Patent ID: 12237098

DETAILED DESCRIPTION OF THE DRAWINGS

FIG.1schematically and partially represents a vehicle1.

The vehicle1includes a chassis2which is generally formed from the assembly, in particular by welding, of several parts which can be made of different metals, more or less good conductors of electricity. In addition to these metal parts, the chassis2can also include non-metal parts, for example made of carbon fibers. The chassis2has welded areas, as well as perforations or slits, to meet the different requirements in terms of anchoring and passages through partitions in the vehicle1. The chassis2forms a ground plane for the vehicle1, and it follows from the above that this ground plane is heterogeneous.

As seen inFIG.1, a partition3fixed to the chassis2separates an engine compartment4, at the front of the vehicle1, from a passenger compartment5where the driver and any passengers will be seated.

In the case of a hybrid vehicle, the engine compartment4includes a heat engine6and an electric motor7. A generator10allows powering the electric motor7. This generator10, typically a battery, can be installed in the passenger compartment5, under a seat9. The generator10includes a positive terminal11and a negative terminal12.

The electric motor7is supplied by the generator10by an electric circuit which includes a cable20forming the outgoing electrical conductor and a sheath30forming the return electrical conductor.

The cable20has a first end21, preferably provided with a connector23, electrically connected to the positive terminal11, and a second end22, preferably provided with a connector23, electrically connected to the electric motor7(or to a conductor28itself connected to the electric motor7).

The sheath30forms a flexible tubular casing which partially houses the cable20, and which has a first end31electrically connected to the negative terminal12of the generator10and a second end32electrically connected to the chassis2. Preferably, a connector33is assembled at each of the ends31,32of said casing of the sheath30.

The end connectors23,33are made of an electrically conductive material, which may further exhibit magnetic properties favorable to the shielding effect. These may be eyelet terminals, as illustrated for example inFIGS.1and12, screwed onto terminal11,12or chassis2. Other embodiments of such connectors are possible. In particular, the connector could be formed of a plate, for example obtained by flattening a tube, welded or otherwise mechanically and electrically connected to the cable20or to the sheath30.

In the embodiment represented inFIGS.1to3, the sheath30includes a first orifice34and a second orifice35separate from the ends31,32of the flexible tubular casing, and spaced from each other. The cable20has a central portion24housed in the sheath30between the two orifices34,35thereof, and passes through the orifices34,35, the cable20thus having two end portions located outside the sheath30. More specifically, the cable20may have a first end portion25between the first end21of the cable20and the central portion24of the cable20, which, in the mounted position, extends from the positive terminal11of the generator10to the orifice34of the sheath30; and a second end portion between the second end22of the cable20and the central portion24of the cable20, which, in the mounted position, extends from the orifice35to the conductor connected to the electric motor7.

The sheath30aims to ensure a magnetic shielding of the cable20, that is to say to form a barrier to the magnetic field emitted by the cable20, when it is traversed by a current, in order to protect the equipment and people in the environment of the cable20. It is therefore preferable that the cable20is largely housed in the sheath30, at least in a space where equipment or people to be protected are located.

By way of example, and depending on the layouts and applications, the central portion24of the cable20, housed in the sheath30, may have a length of at least half, or even at least two thirds, of the total length of the cable20. This central portion24of the cable20preferably corresponds to the portion of the cable located in the passenger compartment5of the vehicle1.

As seen inFIGS.1to3, the cable20is preferably disposed substantially adjacent to the chassis2, at least in its central portion24. The orifice34may be located in the upper portion of the sheath30, to simplify the path of the first end portion25of the cable20to the positive terminal11of the generator10. Moreover, the orifice35can be located in the lower portion of the sheath30and opposite an orifice8formed in the chassis2. The cable20can thus exit through the orifice35of the sheath30and through the orifice8of the chassis2, to pass from the interior of the passenger compartment5to the area located under the chassis2, from one side of the partition3to the other, up to engine compartment4.

The second end32of the sheath30may be located in the passenger compartment5, the connection with the electric motor7being effected via the chassis2and a conductor29connected on the one hand to the electric motor7and on the other hand to the chassis2, usually in the engine compartment4.

The fact of placing the cable20, in the sheath30, in the vicinity of the chassis2, may result from the constraint of available space in the passenger compartment5. This arrangement is advantageous in that it makes it possible to reduce the loop surface (that is to say the surface between the cable20and the ground plane). On the other hand, as the proximity of a heterogeneous chassis2tends to degrade the effectiveness of the shielding, it is important that the disclosure provides a sheath having sufficient magnetic capacities.

The sheath30includes or is formed of an assembly of elongated elements40which may be wires, in particular wires of round section or flat wires, strips, in particular rolled strips, or the like.

The sheath30includes:on the one hand, elongated elements41of a first type which are made of at least one electrically conductive material, in order to ensure the return of the current through the sheath30from the electric motor7to the negative terminal12of the generator10;and on the other hand elongated elements42of a second type, different from the first type, made of at least one material having sufficient magnetic properties to produce the shielding effect.

The elongated elements41of the first type can be made of at least one material having a relative electrical conductivity σr greater than 0.5, preferably greater than 0.6, at room temperature. These elongated elements41can comprise or be made of copper or aluminum.

The elongated elements42of the second type can be made of at least one material having a relative magnetic permeability μr which, at room temperature, and in a range of frequencies between 0 Hz and 500 kHz, can be comprised between 50 and 7000. Preferably, this relative magnetic permeability μr can be greater than 100, better still 200, or even 500. Preferably, this relative magnetic permeability μr can be less than 6000, better still 5500, or even 1000. These elongated elements42can comprise or be produced from iron, nickel, cobalt, or an alloy including at least one of these metals. Preferably, it is neither mumetal nor permalloy.

In practice, it is possible to determine the range of frequencies of the disturbing magnetic field, and to deduce therefrom the most suitable material, that is to say generally that having the greatest relative magnetic permeability in this range.

The assembly of the elongated elements40,41,42in the sheath30is obtained by crisscross assembly and/or encircling.

Thus, the elongated elements40can be assembled by braiding (FIG.6illustrating an example of braiding), by weaving (FIG.7illustrating an example of weaving). The elongated elements40can moreover be assembled by winding with contiguous turns (as illustrated inFIG.8) or by wrapping (as illustrated inFIG.9). Other assembly methods can be used, such as knitting and gimping.

According to one embodiment, as illustrated schematically inFIG.4, the elongated elements41of the first type and the elongated elements of the second type 42 are assembled together in the same layer36of the sheath30.

According to another embodiment, as illustrated schematically inFIG.5, the elongated elements41of the first type are located in a first layer37of the sheath30, while the elongated elements42of the second type are located in a second layer38of the sheath30, distinct from the first layer37, and coaxial with the first layer37. In order to improve the shielding efficiency, it is preferable that the magnetic layer, that is to say here the second layer38including the elongated elements42of the second type, is located as close as possible to the cable, therefore inside the first layer37.

Furthermore, still with the aim of improving the shielding efficiency, the internal diameter of the sheath30can be substantially equal to the external diameter of the cable20, so that the elongated elements42of the second type are located as close as possible to the cable20.

Sufficient shielding can be obtained by providing a conductive metal section of the sheath30greater than 1/10thof the conduction section of the cable20. By choosing a section of the sheath30greater than ⅓ of the section of the cable20, the shielding is very effective. For example, for a cable20with a section equal to 70 mm2, it is possible to opt for a sheath30whose section (that is to say the transverse surface in the form of a ring) is 25 mm2. For even greater efficiency, provision can be made for the section of the sheath30to be greater than half the section of the cable20, which, for a cable20of section equal to 70 mm2, would result in a sheath30of a section of at least 35 mm2.

The sheath30may further include elongated elements43made of a polymer material, such as multifilament or monofilament fibers, as schematically illustrated inFIG.4. These elongated polymer elements43can be assembled with the elongated elements41,42of the first and/or of the second type by crisscross assembly in the same layer36of the sheath30, or be located in an additional layer distinct from the sheath30(this embodiment not being represented). Such elongated polymer elements43can provide mechanical reinforcement, which may prove to be important when the elongated elements41,42of the first and/or of the second type are very fine threads (for example from 0.03 to 0, 20 mm).

For example, as illustrated inFIG.6, respectivelyFIG.7, there can be a braiding, respectively a weaving between:a first kind of strands comprising elongated elements41of the first type and elongated elements42of the second type;and a second kind of strands comprising elongated elements43made of a polymer material.

Nonetheless, other assemblies of elongated elements between them are possible. In particular, the type or types of the elongated elements contained in a given kind of strand could be different.

Moreover, the sheath30can also comprise an external textile layer39(an exemplary embodiment being illustrated inFIG.16). Such a textile layer makes it possible to confer mechanical protection and electrical insulation.

We are now interested in the different configurations that the sheath30can have.

According to one embodiment, as illustrated inFIGS.4and5, the sheath30is produced in the form of a closed tube in which the cable20can be inserted, the tube being obtained from an initially substantially flat sheet. Once the cable20has been inserted, the connectors33can be put in place.

InFIG.8, the elongated elements40are wound around the cable20.

According to another embodiment, the sheath30is produced in the form of an initially substantially flat sheet, suitable for being wound around the cable20. The sheet can be woven, braided, knitted, etc. The sheet can be made flat, or result from flattening by rolling a tubular structure.

InFIG.9, the sheet has the shape of a ribbon, that is to say with a width significantly smaller than its length. The sheet is wound around the cable20by forming contiguous turns or with an overlap.

As a variant, the sheet includes two free edges51,52which, in the mounted position of the sheath30, may be arranged substantially longitudinally, that is to say along the axis of the cable20and of the sheath30. In the mounted position, the free edges51,52can be arranged edge to edge or, as a variant, the sheet can be wound over more than one turn and thus have an overlap. Furthermore, preferably, holding means are provided to hold the sheet in the position wound around the cable20.

InFIG.10, the sheet is wound over a little more than one turn, so that there is an overlap between the end bands of the sheet each located along one of the free edges51,52. The holding means are constituted by self-gripping means53, such as a part carrying loops and a part carrying hooks of a Velcro® system, these parts being fixed (for example sewn) on the sheet near the free edges51,52, in the overlap area. Other holding means could be provided as a variant, such as press studs, rivets, zippers, etc.

InFIG.11, the sheet is wound in several turns around the cable20, then attached by self-adhering means53, for example, to form the sheath30.

InFIG.12, the holding means are formed by one or more links54surrounding the sheath30and tightening it around the cable20. These may for example be metal or plastic ligature collars. The free edges51,52of the sheet may be substantially opposite and contiguous, or there may be a certain overlap as inFIG.10.FIG.13illustrates how, by locally separating the free edges51,52of the sheet, an orifice34is created in the sheath30for the passage of the cable20.

According to yet another embodiment, illustrated inFIGS.14and15, the sheath30is produced in the form of an initially substantially planar sheet which is formed, for example thermoformed, in a pre-wound form having a certain diameter at the unstressed state. When installing around a cable, this pre-wound sheet is elastically deformed, so as to increase its diameter, then it is placed around the cable20. When the sheet is released, it returns elastically towards its position in the unstressed state, but not necessarily up to this position, by reducing its diameter. Thus, in the position of use, the sheet forms a sheath30surrounding the cable, possibly with a certain tightening. This configuration of the sheath30is advantageous on account of the ease of implementation.

Similar to the embodiment ofFIG.13,FIG.15shows the creation of an orifice34for the passage of the cable20by localized spacing of the free edges51,52of the sheet which forms the sheath30.

Finally,FIG.16shows a sheath30comprising a layer38including the elongated elements41,42of the first and of the second type, this layer being able to take any one of the shapes described above, as well as an external textile layer39. In the represented embodiment, the external textile layer39can be produced in the form of an initially substantially flat sheet, and be wound around the cable20and held by suitable holding means. These holding means are represented in the form of self-gripping means53, but this should not be considered as limiting.

It goes without saying that the disclosure is not limited to the embodiments described above by way of examples but that it comprises all the technical equivalents and the variants of the means described as well as their combinations.

In particular, although the disclosure has been described in the context of a hybrid vehicle, it can be applied to an installation other than a vehicle, with an equipment other than an electric motor, for the magnetic shielding of a cable.