seen below, the radial tightening of the split ring, this wall 56 opening onto the other end 52 of the sleeve by a frustoconical wall 58 very slightly flared in the direction of the end 52. It is preferable indeed for the wall 58 to be very slightly frustoconical, rather than being cylindrical, to facilitate the axial sliding of the sleeve 46 around the cable 10.

The device represented in FIG. 1 further comprises a monobloc cap 60, formed of a flexible and insulating material, and comprising a body 62, of generally cylindrical shape, completely enclosing the sleeve 46.

The body 62 extends between two ends 64 and 66. The end 64 is connected to a first end piece 68 of generally cylindrical shape by means of a waterproof and deformable bellows which, in its natural position, is in the compressed state.

The end piece 68 is suitable for being tightly sealed around the cable 10 and thus being immobilized in translation and in rotation relative to the cable 10.

At its end 66, the body 62 of the cap forms a second end piece 74, of generally cylindrical shape, capable of adapting to sealing around the pad 16 and / or of the insulating body 18 supporting the pad 16.

The body 62 of the cap internally has an annular shoulder 76 permanently forming a stop for the end 50 of the sleeve 46 and an annular shoulder 78 forming a stop for the end 52 of the sleeve 46, when the bellows is in the compressed state (FIG. 1 and Figure 2).

Furthermore, the body 62 of the cap 60 comprises, in the vicinity of its end 64, gripping means constituted, in the example, by an annular flange 80.

The operation of the connection device will now be explained with reference to Figures 1 to 3.

First of all, the connection member is presented opposite the stud 16 of the spark plug 20, so that the connection end 32 (split ring) is located opposite and in the axis of the stud 16 The bellows 70 being in its natural position in the compressed state, the sleeve 46 is in a position released from the split ring, the cylindrical internal wall 56 of the sleeve not being in contact with the split ring. Consequently, the end 52 of the sleeve abuts against the annular shoulder 78 (FIG. 1).

An axial thrust is then exerted on the end piece 68 of the cap 60 as shown by the arrow F in FIG. 2, so as to engage the split ring on the stud 16, the sleeve 46 still being in its released position and the bellows 70 always being in the compressed state. During the engagement of the split ring on the stud, this ring expands radially and, at the end of introduction, the tabs 40 of the conductive part 28 come to bear on the front face 42 of the stud 16, while the bosses 44 of the conductive part are received in the annular groove delimited by the stud 16.

Then, an axial force is exerted on the collar 80, as shown by the arrow G in FIG. 3, so as to cause the sleeve 46 to slide relative to the cable 10 and to the conductive part 28. At the end of the race, the intermediate cylindrical internal wall 56 of the sleeve 46 encloses the split ring and prevents its radial expansion, so that the connection of the cable to the stud is practically unbreakable. In the position shown in Figure 3, the bellows 70 is fully expanded and the end 52 of the sleeve 46 is spaced from the internal shoulder 78 of the cap 60. In addition, the end piece 74 seals around the body insulator 18 of the spark plug 20.

Thus, these two successive operations are carried out by exerting a push on the cap, in an area of the latter which is at a distance from the stud, which facilitates the positioning of the device in places of difficult access, by example in a well of an engine cylinder head.

If you want to extract the split ring from the stud, you must carry out the previous operations in reverse order by first bringing the sleeve from its engaged position on the ring to its disengaged position from the ring and then exercising traction on the assembly to allow the extraction of the split ring, the latter expanding radially during the extraction.

In practice, these two operations are carried out in a single movement. It suffices to exert traction on the flange 80 to first ensure the displacement of the sleeve towards its released position and then the extraction of the split ring.

Referring now to FIG. 4 which shows an alternative embodiment of the connection device shown in FIGS. 1 to 3. In this alternative embodiment, the means for gripping the cap 60 comprise, in the vicinity of the end 64 of the cap, on the one hand, a pusher 82 facilitating the movement of the sleeve 46 from its disengaged position from the ring to its position engaged on the ring and, on the other hand, a traction ring 84 facilitating the movement of the sleeve from its position engaged on the ring in its disengaged position from the ring and also facilitating the extraction of the ring from the stud.

Reference is now made to FIG. 5 which shows yet another alternative embodiment in which the cap is formed, not of a part as before, but of two parts 86 and 88. The part 86 comprises a body 90 which surrounds the end 52 of the sleeve 46 and which is connected to a first end piece 92 (analogous to the end piece 68 described above) suitable for being tightened and immobilized to seal around the cable 10. The body 90 is connected to the end piece 92 by the 'through a bellows 94, waterproof and deformable, similar to the bellows 70 described above. This bellows is, again, in the compressed state in its natural position. The body 90 is made integral with the sleeve 46 by means of internal annular grooves 96 which cooperate with external annular ribs 98 of the sleeve 46. Furthermore, the body 90 is provided with a collar 100 similar to the collar 80 described above.

The second part 88 of the cap comprises a body 102 which surrounds the other end 50 of the sleeve 46 and which forms an end piece 104 similar to the end piece 74 described above. The body 102 is immobilized on the sleeve 46 by means of internal annular grooves 106 which cooperate with external annular ribs 108 of the sleeve 48.

The device shown in part in Figure 5 is used in exactly the same way as the device in Figures 1 to 3.

Of course, the invention is not limited to the connection of an ignition cable to a stud of an ignition member such as a spark plug, distributor or coil.

Claims (9)

1. An electrical connection device, in particular of the type comprising a conductive component (28) having one end (30) for receiving an electrical cable (10) and one end (32) suitable for connection to a contact stud (16), this connecting end (32) being constituted by an elastically deformable split ring with a shape matched to that of the contact stud and disposed in the axial extension of the cable, characterized in that it includes:

   - a rigid insulating sleeve (46) capable of axially sliding round the cable (10) and the conductive component (28) between a first position disengaged from the ring for being positioned on the contact stud or for its extraction from the contact stud, and a second position engaged on the ring for tightening the ring on the contact stud; and

   - a cap (60; 86, 88) made of a flexible and insulating material, fixed to the sleeve (46) and having a first end fitting (68; 92) capable of being tightened with a seal round the cable (10) and a second end fitting (74; 104) capable of being fitted with a seal round the contact stud (16) and/or round an element (18) supporting the contact stud, the cap being axially deformable to allow it to be displaced relative to the split ring and to cause the sleeve to pass from one to the other of its two positions.
2. A device according to claim 1, characterized in that the sleeve (46) has a generally cylindrical shape and includes at one end (50) an internal frustoconical wall (53) flaring in the direction towards this end so as to facilitate the engagement of the sleeve on the split ring (32).
3. A device according to claim 2, characterized in that the internal frustoconical wall leads into an intermediate internal cylindrical wall (56) capable of ensuring the radial tight fit of the split ring and leading into the other end (52) of the sleeve via a slightly flared frustoconical wall (58).
4. A device according to one of claims 1 to 3, characterized in that the sleeve (46) is formed from a rigid plastic material, for example from a heat setting resin.
5. A device according to one of claims 1 to 4, characterized in that the cap (60) is made in one piece and includes a body (62) which completely confines the sleeve (46), the body being joined at one end (64) by a leakproof and deformable bellows (70) to an end fitting (68) for gripping on the cable, this body forming at its end (66) the leakproof end fitting (74).
6. A device according to one of claims 1 to 4, characterized in that the cap is formed of two parts, that is to say, a first part (86) having a body (90) which surrounds one end of the sleeve (46) and which is joined by a leakproof and deformable bellows (94) to the end fitting (92) for gripping on the cable, and a second part (88) having a body (102) which surrounds the other end of the sleeve (46) and which forms the leakproof end fitting (104).
7. A device according to one of claims 5 and 6, characterized in that the leakproof and deformable bellows (70, 94) is compressed in its natural position which maintains the sleeve (46) in its position disengaged from the split ring.
8. A device according to one of claims 1 to 7, characterized in that the cap (60; 86) is provided with gripping means (80, 82, 84; 100) facilitating the axial sliding of the sleeve (46) round the cable (10) and the conductive component (28) for passing from the first position to the second position and vice versa.
9. An electric cable, in particular for an ignition system, provided at at least one of its ends with a connecting device according to one of claims 1 to 8.

Images