JP2016100176A - Vehicular lighting fixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicular light emitting device which is improved in heat radiation efficiency.SOLUTION: A vehicular lighting fixture has a light source 11, an outer lens 12 which emits light emitted from the light source 11 to the outside, and a heat sink 13 which radiates heat of the light source. The heat sink 13 includes a plurality of plate-like fins 14 which are arranged in parallel at intervals. Main planes of the fins 14 are arranged facing the outer lens 12 so as to improve heat radiation efficiency.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vehicular lamp having a structure for radiating heat from a light source.

  A heat sink provided with a plurality of fins is used for a vehicular lamp using an LED as a light source in order to dissipate heat from the LED by natural convection (Patent Documents 1 and 2). FIG. 1 of Patent Document 1 discloses a structure in which a plurality of plate-like fins are arranged above a vehicle lamp. 1 to 3 of Patent Document 2 disclose a structure in which a plurality of fins are arranged toward the rear of a vehicular lamp.

  On the other hand, in order to dissipate heat generated by a semiconductor integrated circuit such as an LSI by natural convection, Patent Document 3 discloses a heat sink in which a large number of pillars are erected. In Patent Document 3, an aluminum plate having a hole in the center is mounted on a heat sink, thereby generating natural convection from the outside through the center hole to the upper side to increase the heat dissipation effect.

JP 2009-277535 A JP 2013-120649 A JP 7-335793 A

  In recent years, it has been desired to reduce the weight and amount of light of a vehicular lamp, and in order to realize this, it is necessary to increase the heat dissipation efficiency of the heat sink.

  The objective of this invention is providing the light-emitting device for vehicles which improved heat dissipation efficiency.

  In order to achieve the above object, a vehicular lamp according to the present invention includes a light source, an outer lens that emits light emitted from the light source toward the outside, and a heat sink that dissipates heat from the light source. , Including a plurality of plate-like fins arranged in parallel at intervals. The fins are arranged such that the main plane faces the outer lens.

  ADVANTAGE OF THE INVENTION According to this invention, the light-emitting device for vehicles which improved heat dissipation efficiency can be provided.

The notch perspective view of the vehicle lamp of embodiment. The notch perspective view of the vehicle lamp of a comparative example. (A) The perspective view which shows the model of the vehicle lamp of Example 1, (b) The perspective view which shows the model of the vehicle lamp of the comparative example 1. (A) The figure which shows the temperature distribution of the vehicle lamp of Example 1, (b) The figure which shows the flow-velocity distribution of the vehicle lamp of Example 1. FIG. (A) The figure which shows the temperature distribution of the vehicle lamp of the comparative example 1, (b) The figure which shows the flow-velocity distribution of the vehicle lamp of the comparative example 1. (A) The perspective view which shows the model of the vehicle lamp of Example 2, (b) The perspective view which shows the model of the vehicle lamp of the comparative example 2. (A) The figure which shows the temperature distribution of the vehicle lamp of Example 2, (b) The figure which shows the flow-velocity distribution of the vehicle lamp of Example 2. FIG. (A) The figure which shows the temperature distribution of the vehicle lamp of the comparative example 2, (b) The figure which shows the flow-velocity distribution of the vehicle lamp of the comparative example 2. (A) Light source temperature of Examples 1-2 and Comparative Examples 1-2, thermal resistance, explanatory drawing which shows the weight of a heat sink, (b) Light source temperature, thermal resistance of Examples 3-4 and Comparative Examples 3-4, Explanatory drawing which shows the weight of a heat sink. (A) The perspective view which shows the model of the vehicle lamp of Example 3, (b) The perspective view which shows the model of the vehicle lamp of the comparative example 3. (A) The perspective view which shows the model of the vehicle lamp of Example 4, (b) The perspective view which shows the model of the vehicle lamp of the comparative example 4.

  A vehicle lamp according to an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the vehicular lamp according to this embodiment includes a light source 11 of an LED or LD (laser diode), an outer lens 12 that emits light emitted from the light source 11 to the outside, and heat of the light source. And a heat sink 13 for radiating heat. The heat sink 13 includes a plurality of plate-like fins 14 arranged in parallel at intervals. In the present embodiment, the heat radiation efficiency is improved by arranging the main plane of the fin 14 so as to face the outer lens 12.

  As shown in FIG. 2 of the comparative example, the inventors arrange the main plane of the fin 14 so as to face the outer lens as shown in FIG. 1 rather than the arrangement in which the main plane of the fin 14 is perpendicular to the outer lens. It has been found by simulation that the heat dissipation efficiency is improved. The reason why the heat dissipation efficiency is improved by the arrangement of FIG. 1 is considered to be that the outer lens 12 of the vehicular lamp is in contact with the outside air, and is therefore at a lower temperature than other surfaces facing the engine room. The space inside the outer lens 12 is cooled by the outer lens 12 (for example, 40 to 50 ° C.) and is cooler than the inner space (for example, 60 to 120 ° C.) of the other surface facing the engine room. On the other hand, the heat radiation efficiency of the fins 14 is increased by directing the main plane of the fins 14.

  The arrangement in which the main plane of the fin 14 faces the outer lens 12 is sufficient if the main plane of the fin 14 is directed toward the outer lens 12, and the main plane of the fin 14 is parallel to the main plane of the outer lens 12. In addition to the arrangement, as shown in FIG. 1, the inclined principal plane of the outer lens 12 and the principal plane of the fin 14 may face each other. That is, the normal direction of the main plane of the outer lens 12 only needs to intersect the main plane of the outer lens 12. Thus, if the outer lens 12 is inclined and faces the main plane of the fin 14, the space inside the outer lens 12 is low in temperature, so that the fin 14 is cooled and heat dissipation efficiency can be improved. Therefore, the heat dissipation efficiency of the heat sink 13 as a whole is improved.

  As long as the main plane of the fin 14 faces the outer lens 12, the fin 14 may be disposed downward or upward. For example, as shown in FIG. 1, the heat sink 13 can have a plate-like base 15, the light source 11 is mounted on one surface, and a plurality of fins 14 are erected on the other surface. At this time, as shown in FIG. 1, the plurality of fins 14 may have a structure standing upward from the upper surface of the base 15, or standing downward from the lower surface of the base 15. May be.

  In addition to the above-described configuration, it is of course possible to arrange various configurations necessary as a vehicular lamp. For example, as shown in FIG. 1, a housing 16 that is connected to a front outer lens 12 to cover a top surface, a bottom surface, and a side surface to form a housing, a reflector 17 that reflects light emitted from the light source 11, and a reflector 17 reflects the light. The internal lens 18 that forms a desired light beam from the emitted light and the bracket 19 that holds the heat sink 13 can be provided. The bracket 19 is fixed to the rear surface of the housing by the aiming bolt 20, and the emission direction of the light source 11 can be adjusted by adjusting the aiming bolt 20.

  The light source 11 can use a lamp such as a halogen lamp in addition to the LED and the LD. Between the light source 11 and the base 15, it is desirable to arrange TIM (Thermal Interface Materials), such as grease, a heat conductive sheet, or a heat conductive adhesive, in order to reduce thermal resistance. The heat sink 13 is desirably formed of a metal or metal alloy such as aluminum or magnesium having high thermal conductivity.

  The heat dissipation efficiency of the heat sink 13 can be improved by arranging the main plane of the fins 14 of the heat sink 13 so as to face the outer lens 12 as in the present embodiment. 1 can reduce the size of the heat sink 13 to the extent that the heat radiation efficiency is improved when the light emission amount of the light source 11 is the same as that of the vehicle lamp of the comparative example of FIG. The vehicle lamp can be downsized. Moreover, when making the size of the heat sink 13 the same as the vehicle lamp of the comparative example, the light quantity of the light source 11 can be increased, and a vehicular lamp with a large light quantity can be provided.

  In addition, the vehicular lamp according to the present embodiment can use a heat sink in which pins for heat dissipation are arranged in two directions instead of the heat sink 13 provided with the plate-like fins 14. Of the two directions, the pins are arranged more densely in the first direction than in the second direction. The first direction in which the pins are closely arranged is arranged so as to face the outer lens 12. The plurality of pins arranged closely along the first direction has the same surface as the main plane of the plate-like fins 14 because the surface on which the side surfaces of the pins are arranged acts on the outer lens 12. By facing each other, it is possible to improve the heat dissipation efficiency of the arrangement of pins (first direction) closest to the outer lens 12. Therefore, the heat dissipation efficiency of the heat sink 13 can be improved as compared with the case where the first direction in which the pins are dense is arranged perpendicular to the main plane of the outer lens.

  In this case, the direction of the pin may be upward or downward. For example, with respect to the plate-like base 15, the plurality of pins may be erected upward from the upper surface of the base 15, or may be erected downward from the lower surface of the base 15.

  Moreover, it is preferable that the space | interval of a pin about the dense arrangement direction (1st direction) of a pin is more than the diameter of a pin and 2 times or less of the diameter of a pin. In particular, the pin spacing is preferably 1.5 times or less the pin diameter.

  The shape of the pin can be a desired shape such as a rectangular column, a cylinder, a hexagonal column, or an elliptical column. For example, it can be a 1.5 mm square prism.

  The direction of the fins 14 and the pins is not limited to vertically upward or vertically downward, but may be inclined with respect to the vertical direction.

When the main plane of the fin 14 and the first direction of the pins are inclined with respect to the main plane of the outer lens 12, it is desirable to derive the interval p between the fins 14 by the following expression (1).
p = 5 (h / ΔT) ^0.25 (1)
However, h is the height of the fin 14, and ΔT is the difference between the fin temperature and the ambient temperature. In addition, the space | interval in the 2nd direction of a pin can be similarly set by Formula (1).

  Further, FIG. 1 shows an example of a vehicle headlamp, but the present invention is not limited to a vehicle headlamp, but a fog (FOG) lamp or a daytime running lamp (DRL). Of course, it is possible to have the same configuration.

  Further, the heat dissipation structure of the present invention is not limited to the above-described vehicle lamp, and can be applied to other devices as long as the device has a low-temperature casing surface corresponding to the outer lens. For example, the present invention can be applied to an LED illumination device, a projector light source device, and the like. Not only a light source such as an LED, but also a heat dissipation structure for other heat generating components can be used.

  Hereinafter, the Example which calculated | required the thermal radiation efficiency of the vehicle lamp of this invention by simulation is described.

<Example 1 and Comparative Example 1>
The structure of the vehicle lamp model used in the simulation of Example 1 will be described with reference to FIG. The model shown in FIG. 3A includes a heat sink 13, a rectangular parallelepiped housing (outer lens 12 and housing 16), and a light source 11 (not shown in FIG. 3A). It is fixed to the lower surface of the base 15 via a TIM. The main plane of the fin 14 of the heat sink 13 is disposed in parallel with the surface of the outer lens 12 of the rectangular parallelepiped housing.

  The heat generation amount of the light source 11 was 20 W, and the size was 25 mm square. The size of the housing (the outer lens 12 and the housing 16) was 300 mm width × 200 mm depth × 200 mm height when viewed from the outside of the outer lens 12. The main plane of the base 15 of the heat sink 13 is 120 mm square, the height of the heat sink 13 is 35 mm, the thickness of the fins 14 is 1.5 mm, and the number of fins 14 is 11. The fins 14 face upward as shown in FIG.

  The temperature of the outer lens 12 was 45 ° C., the temperature of the housing 16 was 85 ° C., and the temperature of the light source 12, the temperature distribution of the space in the housing, and the flow velocity distribution by natural convection were obtained by simulation.

  Further, as a comparative example 1, the orientation of the main plane of the fin 14 is arranged perpendicular to the main plane of the outer lens 12 as shown in FIG. 3B, and other conditions are the same as in the first embodiment. For the lamp model, the temperature of the light source 12, the temperature distribution of the space in the housing, and the flow velocity distribution by natural convection were obtained by simulation.

  As a result, the temperature of the light source 12 was 115.6 ° C. in the model of Example 1, whereas 115.7 ° C. in Comparative Example 1, and the temperature of Example 1 was lower, and the temperature was reduced. It was confirmed that the effect of was obtained.

  Further, for the models of Example 1 and Comparative Example 1, the results of obtaining the temperature distribution of the space in the housing (temperature distribution in the cross section passing through the center of the heat sink 13) are shown in FIG. 4 (a) and FIG. 5 (a). The results of obtaining the flow velocity distribution are shown in FIGS. 4 (b) and 5 (b). In the vehicle lamp model of the first embodiment, as shown in FIG. 4A, the entire upper portion of the heat sink 13 exhibits a high temperature, and heat is dissipated to the ambient air near the light source 12 that is a heat source and to the entire heat sink 13. I understand that. Further, regarding the flow velocity distribution, it can be seen that the flow velocity of the entire upper portion of the heat sink 13 is fast as shown in FIG. 4B, and the flow velocity is increased between the fins 14 of the entire heat sink 13. In contrast, the model of Comparative Example 1 shows a high temperature only near the center of the heat sink 13 as shown in FIGS. 5A and 5B, and the flow velocity distribution is also only near the center of the heat sink 13. Is speeding up. As described above, it was confirmed that the heat radiation characteristics of the heat sink 13 as a whole in Example 1 in which the main plane of the fin 14 was directed to the outer lens 12 was higher than that in Comparative Example 1.

<Example 2 and Comparative Example 2>
As a model of the second embodiment, as shown in FIG. 6A, a heat sink 13 in which pins 61 are erected is used instead of the fin 14 of the model of the first embodiment. The pins 61 are 1.5 mm square prisms, and are arranged densely at intervals of 3.5 mm in a first direction 50 parallel to the main plane of the outer lens 12 and are perpendicular to the outer lens 12. The direction 60 is sparsely arranged at intervals of 10.4 mm. Other configurations are the same as those of the first embodiment.

  On the other hand, in the model of Comparative Example 2, as shown in FIG. 6B, the pins 61 are sparsely arranged at intervals of 10.4 mm in the first direction 50, and in the second direction 60 3. It is densely arranged at intervals of 5 mm. Other configurations are the same as those of the second embodiment.

  When the temperature of the light source 11 of the model of Example 2 and Comparative Example 2 was obtained by simulation, Example 2 was 117.6 ° C., whereas Comparative Example 2 was 118.4 ° C. The temperature of 2 was lower than that of Comparative Example 2, and the effect of temperature reduction was obtained.

  Moreover, about the model of Example 2 and the comparative example 2, the result of calculating | requiring the temperature distribution of the space in a housing | casing is shown to Fig.7 (a) and FIG.8 (a), respectively, and the result of calculating | requiring the flow velocity distribution is shown in FIG. It is shown in b) and FIG. Comparing FIG. 7A and FIG. 8A, in the vehicle lamp model of Example 2, the entire upper portion of the heat sink 13 is higher in temperature than in Comparative Example 2. Further, comparing FIG. 7B and FIG. 8B, the model of Example 2 has a higher flow velocity in the entire upper part than Comparative Example 2. From this, it was confirmed that heat was dissipated to the ambient air near the light source 12 as a heat source and the entire heat sink 13.

  In particular, it was found that the pin type heat sink of Example 2 has a large temperature reduction effect along the first direction 50. This is because the main flow of the convection that occurs in the sparsely spaced locations and the double flow of the convection that occurs in the dense locations cause the flow to develop without clogging the heat between the pins and promote heat transfer. It is thought that this is because.

  Note that, as shown in FIG. 9A, the temperature of the light source 11 of the model of the second embodiment is about 2 ° C. higher than that of the model of the first embodiment. Further, when the thermal resistance (° C./W) obtained by dividing the difference between the temperature of the light source 11 and the average temperature of the interior space of the vehicle lamp by the calorific value of the light source 11 was obtained, the thermal resistance of Example 2 was obtained. Was greater than the thermal resistance of Example 1. This is because the heat transfer area of the pin type heat sink 13 is reduced as compared with the fin type heat sink. However, as shown in FIG. 9A, the heat sink 13 has a weight of 300.6 g when the material is an aluminum alloy, whereas the pin type of the second embodiment is 212. 0.0 g, which is reduced by about 30%, and the pin type has a merit that the effect of weight reduction is greater.

<Example 3 and Comparative Example 3>
Next, as Example 3, a simulation was performed for a model in which the heat sink is smaller in the depth direction than Example 1. The structure of the vehicle lamp model used in the simulation of Example 3 will be described with reference to FIG. In Example 3, the width of the base 15 of the heat sink 13 is 120 mm, the depth is 70 mm, the height of the heat sink 13 is 35 mm, and the thickness of the fins 14 is 1.5 mm. The interval between the fins 14 is the same as that in Example 1, and the number of fins 14 is 7 in the depth direction. The size of the housing, the heat generation amount and size of the light source 11, the temperature of the outer lens 12, and the temperature of the housing 16 are the same as in the first embodiment. The fins 14 face upward as shown in FIG.

  Further, in the model of Comparative Example 3, the orientation of the main plane of the fin 14 is arranged perpendicular to the main plane of the outer lens 12 as shown in FIG. 10B, and other conditions are the same as in Example 3. did.

  When a simulation was performed for Example 3 and Comparative Example 3, the temperature of the light source 12 was 122.4 ° C. in Example 3, while 122.8 ° C. in Comparative Example 3. It was confirmed that Example 3 had a lower temperature and the effect of temperature reduction was obtained.

<Example 4 and Comparative Example 4>
As shown in FIG. 11A, as a model of the vehicle lamp of the fourth embodiment, a heat sink 13 in which pins 61 are erected in place of the fins 14 of the third embodiment is used. The pins 61 are 1.5 mm square prisms, which are densely arranged at intervals of 3.5 mm in a first direction 50 parallel to the outer lens 12 and in a second direction 60 perpendicular to the outer lens 12. Are sparsely arranged at intervals of 10.4 mm. Other configurations are the same as those in the fourth embodiment.

  On the other hand, in Comparative Example 4, as shown in FIG. 11B, the pins 61 are sparsely arranged at intervals of 10.4 mm in the first direction 50, and at intervals of 3.5 mm in the second direction 60. It is densely arranged. Other configurations are the same as those in the fourth embodiment.

  When the temperature of the light source 11 of Example 4 and Comparative Example 4 was obtained by simulation, Example 4 was 124.7 ° C., whereas Comparative Example 4 was 125.9 ° C. The temperature was lower than that of Comparative Example 4, and the effect of temperature reduction was obtained.

  Note that, as shown in FIG. 9B, the temperature of the light source 11 of Example 4 is about 2.3 ° C. higher than that of Example 3. Further, the thermal resistance of Example 4 is larger than the thermal resistance of Example 3. This is because the pin type heat sink 13 reduces the overall heat transfer area as compared with the fin type heat sink. However, the weight of the heat sink 13 is as shown in FIG. Is an aluminum alloy, the fin type of Example 3 is 188.0 g, whereas the pin type of Example 4 is reduced by about 28% to 135.0 g, and the pin type is lighter in weight. There is a merit that the effect is great.

  According to the first to fourth embodiments described above, the vehicular lamp in which the main plane of the fins 14 or the first arrangement direction of the pins is parallel to the outer lens 12 is a comparative example in which they are perpendicular to the outer lens 12. It was confirmed that the heat radiating performance was improved by about 2 to 4% compared to the vehicle lamps. As a result, it was found that the vehicular lamp of the example can keep the heat sink performance constant, reduce the size of the heat sink, and reduce the weight as compared with the comparative example. It was also found that it is possible to mount a light source with a large amount of light while improving the heat dissipation performance while maintaining the size of the heat sink.

  In addition, the heat dissipation efficiency of the pin type heat sink is about 7% lower than that of the fin type heat sink, but the heat dissipation efficiency per unit weight is 1.3 times higher for the pin type. In this case, the pin type heat sink can be reduced by about 19% compared to the fin type heat sink.

  DESCRIPTION OF SYMBOLS 11 ... Light source, 12 ... Outer lens, 13 ... Heat sink, 14 ... Fin, 15 ... Base, 16 ... Housing, 17 ... Reflector, 18 ... Internal lens, 19 ... Bracket, 20 ... Aiming bolt

Claims (6)

A light source, an outer lens that emits light emitted from the light source toward the outside, and a heat sink that dissipates heat from the light source,
The vehicular lamp, wherein the heat sink includes a plurality of plate-like fins arranged in parallel with a space therebetween, and the fins are arranged such that a main plane faces the outer lens.   2. The vehicular lamp according to claim 1, wherein the heat sink includes a plate-like base on which the light source is mounted on one surface, and the plurality of fins are erected on the other surface of the base. A vehicular lamp characterized by the above.   The vehicular lamp according to claim 2, wherein the plurality of fins are erected upward on an upper surface of the base.   The vehicular lamp according to claim 2, wherein the plurality of fins are erected downward on a lower surface of the base. A light source, an outer lens that emits light emitted from the light source toward the outside, and a heat sink that dissipates heat from the light source,
The heat sink includes a plurality of pins for heat dissipation arranged upright in two directions,
The pins are arranged more densely than the second direction in the first direction among the two directions, and the first direction is arranged to face the outer lens. Light fixture.   6. The vehicular lamp according to claim 5, wherein the heat sink includes a plate-like base on which the light source is mounted on one surface, and the plurality of pins are erected on the other surface of the base. A vehicular lamp characterized by the above.