The invention relates to the field of manufacturing a plastic element intended to be mounted on a motor vehicle bodywork component. Many modern vehicles are equipped with bodywork components made of plastic that can be fitted, for example, to a tailgate, a door side, front and rear bumpers, a roof, etc.
In particular, since the introduction of driver assistance systems, it has been necessary to place sensors of various kinds on certain plastic bodywork components in order to measure external physical parameters representative of the external environment of the motor vehicle. The values of these parameters together form real-time information about the vehicle environment.
Bodywork elements are thus used which are attached to the bodywork component and have, for example, a radome function, i.e. an element transparent to electromagnetic waves protecting and concealing sensors.
As an example, bumpers are now frequently equipped with proximity radars to assist the driver during parking maneuvers of the motor vehicle at low speeds.
Some sensors, such as the one in the example above, may be affected by a layer of ice, snow or frost in temperatures below 10 degrees Celsius because the movement of the vehicle has a negative effect on the temperature. Frost deposits can therefore be observed even at positive temperatures. A layer of frost disturbs the normal passage of electromagnetic waves and is a source of error in the measurement of external physical parameters.
In order to avoid the deposit of frost, which not only renders the assistance system unusable, but can also generate false alarms, it is essential to provide a deicing system on the element for a bodywork component, for example on the area of the bodywork component that serves as a radome.
Such a deicing system is traditionally made up of a heating track formed of conductive wires capable of transforming electrical energy into thermal energy, associated with two connection plates at each end of the heating track in order to supply it with electrical current, the whole being positioned on an element of a bodywork component and close to a sensor. The thermal energy thus released makes it possible to de-ice the part locally in the event of a layer of frost forming. The heating track, to avoid disturbing the passage of electromagnetic waves, must be positioned according to a particular geometry designated in the following by a “serpentine” positioning. For the sake of clarity, a serpentine heating track is defined as follows: a serpentine heating track follows a boustrophedon path, i.e. a path that describes parallel segments with 180° turns between two segments that rotate alternately in one direction and then in the opposite direction with a constant distance between two parallel segments.
Furthermore, a serpentine track designates a track of which the positioning allows the passage of electromagnetic waves characterized by a certain frequency range.
Indeed, the accuracy of the positioning of the heating track is very important in order to prevent it obstructing the passage of electromagnetic waves; in particular, the parallelism between the different segments of the heating tracks and the spacing between these heating tracks must be respected very precisely. For each frequency of electromagnetic wave, there will be a corresponding configuration of the optimal positioning of the heating track so that this heating track is transparent with respect to the passage of this electromagnetic wave.
Such an embodiment does not protect the connecting plates or the conductive track from the aggressions that can occur from the inside of the element for a bodywork component once mounted on a vehicle, such as corrosion. Vibrations and jolts can also after and/or damage the deicing system in the long term, in particular the connection to a connector that allows the electrical supply of the deicing system. In addition, the molding of the bodywork element is complicated by the presence of conductive pins that must be kept partly outside the molding area, so that they are not covered with plastic so as to maintain their conductive properties. Lastly, it is often necessary to re-solder the conductive pins in order to electrically power the deicing system, for example via a standard connector.
The invention aims to overcome these drawbacks by proposing an easily industrializable method which allows a good positioning and adhesion of the deicing system on an element for a bodywork component in a simple, efficient and watertight way, and which ensures, in particular, an easy and robust connection with a connector, giving the final device a very significant reliability and life span.
To this end, the invention relates to a method for producing an element for a bodywork component, characterized in that:
This ensures a good cohesion between the connection member and the connection part of the heating track by ensuring good contact between them through simple squeezing and welding steps, in order to obtain a robust element for a bodywork component. The connection between the connection member and the heating track is thus very reliable. In addition, the covering of the rough form with an additional layer ensures that the heating track and the connection member are sealed and steadied, thus avoiding external influences such as corrosion. Furthermore, by housing the connection member in the housing, there is no, or very limited protrusion from the first face of the rough form, which makes it possible to avoid the formation of bosses once the additional layer is overmolded.
The method according to the invention may also include the following optional features:
The invention also relates to an element for a bodywork component, characterized in that it comprises:
This makes it possible to ensure a good cohesion between the connection member and the connection part of the heating track, the first end of the connection member being squeezed and welded with the coil of the connection part of the heating track in order to ensure a robust connection. The connection between the connection member and the heating track is thus very reliable, the heating track and the connection member are very well protected with an excellent seal, and external aggressions such as corrosion are avoided. The connection member allows the heating track to be easily connected to a power supply, for example via a standard connector. In addition, the additional layer allows complete material continuity between the material layer protecting the device and the plastic element, so that no air bubbles remain that could disturb the passage of electromagnetic waves, especially in the area of the bodywork component that serves as a radome. Lastly, the additional layer makes it possible to improve the resistance of the connection between the connection member and the heating track to the vibrations of the vehicle on which the element for a bodywork component is mounted during use.
The element for a bodywork component according to the invention may also have the following optional features:
The invention will be better understood by reading the following description given by way of example and made with reference to the drawings, in which:
The element 10 for a bodywork component comprises a plastic rough form 11, a heating track 12, an additional plastic layer 13 and an electrically conductive connection member 14.
The plastic rough form 11 has at least one housing 15. The housing 15 is located on a first face 16 of the rough form 11.
The housing 15 comprises an orifice 17 that extends between a bottom 18 of the housing 15 and a second face 19 of the rough form 11 opposite the first face 16.
In the example described, the rough form 11 has two housings 15, as shown in
Referring to
The heating track 12 comprises an electrically conductive material. In the example described, the heating track 12 comprises copper covered with an insulating enamel layer. It should be noted that the heating track 12 can, for example, comprise tungsten or an alloy based on copper or tungsten. In addition, the insulating layer may, for example, comprise an insulating paint instead of enamel. When a current flows through the heating track 12, it releases calories by the Joule effect. Lastly, in the example described, the heating track 12 has a diameter between 300 and 500 μm.
As can be seen in
In the example described, the first end 21 of the electrical connection element 14 is formed by a tab bent in a hook shape comprising a web 23 connecting a first free branch 24 and a second branch 25 intended to be in contact with the bottom 18 of the housing 15. The second end 22 of the connection member 14 is formed by an extension 26 of the second branch 25, bent with respect to the second branch 25, for example at right angles. In addition, the connection member 14 comprises a silver-copper alloy.
The connection member 14 may also comprise a snap-in tab 27 carried by the second end 22 of the connection member 14 so as to be held in position in the housing 15. This snap-in tab 27 cooperates with the second face 19 of the rough form 11.
Lastly, the additional plastic layer 13 overmolds the first face 16 of the rough form 11. Thus, in the example described, the additional layer 13 covers the heating track 12, the first end 21 of the connection member 14, the housing 15 and the orifice 17 in the rough form 11.
A method according to the invention for manufacturing the element 10 for a bodywork component will be described below.
First of all, the rough form 11 made of plastic is manufactured. In the example described, the rough form 11 comprises two housings 15, each with an orifice 17.
Then, as shown in
The electrically conductive heating track 12 is then positioned on the first face 16 of the rough form 11, for example with the aid of a sonotrode. The heating track 12 comprises a connection part 20c at the housing 15 of the rough form 11, which connection part is free with respect to the first face 16 of the rough form 11 so as to facilitate its connection to the connection member 14. As shown in
In the example described, the heating track 12 is welded to the first face 16 of the rough form 11 by heating the heating track 12, for example by generating an electric current or ultrasound in the heating track 12, to a temperature that allows local melting of the plastic of the rough form 11.
Subsequently, the connection part 20c of the track 12 is affixed to the first end 21 of the connection member 14 by forming at least one coil of the connection part 20c of the track 12 around the first end 21 of the connection member 14. In the example described, as shown in
Referring to
Then, the insulating enamel layer covering the heating track 12 is locally destroyed. In the example described, the insulating enamel layer is destroyed by inputting electrical energy via a tool that squeezes the first end 21 of the connection member 14 with the connection part 20c of the track 12. The combination of the effect of the energy input and the mechanical effect of the squeezing effectively destroys the insulation layer. It should be noted that the amount of energy input is related to the thickness and nature of the insulation and that preferably the squeezing tool 28 used during the squeezing step is used.
Next, the first end 21 of the connection member 14 and the two coils of the connection part 20c of the track 12 are welded together, for example by the input of electrical energy. In the example described, the welding energy is applied via a tool squeezing the first end 21 of the connection member 14 with the connection part 20c of the track 12. It should be noted that the intensity of the electric current or ultrasound depends on the material forming the heating track 12 and may be different from the intensity used to destroy the insulation layer. It should also be noted that the squeezing tool 28 used during the squeezing step is preferably used. The same tool can thus be used to squeeze together the first end 21 of the connection member 14 and the two coils of the connection part 20c of the heating track 12 and to destroy the enamel layer and to weld the first end 21 of the connection member 14 to the connection part 20c of the track 12. In addition, a large contact surface is formed between the connection member 14 and the heating track 12, thus ensuring a robust and quality electrical connection.
It should be noted that the pre-positioning of the connection member 14 with respect to the rough form allows free access to the first end 21 of the connection member 14 for squeezing and welding means.
The first end 21 of the connection member 14 is then positioned in the housing 15. It should be noted that, as shown in
Lastly, the additional layer 13 of plastic is overmolded on the first face 16 of the rough form 11 so as to cover the heating track 12, the first end 21 of the connection member 14, the housing 15 and the orifice 17 of the rough form 11. It should be noted that, in the example described, the additional layer 13 of plastic completely covers the heating track 12 in order to provide good protection against shocks and corrosion of the track 12 and good sealing of the assembly 10. In addition, the additional layer 13, by filling the orifice 17, improves the resistance of the connection between the connection member 14 and the heating track 12 to the vibrations of the vehicle on which the element for a bodywork component is mounted during use.
The invention is not limited to the embodiment presented, and other embodiments will clearly be apparent to a person skilled in the art. In particular, the first end 21 of the connection member 14 may have teeth and the attachment may be achieved by winding or engaging the connection part 20c of the heating track 12 around teeth formed by the first end 21 of the connection member 14. In addition, the connection member 14 can be held in position in the housing 15 by means of complementary snap-in means carried on the second end 22 of the connection member 14 and the second face 19 of the rough form 11, for example the snap-in tab 27 can be carried on the second face 19 of the rough form 11 or on a wall of the orifice 17.
Number | Date | Country | Kind |
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1853420 | Apr 2018 | FR | national |
This application claims priority under 35 U.S.C. § 371 to the International Application No. PCT/EP2019/060241, filed Apr. 19, 2019, and to the French Application No. 1853420, filed Apr. 19, 2018, now pending, the contents of which are hereby incorporated by reference.
Filing Document | Filing Date | Country | Kind |
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PCT/EP2019/060241 | 4/19/2019 | WO | 00 |