JP5597099B2 - Heat sink for in-vehicle LED lamp - Google Patents

Description

  The present invention relates to an aluminum alloy heat sink (heat dissipating part) for dissipating heat from an LED lamp mounted on a vehicle and using a light emitting diode (LED) element as a light source.

  Illumination using a light emitting diode (LED) element as a light source has a low power consumption and a long life, so that it gradually begins to penetrate the market and is replacing existing light bulbs such as incandescent bulbs and fluorescent lamps.

  On the other hand, in-vehicle lamps (vehicle lamps, vehicle headlamps) such as automobile headlights have started to be replaced with LED elements as disclosed in Patent Documents 1 to 4, for example. However, the LED element of the LED lamp is very vulnerable to heat, and there is a problem that when the temperature exceeds the allowable temperature, the light emission efficiency is lowered and the life is also affected.

  In order to solve this problem, it is necessary to dissipate the heat at the time of light emission of the LED element to the surroundings, and thus the LED lamp is provided with a large heat sink (heat dissipating part). For this reason, an in-vehicle lamp using an LED as a light source usually includes an LED substrate on which the LED as a light source is mounted, a reflector that reflects light from the LED forward in the light irradiation direction, and the LED substrate and the reflector. The housing includes an enclosing housing, an outer lens made of a transparent material that closes the open front end of the housing, and a heat sink disposed in thermal contact with the LED substrate.

  A heat sink usually has a large number of fins formed on the outer surface to increase the heat dissipation area, and the complicated fin shape, together with the LED support portion, reflector, rib, connecting portion, etc., is manufactured efficiently and integrally. In addition, as disclosed in Patent Documents 2 and 4 and the like, an aluminum alloy die cast product has been used.

JP 2006-164967 A JP 2007-193960 A JP 2007-324042 A JP 2009-277535 A

  However, as a heat sink, in order to improve the heat dissipation of the fin, it is finally necessary to smooth the fin surface and perform various coatings and anodizing treatment. In contrast, aluminum alloy die-cast products cannot obtain a smooth surface due to the occurrence of burrs, etc., so much effort is required for surface treatment such as surface polishing and painting to obtain this smooth surface. Cost. Specifically, the surface of the die-cast product is required to be buffed, cleaned, degreased, and surface treatment (alumite treatment or coating treatment) to increase the surface emissivity.

  Moreover, in order to form many heat radiation fins on the outer surface of the heat radiating part, an aluminum alloy die cast product requires a complicated mold. Furthermore, even when performing various coatings and anodizing treatments to improve heat dissipation, it is difficult to uniformly coat complex shapes with die-cast castings. Production efficiency is poor because it is necessary.

  Therefore, the aluminum alloy die cast product has a problem that the manufacturing cost becomes high as a heat sink as a result or comprehensively.

  This invention is made | formed in view of such a problem, The place made into the objective is to provide the heat sink of the vehicle-mounted LED lamp with high productivity.

For the purposes achieved, the gist of the heat sink for automotive LED lamp of the present invention, Ri Na aluminum alloy sheet is formed into a heat dissipating fin-shaped waveform that continuously by corrugating, a portion of the waveform to the waveform A step portion formed by crushing is provided, and this step portion is an attachment portion of the LED element .

Here, it is not preferable that precoating treatment emissivity ε is 0.7 or more on the surface of the aluminum alloy sheet is previously subjected before corrugation.

  By using the aluminum alloy thin plate as a raw material and corrugating the plate to create the overall shape of the radiating fin, which is a continuous waveform, many thin fins with relatively narrow intervals can be provided, increasing the heat transfer area In addition, heat dissipation can be improved.

  In addition, by using an aluminum alloy thin plate as a raw material, it is possible to pre-treat the raw material aluminum alloy thin plate in advance before corrugating as a process for improving heat dissipation. For this reason, it is possible to omit or shorten the die casting surface buffing, cleaning process, degreasing process, surface treatment process to increase the emissivity of the surface, etc., which were necessary for the heat sink made of conventional aluminum alloy die cast products, The manufacturing cost of the heat sink can be greatly reduced.

  Furthermore, according to the corrugation processing of the material plate, the component mounting portion for mounting the LED element and the stepped portion such as the unevenness for reinforcement to improve the rigidity are formed along with the molding of the overall shape of the radiating fin which is a continuous waveform. It can be formed by a series of corrugating processes such as a crushing process that is continuous with the molding process. At this time, it is also possible to design these stepped portions so as to be partially wider than the width of the fin. Therefore, a heat sink in which a large number of fins are provided to ensure heat dissipation while securing the mounting area of the LED element can be integrally manufactured from the same material plate.

It is a perspective view which shows the one aspect | mode of the heat sink of this invention. It is a top view of FIG. It is a perspective view which shows another aspect of the heat sink of this invention. FIG. 4 is a plan view of FIG. 3. It is a perspective view which shows another aspect of the heat sink of this invention. It is a perspective view which shows another aspect of the heat sink of this invention. It is a perspective view which shows another aspect of the heat sink of this invention. It is a perspective view which shows another aspect of the heat sink of this invention. It is a perspective view which shows another aspect of the heat sink of this invention. It is a perspective view which shows another aspect of the heat sink of this invention. It is explanatory drawing which shows the aspect which attached the heat sink of this invention to the vehicle-mounted LED lamp. It is explanatory drawing which shows the outline | summary of an emissivity measuring apparatus.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  FIG. 1 is a perspective view showing an embodiment of the heat sink of the present invention, and FIG. 2 is a plan view of FIG. 3 is also a perspective view showing another aspect of the heat sink of the present invention, and FIG. 4 is a plan view of FIG.

  1 to 4 show a heat sink formed by corrugating the material aluminum alloy thin plate 1 having a black coating pre-coating treatment 9 preliminarily formed on the surface thereof, so that the corrugations 2 and 3 are formed into a continuous radiating fin shape. Is shown. Here, as is well known, corrugating means corrugated machining of a flat plate or a smooth tube. The black paint pre-coating treatment 9 is indicated by only the number 9 because it is a very thin surface coating, but is pre-coated (coated) on the entire surface (both sides) of the aluminum alloy thin plate 1 or the necessary surface portion (including one side). The

  The heat sinks shown in FIGS. 1 to 4 are all connected such that waveforms 2 and 3 are alternately arranged. However, the waveforms 2 and 3 in FIGS. 3 and 4 are provided with a step at the center in the longitudinal direction of the heat sink (left and right in the figure), and the levels of the left and right waveforms differ from each other at the center. It has become. According to the design of the space and the convenience of space in the on-vehicle LED lamp of the heat sink, by providing such a step, the entire shape of the continuous waveforms 2 and 3 is like the rectangular shape in FIGS. Not only a uniform shape but also an irregular shape as shown in FIGS.

Radiation fin corrugated shape:
In FIGS. 1-4, the radiation fin = waveform 2 and 3 of the same width and height is repeated continuously with the same pitch alternately. Here, the waveforms 2 and 3 are convex portions or concave portions that are connected to each other and whose concave and convex directions are different by 180 degrees, and more precisely, are continuous waveform elements or waveform units. In the book, they are simply called waveforms 2 and 3.

  Here, the width a of the waveform 2, the width b of the waveform 3, the pitch p between the waveforms 2, 2 or 3, 3, the width w of the waveforms 2, 3 (heat sink), the height h, the continuous waveforms 2, 3 The length 1 of the (heat sink) is designed so as to satisfy the required heat dissipation characteristics of the heat sink according to the specifications of the in-vehicle LED lamp to be mounted.

  Now, from the specifications of the vehicle-mounted LED lamps for ordinary passenger cars, these usage ranges are exemplified. The width a of the waveform 2 and the width b of the waveform 3 are 1 to 20 mm, and the pitch p between the waveforms 2 and 2 or the waveforms 3 and 3 is The width w of 4 to 40 mm, the waveforms 2 and 3 (heat sink) is 50 to 250 mm, the height h is 10 to 60 mm, and the length l of the continuous waveforms 2 and 3 (heat sink) is 30 to 250 mm. The design limit values (upper and lower limits) of the waveforms 2 and 3 are also defined from the waveform forming limit side of the raw aluminum alloy thin plate 1 by corrugation. That is, when the design values of these waveforms 2 and 3 are too small, or conversely too large, corrugation processing itself cannot be performed.

Pre-coat treatment:
1-4, the entire surface of the raw material aluminum alloy thin plate 1 is pre-treated with a black paint pre-coating treatment (coating film) 9 having an emissivity ε of 0.7 or more and a high heat radiation amount. As a result, the amount of heat transmitted by radiation or the amount of radiation heat radiation can be increased as radiating fins = waveforms 2 and 3 (heat sink).

  In addition, since this pre-coating process also serves as a lubricant in the corrugating process of the material aluminum alloy thin plate 1, it also has the effect of improving the formability of the radiation fins = waves 2 and 3. The material aluminum alloy thin plate 1 is pre-coated with a black paint in advance.

  The emissivity ε of the precoat treatment (paint coating) applied to the surface of the material aluminum alloy thin plate is set to 0.7 or more in order to increase the thermal emissivity of the radiation fins = waveforms 2 and 3. If the emissivity ε is less than 0.7, the above-mentioned lubrication effect is obtained, but as the heat radiation fins = waveforms 2 and 3 (heat sinks), the amount of heat transmitted by radiation or the amount of radiation heat radiation decreases, and the bare aluminum alloy is not coated. No big difference from the thin plate 1.

  This emissivity ε is a ratio with respect to a theoretical value of thermal radiation of an actual object (a thermal radiation of a black body which is an ideal thermal radiator), and actual measurement is disclosed in Japanese Patent Application Laid-Open No. 2002-234460. The described method may be used, and measurement may be performed by a portable emissivity measuring apparatus developed by the Japan Aerospace Exploration Agency. The measurement method described in the publication will be described below. The emissivity ε is measured by the emissivity measuring apparatus shown in FIG. In FIG. 12, an emissivity measuring apparatus 30 includes an electric heater 31 whose lower surface is covered with a black paint layer 32, a cooling floor 34 arranged at a certain distance below the electric heater 31, and heat insulation surrounding these from the periphery. It is basically composed of the layer 33. Then, the outer surface of the waveform 2 to be measured of the heat sink 1 is arranged on the cooling floor 34 so that the temperature and the temperature rise of the heat sink 1 with respect to a certain amount of heat Q 1 radiated from the electric heater 8 (heat passing amount Q1). Is measured from the input power or the temperature rise amount of the cooling water 35 in the cooling floor 34 (cooling water amount and rising temperature), and the emissivity ε2 defined by the present invention on the outer surface of the waveform 2 of the heat sink 1 is calculated by the following equation 1. taking measurement.

(但し、Q1;Al合金ヒートシンク1の通過熱量、σ; ステファンボルツマン定数 5.67×10-8W/m2K4、T1; 黒色塗料層9 の温度、T2;ヒートシンク1 の温度、ε1;黒色塗料層３２ の放射率 0.9、ε2; ヒートシンク1の波形２外面の放射率)

(Where, Q1; passing heat amount of Al alloy heat sink 1, σ; Stefan Boltzmann constant 5.67 × 10-8 W / m2K4, T1; temperature of black paint layer 9, T2; temperature of heat sink 1; ε1; radiation of black paint layer 32 (Rate 0.9, ε2; emissivity of wave 2 outer surface of heat sink 1)

Step formation:
In the present invention, as a preferable mode, a step portion (step, unevenness) is provided on a part of the radiating fins = waves 2 and 3 by crushing the waves 2 and 3. This step portion serves as a component attachment portion or an element attachment portion when being mounted as a heat sink for an in-vehicle LED lamp. In addition, this stepped portion has an uneven shape for improving the rigidity as a heat sink against an external force (bending moment) around an axis perpendicular to the paper surface as indicated by arrows on the left and right sides of the heat sink shown in FIG. I will provide a.

  The heat sink of FIG. 5 has the same basic shape as that of FIGS. 1 and 2 in which the waveforms 2 and 3 are alternately connected to each other. However, a part of the waveform 2a and a waveform 3a adjacent thereto are further provided. The waveform 2b, which is separated from the waveform 2a by several pitches, is formed into wider widths a1, b1, and a2 than the widths a and b of the other standard waveforms 2 and 3, respectively. After that, the corrugations 2a, 2b and 3a are crushed to provide step portions (recesses) 4a and 4b. And the components and elements 20a and 20b as a heat sink for vehicle-mounted LED lamps are attached to the step portions 4a and 4b, respectively. Such a wide waveform, stepped portion, or width is appropriately selected according to the required number of components, the number of attached elements 20a, 20b, size, shape, position, etc., or the degree of reinforcement such as rigidity. Here, the components and elements 20a and 20b are specifically an LED substrate for supplying power to the LED elements and an LED element mounted thereon.

  Molding of these stepped parts, including the stepped parts to be described later, after forming by corrugating the corrugated 2 and 3, the molding part of these stepped parts in the corrugated shape is not performed in a separate process such as offline. However, as a process associated with the corrugating process, molding can be performed in a series of corrugating processes.

  Such other embodiments of the reinforcement example are shown in FIGS. Incidentally, the basic shape of the heat sinks in these figures, in which the waveforms 2 and 3 are alternately connected, is the same as that in FIGS.

  In FIG. 6, of the waveforms 2 and 3, a convex portion such as a stepped portion 5 b is provided at the same height (level) as the surface of the waveform 2 at an intermediate position of each waveform 3 (in this case, the center position). Further, the corrugated shape is reinforced by providing stepped portions in the lateral direction of the corrugated shape, and the rigidity of the corrugations 2, 3 = heat sink is improved. The position, the number, and the height of the stepped portion 5b are selected as necessary. In this step portion forming, after forming by corrugation processing of the waveforms 2 and 3, the forming portion of the step portion 5 b in the waveform 3 is partially pushed up in the direction of the waveform 2.

  In FIG. 7, a convex portion such as a step portion 5c is provided at an intermediate position (in this case, the center position) of each waveform 3, and a concave portion such as a step portion 4c is provided at an intermediate position (in this case, the central position) of each waveform 2. It is continuously provided and reinforced. And the surface of the convex part of these step part 5c and the recessed part of the step part 4c is made into the same height (level), and it has reinforced in the form which provided the step part continuously in the waveform horizontal direction. The position, number, and height of the stepped portion 5c and the stepped portion 4c are selected as necessary. In forming these step portions, after forming the corrugations of the waveforms 2 and 3, the forming portion of the step portion 5 c in the waveform 3 is partially pushed up in the direction of the waveform 2, while forming the step portion 4 c in the waveform 2. The portion is partially crushed (pressed down) in the direction of the waveform 3 to perform molding.

  In FIG. 8A, flat flanges such as stepped portions 6a, 6b, 6c, and 6d are provided on the peripheral portions (four circumferences) of the corrugations 2 and 3 (heat sinks), respectively. After forming these step portions by corrugation processing of the waveforms 2 and 3, the waveform 2 at the peripheral portion (four surroundings) is shown in FIG. 8 (b) as shown in the XX ′ cross section of FIG. 8 (a). Crushing (pushing down) and partially crushing (pushing up) the waveform 3 are performed. These ribs or flanges are provided to facilitate attachment of the heat sink and the housing.

  In FIG. 9, a concave portion such as a step portion 7 in which a halfway position of the waveform 2 (in this case, the center position) is cut out in a square shape is provided, but the upper portion (upper side) of the waveform 2 is not cut off at that time. In addition, it is left as a square section 8a, and this section 8a is bent at a right angle like 8b. The reason why the sections 8a and 8b are provided is to attach the element 20 and necessary parts without providing a step.

  FIG. 10 shows an example in which a reinforcing bracket 21 is attached to the back surfaces of the waveforms 2 and 3 (heat sinks) with an adhesive. FIG. 10A shows that the integrated bracket 21 is attached to the entire back surface of the corrugations 2 and 3 (heat sink), and FIG. 10B shows that the brackets 21 and 21 divided into two are attached to the back surface of the waveforms 2 and 3 (heat sink). Each is pasted. FIG. 10C shows a case where brackets 21 having a substantially U-shaped cross section are attached to both ends of the corrugations 2 and 3 (heat sinks). The bracket 21 has flange portions 22 used for attaching other parts, 22 is provided. In FIGS. 10A, 10B, and 10C, an aluminum alloy or a resin material can be used as the material of the brackets 21 and 22.

Attaching the heat sink to the in-vehicle LED lamp:
FIG. 11 shows an aspect of mounting the heat sink to the in-vehicle LED lamp. 11a shows a longitudinal section of the LED lamp, and FIG. 11b is a top view of the section YY ′ of FIG. 11a. In FIG. 11, an in-vehicle LED lamp (vehicle lamp) 10 includes an LED board 11 on which an LED 11a as a light source is mounted, a reflector 12 that reflects light from the LED 11a forward in the light irradiation direction, and these LED boards. 11 and the housing 12 surrounding the reflector 12, an outer lens 14 made of a transparent material closing the open front end of the housing 13, and the heat sink 1 disposed in thermal contact with the LED substrate 11.

  Here, the heat sink 1 formed into a continuous wave 2 or 3 shape as a radiating fin shape of the present invention has step portions 7a and 7b. In addition, the lower surface of the LED base 11 is thermally connected to the upper surface of the stepped portion 7a via a sheet-like heat conducting member 15a. The upper surface of the reflector 12 is connected to the lower surface of the stepped portion 7b.

  On the other hand, the LED substrate 11 is disposed at the center of the step 7 of the heat sink, and the LED 11a is mounted on the upper surface thereof. The reflector 12 is formed of a resin material and includes a parabolic reflecting surface having a focal point near the LED 11 a on the LED substrate 11.

  The housing 13 is open on the front side (the mounting side of the outer lens 14). Moreover, the opening part 13a is provided in the rear surface side (right side of a figure), and the said heat sink 1 is attached so that this rear surface side opening part 13a may be sealed.

  According to the vehicle-mounted LED lamp 10 having such a configuration, the LED 11 a on the LED substrate 11 is driven to emit light, and the light emitted from the LED 11 a is reflected by the reflector 12 and irradiated through the outer lens 14. Irradiated forward in the direction. Here, the heat generated from the LED 11 a is transmitted from the LED substrate 11 to the heat sink 1 via the heat conducting member 15 a and is released from the heat sink 1 to the outside of the housing 13. Thereby, the temperature rise of LED11a is suppressed.

Material aluminum alloy plate:
The material aluminum alloy plate used in the heat sink of the present invention can be molded into the shape of the heat sink 1 as a thin plate having a thickness of 2 mm to 0.4 mm, and it is most important that the corrugate workability is excellent. In addition, in view of the required characteristics of the heat sink, which are excellent in heat transfer and corrosion resistance, a pure aluminum-based 1000 series, which has as little alloying element as possible and is specified or included in the AA or JIS standards, is preferable. Incidentally, in the present invention, these pure aluminum-based materials are also expressed as aluminum alloy plates. However, from the viewpoint of strength such as ensuring the rigidity, an aluminum alloy material selected from 3000 series or the like specified or included in AA to JIS standards is appropriately selected. These aluminum alloy sheets are produced by various ordinary manufacturing processes such as casting (DC casting method or continuous casting method), homogenization heat treatment, hot rolling, intermediate annealing, cold rolling, tempering treatment such as solution treatment and quenching treatment. Manufactured by.

  According to the present invention, a heat sink having high productivity can be provided by using an aluminum alloy thin plate as a raw material and creating the entire shape of the radiating fin having a continuous waveform by corrugating the plate. For this reason, it is suitable for the heat sink of a vehicle-mounted LED lamp.

  1: heat sink, 2, 3: waveform, 4, 5, 6, 7: step, 8: section, 9: precoat treatment film, 10: vehicle-mounted LED lamp, 20: element, 21: resin bracket

Claims (2)

Aluminum alloy sheet is formed into a heat dissipating fin-shaped waveform that continuously by corrugating Ri name, the waveform stepped portion a part of which is formed is pressed and thinned the waveform is provided, this step portion of the LED element A heat sink for in-vehicle LED lamps that is a mounting part .   The heat sink for vehicle-mounted LED lamps of Claim 1 by which the pre-coating process whose emissivity (epsilon) is 0.7 or more is performed previously on the surface of the said aluminum alloy thin plate before the said corrugating process.

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