Heat dissipation structure and vehicle lamp

Abstract

Provided is a novel heat radiation structure in which heat dissipation performance of a vehicle lamp is improved. The heat dissipation structure comprises: a fan 27; a heat sink 20 that the wind generated by the fan 27 hits; a circuit board 18 that is mounted on a surface of the heat sink 20 facing toward the front of a vehicle; and light sources 30a–30c that are mounted on the board so that light-emitting surfaces face toward the front of the vehicle. The circuit board 18 has an opening 18a that is formed above or below the light sources. The heat sink 20 has a penetrating portion 20b that is formed so that wind is directed toward the circuit board 18, the penetrating portion 20b overlapping with the opening 18a in a front view when viewed from the front of the vehicle.

Description

Heat dissipation structure and vehicle lamp

[0001] The present invention relates to a heat dissipation structure used for vehicle lamps.

[0002] Conventionally, a projector-type lamp unit has been devised that mainly includes a plurality of light sources, a common substrate on which the plurality of light sources are mounted on the surface, a light guide, a projection lens, and a heat sink (see Patent Document 1). Specifically, a primary lens as a light guide is disposed between the projection lens and the light source, and the incident surface of the primary lens and the light emitting surface of the light source are close to each other so that the light emitted from the light source efficiently enters the projection lens. Further, a heat sink is disposed on the back surface of the substrate on which the light source is mounted on the surface.

[0003] International Publication No. 2023 / 282238

[0004] By the way, when trying to realize a plurality of light distribution patterns such as a high beam light distribution pattern and a low beam light distribution pattern in one lamp unit, it is necessary to densely mount many light emitting elements on the substrate, and the amount of heat generation increases. Therefore, an improvement in heat dissipation performance more than ever is required.

[0005] The present invention has been made in view of such a situation, and one of its exemplary purposes is to provide a new heat dissipation structure with improved heat dissipation performance for vehicle lamps.

[0006] In order to solve the above problems, a heat dissipation structure according to an aspect of the present invention includes a fan, a heat sink against which the wind generated by the fan hits, a substrate mounted on a surface of the heat sink facing the front of the vehicle, and a light source mounted on the substrate such that the light emitting surface faces the front of the vehicle. An opening is formed above or below the light source in the substrate. The heat sink has a through portion formed so that the wind blows toward the substrate, and the through portion overlaps the opening in a front view seen from the front of the vehicle.

[0007] According to this aspect, the wind passing through the through portion of the heat sink blows out directly from the opening of the substrate as it is. Thereby, the light source in the vicinity of the opening can be directly cooled by the wind generated by the fan, and the heat dissipation performance is improved.

[0008] The circuit board may have power supply wiring for supplying power to the light source. The power supply wiring may be located outside the insulating area at the periphery of the opening on the surface on which the light source is mounted. The width of the insulating area may be smaller than the width of the power supply wiring. This allows for a larger opening. In addition, the presence of an insulating area between the opening and the power supply wiring makes it less likely for short circuits to occur between the power supply wiring and other components near the opening.

[0009] The device may further include a deflection member that directs the airflow from the opening towards the light source. This allows the airflow from the opening to be efficiently directed towards the light source.

[0010] The deflection member may be provided at the edge of the opening. This allows, for example, the deflection member to be formed integrally with the heat sink.

[0011] The system may further include a resin lens positioned opposite the light-emitting surface to deflect the light emitted from the light source.

[0012] The resin lens is made of silicone and may further include a deflection member that directs the airflow from the opening towards the incident surface of the resin lens. This allows the deflection member to be molded integrally with the resin lens.

[0013] The opening may be rectangular in shape, with its longer side aligned with the vehicle width. The length of the opening in the vehicle width direction may be greater than the length of the area where the light source is located in the vehicle width direction. This allows air to reach the entire light source more easily.

[0014] The light source may include a plurality of first light-emitting elements arranged in a line in the vehicle width direction, a plurality of second light-emitting elements arranged in a line above the plurality of first light-emitting elements, and a plurality of third light-emitting elements arranged in a line below the plurality of first light-emitting elements. An opening may be formed between the plurality of first light-emitting elements and the plurality of second light-emitting elements. This allows the first light-emitting elements and the second light-emitting elements to be efficiently cooled by the air coming out of the opening.

[0015] Another aspect of the present invention is a vehicle light fixture. This vehicle light fixture comprises the heat dissipation structure described above and a control unit that controls the on / off switching of the light source. The control unit may form a low-beam light distribution pattern by lighting up a plurality of first light-emitting elements and a plurality of second light-emitting elements, and form a high-beam light distribution pattern by lighting up a plurality of first light-emitting elements and a plurality of third light-emitting elements.

[0016] According to this embodiment, the first and second light-emitting elements that form a low-beam light distribution pattern, which is illuminated for a high proportion of the time when the vehicle lighting is in use, can be efficiently cooled.

[0017] Any combination of the above components, or any conversion of the expression of the present invention between manufacturing methods, devices such as luminaires and lighting fixtures, light-emitting modules, light sources, etc., are also valid embodiments of the present invention.

[0018] According to the present invention, the heat dissipation performance of vehicle lighting equipment can be improved.

[0019] This is a perspective view of a vehicle light fixture according to this embodiment. This is an exploded perspective view of the vehicle light fixture shown in Figure 1. This is a schematic diagram illustrating the layout of each component arranged near the circuit board in the vehicle light fixture according to this embodiment, as seen from above. This is a schematic diagram illustrating the heat dissipation structure according to this embodiment. Figure 5(a) is a schematic diagram showing an example of a deflection member according to this embodiment, and Figure 5(b) is a schematic diagram showing another example of a deflection member according to this embodiment. This is a front view of the circuit board according to this embodiment. This is a schematic diagram illustrating a heat dissipation structure according to another example of this embodiment. Figures 8(a) to 8(c) show modified examples of the heat sink according to this embodiment.

[0020] The present invention will be described below with reference to the drawings, based on preferred embodiments. The same or equivalent components, members, and processes shown in each drawing will be denoted by the same reference numerals, and redundant descriptions will be omitted as appropriate. Furthermore, the embodiments are illustrative and not limiting, and not all features or combinations thereof described in the embodiments are necessarily essential to the invention.

[0021] Figure 1 is a perspective view of a vehicle light fixture according to this embodiment. Figure 2 is an exploded perspective view of the vehicle light fixture shown in Figure 1. The vehicle light fixtures shown in Figures 1 and 2 are vehicle headlights and are configured to form both low beam and high beam light distribution patterns.

[0022] The vehicle light fixture 10 comprises a projection lens 12, a lens holder 14, a reflector 16, a circuit board 18, a heat sink 20, and a fan 27. The heat sink 20 is configured so that the air generated by the fan 27 hits multiple fins 20a. The projection lens 12 consists of two parts: a first projection lens 12a located below and a second projection lens 12b located above, which control the optical path of the light emitted from each light source. Each lens is mounted in a predetermined position on the lens holder 14. Each lens is manufactured by injection molding using a resin material with high transparency and heat resistance, such as acrylic or polycarbonate. The lens holder 14 is fastened to the heat sink 20 by screws 22.

[0023] The reflector 16 is made of a metal or resin material. The reflector 16 has a horizontally elongated base surface portion 16a facing in the front-to-back direction, openings 16b and 16c formed in the center of the reflector 16, lateral reflectors 16d provided to protrude forward from both the left and right sides of the opening 16b, and an upper reflector 16e whose inner surface of the beam-like portion above the opening 16b is a reflective surface.

[0024] A plate-shaped member, a shade 24, is attached to the lower surface of the lateral reflector 16d, and it protrudes forward from the lower edge of the opening 16b. The shade 24 is held by the reflector 16 so that its plate surface is aligned with the horizontal direction of the vehicle. A plate-shaped member, a shade 26, is attached to the base surface 16a. The shade 26 is a plate-shaped member, and it is held by the reflector 16 so that its plate surface is aligned with the vertical direction of the vehicle.

[0025] The circuit board 18 includes a first light source 30a in which a plurality of light-emitting elements 28a for forming a first region of the low-beam light distribution pattern are arranged in a horizontal row on a horizontally elongated first mounting area 29a; a second light source 30b in which a plurality of light-emitting elements 28b for forming a second region of the low-beam light distribution pattern are arranged in a horizontal row on a horizontally elongated second mounting area 29b; a third light source 30c in which a plurality of light-emitting elements 28c for forming a high-beam light distribution pattern are arranged in a horizontal row on a horizontally elongated third mounting area 29c; and a drive circuit (not shown) for driving each light-emitting element. An opening 18a is formed between the first mounting area 29a and the second mounting area 29b. The opening 18a may be formed above or below any of the first light source 30a, the second light source 30b, or the third light source 30c.

[0026] The third light source 30c, mounted on the circuit board 18, is positioned adjacent to the first light source 30a. The first light source 30a is located on the upper side, and the third light source 30c is located on the lower side. The drive circuit is a combination of passive elements such as capacitors and coils, active elements such as transistors and diodes, an IC chip, memory, etc., and functions as a control unit that controls the on / off switching of the first light source 30a, the second light source 30b, and the third light source 30c. The circuit board 18 is the mounting section on which each light source is mounted, and is fixed to a predetermined position on the heat sink 20. In other words, the circuit board 18 and the heat sink 20 are also an integrated mounting section. The heat sink 20 has a horizontally elongated rectangular through-hole 20b formed so that the air generated by the fan 27 is directed towards the circuit board 18.

[0027] Lens plates 32 are positioned in front of the first light source 30a and the third light source 30c to concentrate or partially block the light emitted from the first light source 30a and the third light source 30c. A lens plate 34 is positioned in front of the second light source 30b to concentrate the light emitted from the second light source 30b. Lens plates 32 and 34 are sandwiched between the reflector 16 and the circuit board 18. The positional relationship of each component is determined by fastening the reflector 16 to the heat sink 20 with screws 36 in this state. Furthermore, lens plates 32 and 34 are positioned facing the light-emitting surfaces of each light-emitting element, deflecting the light emitted from each light-emitting element.

[0028] The first light emitted from the first light source 30a is partially blocked by the shade 24. The first projection lens 12a projects the blocked first light onto a first region below the horizon. The second light emitted from the second light source 30b is partially blocked by the shade 26. The second projection lens 12b projects the blocked second light onto a second region below the horizon.

[0029] The control unit according to this embodiment forms a low-beam light distribution pattern including a first region and a second region by lighting up the first light source 30a and the second light source 30b.

[0030] As described above, the vehicle light fixture 10 according to this embodiment further includes a third light source 30c in which a plurality of light-emitting elements 28c are arranged in an array. The third light source 30c is mounted on the circuit board 18 so as to be positioned below the first light source 30a when viewed from the front of the vehicle. The shade 24 blocks a portion of the third light emitted from the third light source 30c. The first projection lens 12a projects the blocked third light into a third region above the horizon.

[0031] The control unit according to this embodiment lights up the first light source 30a and the third light source 30c to form a high-beam light distribution pattern that includes the first region and the third region. This makes it possible to form a high-beam light distribution pattern that includes a region above the low-beam light distribution pattern.

[0032] Furthermore, the control unit can form a variable light distribution pattern that includes the first region and a portion of the third region by lighting up the first light source 30a, lighting up only a portion of the multiple light-emitting elements 28c of the third light source 30c, and turning off or dimming the second light source 30b.

[0033] Figure 3 is a schematic diagram illustrating the layout of the components arranged near the circuit board in the vehicle lighting device according to this embodiment, as viewed from above. The distance D1 between the surface of the circuit board 18 and the back surface of the reflector 16 is 3.5 mm ± 0.5 mm. The height D2 of the light-emitting element 28a mounted on the circuit board 18 is 0.75 mm ± 0.25 mm. The distance D3 between the surface of the circuit board 18 and the back surface of the lens plate 32 is 1.05 mm ± 0.25 mm. As a result, the distance D4 between the light-emitting surface of the light-emitting element 28a and the lens plate 32 is 0.3 mm ± 0.25 mm, making the light-emitting element 28a and the lens plate 32 very close together. Note that if the distance D4 is at least 1 mm or less, the heat from the light-emitting element 28a will have a greater impact on the lens plate 32, and the heat dissipation structure according to this embodiment is very useful in such a layout.

[0034] With the above configuration, much of the light emitted from the light-emitting element 28a is incident on the lens plate 32, improving the luminous efficiency as a vehicle light fixture. On the other hand, because the light-emitting element 28a, which is a heat source, and the lens plate 32 are very close together, the lens plate 32 (lens plate 34) requires a heat-resistant material. In addition, a resin material that does not change shape much due to temperature changes is required. Therefore, in this embodiment, a resin lens made of silicone is used for the lens plate.

[0035] If the heat dissipation of the aforementioned vehicle lighting fixtures can be further improved, the Tj temperature will decrease and the lifespan will be extended. It will also contribute to miniaturization of the heat sink and reduction of fan power. Furthermore, distortion due to temperature rise of the lens plate and output reduction due to temperature rise of the light-emitting elements can be suppressed.

[0036] Therefore, in the heat dissipation structure according to this embodiment, not only is the heat sink cooled by the airflow generated by the fan, but a portion of that airflow is also directed directly towards the circuit board. Figure 4 is a schematic diagram illustrating the heat dissipation structure according to this embodiment. The heat dissipation structure 100 comprises a fan 27, a heat sink 20 to which the airflow W generated by the fan 27 hits, a circuit board 18 mounted on the surface 20c of the heat sink 20 facing forward of the vehicle, and a light source 30a mounted on the circuit board 18 such that its light-emitting surface 30a1 faces forward of the vehicle. The circuit board 18 has an opening 18a formed above the light source 30a. The heat sink 20 has a through-hole 20b formed so that the airflow W is directed towards the board, and the through-hole 20b overlaps with the opening 18a in a front view from the front of the vehicle.

[0037] As a result, the air W that passes through the penetration 20b of the heatsink 20 is blown out directly from the opening 18a of the circuit board 18. This allows the air W generated by the fan 27 to directly cool the light source 30a located near the opening 18a, thus improving heat dissipation.

[0038] Figure 5(a) is a schematic diagram showing an example of a deflection member according to this embodiment, and Figure 5(b) is a schematic diagram showing another example of a deflection member according to this embodiment. The heat dissipation structure 100 further includes a deflection member 38 that directs the airflow W exiting from the opening 18a toward the light source 30a. This makes it possible to efficiently direct the airflow W exiting from the opening 18a toward the light source 30a.

[0039] The deflection member 38 shown in Figure 5(a) is a plate-shaped member provided to protrude from the upper edge of the horizontally elongated rectangular opening 18a. This allows the deflection member 38 to be formed integrally with the heat sink 20. The amount of protrusion of the deflection member 38 from the surface of the heat sink 20 is, for example, about 3 to 5 mm. Furthermore, the deflection member 38 should be provided such that the angle θ between the direction X1 from the front of the heat sink 20 toward the front of the light fixture and the plate surface 38a of the deflection member 38 is 0 to 60°. This makes it easier for the wind W passing through the opening 18a to be directed toward the light source 30a and lens plate 32 below.

[0040] The light source 30a illuminates in both low-beam and high-beam light distribution patterns, and the light source 30a and lens plate 32 tend to become hotter than other light sources and lens plate 34. Therefore, by providing the deflection member 38 on the upper edge of the opening 18a or by facing the plate surface 38a downwards, the light source 30a and lens plate 32 can be cooled preferentially.

[0041] The deflection member 40 shown in Figure 5(b) is provided so as to protrude from the upper and left and right edges of the opening 18a. This makes it easier for the wind W passing through the opening 18a to be directed towards the light source 30a below, rather than escaping to the sides. The deflection member 40 may also be provided so that the protruding portion widens as it moves towards the front of the vehicle. This can widen the range over which the wind exiting the opening 18a is directed.

[0042] Figure 6 is a front view of the circuit board according to this embodiment. The circuit board 18 has power supply wiring 42 that supplies power to light sources 30a to 30c. The power supply wiring 42 is located outside the insulating region 18b at the periphery of the opening 18a on the surface on which the light sources 30a to 30c are mounted. The width W1 of the insulating region 18b is smaller than the width W2 of the power supply wiring 42. In this embodiment, the width W1 of the insulating region 18b is 0.5 mm. This allows the opening 18a to be made larger. In addition, the presence of the insulating region 18b between the opening 18a and the power supply wiring 42 makes it less likely for the power supply wiring 42 to short-circuit between other components near the opening 18a and the power supply wiring 42. For example, as shown in Figure 6, even if a deflection member 38 is provided on the edge of the opening 18a, the presence of the insulating region 18b prevents a short circuit between the power supply wiring 42 and the deflection member 38.

[0043] The opening 18a has a rectangular shape with its longer side aligned with the vehicle width direction. The length W3 of the opening 18a in the vehicle width direction is greater than the length in the vehicle width direction of the area where the light sources 30a to 30c are located. This makes it easier for air to reach the entire area of ​​the light sources 30a to 30c.

[0044] The light source 30a includes a plurality of first light-emitting elements 28a arranged linearly in the vehicle width direction. The light source 30b includes a plurality of second light-emitting elements 28b arranged linearly above the plurality of first light-emitting elements 28a. The light source 30c includes a plurality of third light-emitting elements 28c arranged linearly below the plurality of first light-emitting elements 28a. The opening 18a is formed between the plurality of first light-emitting elements 28a and the plurality of second light-emitting elements 28b. Thereby, the first light-emitting element 28a, the second light-emitting element 28b, and the third light-emitting element 28c can be efficiently cooled by the wind that exits from the opening 18a.

[0045] In addition, the vehicle lamp 10 according to the present embodiment includes the above-described heat dissipation structure and a control unit that controls the lighting and extinguishing of the light sources 30a to 30c. The control unit forms a low beam light distribution pattern by lighting the plurality of first light-emitting elements 28a and the plurality of second light-emitting elements 28b, and forms a high beam light distribution pattern by lighting the plurality of first light-emitting elements 28b and the plurality of third light-emitting elements 28c. Thereby, the first light-emitting element 28a and the second light-emitting element 28b that form the low beam light distribution pattern, which is lit at a high rate when the vehicle lamp is used, can be efficiently cooled.

[0046] FIG. 7 is a schematic diagram for explaining a heat dissipation structure according to another example of the present embodiment. The heat dissipation structure 110 according to the present embodiment includes a deflecting member 44 that directs the wind W exiting from the opening 18a toward the incident surface of the lens plate 32. Thereby, the deflecting member 44 can be integrally formed with the lens plate 32.

[0047] FIGS. 8(a) to 8(c) are diagrams showing modified examples of the heat sink according to the present embodiment. The heat sink 46 shown in FIG. 8(a) has a plurality of cylindrical pins 46a arranged in a lattice pattern so as to surround the through-hole 20b. The heat sink 48 shown in FIG. 8(b) has a plurality of prismatic pins 48a arranged in a lattice pattern so as to surround the through-hole 20b. The heat sink 50 shown in FIG. 8(c) has a plurality of prismatic pins 50a arranged in a staggered pattern so as to surround the through-hole 20b. In all of these heat sinks, the wind generated by the fan can easily pass between the pins, and the wind from the through-hole toward the substrate can be increased.

[0048] As described above, the present invention has been described with reference to the above-described embodiments. However, the present invention is not limited to the above-described embodiments, and the present invention also includes combinations and substitutions of the configurations of the embodiments as appropriate. Further, it is possible to appropriately rearrange the combinations and processing orders in the embodiments based on the knowledge of those skilled in the art and to add various design changes and other modifications to the embodiments. Embodiments with such modifications added are also included in the scope of the present invention.

[0049] This international application claims priority based on Japanese Patent Application No. 2024-166693, which was filed in Japan on September 25, 2024, and the entire contents of the Japanese Patent Application No. 2024-166693 are incorporated herein by reference.

[0050] The above description of specific embodiments of the present invention has been presented for purposes of illustration. They are not intended to be exhaustive or to limit the invention to the forms described. It will be apparent to those skilled in the art that numerous modifications and variations are possible in light of the above description.

[0051] 10 Vehicle lighting fixture, 18 Circuit board, 18a Opening, 18b Insulating area, 20 Heat sink, 20a Fin, 20b Through-hole, 27 Fan, 28a Light-emitting element, 28b Light-emitting element, 28c Light-emitting element, 30a First light source, 30b Second light source, 30c Third light source, 32 Lens plate, 34 Lens plate, 38 Deflection member, 40 Deflection member, 42 Power supply wiring, 44 Deflection member, 100 Heat dissipation structure, 110 Heat dissipation structure.

Claims

1. A heat dissipation structure comprising: a fan; a heat sink to which the air generated by the fan blows; a substrate mounted on the surface of the heat sink facing the front of the vehicle; and a light source mounted on the substrate such that its light-emitting surface faces the front of the vehicle, wherein the substrate has an opening formed above or below the light source, and the heat sink has a through-hole formed so that the air flows towards the substrate, and the through-hole overlaps with the opening in a front view as seen from the front of the vehicle.

2. The heat dissipation structure according to claim 1, wherein the substrate has power supply wiring for supplying power to the light source, the power supply wiring is located outside the insulating region at the periphery of the opening on the surface on which the light source is mounted, and the width of the insulating region is smaller than the width of the power supply wiring.

3. The heat dissipation structure according to claim 1, further comprising a deflection member that directs the air coming out of the opening toward the light source.

4. The heat dissipation structure according to claim 3, characterized in that the deflection member is provided on the edge of the opening.

5. The heat dissipation structure according to claim 1, further comprising a resin lens provided opposite to the light-emitting surface and deflecting the light emitted from the light source, wherein the shortest distance between the light-emitting surface of the light source and the incident surface of the resin lens is 1 mm or less.

6. The heat dissipation structure according to claim 5, characterized in that the resin lens is made of silicone and further comprises a deflection member that directs the air coming out of the opening towards the incident surface of the resin lens.

7. The heat dissipation structure according to claim 1, characterized in that the opening has a rectangular shape with its longer side aligned with the vehicle width direction, and the length of the opening in the vehicle width direction is greater than the length of the area in the vehicle width direction in which the light source is arranged.

8. The heat dissipation structure according to any one of claims 1 to 7, wherein the light source comprises a plurality of first light-emitting elements arranged in a line in the vehicle width direction, a plurality of second light-emitting elements arranged in a line above the plurality of first light-emitting elements, and a plurality of third light-emitting elements arranged in a line below the plurality of first light-emitting elements, and the opening is formed between the plurality of first light-emitting elements and the plurality of second light-emitting elements.

9. A vehicle lamp comprising the heat dissipation structure described in claim 8 and a control unit for controlling the on / off switching of the light source, wherein the control unit forms a light distribution pattern for low beam by lighting the plurality of first light-emitting elements and the plurality of second light-emitting elements, and forms a light distribution pattern for high beam by lighting the plurality of first light-emitting elements and the plurality of third light-emitting elements.

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