Lighting device for a motor vehicle

Abstract

The invention relates to a lighting device (1) for a motor vehicle, comprising: - a device housing (3) which partially delimits a light guide receiving space (11) for receiving a light guide element (5); - the light guide element (5) which is arranged in the light guide receiving space (11) which has a light coupling-in surface (13) for coupling in light; - a coupling-in element (7), light coupled into the coupling-in element (7) being coupled into the light guide element (5) by means of the light coupling-in surface (13), and - a light generating device (9) having a plurality of light sources (15), at least one first light source (15.1) being configured to emit white light, the light generating device (9) being arranged relative to the coupling-in element (7) in such a way that light emitted by the light sources (15) is coupled into the coupling-in element (7).

Description

[0001] Daimler Truck AG 1 Michael Lierheimer

[0002] August 27, 2025

[0003] Lighting device for a motor vehicle

[0004] The invention relates to a lighting device for a motor vehicle, in particular a commercial vehicle.

[0005] Motor vehicles, especially commercial vehicles, typically have a lighting system in which several functions are implemented using a single light guide element. Light emitted by different colored LEDs is coupled into this element. For example, white light is coupled into the light guide element to create a daytime running light function. At a different time, yellow, and especially amber, light is coupled in to create a turn signal function. A position light function can also be implemented in this way. To implement the turn signal function, the light guide must have a specified minimum diameter to allow a sufficient number of LEDs, particularly amber ones, to be arranged in such a way that the light emitted by the LEDs is coupled into the light guide element through a light coupling surface.The LEDs are positioned relatively close together because space is limited and costs and manufacturing times need to be kept comparatively low. However, such a close arrangement leads to a build-up of heat emitted by the LEDs. This heat is therefore usually dissipated via an aluminum heat sink. To withstand the thermal stress, the circuit boards on which the LEDs are mounted feature aluminum, a copper core, or ceramic, which also increases the cost of such a component. To couple the light emitted by the LEDs, a relatively close positioning of the LEDs to the light coupling surface is necessary. This, however, results in a comparatively high thermal load on the light guide element, which is typically made of plastic.Therefore, only materials with sufficient thermal resistance, particularly a sufficiently high melting point, can be used. Conversely, for a light guide element, only materials that maintain a consistent color spectrum of the coupled light, even over a relatively long spatial extent, can be used. This is precisely the case, for example, with Daimler Truck AG 2 Michael Lierheimer.

[0006] This is not the case with a polycarbonate light guide element as of August 27, 2025. When white light is coupled into it, a change towards yellow light occurs along a spatial extent. However, an excessive change in the color spectrum can lead to the ECE color requirements no longer being met.

[0007] The invention is therefore based on the objective of creating a lighting device for a motor vehicle, in particular a commercial vehicle, whereby the aforementioned disadvantages are reduced, or preferably do not occur.

[0008] The problem is solved by providing the present technical teaching, in particular the teaching of the independent claims and of the preferred embodiments disclosed in the dependent claims and the description.

[0009] The problem is solved, in particular, by providing a lighting device for a motor vehicle, especially a commercial vehicle, comprising a device housing, a light guide element, a coupling element, and a light-generating device. The device housing partially defines a light guide receiving space for receiving the light guide element. The light guide element is arranged in the light guide receiving space and, in particular, is snapped into place with the device housing. The light guide element has a light coupling surface for coupling light into it. The coupling element is a separate element from the light guide element. The coupling element is designed and arranged in the region of the light coupling surface, and in particular connected to the light guide element, such that light coupled into the coupling element is coupled into the light guide element by means of the light coupling surface, and in particular through the light coupling surface.The light-generating device comprises a plurality of light sources. At least one of the plurality of light sources is configured to emit white light. The light-generating device is arranged relative to the coupling element such that light generated by the light sources is coupled into the coupling element.

[0010] Advantageously, the light emitted by the light sources is first coupled into the coupling element. The light coupled into the coupling element is then guided and, in particular, focused by the coupling element, especially by means of total internal reflection. The focused light is then coupled from the coupling element into the light guide element. This arrangement makes it possible, in particular, to reduce the thermal stress on the light guide element. (Daimler Truck AG 3 Michael Lierheimer)

[0011] 27.08.2025 a light coupling surface of the light guide element further away from the light sources than without a coupling element.

[0012] In one embodiment, the light guide element has a comparatively large longitudinal extent and a relatively small transverse and vertical extent. In particular, the light guide element is rod-shaped and, in particular, curved. Specifically, the light guide element has a first, in particular circular, base surface, a second, in particular circular, base surface, and a lateral surface connecting the first and second base surfaces. Specifically, the light guide element has a first end – in particular at the first base surface – and a second end – at the second base surface – spaced apart along its longitudinal extent from the first end. In particular, the light coupling surface is formed by the first or the second base surface. Specifically, the light coupling surface is arranged at the first or second end and is formed, in particular, by the light guide element.

[0013] In one embodiment, the light-generating device is the only light-generating device that couples light – mediated via the coupling element – ​​into the light guide element – ​​through the light coupling surface. In particular, the lighting device is free of a further light-generating device that couples light into the light guide element via the outer surface.

[0014] In particular, the light guide element has several coupling structures by means of which the light contained in the light guide element is coupled out of the light guide element.

[0015] In one embodiment, the lighting device has a transparent housing cover which, together with the device housing, defines the light guide receiving space. In particular, the transparent housing cover is a design element of the lighting device.

[0016] In one embodiment, the light guide element is connected to the housing cover, in particular by snapping it into place.

[0017] According to a further development of the invention, the light guide element is formed from or comprises a first material. The coupling element is made of a material developed by Daimler Truck AG 4 Michael Lierheimer

[0018] 27.08.2025 first material different second material formed or has a second material.

[0019] Therefore, it is advantageously possible to select a material for both the optical fiber element and the coupling element that is particularly suitable for the function to be performed by each element. For the optical fiber element, it is possible to select a material that alters the color spectrum of the light coupled into it as little as possible, while for the coupling element, a material is selected that exhibits the highest possible thermal resistance, in particular a comparatively high melting point.

[0020] According to a further development of the invention, the light guide element is made of or comprises polymethyl methacrylate. Alternatively or additionally, it is provided that the coupling element is made of or comprises polycarbonate.

[0021] Polymethyl methacrylate advantageously alters the color spectrum of the light coupled into the light guide element relatively little, but exhibits comparatively low temperature resistance. In particular, it facilitates compliance with ECE color requirements. Polycarbonate advantageously has a sufficiently high melting point, so that the coupling element possesses sufficient thermal resistance to the heat generated by the light sources. Although polycarbonate causes a shift in the color spectrum towards yellow, the coupling element is relatively small, so that the light is only minimally altered.

[0022] Alternatively, the coupling element is made of or contains polymethacrylmethylimide.

[0023] According to a further development of the invention, the coupling element is formed from a solid material. Advantageously, this makes it possible to guide light coupled into the coupling element particularly easily by means of the physical effect of total internal reflection.

[0024] According to a further development of the invention, the light sources are designed as light-emitting diodes. Light-emitting diodes advantageously consume comparatively little energy and require relatively little installation space. Daimler Truck AG 5 Michael Lierheimer

[0025] August 27, 2025

[0026] According to a further development of the invention, the coupling element has a light entry surface facing the light-generating device and a light exit surface facing the light guide element. The light entry surface is larger than the light exit surface.

[0027] It is advantageous to increase the distance between the light sources, particularly such that the imaginary area spanned by the light sources is larger than the light coupling area of ​​the optical fiber. This makes it possible to reduce the thermal load on the light sources. In particular, it is easier to dissipate the heat generated by the light sources. It is also advantageous to reduce the transverse and / or vertical extent of the optical fiber element, especially its diameter. This makes it easier to bend the optical fiber element, particularly to bend it with a tighter radius of curvature than with a standard diameter.

[0028] Alternatively or additionally, the coupling element is designed in a frustoconical shape. This represents a particularly simple design of the coupling element for achieving total internal reflection and two differently sized light entry surfaces.

[0029] Alternatively, the coupling element is cylindrical, in particular circular cylindrical.

[0030] According to a further development of the invention, the coupling element is welded and / or screwed and / or snapped to the light guide element. This makes it possible to attach the coupling element to the light guide element in various ways.

[0031] According to a further development of the invention, at least one second light source of the plurality of light sources is configured to emit yellow light, in particular amber-colored light. The lighting device is designed as a position light and / or as a daytime running light and / or as a direction indicator light.

[0032] In one embodiment, the lighting device has a plurality of first light sources that emit white light and a plurality of second light sources that emit yellow, in particular amber, light.

[0033] In one embodiment, the first light sources are grouped into a first group, and the second light sources are grouped into a second group. In particular, the first Daimler Truck AG 6 Michael Lierheimer

[0034] August 27, 2025

[0035] The first group and the second group are arranged side by side, specifically one above the other, facing away from the main direction of light emission. Specifically, the first light sources within the first group are arranged side by side in a first row. Specifically, the second light sources within the second group are arranged side by side in a second row.

[0036] In one embodiment, the light-generating device has, in particular, exactly three first light sources and, in particular, exactly three second light sources.

[0037] According to a further development of the invention, the light-generating device comprises a support component. The majority of light sources are connected to the support component on a first side of the component. A heat sink is connected to the support component on a second side of the component, opposite the first side. The heat sink is designed and arranged to absorb heat generated by the light sources and dissipate it to an ambient medium, in particular ambient air.

[0038] Advantageously, the heat sink ensures sufficient dissipation of the heat generated by the light sources.

[0039] In one embodiment, the heat sink has a plurality of cooling fins. In particular, the heat sink has a fastening element on a body side facing the support component, by means of which the support component can be attached to the heat sink.

[0040] In one embodiment, the heat sink is made of an aluminum material or an aluminum alloy, or comprises an aluminum material or an aluminum alloy.

[0041] According to a further development of the invention, the light sources are arranged on the same component of the light-generating device. Advantageously, the heat generated by the light sources can be dissipated by means of a single heat sink. Furthermore, such an arrangement requires particularly little installation space. In particular, all first light sources and all second light sources are arranged on the same component.

[0042] In one embodiment, the light sources are arranged on the support component. In particular, all first light sources and all second light sources are on the same Daimler Truck AG 7 Michael Lierheimer

[0043] August 27, 2025

[0044] The support component is arranged. In particular, the light sources are electrically connected to the support component, especially by soldering. In particular, the support component is designed as an electronic circuit board.

[0045] According to a further development of the invention, the light sources are spaced apart from the coupling element by a distance A, wherein the distance A is from 0.5 mm to 1 mm.

[0046] In particular, this ensures that the light sources are positioned with a minimal gap to the coupling element.

[0047] According to a further development of the invention, the lighting device has a hollow connecting element. The light guide element is inserted into the hollow connecting element from a first side and, in particular, locked into place. The coupling element is inserted into the hollow connecting element from a second side and, in particular, locked into place. This provides a particularly simple way to correctly position the coupling element in the area of ​​the light coupling surface.

[0048] In one embodiment, the first side and the second side are arranged opposite each other on the connecting element.

[0049] In one embodiment, the hollow connecting element is cylindrical in shape, particularly annular in shape. In particular, the hollow connecting element is designed as a connecting sleeve.

[0050] In one embodiment, the coupling element comprises or is made of an opaque material. In particular, the material is opaque. This advantageously allows light hotspots and stray light that arise during coupling to be shielded.

[0051] According to a further development of the invention, a first element, selected from the light guide element, the connecting element, and the coupling element, comprises at least one alignment element. A second element, different from the first element and also selected from the connecting element, the coupling element, and the light guide element, comprises at least one counter-alignment element. The at least one alignment element and the at least one counter-alignment element are arranged relative to each other and interact in such a way that a distance and a specific positioning between the majority of Daimler Truck AG 8 Michael Lierheimer

[0052] August 27, 2025

[0053] light sources and the coupling element, in particular the light entry surface of the coupling element, is ensured.

[0054] According to a further development of the invention, the at least one alignment element is designed as a pin. The at least one counter-alignment element is designed as a recess corresponding to the pin. In particular, the at least one alignment element engages with the at least one counter-alignment element. In particular, the at least one alignment element is latched to the at least one counter-alignment element.

[0055] The invention will be explained in more detail below with reference to the drawing. The drawing shows:

[0056] Fig. 1 shows a schematic first representation of an embodiment of a lighting device for a motor vehicle,

[0057] Fig. 2 is a schematic, enlarged second representation of the lighting device of Figure 1.

[0058] Fig. 3 is a schematic, enlarged third representation of the lighting device of Figure 1, and

[0059] Fig. 4 shows a schematic representation of the lighting device of Figure 1 in comparison with a second embodiment of a lighting device.

[0060] Figure 1 shows a schematic first representation of an embodiment of a lighting device 1 for a motor vehicle (not shown). The lighting device 1 is shown in an unassembled state – in an exploded view.

[0061] The lighting device 1 comprises a housing 3, a light guide element 5, a coupling element 7, and a light-generating device 9 shown in Figure 3. The housing 3 partially defines a light guide receiving space 11 for receiving the light guide element 5. In the assembled state, the light guide element 5 is arranged in the receiving space 11 and, in particular, is snapped into the housing 3. The light guide element 5 has a light coupling surface 13 for coupling light into it. The coupling element 7 is a separate element from the light guide element 5. The coupling element 7 is designed and arranged in the region of the light coupling surface 13, and in particular connected to the light guide element 5, such that light coupled into the coupling element 7 is coupled into the light guide element 5 via the light coupling surface 13.The light generating device 9 has a plurality Daimler Truck AG 9 Michael Lierheimer.

[0062] 27.08.2025 from light sources 15 (see Figure 4). At least one first light source 15.1 of the plurality of light sources 15 is configured to emit white light. The light-generating device 9 is arranged relative to the coupling element 7 such that light emitted by the light sources 15 is coupled into the coupling element 7. The light guide element 5 is made of polymethyl methacrylate. Additionally, the coupling element 7 is made of solid polycarbonate. The coupling element 7 is welded and / or screwed and / or – as in this case – snapped to the light guide element 5.

[0063] A section B, outlined with a dashed line, is shown enlarged in Figure 2.

[0064] Figure 2 shows a schematic, enlarged second representation of the dashed-edged section B of the lighting device 1 from Figure 1.

[0065] In this context, identical and functionally equivalent elements in all figures are provided with the same reference symbols, so that reference is made to the preceding description in each case.

[0066] The lighting device 1 further comprises a hollow connecting element 17. The light guide element 5 is inserted into the hollow connecting element 17 from a first side 19.1 and thus locked in place. The coupling element 7 is inserted into the hollow connecting element 17 from a second side 19.2 and thus locked in place.

[0067] In an embodiment not shown, a first element, selected from the light guide element 5, the connecting element 17, and the coupling element 7, has at least one alignment element. A second element, distinct from the first element and also selected from the connecting element 17, the coupling element 7, and the light guide element 5, has at least one counter-alignment element. The at least one alignment element and the at least one counter-alignment element are arranged relative to each other and interact in such a way as to ensure a distance and a specific positioning between the plurality of light sources 15 and the coupling element 7, in particular a light entry surface 21 of the coupling element 7.

[0068] Figure 3 shows a schematic, enlarged third view of a right side 24 of the lighting device 1 from Figure 1. The device housing 3 and the light guide element 5 are not shown. Daimler Truck AG 10 Michael Lierheimer

[0069] August 27, 2025

[0070] The light-generating device 9 further comprises a support component 23, which is designed, for example, as an electronic circuit board. A plurality of light sources 15 are connected to the support component 23 on a first component side 25.1. In the assembled state, a heat sink 27 is connected to the support component 23 on a second component side 25.2 opposite the first component side 25.1. The heat sink 27 is designed and arranged to absorb heat generated by the light sources 15 and dissipate it to an ambient medium, in particular ambient air. For this purpose, the heat sink 27 has a plurality of cooling fins 29. The light sources 15 arranged on the support component 23 are designed as light-emitting diodes.

[0071] Preferably, all light sources 15 are arranged on the same support component 23. In particular, all light sources 15 are electrically connected to the support component 23, especially by soldering.

[0072] In the assembled state of the lighting device 1, the support component 23 in Figure 1 is arranged on the right side 24 of the device housing 3 (see Figure 1), so that the heat sink 27 is located outside the device housing 3, with the light sources 15 radiating into the light guide receiving space 11 - into the coupling element 7.

[0073] Figure 4 shows a schematic representation of the lighting device 1 of Figure 1 in comparison with a second embodiment of a lighting device 1.

[0074] Figure 4 comprises sub-figures 4a and 4b. In the embodiments shown in these two sub-figures, the coupling element 7 has a light-entry surface 21 facing the light-generating device 9 and a light-emission surface 31 facing the light guide element 5. At least one second light source 15.2 of the plurality of light sources 15 is configured to emit yellow light, in particular amber light. The light sources 15 are spaced apart from the coupling element 7 by a distance A, where the distance A is from 0.5 mm to 1 mm. The right-hand part of each of the two sub-figures shows a relative arrangement of the light sources 15 with a view to the light-entry surface 21 of the coupling element 7.

[0075] The first light sources 15.1, which emit white light, are grouped into a first group 33.1 (shown with dashed lines), while the second light sources 15.2, which emit yellow light, are grouped into a second group 33.2 (shown with dashed lines). Preferably, the first group 33.1 and the second group 33.2 are positioned next to each other, particularly one above the other, facing away from the main emission direction of the light sources 15; i.e., into the image plane. (Daimler Truck AG, Michael Lierheimer)

[0076] The first light sources 15.1 are preferably arranged side by side in a first row 35.1 within the first group 33.1. Preferably, the second light sources 15.2 are arranged side by side in a second row 35.2 within the second group 33.2.

[0077] In the first embodiment of the lighting device 1 in partial figure 4a, the coupling element 7 is cylindrical in shape. The light sources 15 are arranged relatively close together. The light entry surface 21 and the light exit surface 31 are of the same size.

[0078] In the second embodiment of the lighting device 1 in partial figure 4b, the coupling element 7 is designed in a frustoconical shape, in that the light entry area 21 is larger than the light exit area 31. The light sources 15 can be spaced further apart than in partial figure 4a.

[0079] Daimler Truck AG 12 Michael Lierheimer

[0080] August 27, 2025

[0081] Reference symbol list

[0082] I Lighting device Device housing Light guide element Coupling element Light generating device

[0083] II Fiber optic reception room

[0084] 13 Light coupling area

[0085] 15 light sources

[0086] 15.1 First light sources

[0087] 15.2 Second light sources

[0088] 17 Connecting element

[0089] 19.1 first page

[0090] 19.2 second side 1 Light entry surface 3 Support component 5.1 first component side 5.2 second component side 7 Heat sink 9 Cooling fins 1 Light exit surface 3.1 first group 3.2 second group 5.1 first row 5.2 second row

Claims

Daimler Truck AG 13 Michael Lierheimer August 27, 2025 Patent claims 1. Lighting device (1) for a motor vehicle, comprising: - a device housing (3) that partially defines a fiber optic receiving space (11) for receiving a fiber optic element (5); - the light guide element (5) which is arranged in the light guide receiving space (11), wherein the light guide element (5) has a light coupling surface (13) for coupling in light; - a coupling element (7) which is a different element from the light guide element (5), wherein the coupling element (7) is designed and arranged in the area of ​​the light coupling surface (13) such that light coupled into the coupling element (7) is coupled into the light guide element (5) by means of the light coupling surface (13), and - a light-generating device (9) comprising a plurality of light sources (15), wherein at least one first light source (15.1) of the plurality of light sources (15) is configured to emit white light, wherein the light-generating device (9) is arranged relative to the coupling element (7) such that light emitted by the light sources (15) is coupled into the coupling element (7).

2. Lighting device (1) according to claim 1 , wherein - the optical fiber element (5) is made of or comprises a first material, wherein - the coupling element (7) is made of a second material different from the first material or has a second material.

3. Lighting device (1) according to one of the preceding claims, wherein - the light guide element (5) is made of polymethyl methacrylate or contains polymethyl methacrylate, and / or wherein Daimler Truck AG 14 Michael Lierheimer August 27, 2025 - the coupling element (7) is made of polycarbonate or comprises polycarbonate, or wherein the coupling element (7) is made of polymethacrylic methylimide or comprises polymethacrylic methylimide.

4. Lighting device (1) according to one of the preceding claims, wherein - the coupling element (7) is made of a solid material.

5. Lighting device (1) according to one of the preceding claims, wherein - the light sources (15) are designed as light-emitting diodes.

5. Lighting device (1) according to one of the preceding claims, wherein - the coupling element (7) has a light entry surface (21) facing the light generating device (9) and a light exit surface (31) facing the light guide element (5), wherein the light entry surface (21) is larger than the light exit surface (31), and / or wherein - the coupling element (7) is shaped in a frustoconical shape.

7. Lighting device (1) according to one of the preceding claims, wherein - the coupling element (7) is welded and / or screwed and / or locked to the light guide element (5).

8. Lighting device (1) according to one of the preceding claims, wherein - at least one second light source (15.2) of the plurality of light sources (15) is set up to emit yellow light, wherein - the lighting device (1) is designed as a position light and / or as a daytime running light and / or as a direction indicator light.

9. Lighting device (1) according to one of the preceding claims, wherein - the light-generating device (9) has a support component (23), wherein - the majority of light sources (15) are connected to the support component (23) on a first component side (25.1), wherein - a heat sink (27) is connected to the support component (23) on a second component side (25.2) opposite the first component side (25.1), wherein Daimler Truck AG 15 Michael Lierheimer August 27, 2025 - the heat sink (27) is set up and arranged in such a way as to absorb heat generated by the light sources (15) and transfer it to an ambient medium.

10. Lighting device (1) according to one of the preceding claims, wherein - the light sources (15) are arranged on the same component of the light-generating device (9).

11. Lighting device (1) according to one of the preceding claims, wherein - the light sources (15) are spaced apart from the coupling element (7) by a distance A, where the distance A is from 0.5 mm to 1 mm.

12. Lighting device (1) according to one of the preceding claims, comprising a hollow connecting element (17), wherein - the light guide element (5) is inserted into the hollow connecting element (17) from a first side (19.1), wherein - the coupling element (7) is inserted into the hollow connecting element (17) from a second side (19.2).

13. Lighting device (1) according to claim 12, wherein - a first element, selected from the light guide element (5), the connecting element (17) and the coupling element (7), comprising at least one alignment element, wherein - a second element, different from the first element, selected from the connecting element (17), the coupling element (7) and the light guide element (5), comprising at least one counter-alignment element, wherein - that at least one alignment element and at least one counter-alignment element are arranged and interact in such a way that a distance and a specific positioning between the plurality of light sources (15) and the coupling element (7) is ensured.

14. Lighting device (1) according to claim 13, wherein - that at least one alignment element is designed as a pin, wherein - that at least one counter-alignment element is designed as a recess corresponding to the pin.

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