Headlights for a motor vehicle with improved temperature compensation

Abstract

Headlight (1) for a motor vehicle with a housing (10) in which at least one light module (11) is received in a predetermined position, wherein the receiving of the light module (11) has at least one compensating element (12) for compensating for thermally induced deviations of the position of the light module (11) from the predetermined position in the headlight (1), characterized in that the compensating element (12) has an effective extension length (L) and comprises a device (15, 16) for adjusting the effective extension length (L), wherein the device for adjusting is designed to change the effective extension length (L) of the compensating element (12) during operation of the headlight (1).

Description

Changed description (pure version)

[0001] The present invention relates to a headlight for a motor vehicle having a housing in which at least one light module is accommodated in a predetermined position, wherein the receptacle of the light module has at least one compensating element for compensating thermally induced deviations of the position of the light module from the predetermined position in the headlight.

[0002] Headlights consist of various assemblies with corresponding functions. These assemblies include, for example, the housing assembly with connections to the vehicle, the housing itself, as well as cable assemblies and fastening and adjustment mechanisms. Another assembly consists of the light module with the support frame, whereby the light module has reflectors, projectors, and associated light sources. Furthermore, a headlight has a cover lens, which, together with a cover frame and light and cover lenses, forms a cover lens assembly. These assemblies, as part of the overall headlight, are exposed to external and internal influences, such as mechanical forces, chemical compounds, and, in particular, thermal stresses caused by temperature changes. The shape of the respective assemblies and their components can change under these influences.A change in the linear expansion of the bodies due to temperature changes can lead to a deviation from the specified position of the light module in the headlight. These temperature changes can be caused by engine heat, weather conditions, or the operation of the lamp in the light module.

[0003] The light module emits a light field with a cut-off line, which forms the low beam of the headlight. This cut-off line has a specific angle to the horizontal, whereby thermal influences of the headlight can cause the horizontal position of the cut-off line to be unduly altered, as the cut-off line must usually lie within a specified angular range. To maintain this angle or angular range, the light module must maintain a specific inclination in the headlight and to the horizontal of the vehicle. The cut-off line is unduly increased if the light module is tilted backwards against the direction of travel. Tilting in the direction of travel produces a light cone that is too low, as the cut-off line moves downwards.

[0004] Compensating elements are known from the prior art for arranging the light module in the headlight housing. Supporting frames are often used to arrange the light module in the headlight housing, and it is known to arrange at least one corresponding compensating element between the support frame and the light module or between the support frame and the headlight housing. The compensating element is made of a material with a comparatively high coefficient of thermal expansion. If, for example, the temperature in the headlight increases, the compensating element heats up and expands. The compensating element is involved in suspending the light module in the headlight housing in such a way that, despite a thermally induced change in the shape of the headlight housing, the position of the light module does not deviate from the predetermined position.A disadvantage, however, is the complex adjustment of the compensation elements to compensate for changes in the position of the light module in the headlight. Both different headlight designs and different arrangements of the compensation elements within a headlight require a specific adjustment of the compensation element for each headlight in order to incorporate the required correction amount into the overall structure of the light module arrangement in the headlight. Headlight arrangements with temperature-compensating light module mounts are known from documents DE 10 2007 052 ​​985 A1 and DE 10 2008 003 706 A1. Document DE 20 2007 016 945 U1 discloses an adjustment element for the precise positioning of a headlight on a motor vehicle.

[0005] It is therefore the object of the present invention to provide a headlight for a motor vehicle with improved compensation of thermally induced positional deviations of the light module in the headlight.

[0006] This object is achieved by a headlight for a motor vehicle according to the preamble of claim 1 with the characterizing features. Advantageous developments of the invention are specified in the dependent claims.

[0007] The invention includes the technical teaching that the compensating element has an effective extension length and comprises a device for adjusting the effective extension length.

[0008] The core of the invention is an adjustable compensating element that can be adapted to the specific requirements of each individual installation situation. The effective extension length determines the total amount of correction travel that can be used to correct the specified position of the light module in the headlight using the compensating element. If only a small extension travel is required, the effective extension length is reduced, whereas if a larger extension travel is required, the effective extension length is extended by the adjustment device. The effective extension length is changed via the adjustment device during operation of the headlight, for example during readjustment. The result is a flexible and versatile compensating element with a variable extension length that can be adapted to different installation situations in a headlight.For example, headlights can be provided that have a standardized housing, whereby the light module accommodated in the housing can have various designs. Depending on the design of the light module, a standardized compensating element can be used, in which only the effective expansion length is adjusted by the device according to the invention. Furthermore, the effective expansion length can be adapted by the device for adjusting the installation situation of the compensating element, so that it can be installed, for example, between the light module and the housing of the headlight in an upper segment or in a lower segment, whereby the different installation situations require different effective expansion lengths.

[0009] The light module emits light with a cut-off line that has a predetermined angle to the horizontal, wherein the compensating element is arranged such that a thermally induced deviation of the cut-off line from the horizontal can be compensated by influencing the position of the light module via the compensating element. The light serves to illuminate the area in front of the motor vehicle and leaves the light module in a light exit direction that has a predetermined angle to the horizontal. The compensating element is preferably arranged such that changing the length of the compensating element in the direction of the extension length enables tracking of the light module so that the predetermined angle of the cut-off line to the horizontal is maintained. The compensating element has an extension direction that corresponds to the direction of the extension length.The compensating element is preferably arranged so that its extension direction approximately coincides with the direction of light propagation. If the compensating element expands or contracts, the effective extension length changes by a certain amount, which is then used to correct the position of the light module. A different arrangement of the compensating element, in which the extension direction of the compensating element does not coincide with the direction of light propagation, may be necessary and advantageous if a position correction of the light module in the headlight is required in other directions.

[0010] To arrange the light module in the housing of the headlight, a support frame can be provided so that the light module is accommodated in the housing above the support frame. The compensating element can preferably be arranged between the support frame and the light module. It is also possible to arrange the compensating element between the support frame and the housing of the headlight. Within the scope of the present invention, an arrangement of several compensating elements is also possible, so that, for example, a first number of compensating elements can be provided between the light module and the support frame, wherein a further number of compensating elements can also be arranged between the support frame and the housing of the headlight. The support frame is usually annular and has a support plane that is arranged approximately perpendicular to the light exit direction.If the compensation elements extend in their direction of extension approximately in the direction of light propagation, the compensation elements are perpendicular to the supporting plane of the supporting frame.

[0011] It is particularly advantageous that three receiving means are arranged between the support frame and the light module in order to form a receiving plane for receiving the light module in the support frame, wherein two rigid receiving means can be arranged in the underside region of the headlight between the support frame and the light module, and wherein the third receiving means in the upper region is formed from the compensating element. The use of two rigid receiving means in the lower region between the headlight and the support frame creates a joint arrangement that enables an articulated movement of the support frame and consequently of the light module about an imaginary joint axis, wherein the imaginary joint axis is formed by the connecting axis between the two lower, rigid receiving means.If the compensation element forms the support means in the upper area between the support frame and the spotlight, the compensation element's thermal expansion behavior allows for a corresponding tilt of the support frame and consequently of the light module around the imaginary joint axis. This tilt directly influences the angle of the cut-off line to the horizontal, allowing it to be corrected accordingly if the cut-off line deviates from its specified angle to the horizontal due to thermal influences.

[0012] To enable a device for adjusting the effective expansion length of the compensating element, the compensating element is constructed from several individual parts. First, the compensating element has a compensator screw and a stator element, with the compensator screw being screwed against the stator element to change the effective expansion length. For this purpose, the stator element has an internal thread, and the compensator screw has an external thread, with the external thread being screwed into the internal thread. The stator element has a bore into which the internal thread is inserted, allowing the compensator screw to extend into the stator element. Furthermore, the compensating element has a threaded bolt, with the compensator screw being screwed onto the threaded bolt.The threaded bolt has an external thread for this purpose, and the compensator screw also has an internal thread, allowing the threaded bolt to be screwed into the internal thread of the compensator screw via the external thread. This creates two screw connections, whereby the compensator screw can be adjusted in its screw-in depth into the stator element while simultaneously changing the screw-in width on the external thread of the threaded bolt. If the stator element and the threaded bolt remain at a constant distance from each other, the compensator screw can be adjusted in its screw-in depth into the stator element due to the preferably identical pitches of all external and internal threads involved.If the screw-in depth into the stator element is changed, the position of the compensator screw on the external thread of the threaded bolt changes at the same time, so that the stator element and the threaded bolt maintain a fixed position relative to each other, independent of the screw-in position of the compensator screw.

[0013] The stator element can, for example, be fixedly arranged in the support frame, with the threaded bolt being fixedly connected to the light module. Alternatively, the threaded bolt can also be fixedly arranged with the light module, with the stator element forming a fixed arrangement with the support frame. The force flow in the support element thus formed occurs from the stator element via the compensator screw into the threaded bolt. Consequently, with the appropriate choice of material for the components of the compensating element, different expansion behaviors can be achieved, since the components involved are located at different lengths in the force flow of the support element.

[0014] The aforementioned arrangement of the compensating element between the light module and the support frame can alternatively or additionally also be used between the support frame and the housing of the headlight. In particular, one or more compensating elements can be used, whereby, for example, the receiving means located in the underside of the headlight between the support frame and the light module can also be formed by corresponding compensating elements.

[0015] According to one possible embodiment, the thermal expansion coefficient of the compensator screw can be greater than the thermal expansion coefficient of the threaded bolt and / or the stator element. If the compensator screw is screwed deeply into the internal thread of the stator element, the resulting expansion length is small, since the section of the compensator screw located in the force flow between the stator element and the threaded bolt is comparatively small. If the compensator screw is screwed far out of the stator element, the expansion length created by the compensator screw increases. The relevant section of the threaded bolt located in the force flow between the stator element and the end of the threaded bolt is correspondingly small.

[0016] Of course, if the thermal expansion coefficients are inverted, for example, if the thermal expansion coefficient of the threaded bolt is greater than the thermal expansion coefficient of the compensator screw, the effect can also be reversed. If the compensator screw is screwed deeply into the stator element, the resulting length of the threaded bolt lies in the force flow between the stator element and the end of the threaded bolt. However, if the compensator screw is unscrewed from the internal thread of the stator element, the length of the threaded bolt that lies in the force flow decreases.

[0017] The stator element and / or the threaded bolt can, for example, comprise a glass-fiber-reinforced polybutylene terephthalate material (PBT GF) and have a thermal expansion coefficient of at most 40*10EX-6 1 / K and preferably of at most 25*10EX-6 1 / K. Furthermore, the compensator screw can comprise a polybutylene terephthalate material (PBT) and have a thermal expansion coefficient of at least 100*10EX-6 1 / K and preferably of at least 145*EX-6 1 / K. This means that the thermal expansion coefficient of the compensator screw is, for example, approximately five times greater than the thermal expansion coefficient of the threaded bolt. The greater the length of the compensator screw located in the force flow, the greater the expansion of the entire compensating element when the temperature increases. This can be achieved by unscrewing the compensator screw far out of the stator element as described above.For example, since the thermal expansion coefficient of the threaded bolt is only one fifth of the thermal expansion coefficient of the compensator screw, there is a small change in the total length of the compensating element if the compensator screw is screwed deep into the stator element and there is a large length of the threaded bolt that lies in the force flow.

[0018] Further measures improving the invention are presented in more detail together with the description of a preferred embodiment of the invention with reference to the figures. It shows: Fig. 1 a perspective view of an embodiment of a headlight with a light module arranged in the housing of the headlight via a support frame, Fig. 2 an embodiment of a light module which is arranged in a support frame via receiving means, wherein one of the receiving means is designed as a compensating element, Fig. 3 a perspective detailed view of the compensation element, Fig. 4 a cross-sectional view of a compensating element with a compensator screw screwed deep into the stator element and Fig. 5 a cross-sectional view of a compensating element with a compensator screw screwed far out of the stator element.

[0019] Fig. 1 shows an embodiment of a headlight 1 for a motor vehicle, wherein the basic structure of the headlight 1 is formed by a housing 10. The front cover plate as well as a frame and further details are not shown in the view for clarity. The headlight 1 is rigidly fastened to a frame element of the motor vehicle via the housing 10 shown. Fastening tabs 24, which are integrally formed on the housing 10 of the headlight 1, are used to fasten the housing 10 in the frame element. According to the illustration, an upper and a lower fastening tab 24 are shown, and a third fastening tab 24 is present in the rear region of the housing 10, which is not shown in the illustration due to the perspective.

[0020] A light module 11 is housed in the housing 10 of the headlight 1. The light module 11 is designed to emit a light field to illuminate the area in front of the motor vehicle. The light field can be designed as a dipped beam defined by a cut-off line that must not deviate from a predetermined angle to a horizontal line H within a specified area, in order, on the one hand, to avoid dazzling other road users and, on the other hand, to illuminate a minimum area in front of the motor vehicle. The light module 11 is housed in the housing 10 via a support frame 13, which is approximately ring-shaped and encloses the light module 11. The support frame 13 is fastened in the housing 10 via fastening means 21, wherein the fastening can have adjustment devices via at least one of the fastening means in order to adjust the position of the support frame 13 and consequently of the light module 11 in the housing 10 once or to change it dynamically.For example, the fastening means 21 shown on the underside can create a rigid arrangement of the support frame 13 in the housing 10, wherein the fastening means 21 shown on the upper side can be changed in position via a servo motor in order to tilt the support frame 13 and consequently the light module 11.

[0021] The light module 11 is rigidly mounted in the support frame 13, preferably with three mounting means. One of the mounting means can be designed as a compensating element 12 to compensate for thermally induced changes in the structure of the housing 10. A detailed view of the arrangement of the light module 11 in the support frame 13 is shown in the following Fig. 2 is shown in more detail.

[0022] Fig. Figure 2 shows a cross-section of a light module 11, in which a reflector 18 is shown on the left side and a projection optics 19 on the right side. The reflector 18 and the projection optics 19 are accommodated in a module body 25, which has an elongated extension in the horizontal direction H. On the reflector side, the module body 25 comprises the reflector 18, with a socket for receiving the projection optics 19 being formed in the module body 25 on the right side.

[0023] The light module 11 is fastened in the support frame 13 via three receiving means 14. Two receiving means 14 are located on the underside and form a rigid connection between the support frame 13 and the module body 25. On the upper side, a further receiving means 14 is shown, which is designed as a compensating element 12. The compensating element 12 has an effective expansion length L, wherein a mounting bracket 22 is provided to receive the elongated compensating element 12. The compensating element 12 is mounted via the respective end side, on the one hand between the end of the mounting bracket 22 and on the other hand between the module body 25. According to the illustration, the compensating element 12 is shown only in abstract form, wherein in the following Fig. 3 to 5 show a detailed view of the compensating element 12.

[0024] Fig. 3 shows an embodiment of a compensating element 12 according to the invention in a perspective view. The compensating element 12 is designed in several parts and extends in an extension direction 23 to form an elongated basic structure. The compensating element 12 comprises at least one stator element 16, a compensator screw 15, and a threaded bolt 17. The compensator screw 15, the stator element 16, and the threaded bolt 17 are designed to be substantially rotationally symmetrical about the extension direction 23, with the compensator screw 15 having a wrench size of 20 to allow it to be rotated about the extension direction 23 using a tool. The stator element 16 can be connected, for example, to the light module 11, and the threaded bolt 17 can be connected at the end to the support frame 13, whereby the respective connection can also be carried out in the reverse manner.The stator element 16 is connected to the threaded bolt 17 via the compensator screw 15, so that the force flow between the stator element 16 and the threaded bolt 17 runs via the compensator screw 15.

[0025] As in Fig. As shown in Figure 4, the stator element 16 has an internal thread 16a, while the compensator screw 15 has an external thread 15a. Thus, the compensator screw 15 can be screwed into the internal thread 16a in the stator element 16 via the external thread 15a. Furthermore, the compensator screw 15 has an internal thread 15b, into which the threaded bolt 17 can be screwed via an external thread 17a. All threads have the same pitch, so that with a rigid arrangement of the stator element 16 relative to the threaded bolt 17, the compensator screw 15 can be changed both in its screw-in depth into the stator element 16 and in its screw-on position on the threaded bolt 17 by rotating it about the direction of extension 23.If at least one of the components shown, preferably the compensator screw 15 or the threaded bolt 17, has different expansion coefficients from one another, an effective expansion length can be varied without changing the relative position between the stator element 16 and the threaded bolt 17.

[0026] In the Fig. 4 and Fig. 5 shows a compensating element 12, wherein in Fig. 4 the compensator screw 15 is screwed deep into the internal thread 16a of the stator element 16 to create a short effective expansion length L. In contrast, Fig. 5 shows an arrangement of the compensating element 12 with a large effective expansion length L, wherein the compensator screw 15 is screwed far out of the stator element 16. The illustrations illustrate the double thread guide of the compensator screw 15, which has an external thread 15a on the one hand and an internal thread 15b on the other, so that the compensator screw 15 can be screwed into or onto the internal thread 16a in the stator element 16 and onto the external thread 17a of the threaded bolt 17.If the compensator screw 15 comprises a material, for example, a polybutylene terephthalate material (PBT) with a thermal expansion coefficient of, for example, 145*10EX-6 1 / K, and the stator element 16 and the threaded bolt 17 comprise, for example, a polybutylene terephthalate material with glass fiber reinforcement (PBT GF), which has a thermal expansion coefficient of, for example, at most 25*10EX-6 1 / K, the temperature-dependent total expansion can be changed accordingly in the manner shown. To clarify the force flow, a force flow path 26 is shown, which is arranged according to . Fig. 4 only a short way through the compensator screw 15 and in Fig. 5 has a long path through the compensator screw 15. Due to the larger thermal expansion coefficient of the compensator screw, the effective expansion length L is correspondingly Fig. 5 larger than these accordingly Fig. 4 is executed.

[0027] Deviating from the variant shown above, the threaded bolt 17 can also have a larger thermal expansion coefficient than the compensator screw 15, so that a variation of the effective expansion length L is possible depending on the screwing position of the internal thread 15b of the compensator screw 15 on the external thread 17a of the threaded bolt 17.

[0028] The invention is not limited in its embodiment to the preferred embodiment specified above. Rather, a number of variants are conceivable, which make use of the solution presented even in fundamentally different embodiments. All features and / or advantages emerging from the claims, the description or the drawings, including design details, spatial arrangements and method steps, can be essential to the invention both individually and in a wide variety of combinations. Deviating from the arrangement shown, the compensating element 12 can be inserted between the support frame 13 and the light module 11, and also between the support frame 13 and the housing 10 of the headlight 1. This enables an effective correction of the deviation of the cut-off line of the light module 11 from the horizontal H just as effectively.Furthermore, the compensating element according to the invention can also be inserted between the housing 10 of the headlight 1 and the frame element of the motor vehicle, wherein a combination of various compensating elements 12, which are designed according to the type of the present invention, can also be inserted between the frame element of the motor vehicle and the housing 10, the housing 10 and the support frame 13, and the support frame 13 and the light module 11. The result is the use of a compensating element 12 according to the type of the present invention, which is located in the connection chain between the motor vehicle and the light module 11. Furthermore, it can even be provided to insert the compensating element according to the invention between the reflector 18, the module body 25, or the reflector 18 and the projection optics 19.It is also possible to use a compensating element 12 according to the invention between the projection optics 19 and the module body 25, for example in order to compensate for changes in the refractive index of the materials of the projection optics 19, which may be thermally induced, by means of a corresponding compensating element 12. List of reference symbols 1 headlight 10 housings 11 Light module 12 Compensating element 13 supporting frames 14 Recording equipment 15 Compensator screw 15a external thread 15b internal thread 16 Stator element 16a internal thread 17 threaded bolts 17a external thread 18 Reflector 19 Projection optics 20 key size 21 Fasteners 22 mounting brackets 23 Direction of extension 24 mounting tab 25 module bodies 26 Power flow path H Horizontal L effective extension length

Claims

[1] Headlight (1) for a motor vehicle with a housing (10) in which at least one light module (11) is accommodated in a predetermined position, wherein the receptacle of the light module (11) has at least one compensating element (12) for compensating for thermally induced deviations of the position of the light module (11) from the predetermined position in the headlight (1), characterized by that the compensating element (12) has an effective extension length (L) and comprises a device (15, 16) for adjusting the effective extension length (L), wherein the device for adjusting is designed to change the effective extension length (L) of the compensating element (12) during operation of the headlight (1). [2] Headlight (1) according to claim 1, characterized bythat the light module (11) emits light with a light-dark boundary which has a predetermined angle to the horizontal (H), wherein the compensating element (12) is arranged such that a thermally induced deviation of the light-dark boundary from the horizontal (H) can be compensated by influencing the position of the light module (11) by the compensating element (12). [3] Headlight (1) according to claim 1 or 2, characterized by that a support frame (13) is provided, wherein the light module (11) is received in the housing (10) via the support frame (13), and wherein at least one compensating element (12) is arranged between the support frame (13) and the light module (11). [4] Headlight (1) according to claim 3, characterized bythat three receiving means (14) are arranged between the support frame (13) and the light module (11) in order to form a receiving plane for receiving the light module (11) in the support frame (13), wherein in the underside region of the headlight (1) between the support frame (13) and the light module (11) two rigid receiving means (14) are arranged, and wherein the receiving means (14) in the upper region is formed from the compensating element (12). [5] Headlight (1) according to one of the preceding claims, characterized by that the compensating element (12) has a compensator screw (15) and a stator element (16), wherein the compensator screw (15) can be screwed against the stator element (16) in order to change the effective expansion length (L). [6] Headlight (1) according to claim 5, characterized bythat the stator element (16) has an internal thread (16a) and the compensator screw (15) has an external thread (15a), wherein the external thread (15a) can be screwed into the internal thread (16a). [7] Headlight (1) according to one of claims 5 or 6, characterized by that the compensating element (12) further comprises a threaded bolt (17), wherein the compensator screw (15) can be screwed onto the threaded bolt (17). [8] Headlight (1) according to claim 7, characterized by that the threaded bolt (17) has an external thread (17a) and the compensator screw (15) further has an internal thread (15b), wherein the external thread (17a) can be screwed into the internal thread (15b). [9] Headlight (1) according to claim 7 or 8, characterized by that the compensator screw (15) is sleeve-shaped, wherein the thermal expansion coefficient of the compensator screw (15) is greater than the thermal expansion coefficient of the threaded bolt (17) and / or the stator element (16). [10] Headlight (1) according to one of claims 7 to 9, characterized by that the stator element (16) and / or the threaded bolt (17) comprises a glass fiber reinforced polybutylene terephthalate material (PBT GF) and has a thermal expansion coefficient of at most 40*10EX-6 1 / K and preferably of at most 25*10EX-6 1 / K. [11] Headlight (1) according to one of claims 5 to 10, characterized by that the compensator screw (15) comprises a polybutylene terephthalate material (PBT) and has a thermal expansion coefficient of at least 100*10EX-6 1 / K and preferably of at least 145*10EX-6 1 / K.

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