Sensor arrangement comprising a cover element and method for producing the cover element

Abstract

A sensor arrangement of a motor vehicle, the sensor arrangement having a sensor element emitting electromagnetic radiation in a measuring direction to determine a measurement signal, and a cover element disposed in front of the sensor element in the measuring direction and being an injection-molded plastic part permeable to the electro-magnetic radiation and having an outer side facing a vehicle environment and an inner side facing the sensor element, and a heating means comprising conductor tracks. The conductor tracks can be applied to a film formed to the inner side of the cover element during production of the cover element by injection-molding, the film with the conductor tracks thus forming an insert of the injection-molded cover element, the conductor tracks being located on the side of the film facing away from the sensor element.

Claims

1. A sensor arrangement of a motor vehicle, the sensor arrangement comprising: a sensor element emitting electromagnetic radiation in a measuring direction to determine a measurement signal, and a cover element disposed in front of the sensor element in the measuring direction and being an injection-molded plastic part permeable to the electromagnetic radiation and having an outer side facing a vehicle environment and an inner side facing the sensor element, and a heating means comprising conductor tracks, wherein the conductor tracks are applied to a film formed to the inner side of the cover element during production of the cover element by injection-molding, the film with the conductor tracks thus forming an insert of the injection-molded cover element, the conductor tracks being located on the side of the film facing away from the sensor element.

2. The sensor arrangement according to claim 1, wherein the film has an anti-reflection coating on its side facing away from the conductor tracks.

3. The sensor arrangement according to claim 2, wherein the anti-reflection coating is reflective for electromagnetic radiation having a wavelength outside of a specific wavelength spectrum.

4. The sensor arrangement according to claim 2 wherein the anti-reflection coating has a surface structure.

5. The sensor arrangement according to claim 1, wherein the plastic of the cover element is made of a polycarbonate material.

6. The sensor arrangement according to claim 1, wherein the film comprises a polycarbonate material.

7. The sensor arrangement according to claim 1, wherein the cover element is provided with a protective coating on its outer side.

8. The sensor arrangement according to claim 7, wherein the protective coating has a refractive index less than that of the plastic material of the cover element.

9. The sensor arrangement according to claim 1, wherein the cover element is an outer skin element of a vehicle roof.

10. The sensor arrangement according to claim 1, wherein the cover element is an outer skin element of a vehicle front or of a vehicle rear.

11. A method for producing a cover element of a sensor arrangement of a motor vehicle, the method comprising the following steps: providing a film having a first side and a second side; applying conductor tracks to the first side of the film; introducing the film with the conductor tracks into a mold cavity of an injection mold; filling the mold cavity of the injection mold with a plastic material; hardening the plastic material in the mold cavity to form the cover element having the film molded thereon; and demolding the cover element having the film molded thereon.

12. The method according to claim 11, wherein an anti-reflection coating is applied to the second side of the film.

13. The method according to claim 11, wherein the anti-reflection coating is subjected to a structuring process.

14. The method according to claim 12, wherein the film is unwound from a first roller and then wound onto a second roller to apply the anti-reflection coating.

15. The method according to claim 14, wherein the film is unwound from the second roller to apply the conductor tracks.

16. The method according to claim 11, wherein after demolding, the cover element is provided with a protective coating on the side facing away from the film.

17. The method according to claim 13, wherein the structuring process is a plasma etching process.

Description

[0039] The drawing illustrates a motor vehicle 10, which is realized as a station wagon in the case at hand and which has a vehicle roof 12 covering a vehicle interior. At the front, i.e., in the direction of the vehicle front, vehicle roof 12 ends in a wind-shield 14.

[0040] Vehicle roof 12 is an injection-molded part made of a plastic material, which is a polycarbonate material in the case at hand.

[0041] Motor vehicle 10 is designed in such a manner that it allows autonomous or semi-autonomous driving. For this purpose, four sensor arrangements 16, which are environment monitoring sensors, are realized on vehicle roof 12. This makes the sensor arrangements what is referred to as LiDAR sensors, which use laser light as electromagnetic radiation.

[0042] Sensor arrangements 16 are essentially identical and, as illustrated in FIGS. 2 and 3, each comprise a cover element 18 forming a sensor housing in which a sensor element 20 is disposed, sensor element 20 emitting the laser light in a measuring direction X, the laser light passing through the cover element and being used to monitor the vehicle environment.

[0043] Cover element 18 comprises an injection-molded core 22 made of a polycarbonate material and carrying a film arrangement 26 on its inner side 24, which faces sensor element 20. On its outer side 28, which faces the vehicle environment, polycarbonate core 22 is provided with a protective coating 30, which is a protection against scratching, weather and chemicals and is formed by a paint system.

[0044] Film arrangement 26 comprises a film 32 made of a polycarbonate material and provided with conductor tracks 34, which are a heating means for cover element 18, on its side facing core 22. An anti-reflection coating 36 made of a polysiloxane compound is applied to film 32 on the side facing sensor element 20. Anti-reflection coating 36 is structured to increase its anti-reflection effect. In particular, it has what is known as a moth-eye structure, which is produced by plasma etching. In the case at hand, anti-reflection coating 36 has an anti-reflection effect for electromagnetic radiation in the wavelength range between 800 nm and 1200 nm. Electromagnetic radiation having wavelengths greater than 1200 nm and less than 800 nm is reflected by anti-reflection coating 36.

[0045] The production of cover element 20 of sensor arrangement 16 is explained below with reference to highly schematized FIGS. 4 to 7.

[0046] In a first step, film 32, which has a thickness between 100 μm and 400 μm, is provided on a roller 38 and unwound therefrom. At a coating station 39, one side of film 32 is then extensively coated with material 40, which is produced based on polysiloxane and stored in a container 41, to form anti-reflection coating 36, applied material 40 being evenly distributed on film 32 by means of a doctor blade 43. Once anti-reflection coating 36 has been formed and structured by plasma etching, film 32, together with anti-reflection coating 36, is wound onto a second roller 42. Roller 42 is then made available to another processing station 44. There, film 32 provided with anti-reflection coating 36 is unwound from second roller 42 and provided with conductor tracks 34 and contact points on the side facing away from anti-reflection coating 36. In the case at hand, this happens by transfer printing, laser radiation being used for the hardening process. Alternatively, however, the conductor tracks can also be applied by screen printing, dispensing, hot stamping or the like. Film 32 provided with conductor tracks 34 including contact points and with anti-reflection coating 36 is then wound onto a third roller 46. Roller 46 is made available to a cutting station 48, where film 32 provided with conductor tracks 34 and anti-reflection coating 36 is unwound and cut to size on a conveyor belt 50 by means of a die cutting tool 52, which results in film cuts 54 corresponding to film arrangement 26 disposed on cover element 18 in question.

[0047] Film cuts 54 can be removed from conveyor belt 50 by means of a transfer robot and can be placed in a mold cavity 56 of an injection mold 58 as an insert. Injection mold 58 comprises a first tool half 60 and a second tool half 62. The two tool halves 60 and 62 define and limit mold cavity 56 when injection mold 58 is closed. Film cut 54 is mounted on tool half 60 while injection mold 58 is open. Subsequently, injection mold 58 is closed so as to form mold cavity 56, whereupon polycarbonate material for forming polycarbonate core 22 of cover element 18 is introduced into mold cavity 56 via a gate runner 64.

[0048] After hardening of the polycarbonate material in mold cavity 56, injection mold 58 is opened and the cover element comprising film cut 54, i.e., film arrangement 26, and core 22 is demolded.

[0049] In a last method step, core 22 is provided with protective coating 30 on the side facing away from film arrangement 26. Protective coating 30 can be applied in one or two layers. The material used is formed by a paint system which hardens thermally or with the aid of UV radiation. It is applied by spraying or flow coating.

[0050] Resulting cover element 18 can be used to produce sensor arrangement 16.

REFERENCE SIGNS

[0051] 10 motor vehicle

[0052] 12 vehicle roof

[0053] 14 windshield

[0054] 16 sensor arrangement

[0055] 18 cover element

[0056] 20 sensor element

[0057] 22 core

[0058] 24 inner side

[0059] 26 film arrangement

[0060] 28 outer side

[0061] 30 protective coating

[0062] 32 film

[0063] 34 conductor tracks

[0064] 36 anti-reflection coating

[0065] 38 roller

[0066] 39 coating station

[0067] 40 material

[0068] 41 container

[0069] 42 roller

[0070] 43 doctor blade

[0071] 44 processing station

[0072] 46 roller

[0073] 48 cutting station

[0074] 50 conveyor belt

[0075] 52 die-cutting tool

[0076] 54 film cut

[0077] 56 mold cavity

[0078] 58 injection mold

[0079] 60 tool half

[0080] 62 tool half

[0081] 64 gate runner