VEHICLE STEERING WHEEL

A vehicle steering wheel includes at least one plastic part made from a fluid base material using a process such as injection. At least one electrical conductor includes at least a first portion which is at least partially overmolded by the at least one plastic part and further includes at least one second portion that extends outside of the at least one plastic part. The steering wheel further includes at least one sheath that is added around a third portion of the at least one electrical conductor and extends from the at least one first portion to the at least one second portion, with the at least one sheath forming a sealing interface for preventing leakage of base material along the at least one electrical conductor during the overmolding of the at least one first portion by the at least one plastic part.

The present invention relates in a general manner to a vehicle steering wheel mounted on an automobile, and particularly to a vehicle steering wheel with at least one electrical conductor that is at least partially submerged or overmolded in a plastic material such as polyurethane.

Steering wheels having electrical conductors that are partially submerged in a plastic material are known from the prior art. In particular, the document US 2007228028 discloses a steering wheel with a ground cable, a portion of which is overmolded in a foam and which emerges from this foam. Typically, the foam is molded by means of pressurized injection, and this arrangement can pose problems involving the leakage of the foam when it is injected under pressure. Typically, the ground cable must emerge from the mold for manufacturing, thus forming a leakage path, especially since a foam such as polyurethane is particularly fluid when it is injected.

It is an object of the present invention to address the drawbacks of the abovementioned documents of the prior art and, in particular, first and foremost, to provide a vehicle steering wheel with an electrical conductor which is at least partially overmolded in a plastic material such as polyurethane but the manufacture of which, at the time of the operation of producing the plastic part, poses diminished risks of the leakage of liquid plastic.

To achieve this, a first aspect of the invention relates to a vehicle steering wheel comprising:at least one plastic part made from a fluid base material using a process such as injection,at least one electrical conductor, at least a first portion of which is at least partially overmolded by the at least one plastic part and which comprises at least one second portion that extends outside of the at least one plastic part, characterized in that the steering wheel comprises at least one sheath that is added around a third portion of the at least one electrical conductor and extends from the at least one first portion to the at least one second portion, with the at least one sheath forming a sealing interface for preventing leakage of base material along the at least one electrical conductor during the overmolding of the at least one first portion by means of the at least one plastic part.

The vehicle steering wheel according to the present embodiment comprises at least one electrical conductor which is partially overmolded/submerged in a plastic material such as polyurethane. The invention proposes that a portion of sheath be arranged around this electrical conductor in the area straddling the plastic material and the free part of the electrical conductor. In other words, this area (the third portion) is across from the manufacturing mold used to mold the plastic part. As a result, the sheath acts as a sealing interface at the mold, and since it has an outside surface that is smooth or is continuous without asperities, it prevents leakage of the liquid or fluid plastic to the outside along the electrical conductor. Moreover, at the time of the closing of the mold, it limits any risk of aggression of the mold with respect to the connector.

Advantageously, the at least one sheath is a heat-shrinkable sheath that is shrunk around the at least one electrical conductor. Such a sheath is easy to put in place and ensures good contact between the electrical conductor and the interior of the sheath, which further limits the risk of leakage between the sheath and the conductor.

Advantageously, the at least one electrical conductor is a bundle comprising at least two electrical cables or wires.

Advantageously, the bundle is a cable bundle.

Advantageously, the vehicle steering wheel comprises a glue that is disposed between the at least one sheath and the at least one electrical conductor. Such a glue makes it possible to fill the voids or spaces between the electrical conductor and the sheath in the event that the electrical conductor has asperities or discontinuities on its outside surface.

Advantageously, the vehicle steering wheel comprises at least one other plastic part which is made prior to the at least one plastic part and comprises retaining means provided to retain and/or position the at least one second portion on the steering wheel, at least during the fabrication of the at least one plastic part. The retaining means on the other plastic part makes it possible to simplify the tools or mold for manufacturing the plastic part that is molded at least partially over the electrical conductor. This also ensures that the conductor will be in the proper position when the mold is closed, thus avoiding any risk of a degradation of the connector or a quality defect in the positioning of the connector.

Advantageously, the at least one other plastic part comprises at least one cavity which is provided for the purpose of receiving the at least one second portion.

Advantageously, the at least one other plastic part is made of polyurethane.

Advantageously, the vehicle steering wheel comprises a connector that is arranged at a free end of the at least one second portion.

Advantageously, the cavity is devised to receive and hold the connector.

Advantageously, the at least one plastic part is made with polyurethane.

A second aspect of the invention relates to an automobile comprising at least one vehicle steering wheel according to the first aspect of the invention.

A third aspect of the invention relates to a method for manufacturing a vehicle steering wheel comprising a step that consists in overmolding, at least partially, at least one first portion of at least one electrical conductor with a plastic part that is made from a fluid base material by means of a process such as injection, such that a second portion of the at least one electrical conductor extends outside of the at least one plastic part, with the method comprising a step prior to the overmolding step consisting in adding at least one sheath around a third portion of the at least one electrical conductor extending from the at least one first portion to the at least one second portion so as to form, with the at least one sheath, a sealing interface for preventing leakage of base material along the at least one electrical conductor during the overmolding of the at least one first portion with the at least one plastic part.

In other words, the invention relates to a method for manufacturing a vehicle steering wheel according to the first aspect of the invention.

FIG. 1shows a front view of a steering wheel according to the invention which comprises a plastic part10and another plastic part40. An electrical conductor20is partially overmolded in the plastic part10and leads to above the other plastic part40in order to house a connector24that is attached to a free end of the electrical conductor20in a cavity41formed in the other plastic part40.

The electrical conductor20thus comprises a first portion that is overmolded or submerged in the plastic part10and a second free portion that extends outside of the plastic part10. Moreover, the electrical conductor20comprises two unitary conductors22and23that feed heating resistors arranged in the rim of the steering wheel, for example, with it being possible for these conductors to be protected by insulating sleeves (not shown).

The plastic part10is made by means of a molding operation. An injectable polymer such as polyurethane, for example, can be used in liquid or fluid form. During the execution of the operation for molding the plastic part10, the electrical conductor20must pass through the manufacturing mold, which entails risks of leakage along the electrical conductor20. In order to limit this risk of leakage, the invention makes a provision that a sheath30having a length of between 5 and 50 mm, inclusive, is added around the electrical conductor20locally near the part of the electrical conductor20opposite the manufacturing mold. That is, the sheath30is in contact with at least one of the die cavities of the mold during the injection of the plastic part10, with a first end of the sheath30being positioned in the die cavity receiving the plastic part10and the other end leading to the outside of the die cavity.

Accordingly, a third portion, which extends from the first portion of the overmolded electrical conductor20to the second, free portion of the electrical conductor20, is covered by the sheath30. It is conceivable, for example, for a heat-shrinkable sheath be used that is easy to position in the proper place and then shrunk around the electrical conductor20under the effect of heating.

To facilitate the manufacturing operations, particularly that of the molding of the plastic part10, a provision is made that the retaining means is arranged in the cavity41of the other plastic part40(which is made prior to the plastic part10). The retaining means is embodied so as to retain the electrical conductor20and/or the connector24in the cavity41, which improves the molding of the plastic part10, since the position of the electrical conductor20is controlled.

FIG. 2shows a cross section of the steering wheel ofFIG. 1along a broken line (II-II). For better clarity, only the conductors22,23and the plastic materials10and40are shown in this figure. The other components that are generally used for the construction of a steering wheel, such as the framework or the sheathing, are therefore not shown.

This cross section is thus made through the left part of the structural break at the overmolded part in the plastic material10of the electrical conductor20and in the right part of the structural break near the other part of the electrical conductor20that leads to above the other plastic part40.

At the level of the overmolded part of the electrical conductor20(to the left inFIG. 2), the sheath30thus ensures that there is a seal between it and the electrical conductor20.

At the level of the part that leads to above the other plastic part40(to the right inFIG. 2), the sheath30still ensures that there is a seal between it and the electrical conductor20, but also:between it and a manufacturing mold (which would contact the sheath30and the other plastic part40from above);between it and the other plastic part40(in which the sheath30can be partially accommodated via a preexisting groove, for example).

The electrical conductor20thus comprises two unitary conductors22and23that are wound around one another in the standard manner to form a strand, for example. Such winding results in the electrical conductor20having an outside surface that is irregular and has asperities. However, the sheath30covering the electrical conductor20has a smooth and continuous outside surface, which makes it possible to form an effective sealing interface with the manufacturing mold in order to limit leakage.

A fill material is also disposed between the sheath30and the electrical conductor20in order to fill in the internal voids or spaces between these two components. This fill material thus blocks the leakage paths in the sheath30itself. A glue31can be provided, for instance, which can also be present on the heat-shrinkable sheath before it is positioned on the connectors.

It will readily be understood that various modifications and/or improvements that are obvious to a person skilled in the art can be made to the different embodiments of the invention described in the present description without departing from the scope of the invention defined by the enclosed claims.