Method for Producing a Surface Heater for a Sub-Region of a Vehicle

Abstract

A method for producing a surface heater for heating a sub-region of a vehicle includes a first step, a second step, a third step, and a fourth step. The first step includes arranging heating wires on a film and either: i) the film is subsequently formed to a predefined shape, or ii) providing a film which has been formed to a predefined shape. The second step includes inserting the formed film into an injection-molding tool. The heating wires point either toward the wall or into the hollow space of the injection-molding tool. The third step includes overmolding with a predefined material. The fourth step includes applying a transparent lacquer layer to the finished injection-molded part.

Claims

1.-10. (canceled)

11. A method for producing a surface heater for heating a sub-region of a vehicle, the method comprising: a first step of arranging heating wires on a film and either: i) the film is subsequently formed to a predefined shape, or ii) providing a film which has been formed to a predefined shape; a second step of inserting the formed film into an injection-molding tool, wherein the heating wires point either toward the wall or into the hollow space of the injection-molding tool; a third step of overmolding with a predefined material; and a fourth step of applying a transparent lacquer layer to the finished injection-molded part.

12. The method according to claim 11, wherein the thickness of the lacquer layer in the fourth step is selected in such a way that the heating wires are completely embedded in the material.

13. The method according to claim 12, wherein the thickness of the total layered composite composed of film with heating wires, material and lacquer layer is between 2 mm and 7 mm inclusive, and is a multiple of half the wavelength of the radar beams in the material.

14. The method according to claim 13, wherein the lacquer layer has a thickness of between 0.2 mm and 1.0 mm.

15. The method according to claim 14, wherein the lacquer layer is applied in the tool via flooding.

16. The method according to claim 15, wherein the formed film occupies a sub-region of the injection-molding tool.

17. The method according to claim 16, wherein the heating wires are colored at least in sub-regions, over the entire area, in the color of the material.

18. The method according to claim 17, wherein, in the third step, the overmolding is performed with the predefined material in such a way that a structured surface with a predefined structure is generated.

19. The method according to claim 18, wherein the material is a polycarbonate.

20. The method according to claim 19, wherein the sub-region of the vehicle is one or more regions on which radar components and/or further sensor components to be heated are arranged.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 is a flow diagram of the inventive method; and

[0018] FIG. 2 is a component with connector, produced by way of the inventive method.

DETAILED DESCRIPTION OF THE DRAWINGS

[0019] In the following descriptions of the figures, identical elements or functions are provided with identical reference designations.

[0020] The production method for the above-described surface heater is described below. In a first step S1, a film heater is provided, comprising a film 1 with heating wires 11, which is intended to be used as a heater for, for example, a radar sensor at the front of a vehicle. This film heater can either already be present as a finished component or can be manufactured in a pre-processing step. Here, heating wires 11, which are composed of an electrically conductive material such as copper, are applied, for example adhesively bonded, to a film 1. The process is known to the person skilled in the art. The film 1 with the heating wires 11 is formed to a predefined shape. This shape is for example the shape of a front panel, in particular a kidney panel, of a vehicle. The film heater is thus formed such that it is flush with the surface of the sub-region to be produced of the vehicle, for example of the front panel, or can be arranged thereon.

[0021] Before the film heater is inserted into the injection-molding tool in the second step S2, it is advantageous if said heater is cleaned. To this end, corresponding processes are known to the person skilled in the art.

[0022] In the second step S2, the formed film heater is inserted into an injection-molding tool. Here, the heating wires 11 can point either toward the wall or into the hollow space of the injection-molding tool.

[0023] In the third step S3, an overmolding operation is then performed with a predefined material 2, for example polycarbonate.

[0024] In the fourth step S4, a transparent lacquer layer 3 is then applied to the finished injection-molded part.

[0025] The thickness of the lacquer layer 3 is selected in the fourth step S4 depending on how the heating wires 11 were inserted into the injection-molding tool in the second step S2.

[0026] After the insertion of the film 1 with the heating wires 11 into the injection-molding tool in the second step S2, the overmolding operation is performed with the material 2, for example polycarbonate, in the third step S3. The thickness of the material 2 is selected in such a way that the heating wires 11 are completely embedded in the material 2, for example polycarbonate. This corresponds, for example, to a thickness of the material 2 between 2 mm or 3 mm to 12 mm (in each case inclusive). A thickness of approximately 2 mm, 3 mm, 5 mm, 7 mm or 10 mm is advantageous depending on the type of heating wires 11 and their orientation in the tool.

[0027] If the heating wires 11 point toward the wall of the injection-molding tool after insertion into the injection-molding tool in the second step S2, the thickness of the lacquer layer 3 can, on account of the back-molding with the material 2, be somewhat thinner than if the heating wires 11 point into the hollow space of the injection-molding tool after insertion into the injection-molding tool in the second step S2. Depending on the embodiment, the thickness is selected to be between 0.2 mm and 1.0 mm (in each case inclusive), advantageously approximately 0.7 mm.

[0028] The thickness of the total layered composite composed of film 1 with heating wires 11, material 2 and lacquer layer 3 advantageously lies between 2 mm and 7 mm inclusive, and is advantageously a multiple of half the wavelength of the radar beams in the material.

[0029] The lacquer layer 3 is transparent, such that the underlying material 2 with the film heater is substantially visible. For this reason, it is expedient for the heating wires 11 to be provided in a color which corresponds to the color of the material 2. The heating wires 11 can be colored prior to production of the film heater.

[0030] The material of which the lacquer layer 3 is composed is for example PUR or polyurea. This coating above the material 2, for example consisting of polycarbonate, is used to protect the material 2 against UV radiation and other media which would attack the material 2. On account of the low viscosity of the polyurethane, very low layer thicknesses are possible, without large shear forces being applied. This increases the process safety during the overmolding. The film heater with the heating wires 11 can be positioned closer to the surface to be heated, for example a radar sensor, as a result of which the energy requirement is reduced, and the response behavior of the heater is improved. As a result of the subsequent flooding of the film 1, the visible film edges can be concealed, and non-visible integration of a partial heating region in a large component such as a front panel is thus made possible even for transparent materials.

[0031] The material used for the lacquer layer 3 should in any case be transparent and suitable for use for the flooding operation, that is to say have a correspondingly suitable viscosity. Alternatively, a spraying operation can also be performed.

[0032] For the application of the lacquer layer 3, it is advantageous if the finished injection-molded part, that is to say the produced sub-region of the vehicle with the film heater, remains in the injection-molding tool.

[0033] The contact-connection of the heating wires 11 is effected by way of a corresponding connector 4, which can be attached, and contact-connected, to the film heater prior to or after the injection-molding process. The introduction of current heats the heating wires 11 and a defrosting or de-icing operation can be performed.

[0034] By means of the proposed method, it is possible to achieve the target of providing a transparent vehicle front which makes it possible to view the exterior component produced from the described material and possibly provided with design elements, but in the case of which the heating wires 11 are not visible (to a detrimental extent) and cannot be felt when touched. This is achieved by the application of the transparent lacquer layer 3. The heating wires 11 have a diameter of approximately 0.05 mm to 0.1 mm, such that the lacquer layer 3 can likewise be selected to be very thin.

[0035] The method, for heating a predefined area of a vehicle, in particular a region with a radar sensor, is thus implemented in such a way that a film-based heating element is inserted with the wire side pointing toward the cavity or toward the injection-molding tool in the injection-molding tool, and the film side is subsequently back-molded with a predefined material, for example polycarbonate, in a first shaping process. Subsequently, the cavity is opened, and the composite component composed of film heater and first plastics constituent is assigned to a second cavity, either inside one tool or a further tool is used. Thereafter, a further coating operation is carried out with a transparent polyurethane (PUR). In this case, the coating is flooded over the wire side of the entire component for complete embedding of the film-based heater. In order to conceal any noticeable structures which may still be present through the film 1, more specifically the edges thereof, the material 2 can be produced in a predefined structure which integrates the edges of the film 1 in said structure and thus makes them part of the design.