JP2008123836A - Vehicle headlamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle headlamp efficiently dissipating heat generated in the LED, using a simple composition. <P>SOLUTION: The vehicle headlamp 10 contains a housing 11 which is open toward front, at least one LED lamp unit 12, with at least one LED, respectively installed to emit light toward the front in the housing and a front surface lens 13 comprising a translucent material closing the front surface which is open in the housing. The vehicle headlamp 10 is constituted, in such a way with it has one tier or more of recessed and projected surface for heat dissipation 15 in a region, where a member does not exist inside or at the outside that would impair the planarity of the housing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle headlamp such as a headlamp using an LED as a light source.

Conventionally, LED headlamps using LEDs as light sources are configured as shown in FIGS. 7 and 8, for example.
That is, in FIG. 7 and FIG. 8, an LED headlamp 1 includes a resin-made casing 2 having an open front surface, and a plurality (three in the illustrated example) of LED wrap units provided in the casing 2. 3 and a front lens 4 made of a translucent resin material attached to the housing 2 so as to cover the front surface of the housing 2.

  Each of the LED lamp units 3 includes at least one LED 3a and a reflector 3b that reflects light from the LED 3a forward, and is fixedly held inside the housing 2 by a lamp unit support 3c. Has been.

  According to the LED headlamp 1 having such a configuration, the LED 3a of each LED lamp unit 3 is driven to emit light by supplying power to each LED lamp unit 3 from the outside. Light emitted from each LED lamp unit 3 is irradiated forward through the front lens 4.

  In such an LED headlamp 1, heat is generated as the individual LEDs 3a of the LED lamp units 3 emit light.

By the way, LED generally has a negative characteristic with respect to temperature. That is, it is known that the luminous efficiency decreases as the temperature increases.
Therefore, in the LED headlamp, since the housing 2 and the front lens 4 are made of a resin having low thermal conductivity, a countermeasure against the heat generation of each LED is particularly important. Therefore, in the LED headlamp 1 shown in FIGS. 7 and 8, the LED lamp unit 3 is attached to the heat sink 5 by the lamp unit support 3c, and the heat from each lamp unit 3 is transferred to the lamp unit support. Heat is radiated to a heat radiating member such as the heat sink 5 through 3c.

On the other hand, in Patent Document 1, the amount of heat generated by each LED is suppressed when the temperature rises by detecting the temperature in the housing and controlling the drive current supplied to the LEDs based on the temperature in the housing. A vehicular lamp is disclosed.
Further, in Patent Document 2, each LED is supported on a metal support member that functions as a heat sink having a large heat capacity, and heat generated in each LED is conducted to the metal support member to release heat from each LED. A vehicular headlamp that is adapted to perform is disclosed.

Furthermore, in Patent Document 3, each LED is supported in the vicinity of one end of the heat pipe, and the other end of the heat pipe is disposed outside the casing, so that heat generated in each LED is transmitted to the casing through the heat pipe. A vehicular lamp is disclosed which is discharged to the outside.
Further, in Patent Document 4, a heat sink fin of a heat sink to which each LED is attached is arranged outside the casing, and outside air is introduced into the heat sink fin through a vent hole to radiate each LED. Thus, a headlamp is disclosed.

Furthermore, Patent Document 5 discloses a vehicular lamp device in which outside air is introduced from a gap between a light emitting unit and a casing to radiate heat from the light emitting unit.
Patent Documents 6 and 7 disclose a lamp that heats the LED by directly fixing the LED to the heat dissipation substrate.
Further, Patent Document 8 discloses an LED light emitting lamp in which an LED is directly adhered to a heat radiating plate to dissipate the LED and further includes an exhaust fan that discharges air inside the housing to the outside. Is disclosed.

On the other hand, in Patent Document 9, by providing a cooling device in the housing, the temperature of the air heated by the heat generated in each LED is lowered by the cooling device, so that the environmental temperature of the LEDs in the housing is reduced. A vehicular lamp that is held low is disclosed.
Patent Document 10 discloses an automobile in which a lamp or a lamp unit is disposed in a cooling air port so that heat is radiated from the lamp or the lamp unit.

  Further, in Patent Documents 11 and 12, an air flow (or traveling wind) by a blower is introduced into a space around a cooling target such as a lighting control unit and a light emitter, and the lighting control unit and the light emitter are radiated. A vehicle headlamp is disclosed in which a radiated airflow is cooled by a heat exchanger.

Further, in Patent Document 13, a reinforcing rib is provided on the outer wall surface of the housing so as to increase the rigidity and have a surface area larger than the wall surface, thereby reducing the vibration of the housing and increasing the cooling performance. A housing of an electric device such as a converter is disclosed.
JP 2004-276738 A JP 2004-31224 A JP 2004-127782 A JP 2005-063754 A JP 2005-122945 A JP 2006-0666108 JP 2006-134810 A JP 2005-297865 A JP 2005-222785 A JP 2005-263213 A JP 2005-293938 A JP 2006-079881 A JP-A-2005-323443

  However, the vehicular lamp according to Patent Document 1 suppresses the amount of heat generated by the LED by controlling the drive current, and is not configured to radiate the heat generated by the LED. Therefore, once the temperature in the housing is raised, the light emission efficiency of the LED is lowered, and it takes time until the temperature is lowered.

  Moreover, in the vehicle headlamp according to Patent Document 2 and the lamps according to Patent Documents 6 and 7, heat generated in each LED is radiated into the housing by a metal support member and a heat dissipation substrate. For this reason, in the same manner, once the temperature in the housing is raised, the luminous efficiency of the LED is lowered, and it takes time until the temperature is lowered.

  On the other hand, in the LED light-emitting lamp according to Patent Document 8, the temperature inside the casing can be quickly lowered by discharging the air inside the casing to the outside by the exhaust fan, but the inside of the casing communicates with the outside. Will do. For this reason, there is a possibility that external dirt, dust, or the like may enter the housing.

  Moreover, in the lamp by patent document 3 and 4, the heat sink of the heat pipe or a heat sink is pulled out outside from the inside of a housing | casing. For this reason, there is a possibility that rainwater, dust, or the like may invade in these drawer portions, and the reliability of the lamp will be reduced.

On the other hand, in the vehicular lamp device according to Patent Document 5, since outside air is introduced into the casing, there is a risk that external dirt, dust, or the like may enter the casing.
Further, in the vehicular lamp according to Patent Document 9, since it is necessary to provide a cooling device in the casing, the casing itself is enlarged, which is against the demand for downsizing and the structure is complicated. Thus, the parts cost and the assembly cost increase.

Furthermore, in the automobile according to Patent Document 10, a space for a cooling air port is required around the lamp or the lamp unit. For this reason, the installation space of a lamp or a lamp unit will become large as a result.
Further, in the vehicle headlamps according to Patent Documents 11 and 12, heat can be effectively radiated by the airflow from the blower, and the temperature inside the housing can be made uniform, but the power line for the blower is drawn. And installation space is required. In addition, the parts cost and the assembly cost increase, and the reliability of the blower itself is also difficult to put into practical use.

  In addition, the casing of the electric device according to Patent Document 13 is configured to add a cooling function by providing cooling fins on the reinforcing rib provided to reduce vibration generated by the operation of the electric device. Therefore, it is not configured to maintain the airtightness inside the housing, and the object and configuration are different from those of the present invention.

  In view of the above, an object of the present invention is to provide a vehicle headlamp that efficiently dissipates heat generated from an LED with a simple configuration.

  According to the present invention, the object is as follows: a housing that is open at the front, and at least one LED lamp unit that has at least one LED arranged to emit light forward in the housing; In a vehicle headlamp including a front lens made of a translucent material that closes the open front surface of the housing, one or more steps are provided in a region where members that impair the planarity of the housing do not exist inside and outside. This is achieved by a vehicle headlamp characterized by having an uneven surface for heat dissipation.

  In the vehicle headlamp according to the present invention, preferably, the uneven surface of the casing has a shape that enlarges the surface area of the casing surface where the air inside and outside the casing contacts each other.

  In the vehicle headlamp according to the present invention, the uneven surface for heat dissipation is preferably provided in a region excluding the front surface of the housing.

  The vehicle headlamp according to the present invention is preferably formed such that the uneven surface for heat dissipation extends along the vehicle vertical direction on the side surface of the housing.

  The vehicle headlamp according to the present invention is preferably formed such that the uneven surface for heat dissipation extends along the vehicle front-rear direction at least on the upper surface or the lower surface of the housing.

According to the said structure, by supplying electric power from the exterior with respect to LED of each LED lamp unit, each LED is driven and light-emits.
Light emitted from each LED lamp unit is irradiated forward through the front lens.

In this case, the heat generated by the LEDs of each LED lamp unit rises by convection, is transmitted to the upper part in the casing, and is further transmitted to the entire casing.
Here, since the heat radiation uneven surface is provided in a substantially flat region of the housing, the heat is transmitted from the housing to the heat radiation uneven surface, and from the heat radiation uneven surface. By radiating heat to the outside of the housing, heat can be efficiently transferred to the outside.

Therefore, the heat generated in each LED of each LED lamp unit is efficiently radiated to the outside, and the temperature of each LED can be kept relatively low. For this reason, the luminous efficiency of each LED does not decrease, and bright illumination light can be obtained as a headlamp.
In addition, the uneven | corrugated surface for heat dissipation may have arbitrary shapes, such as not only a continuous rectangular thing but the square shape, curved surface shape, or island shape arrange | positioned discontinuously or irregularly.

  When the concave and convex surface of the casing has a shape that enlarges the surface area of the casing surface where the air inside and outside of the casing is in contact with each other, the surface area for radiating heat to the outside of the casing is small. By increasing the heat dissipation efficiency, the heat dissipation efficiency can be improved and the heat can be radiated more effectively.

  When the uneven surface for heat dissipation is provided in a region excluding the front surface of the housing, the uneven surface for heat dissipation is provided by providing the uneven surface for heat dissipation except for the front surface that affects the irradiation light. The heat dissipating efficiency is maximized, and heat can be dissipated more effectively.

  When the uneven surface for heat dissipation is formed so as to extend in the vertical direction on the side surface of the housing, when the automobile stops, heat is radiated from the uneven surface for heat dissipation to the outside air, The heated outside air can easily move upward along the uneven surface for heat dissipation, and heat can be efficiently radiated.

  When the uneven surface for heat dissipation is formed so as to extend along the front-rear direction on the upper surface of the housing, the traveling wind from the front is along the uneven surface for heat dissipation when the automobile is traveling. And can easily move backwards. For this reason, heat dissipation can be performed efficiently.

Thus, according to the present invention, in the vehicle headlamp having at least one LED lamp unit, heat is radiated to the outside air from the heat radiation uneven surface provided in a partial region of the housing. Thereby, the heat generated in the LED lamp unit can be efficiently radiated to the outside.
Therefore, the luminous efficiency of each LED of each LED lamp unit is not reduced by heat, and bright irradiation light can be obtained.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS.
The embodiments described below are preferable specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. As long as there is no description of the effect, it is not restricted to these aspects.

[Example 1]
FIG.1 and FIG.2 has shown the structure of 1st embodiment of the vehicle headlamp by this invention.
1 and 2, a vehicle headlamp 10 is a headlamp that uses an LED as a light source. The vehicle headlamp 10 includes a housing 11 having an open front surface and a plurality of (in the illustrated case) provided in the housing 11. , Three) LED wrap units 12, a front lens 13 made of a translucent resin material attached to the housing 11 so as to cover the front surface of the housing 11, and fixedly disposed in the housing 11 And a heat radiating member 14.

  The casing 11 is formed so that the front surface is open, and is made of, for example, metal or resin.

Each of the LED lamp units 12 includes at least one LED 12a and a reflector 12b that reflects the light from the LED 12a forward. The heat sink 14 is fixedly held.
Here, as shown in FIG. 1, the LED lamp units 12 are arranged in three rows in the horizontal direction in the housing 11.

  The heat radiating member 14 is configured as a heat sink or the like from a material having good thermal conductivity such as aluminum, and is fixedly disposed in the housing 11. Each LED lamp unit 12 described above is fixedly held via a lamp unit support 12c.

  The above configuration is the same as that of the conventional LED lamp 1 shown in FIG. 7, but in the LED lamp 10 according to the embodiment of the present invention, the casing 11 further has a heat dissipation unevenness on its flat upper surface. A surface 15 is provided.

As shown in detail in FIG. 3, the heat dissipation uneven surface 15 is formed such that the upper surface of the housing 11 has an uneven shape in cross section.
In the case of illustration, this uneven | corrugated surface 15 for heat dissipation has cross-sectional shape like the square wave continued in the horizontal direction, and this shape is extended toward the front-back direction.
Thereby, the region of the heat dissipation uneven surface 15 of the housing 11 has a larger surface area compared to a flat shape, and heat can be radiated to the outside air over the entire large surface. It has become.

The LED lamp 10 according to the embodiment of the present invention is configured as described above, and power is supplied to each LED lamp unit 12 from the outside. Thereby, each LED12a of each LED lamp unit 12 is driven, and light-emits.
Light emitted from each LED lamp unit 12 is irradiated forward through the front lens 13.

In this case, the heat generated in each LED of each LED lamp unit 12 is transmitted to the heat radiating member 14 via the lamp unit support 12c, and the air in the housing 11 is heated from the heat radiating member 14 so-called. It rises due to thermal convection and heats the upper surface of the casing 11. Thereby, the heat generated by the LED is transmitted to the upper surface of the casing 11.
The heat is transmitted to the outside air from the heat radiation uneven surface 15 provided on the upper surface of the housing 11, and is radiated.

  In this way, the heat generated in each LED 12a is transmitted to the upper surface of the housing 11 and is radiated to the outside air from the heat radiation uneven surface 15. Therefore, since the uneven surface 15 for heat dissipation has a surface area larger than the surface area when the housing 11 is flat, heat is efficiently radiated from the upper surface of the housing 11 to the outside air. .

  In this way, by efficiently dissipating heat from the inside of the housing 11 of the vehicle headlamp 10 to the outside air, the individual LEDs 12a of each LED lamp unit 12 are held at a relatively low temperature. . For this reason, the luminous efficiency of each LED 12a is not lowered, and bright illumination light can be obtained as the entire vehicle headlamp 10.

In this case, the heat radiation uneven surface 15 is formed by the shape of the housing 11 itself, and is not provided with heat radiation fins in a partial region of the housing 11.
Therefore, for example, when the casing is made of metal, the manufacturing of the casing 11 itself can be performed by press working at the time of manufacturing the casing, and when the casing is made of resin, based on the shape of the molding die. Formed simultaneously. This eliminates the need for separate retrofitting parts, so that the part cost and assembly cost do not increase.

Next, a pseudo experiment was performed in order to confirm the heat dissipation effect of the uneven surface for heat dissipation.
The experiment was conducted by placing a heat sink with a heating element in a test box, heating the heating element, and measuring the temperature change of each part.
The test box has a length of 200 mm, a width of 300 mm, and a depth of 150 mm. The front surface is made of a transparent acrylic material (2 mm thickness), and the other five surfaces are made of a black acetal material (similarly 2 mm thickness).

Moreover, in the experimental example, the uneven surface for heat radiation having a space of 10 mm and a height of 25 mm in a part of the upper surface, a region of 175 mm long × 94 mm deep. In addition, the thing which is not provided with this uneven | corrugated surface for heat radiation was prepared as a comparative example.
As a result, the entire upper surface of the test box has a surface area of about 1.9 times that of a flat case.

Further, five 60 × 60 × 25 mm heat sinks with ceramic heaters as heating elements were accommodated in the housing.
In this state, 12 W of electric power was supplied to each ceramic heater, and the temperature change of each part after 1 hour was measured.
The above parts are respectively the upper stage A and the lower stage B of the ceramic heater, the upper stage C and the lower stage D of the heat sink, the upper outer side E, the upper inner side F, the lower outer side G, the lower inner side H, the upper left I in the casing, the upper right J, Lower left K, lower right internal temperature L, upper outside air M, and lower outside air N.

The temperature change of each part during the energization for the above-mentioned time was as shown in FIG. 4A in the experimental example and as shown in FIG. 4B in the comparative example.
Specifically, the temperature of each part after one hour is as follows: Part A to 107 ° C. (109 ° C.), Part B to 103 ° C. (106 ° C.), Part C to 97 ° C. (100 ° C.), Part D to 91 ° C (93 ° C), E part to 49 ° C (51 ° C), F part to 50 ° C (51 ° C), G part to 40 ° C (42 ° C), H part to 41 ° C (43 ° C), I part to 67 ° C (68 ° C), J part to 64 ° C (68 ° C), K part to 41 ° C (43 ° C), L part to 42 ° C (46 ° C), M part to 30 ° C (27 ° C), N part to 27 It became ° C (27 ° C) (in the parentheses are comparative examples).
Thereby, it turns out that an experimental example is about 2.5 degreeC lower than a comparative example with respect to a ceramic heater, a heat sink, and inside air.
Therefore, the effectiveness of the heat dissipation effect of the heat dissipation uneven surface in the present invention was confirmed.

  Furthermore, if the entire upper surface of the test box described above is a similar heat radiating uneven surface, the surface area of this upper surface will be about 3.5 times, and the temperature of each part in the test box will decrease by about 5 ° C., respectively. Can be expected.

FIG. 5 shows a second embodiment of a vehicle headlamp according to the present invention.
In FIG. 5, the vehicle headlamp 20 is formed on each surface except the front surface of the housing 11, that is, on the heat radiating uneven surface 15 on the upper surface thereof, as compared with the vehicle headlamp 10 shown in FIGS. 1 and 2. In addition, the structure differs only in that the second heat-dissipating uneven surface 21 is provided on both side surfaces.
The second heat radiating uneven surface 21 is configured in the same manner as the heat radiating uneven surface 15 and extends in the vertical direction.

According to the vehicle headlamp 20 having such a configuration, the vehicle headlamp 10 operates in the same manner as the vehicle headlamp 10 shown in FIGS. 1 and 2. Further, the heat from the LED lamp unit 12 is transmitted to the entire housing 11 through the heat radiating member 14, and not only from the heat radiating uneven surface 15 on the upper surface but also from the second heat radiating uneven surfaces 21 on both sides. The heat is radiated to the outside air.
Therefore, the heat dissipation performance of the entire housing 11 is improved, the heat dissipation efficiency can be increased, and the heat dissipation can be performed more reliably.

  In this case, when the automobile is stopped, heat is radiated from the second heat radiating uneven surface 21 to the outside air, so that the heated outside air can easily move upward along the heat radiating uneven surface 21 to dissipate heat. Can be performed efficiently.

FIG. 6 shows a configuration of a third embodiment of the vehicle headlamp according to the present invention.
In FIG. 6, the vehicle headlamp 30 is different from the vehicle headlamp 20 shown in FIG. 5 in that the heat dissipation uneven surface 15 on the upper surface of the casing 11 and the second heat dissipation uneven surface 21 on both side surfaces. Only different in that the extending direction of is different.
That is, the heat radiation uneven surface 15 provided on the upper surface of the housing 11 extends in the lateral direction in this case, and the second heat radiation uneven surface 21 provided on both side surfaces of the housing 11 Extending in the direction.

According to the vehicle headlamp 30 having such a configuration, the vehicle headlamp 20 operates in the same manner as the vehicle headlamp 20 shown in FIG. Further, the heat from the LED lamp unit 12 is transmitted to the entire housing 11 through the heat radiating member 14, and not only from the heat radiating uneven surface 15 on the upper surface but also from the second heat radiating uneven surfaces 21 on both sides. The heat is radiated to the outside air.
Therefore, the heat dissipation performance of the entire housing 11 is improved, the heat dissipation efficiency can be increased, and the heat dissipation can be performed more reliably.

  In this case, when the vehicle is traveling, traveling wind from the front moves rearward along the second heat radiating uneven surface 21. For this reason, the heated outside air can easily move rearward along the heat radiating uneven surface 21, and heat can be efficiently radiated.

  In the embodiment described above, the heat radiation uneven surfaces 14 and 21 each have a regularly continuous square-wave cross-sectional shape as shown in FIG. The concavo-convex surfaces 14 and 21 may have a square-wave or curved cross-sectional shape arranged irregularly or discontinuously, or may have any cross-sectional shape such as an island shape.

In the above-described embodiment, the heat dissipation uneven surfaces 14 and 21 are provided on the upper surface or both side surfaces of the housing. However, the present invention is not limited to this, and the flatness is provided on the inner surface or the outer surface of the housing 11. May be provided in a region where there is no member that damages the surface, for example, all flat regions except the opened front surface, for example, the bottom surface and the rear surface.
In this case, since the vehicle headlamp is generally assembled in a predetermined place together with various components in the engine room, these external components, internal LED lamp units, heat dissipation members, etc. In order to avoid these parts, at least one step of the uneven surface for heat dissipation is provided in a flat region. As a result, higher heat dissipation efficiency can be obtained.

  Although the vehicle headlamp 10 according to the present invention is configured as an automotive headlamp, the present invention is not limited thereto, and the present invention can be applied to other types of vehicle headlamps including auxiliary headlamps and the like. It is.

  As described above, according to the present invention, an extremely excellent vehicular lamp that can efficiently dissipate heat generated from the LED can be provided with a simple configuration.

It is a schematic front view which shows the structure of 1st embodiment of the vehicle headlamp by this invention. It is a schematic sectional drawing of the vehicle headlamp of FIG. It is a partial expansion perspective view of the uneven | corrugated surface for thermal radiation in the vehicle headlamp of FIG. It is a graph which shows the temperature change of each part of (A) Experimental example and (B) Comparative example for confirming the thermal radiation effect of the uneven | corrugated surface for thermal radiation in the vehicle headlamp of FIG. It is a schematic perspective view which shows the structure of 2nd embodiment of the vehicle headlamp by this invention. It is a schematic perspective view which shows the structure of 3rd embodiment of the vehicle headlamp by this invention. It is a schematic front view which shows the structure of an example of the conventional LED headlamp. It is a schematic sectional drawing of the vehicle headlamp of FIG.

Explanation of symbols

10, 20, 30 Vehicle headlamp 11 Housing 12 LED lamp unit 12a LED
12b Reflector 12c Lamp unit support 13 Front lens 14 Heat dissipation member 15 Heat dissipation uneven surface 21 Second heat dissipation uneven surface

Claims (5)

A housing open at the front, at least one LED lamp unit having at least one LED arranged so as to irradiate light forward in the housing, and a transparent that closes the open front of the housing. A vehicle headlamp including a front lens made of a light-sensitive material,
A vehicle headlamp characterized by comprising one or more heat radiation uneven surfaces in a region where there is no member inside or outside that impairs the flatness of the housing.   2. The vehicle headlamp according to claim 1, wherein the uneven surface of the housing has a shape that increases a surface area of the housing surface where air inside and outside the housing contacts each other. .   The vehicle headlamp according to claim 1, wherein the uneven surface for heat dissipation is provided in a region excluding the front surface of the housing.   The vehicle headlamp according to any one of claims 1 to 3, wherein the uneven surface for heat dissipation is formed on a side surface of the housing so as to extend along a vehicle vertical direction.   5. The front of a vehicle according to claim 1, wherein the uneven surface for heat dissipation is formed to extend along the vehicle front-rear direction on at least an upper surface or a lower surface of the housing. Lighting.

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