Vehicle lamp

There is provided a vehicle lamp. The vehicle lamp includes a lamp body including a hole portion therein; an outer lens, attached to the lamp body to form a lamp chamber; a lamp unit provided in the lamp chamber and including a light emitting element serving as a light source; a heat sink; and a fan. The heat sink includes a base portion fitted into the hole portion of the lamp body; outer fins disposed on a surface of the base portion and extending outside of the lamp body; and inner fins disposed on another surface of the base portion and extending into the lamp chamber. The fan moves air in the lamp chamber toward the inner fins, which are configured such that the air passing between the respective inner fins is guided toward the outer lens.

This application claims priority from Japanese Patent Application No. 2008-148932, filed on Jun. 6, 2008, the entire contents of which are herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

The present disclosure relates to vehicle lamps, and more particularly, to vehicle lamps that use a semiconductor light emitting element as a light source.

2. Related Art

In the past, a vehicle lamp using a semiconductor light emitting element such as an Light Emitting Diode (LED) as a light source has been known. In the case where the semiconductor light emitting element is used as the light source of the vehicle lamp, it is necessary to satisfy a light intensity level required for the vehicle lamp by maximally using the light emission of the semiconductor light emitting element.

In general, when a large amount of current is supplied to the semiconductor light emitting element in order to obtain the high output, heat generated from the semiconductor light emitting element increases. However, when the temperature of the semiconductor light emitting element becomes high, the efficiency of light emission decreases. For this reason, in order to efficiently radiate the heat generated from the semiconductor light emitting element, various heat radiation structures for a vehicle lamp have been proposed (see e.g., JP-A-2006-286395).

However, in the related art vehicle lamp described in JP-A-2006-286395, since a natural convection current occurs in the lamp chamber where the LED is provided, the related art vehicle lamp has a disadvantage in that the circulation of air in the lamp chamber is not particularly efficient.

SUMMARY OF THE INVENTION

Exemplary embodiments of the present invention address the above disadvantages and other disadvantages not described above. However, the present invention is not required to overcome the disadvantages described above, and thus, an exemplary embodiment of the present invention may not overcome any disadvantages described above.

Accordingly, it is an aspect of the present invention to provide a vehicle lamp capable of efficiently radiating heat generated from a semiconductor light emitting element.

According to one or more illustrative aspects of the present invention, there is provided a vehicle lamp comprising a lamp body comprising a hole portion therein; an outer lens, attached to the lamp body to form a lamp chamber; a lamp unit provided in the lamp chamber and comprising a light emitting element serving as a light source; a heat sink; and a fan. The heat sink comprises a base portion fitted into the hole portion of the lamp body; a plurality of outer fins disposed on a surface of the base portion and extending outside of the lamp body; and a plurality of inner fins disposed on another surface of the base portion and extending into the lamp chamber. The fan moves moves air in the lamp chamber toward the inner fins, and the inner fins are configured such that the air passing between the respective inner fins is guided toward the outer lens.

Hereinafter, an exemplary embodiment of the invention will now be described with reference to the accompanying drawings.

FIG. 1is a schematic sectional view showing a vehicle lamp10according to an exemplary embodiment of the present invention. As shown inFIG. 1, the vehicle lamp10has a configuration in which a lamp unit30using a semiconductor light emitting element as a light source is accommodated in a lamp chamber35. The lamp chamber35includes a resinous lamp body48of which the front surface is opened and an outer lens34which is formed of a light transmitting material and hermetically covers the front surface of the lamp body48. The vehicle lamp10includes a first heat sink14, a second heat sink50, and a fan56in addition to the lamp unit30.

The lamp unit30is a so-called projector-type lamp unit using an LED as a light source. In the example shown in the drawing, the number of lamp units30is one, but a plurality of lamp units30may be provided.

The lamp unit30includes an LED20, a thermal conductive insulating substrate24, a reflector22, a fixed member26, and a projection lens32. The LED20is a white LED including an LED chip (not shown) and a cap which is formed in a substantially semi-spherical shape so as to cover the LED chip. The LED20is disposed on the thermal conductive insulating substrate24formed of ceramic or the like. The LED20is disposed on an optical axis Ax such that a light emitting direction thereof is perpendicular to the optical axis Ax of the lamp unit30. Power is supplied to the LED20via an interconnection pattern formed in the thermal conductive insulating substrate24.

The reflector22is formed of, for example, polycarbonate so as to have a semi-dome shape, and is disposed above the LED20. The inner upper surface of the reflector22is provided with a reflection surface which reflects light generated from the LED20in a forward direction so that the light is concentrated in the vicinity of the optical axis Ax.

The projection lens32is formed as a plane-convex nonspherical lens of which the front surface is a convex surface and the rear surface is a flat surface so that a light source image formed in a rear focal surface is irradiated in a forward direction as an inverse image. The fixed member26is formed of metal mainly containing aluminum by die-casting, and is formed in a substantially flat plate shape by extending the metal, where the upper surface thereof is mounted with the reflector22and the substrate24equipped with the LED20. In addition, the front end of the fixed member26is attached with the projection lens32.

The rear end of the fixed member26is attached to the first heat sink14provided in the lamp chamber35. The first heat sink14radiates heat generated from the LED20to air in the lamp chamber35.

The first heat sink14is formed of high thermal conductive metal such as aluminum, and includes a base portion16and a plurality of flat plate fins18. The base portion16is a member formed in a rectangular flat plate shape, where the long side thereof is aligned in a vertical direction and the short side thereof is aligned in a horizontal direction.

The rear surface of the base portion16is attached with the fixed member26of the lamp unit30. In addition, the plurality of flat plate fins18is uprightly formed in the front surface of the base portion16in parallel with a given gap interposed therebetween. The flat plate fins18are formed such that an extension direction thereof is aligned in the vertical direction. The extension direction of the flat plate fins18represents a longitudinal direction of the flat plate fins18.

The lamp unit30and the first heat sink14are attached to a support member (not shown) in the lamp chamber35so that light emitted from the lamp unit30is irradiated in a forward direction of the vehicle lamp10. In this exemplary embodiment, the lamp unit30and the first heat sink14are provided in the vicinity of the center of the lamp chamber35.

An upper surface48aof the lamp body48is provided with the second heat sink50. The second heat sink50is disposed in a fan case58at the almost center in a transverse direction of the lamp body48, and is disposed on the rear side of the base portion16of the first heat sink14in a longitudinal direction.

The second heat sink50includes a plurality of outer fins52, a plurality of inner fins54, and a base portion55. The base portion55of the second heat sink50is hermetically fitted and fixed to a hole portion provided in the upper surface48aof the lamp body48. The outer fins52are uprightly formed in the upper surface of the base portion55and extend toward the outside of the lamp chamber35. The inner fins54are uprightly formed in the lower surface of the base portion55and extend toward the inside of the lamp chamber35. In addition, the fan56is provided below the second heat sink50.

FIG. 2is a view showing the second heat sink50.FIG. 2shows the shape when the second heat sink50is viewed from the inside of the lamp chamber35. In addition, inFIG. 2, the outer fins52, which are uprightly formed toward the outside of the lamp chamber35are depicted using dotted lines for the description thereof.

The second heat sink50is formed of high thermal conductive metal such as aluminum. As described above, the plurality of outer fins52are uprightly formed in the upper surface of the square base portion55and extend toward the outside of the lamp chamber35. Each of the plurality of outer fins52is a flat plate fm, and the plurality of outer fins52are uprightly formed in parallel with a given gap interposed therebetween. As shown inFIG. 2, the extension direction of the outer fins52is aligned in a longitudinal direction (i.e., a forward direction indicated inFIG. 2). The extension direction of the outer fins52represents a longitudinal direction of the outer fins52.

As shown inFIG. 2, the lower surface of the base portion55is provided with the plurality of inner fins54and the fan56. The inner fins54are uprightly formed in the front half surface of the lower surface of the base portion55toward the inside of the lamp chamber35. The fan56is provided on the rear half surface of the lower surface of the base portion55.

In this exemplary embodiment, the fan56is a centrifugal fan which sucks air in an axial direction and exhausts the air in a centrifugal direction. The fan56includes the fan case58and a plurality of blades60which are rotated by a fan motor (not shown). The fan case58is a square frame covering the outer periphery of the fan56. Alternatively, the fan case58may have another geometry as long as air flow is not impeded. The fan case58has an opening which is formed on the front side of the vehicle lamp10, that is, a front side surface58alocated on the side of the inner fins54. When the blades60of the fan56are rotated, air in the lamp chamber35is sucked in an axial direction, and is blown through the opening of the front side surface58atoward the inner fins54.

The attaching operation of the fan56is carried out in such a manner that the fan case58comes into contact with the lower surface of the base portion55. With the fan56having the above-described configuration, heat generated from a fan motor and a driving circuit (not shown) thereof is transmitted to the second heat sink50via the fan case58, and is radiated to the outside of the lamp chamber35via the outer fins52. Accordingly, it is possible to prolong the durable years of the fan56.

The inner fins54are formed such that air passing through a gap between the inner fins54is guided to the outer lens34located on the front side of the second heat sink50. The inner fins54are flat plate fins, and extend radially in a forward direction from the front side surface58aof the fan case58. Accordingly, as shown inFIG. 2, the gap between the inner fins54that is formed at the front side surface58aof the fan case58is broadened from the upstream side to the downstream side of the air stream. With the inner fins54having the above-described configuration, the blow range of the air blown from the front side surface58aof the fan case58is broadened in a transverse direction, and the air is guided to the upper portion of the outer lens34.

In addition, in this exemplary embodiment, as shown inFIG. 1, first extension member62and second extension member64are provided above and below the first heat sink14in the lamp chamber35so that the inner structure of the lamp chamber35is not visible. The first extension member62provided above the first heat sink14is a plate-shaped member, and extends upward from the upper end of the base portion16of the first heat sink14, where the upper end thereof is curved toward the second heat sink50. A gap having, for example, a height substantially equal to a height of the inner fins54is formed between the upper end of the first extension member62and the upper surface48aof the lamp body48so as not to disturb the flow of the air blown from the inner fins54of the second heat sink50flows to the upper portion of the outer lens34.

The second extension member64is a plate-shaped member, and is provided between the first heat sink14and the bottom surface48b. The second extension member64is disposed at the rear side of the base portion16of the first heat sink14, and guides air flowing along the bottom surface48bof the lamp body48to the lower end of the first heat sink14.

Next, a convection current of air in the vehicle lamp10according to this exemplary embodiment will be described. InFIGS. 1 and 2, the white arrow indicates an air stream. In the vehicle lamp10, when light is emitted from the LED20, heat generated by the light emission is transmitted to the fixed member26via the thermal conductive insulating substrate24mounted with the LED20. The heat transmitted to the fixed member26is transmitted to the base portion16of the first heat sink14contacting with the rear end of the fixed member26. The thermal conductive insulating substrate24and the fixed member26having the above-described configuration serve as a thermal conductive portion which transmits the heat generated from the LED20to the first heat sink14. The heat transmitted to the base portion16of the first heat sink14is transmitted to the flat plate fins18of the first heat sink14, and is radiated to the ambient air. The high-temperature air heated by the heat radiated from the flat plate fins18of the first heat sink14passes through a gap between the flat plate fins18, and rises along the extension direction of the flat plate fins18.

The heated air rising via the gap between the flat plate fins18of the first heat sink14is sucked into the fan56provided in the upper surface48aof the lamp body48, and is blown through the front side surface58atoward the inner fins54. The blown air passes through the gap between the inner fins54, and is guided to the upper portion of the outer lens34. Here, in this exemplary embodiment, since the gap between the inner fins54is formed in a broad range from the upstream side to the downstream side of the air stream, the blow range of the air is broadened in a transverse direction, thereby blowing warm air over substantially the entire surface of the outer lens34.

During the time when the air blown from the fan56flows through the gap between the inner fins54, a heat exchange is carried out between the air and the inner fins54. The heat transmitted to the inner fins54is transmitted to the outer fins52via the base portion55, and is radiated to the air on the outside of the lamp chamber35. Here, since the extension direction of the outer fins52is aligned in a longitudinal direction, air flows through the gap between the outer fins52in a direction from the front side of the gap to the rear side thereof in a vehicle travel mode. Accordingly, it is possible to improve the efficiency of the heat radiation since the air heated by the outer fins52is not accumulated.

Since the outer lens34is exposed to the outside of the vehicle, the temperature of the outer lens34is lower than that of the air blown from the inner fins54. Accordingly, during the time when the air blown from the inner fins54flows from the upper portion of the outer lens34to the lower portion thereof, the air is cooled by a heat exchange in the outer lens34. The cooled air flows in a backward direction along the bottom surface48bof the lamp body48and contacts with the second extension member64. Subsequently, the air flows from the lower end of the first heat sink14to the gap between the flat plate fins18, is heated again by the heat generated from the LED20, and then is sucked by the fan56.

In addition, as shown inFIG. 1, a part of the air blown from the inner fins54is branched by the upper end of the first extension member62, and flows to the upper end of the first heat sink14. The branched air flows from the upper end of the first heat sink14to the gap between the flat plate fins18, and is mainly used for a heat exchange with the upper portions of the flat plate fins18, and then is sucked by the fan56.

In the vehicle lamp10according to this exemplary embodiment, since the air is circulated in the lamp chamber35in this manner, it is possible to efficiently radiate the heat generated from the LED20. In addition, in the vehicle lamp10, since the heat is transmitted from the air, which is blown into the inner fins54, to the outer lens34, it is possible to suppress occurrence of snow or ice attached to the outer surface of the outer lens34.

In this exemplary embodiment, since the gap between the inner fins54is formed in a broad range from the upstream side to the downstream side of the air stream, the blow range of the inner fins54is broadened in a transverse direction, thereby blowing the warm air to the broad area of the outer lens34. Accordingly, since the efficiency of the heat exchange between the heated air and the outer lens34is improved, it is possible to further efficiently radiate the heat generated from the LED20. In addition, it is possible to increase an area of the outer lens34capable of suppressing occurrence of snow or ice attached thereto.

Additionally, in this exemplary embodiment, the upper surface48aof the lamp body48is provided with the second heat sink50. A natural convection current of the air, heated by the heat generated from the LED20, occurs in an upward direction. Accordingly, it is possible to improve the efficiency of heat radiation since the upper surface48aof the lamp body48is provided with the second heat sink50.

In the above-described exemplary embodiment, an LED is used as the light source, but for example, a semiconductor light emitting element such as a semiconductor laser may be used.

In the above-described exemplary embodiment, a lamp unit of a projector type is used as the lamp unit, but a lamp unit of a parabola type or direct projection type may be used.

According to one or more aspects of the present invention, there is provided a vehicle lamp in which a lamp unit using a semiconductor light emitting element as a light source is accommodated in a lamp chamber including an outer lens and a lamp body, the vehicle lamp including a heat sink which has a plurality of outer fins uprightly formed in a base portion of the lamp body and extending toward the outside of the lamp chamber; and a plurality of inner fins uprightly formed in the base portion toward the inside of the lamp chamber; and a fan which blows air in the lamp chamber toward the inner fins, wherein the inner fins are formed so that the air passing through a gap between the inner fins is guided to the outer lens.

With such a configuration, the air in the lamp chamber is heated by the heat generated from the semiconductor light emitting element, and is blown toward the inner fins of the heat sink by the fan, thereby carrying out a heat exchange between the inner fins. The heat transmitted to the inner fins is transmitted to the outer fins via the base portion, and is radiated to the outside of the lamp chamber by the outer fins. In addition, the air passing through the gap between the inner fins is guided to the outer lens, and is cooled by a heat exchange carried out in the outer lens. The cooled air is heated again by the heat generated from the semiconductor light emitting element, and is sucked by the fan. By the circulation of the air in the lamp chamber, it is possible to efficiently radiate the heat generated from the semiconductor light emitting element. In addition, it is possible to suppress occurrence of snow or ice attached to the outer surface of the outer lens by means of the heat transmitted to the outer lens.

In the vehicle lamp having the above-described configuration, an upper surface of the lamp body may be provided with the heat sink. A natural convection current of the air, heated by the heat generated from the semiconductor light emitting element, occurs in an upward direction. Accordingly, it is possible to further efficiently radiate the heat generated from the semiconductor light emitting element in such a manner that the upper surface of the lamp body is provided with the heat sink.

In the vehicle lamp having the above-described configuration, the inner fins may be formed so that the gap between the inner fins is formed in a broad range from the upstream side to the downstream side of an air stream. In this case, since the blow range of the inner fins is broadened, it is possible to blow warm air to the broad area of the outer lens. Accordingly, since the efficiency of heat exchange between the heated air and the outer lens is improved, it is possible to further efficiently radiate the heat generated from the semiconductor light emitting element. In addition, it is possible to broaden an area of the outer lens capable of suppressing occurrence of snow or ice attached thereto.

In the vehicle lamp having the above-described configuration, the fan may be formed so that a fan case covering the outer periphery of the fan contacts with a base portion of the heat sink. In this case, it is possible to radiate heat, generated from a fan motor or a driving circuit used for driving the fan, to the outside of the lamp chamber via the outer fins. Accordingly, it is possible to prolong the durable years of the fan.

According to exemplary embodiments of the invention, it is possible to efficiently radiate heat generated from a semiconductor light emitting element.