Patent Application
20140020882
The present invention relates to a heat sink for LED lighting in which LED lighting having a light emitting diode (LED) element as a light emitting source dissipates heat generated at the time of emitting light into a surrounding space.
Lighting having a light emitting diode (LED) element as a light emitting source is low in power consumption and is long in life and hence gradually begins to prevail in the market. Among the lighting, it is a vehicle-mounted LED lighting such as a headlight of an automobile that especially gets much attention in recent years, and it has been started to replace embedded lighting in buildings and other fields with the LED lighting as an application of the vehicle-mounted LED.
However, the LED element of the light emitting source of the LED has the following problems: the LED element is very weak against heat; and when temperature is higher than an allowable temperature, the LED element is reduced in light emitting efficiency and has its life affected. In order to solve these problems, the heat generated when the LED element emits light needs to be dissipated into a space surrounding the LED element and hence the LED lighting is provided with a large heat sink.
An aluminum die-cast heat sink using aluminum or aluminum alloy as a raw material has been widely used as a heat sink for LED lighting. In patent literatures 1 to 4 have been disclosed heat sinks having typical constructions of these heat sinks. Each of these heat sinks has a base plate part having an LED light source arranged and fixed on a front side thereof and a plurality of fin parts arranged in parallel to each other on the back side of the base plate part in such a way as to protrude separately from each other and uses the base plate part and the fin parts as heat dissipating surfaces and hence can acquire a large heat dissipating area, which makes it possible to think that the heat sink has a given heat dissipation capability.
However, in a case where a heat sink 4 for LED lighting that has a base plate part 2 having an LED light source 1 arranged and fixed on a front side thereof and a plurality of fin parts 3 in parallel to each other on the back side of the base plate part 2 in such a way as to protrude separately from each other, as shown in
In this way, in the case where the heat sink 4 is used in the state where the fin parts 3 of the heat sink 4 are protruded into the closed space on the back side, heat dissipation from the heat sink 4 becomes heat dissipation into the closed space in which the convection of air is not caused. Hence, the heat sink 4 having the plurality of fin parts arranged in parallel to each other cannot dissipate heat efficiently.
That is, heat dissipation from a heat sink in a closed space is mainly done not by convection but by radiation. For this reason, it can be thought that increasing all projected areas in an x-axis direction, a y-axis direction, and a z-axis direction, that is, in three directions of the heat sink is more effective for enhancing a heat dissipation capability than providing the heat sink with a plurality of fin parts to simply increase their surface areas.
An object of the present invention is to provide a heat sink for LED lighting that can efficiently dissipate heat even in a closed space.
In order to solve the problems, a heat sink for LED lighting according to the present invention is a heat sink for LED lighting formed of an aluminum material and is constructed of: a mounting face part having an LED element mounted on a surface thereof; a first fin part extending in a direction perpendicular to the mounting face part; and a second fin part extending in a direction perpendicular to the mounting face part and extending in a direction intersecting the first fin part.
In this heat sink for LED lighting, the first fin part and the second fin part extend in a direction perpendicular to the mounting face part mounted with the LED element and the first fin part extends in a direction intersecting the second fin part. Hence, the heat sink for LED lighting can increase all projected areas in three dimensional directions of an x-axis direction, a y-axis direction, and a z-axis direction. Therefore, even when the heat sink dissipates heat in a closed space in which the convection of air is hardly caused, the heat sink can efficiently dissipates heat.
In the heat sink for LED lighting according to the present invention, it is preferable that: the mounting face part has the first fin part or/and the second fin part formed integrally with any one or both of top and bottom faces thereof, each of the first fin part and the second fin part being shaped like a plate; the respective fin parts are formed in such a way as to erect outward and separately from each other; and the number of the fin parts extending in a same direction is two or less at an arbitrary section perpendicular to any one of the top and bottom faces of the mounting face part.
In this case, it is preferable that the respective fin parts are formed at positions between which the LED element is mounted.
Further, it is preferable that the first fin part and the second fin part are formed by a total of 2 to 8.
In this way, the object of the present invention can be achieved without complicating the shape and structure of the heat sink, especially, the shape and structure of the fin part for dissipating heat and without increasing the number of fin parts. On the contrary, the object of the present invention can be achieved by simplifying the shape and structure of the fin part and by decreasing the number of fin parts. Further, in the present invention, the base plate and the heat dissipating fins of the heat sink are integrally formed, so that the face of the base plate and the faces of the heat dissipating fins are continuous with each other and hence the path of heat conduction by the surfaces or materials of these parts is continuously formed. Hence, since there is no impediment such as a slit for cutting the path of heat conduction, the path of heat condition in the heat sink is not cut and heat from the LED element can be transferred to the respective parts constructing the heat sink. Therefore, an extremely high heat dissipation capability of the heat sink can be ensured
Further, in the heat sink for LED lighting according to the present invention, it is preferable that the mounting face part and the first fin part are formed in a continuous stepped shape.
In this case, it is preferable that the mounting face part, the first fin part, and the second fin part are integrally formed by bending a blank of aluminum material.
Further, it is preferable that the first fin part has the second fin part further formed on an end portion thereof, the second fin part extending in a direction intersecting the first fin part.
Still further, it is preferable that the mounting face part or/and the first fin part is/are larger in thickness than the second fin part.
Still further, it is preferable that the second fin parts, or the second fin part and the mounting face part or/and the first fin part are overlaid on each other.
Still further, it is preferable that a portion at which the LED element is mounted of the mounting face part is partially increased in thickness.
The heat sink for LED lighting constructed in this way is a heat sink which is formed of an aluminum material and has a simple structure, so that the heat sink can be comparatively easily manufactured by bending a blank acquired by punching and cutting a rolled plate such as sheet or coil or an extruded plate and is lightweight. Hence, the heat sink for LED lighting according to the present invention is most suitable for a heat sink for LED lighting for a vehicle.
Further, in the heat sink for LED lighting according to the present invention, it is preferable that the mounting face part has the LED element arranged and fixed on a front side thereof and has a plurality of the first fin parts formed on a back side thereof in such a way as to protrude separately from each other and in parallel to each other, and that of the first fin parts, at least one first fin part has a portion thereof bent at a right angle, whereby the portion is made the second fin part, and that the second fin part has a heat dissipating surface in a direction which is perpendicular to a heat dissipating surface of the first fin part and to a heat dissipating surface of the mounting face part, respectively.
The heat sink for LED lighting constructed in this way can be manufactured from an aluminum material by a comparatively simple working method such as cutting and bending and the number of parts constructing the heat sink is not increased.
In the heat sink for LED lighting according to the present invention, it is preferable that the mounting face part has the LED element arranged and fixed on a front side thereof and has a plurality of the first fin parts formed on a back side thereof in such a way as to protrude separately from each other and in parallel to each other, and that the mounting face part is bent in a direction perpendicular to a longitudinal direction of the first fin part and hence is formed in a shape of a letter L, and that the second fin part is formed by bending the mounting face part in this manner.
In this way, the heat sink for LED lighting can be manufactured from an aluminum material by the use of a comparatively simple working method such as slitting and bending and the number of parts constructing the heat sink is not increased. In addition, the heat sink for LED lighting can be fixed even in a narrow limited space and in an indented space, which hence makes it possible to ensure a sufficient amount of heat dissipation from LED lighting even in such a limited space.
In this case, it is preferable that the first fin part is protruded to an outside of the mounting face part bent in the shape of the letter L and has a linear slit formed in a bent portion thereof at the time of bending and hence is divided, the slit reaching an outside surface of the mounting face part.
In this way, the heat sink for LED lighting can be fixed even in a concave corner of a narrow limited space, and when the base plate part is bent, it is not caused that the fin part has an effect on bending, and an amount of protrusion of the fin part does not need to be made small, which hence further makes it possible to further ensure a sufficient amount of heat dissipation from LED lighting.
Alternatively, it is preferable that the first fin part is protruded to an inside of the mounting face part bent in the shape of the letter L and has a slit formed in a bent portion thereof at the time of bending and hence is divided, the slit reaching an inside surface of the mounting face part and being formed in a shape of a letter V having an angle of 90 degrees or more.
In this way, the heat sink for LED lighting can be fixed even in a narrow limited space and can ensure a sufficient heat dissipating space by the surface areas of the base plate part and the fin parts, which hence makes it possible to further ensure a sufficient amount of heat dissipation from LED lighting. Further, the heat sink for LED lighting can be fixed even in a convex corner of a limited indented space. Still further, it is not caused that when the base plate part is bent, the fin part has an effect on the bending, and an amount of protrusion of the fin part does not need to be made small, which hence makes it possible to still further ensure a sufficient amount of heat dissipation from LED lighting.
Further, in the heat sink for LED lighting according to the present invention, it is preferable that the first fin part and the second fin part are formed in a shape of continuous wavy heat dissipating fins by corrugating and have a part thereof pressed into a stepped part, the stepped part constructing the mounting face part.
In this case, before the corrugating, the first fin part and the second fin part have their surfaces previously subjected to pre-coating having an emissivity ε of 0.7 or more.
According to the heat sink for LED lighting constructed in this way, by forming the whole shape of the heat dissipating fins of the continuous wavy shapes by corrugating, it is possible to form many thin fins at comparatively narrow intervals and hence to increase a heat transfer area and to enhance a heat dissipation capability.
Further, by using an aluminum alloy thin plate as a raw material, as a treatment for enhancing a heat dissipation capability, it is possible to previously apply pre-coating to the aluminum alloy thin plate as the raw material before corrugating. This makes it possible to omit or shorten processes that are necessary for a conventional heat sink manufactured by an aluminum alloy die casting, for example, a process of buffing the surface of a die casting, a cleaning process, a degreasing process, and a surface treatment process for enhancing the emissivity of a surface and hence to significantly reduce the manufacturing cost of the heat sink.
Still further, when a raw material plate is corrugated, the part on which the LED element is fixed and the stepped part such as a depression and a protrusion for reinforcing rigidity can be formed by a series of corrugating processes including a forming process of the whole shape of the heat dissipating fins of continuous wavy shapes and a crushing process following the forming process. At this time, it is possible to design and form a portion to become the stepped part partially in a larger width than the width of the fin. Hence, it is possible to integrally manufacture a heat sink, which ensures an LED element mounting area and has many fins to ensure a heat dissipation capability, from the same raw material plate. The heat sink for LED lighting of the present invention can increase all projected areas in the three dimensional directions of the x-axis direction, the y-axis direction, and the z-axis direction and hence can efficiently dissipate heat even in a closed space in which the convection of air is not caused.
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
a), 23(b) and 23(c) show a heat sink for LED lighting of the fourth embodiment.
a), 24(b) and 24(c) show plan views showing modified examples of the heat sink for LED lighting of the fourth embodiment.
a) and 42(b) show a heat sink for LED lighting of a fifth modified example of the sixth embodiment, and
a), 44(b), and 44(c) are perspective views showing the heat sinks for LED lighting of a seventh modified example of the sixth embodiment.
a) and 45(b) illustrate a mode in which the heat sink of the sixth embodiment is mounted in a vehicle-mounted LED lamp.
a), 49(b), and 49(c) show the conventional heat sink for LED lighting, and
Hereinafter, the present invention will be further described in detail on the basis of embodiments shown in the accompanying drawings.
Specifically, a first embodiment of the heat sink 101 for LED lightning of the present invention will be shown by a perspective view in
Basic Structure of a Heat Sink:
First, there will be described a basic structure common to the heat sink 101 for LED lightning of the first embodiment of the present invention in
Further, the top and bottom faces 1021, 1022 of the base plate 102 have the plate-shaped heat dissipating fins 103 to 106 which extend in the y direction (the up and down direction) in each drawing in such a way as to protrude perpendicularly to any one or both of the top and bottom faces 1021, 1022 (direction in which the face extends=perpendicular to the x direction and the z direction in each drawing). These plate-shaped heat dissipating fins 103 to 106 are erected on the top and bottom faces 1021, 1022 of the base plate 102 in such a way as to direct to the outside. However, in the plate-shaped heat dissipating fins 103 to 106, their plate-shaped heat dissipation side surfaces do not necessarily need to be perpendicular to the top and bottom faces 1021, 1022 of the base plate 102 at an angle of 90 degrees as shown in
For this reason, there are formed continuous heat transfer surfaces in which heat from the LED element 100 is continuously transferred to the bottom face 1022, the side faces surrounding the heat dissipating fins 103 to 106, and faces in a thickness direction via the face (surface) 1021, on which the LED element is mounted, of the base plate 102. Further, there are formed also continuous heat dissipating surfaces for continuously radiating heat from these continuous heat transfer surfaces.
In this regard, at to the shape of the base plate 102, a rectangular (or square) plate shape or planar shape is shown in
Feature of Heat Dissipating Fin:
The above-mentioned basic structure of the heat sink 101 for LED lighting 101 of the present invention, when glanced, seems to be not much different from the structure of a conventional heat sink 4 shown in
First, in the heat sink for LED lighting 101 of the present invention 1, on the premise of the basic structure of the heat sink, the plate-shaped heat dissipating fins 103 to 106, preferably, a total of 2 to 8 heat dissipating fins to be mounted on the two faces 1021, 1022 of the base plate 102, are formed continuously and integrally with the faces 1021, 1022 of the base plate 102 and separately from each other.
Of these heat dissipating fins 103 to 106, the number of the fins extending in the same direction (including a parallel state) is made two or less in an arbitrary section perpendicular to the two faces 1021, 1022 of the base plate 102, in other words, two or less in any section of the heat sink 101 which is cut at an arbitrary section perpendicular to the two faces 1021, 1022 of the base plate 102.
Meaning of Specification of Direction in which Heat Dissipating Fin Extends:
Here, the meaning of “extending in the same direction”, which is described in the present invention, naturally includes a parallel state and includes not only a parallel state in the strict sense of the word but also a state in which angles in which the plate-shaped side faces of the heat dissipating fins extend are slightly different from each other. An object of the present invention is to eliminate the excessive overlap of the heat dissipating fins in any direction of the three dimensional directions of the heat sink, to reduce the waste of material, and to achieve high performance in heat radiation efficiency. Hence, even if the angles in which the plate-shaped side faces of the heat dissipating fins extend are slightly different from each other within a range not to impair the object and the effect of the invention, it is possible to regard the plate-shaped side faces of the heat dissipating fins as extending in the same direction. This is because even if the angles in which the plate-shaped side faces of the heat dissipating fins extend are slightly different from each other or are not different from each other because the plate-shaped side faces are strictly parallel to each other, there is not much difference in that the heat dissipating fins extend in the same direction and overlap each other, which is to be specified in the present invention.
At to the degree of this difference in the angle, in the case where an angle formed by the directions in which the plate-shaped side faces of the heat dissipating fins extend is 30 degrees or less, the heat dissipating fins are regarded as extending in the same direction. On the contrary, in the case where the angle formed by the directions in which the plate-shaped side faces of the heat dissipating fins extend is more than 30 degrees, the heat dissipating fins are not regarded as extending in the same direction.
In
In addition, it is because of preventing the heat dissipating fins from overlapping each other excessively with respect to a certain direction in a three-dimensional space “that the number of the heat dissipating fins extending in the same direction is specified to be two or less in an arbitrary section perpendicular to the two faces 1021, 1022 of the base plate 102 (at any section of the heat sink cut at the section in this direction). In this regard, as will be described later, even in the case of one heat dissipating fin, there is a case where the one heat dissipating fin has a plurality of plate-shaped heat dissipating surfaces (heat dissipating side surfaces) extending in different directions, for example, a case of a heat dissipating fin formed in the shape of a letter L or C. Not only for a plate-shaped heat dissipating fin but also for a heat dissipating fin of a shape having a plurality of heat dissipating surfaces which are different from each other in an extending direction or in a shape, for example, each of straight portions in which a planar shape is formed in the shape of a letter L or C is regarded as a single heat dissipating fin and the number of the heat dissipating fins in the same direction (the degree of overlapping of the heat dissipating fins) are estimated. In this way of estimation, the number of the heat dissipating fins extending in the same direction in an arbitrary section perpendicular to either of the top face and the bottom faces of the base plate 102 is made two or less, whereby the heat dissipating fins or the heat dissipating side surfaces of the heat dissipating fins can be prevented from overlapping each other in the same direction. That is, the above-mentioned specification is provided for the following purpose: regardless of whether or not the heat dissipating surfaces are of the same heat dissipating fin, the number of the heat dissipating surfaces (heat dissipating side surfaces) of the heat dissipating fins is regarded as the number of the heat dissipating fins and is specified to be two or less so as to prevent the heat dissipating surfaces of the heat dissipating fins from overlapping each other excessively in the same direction regardless of the positions of the two faces 1021, 1022 of the base plate 102.
In this point, in the case where the number of the heat dissipating fins extending in the same direction is temporarily specified to be “two or less even in either of faces 1021, 1022 of the base plate 102” as another expression different from the above-mentioned specification, the absolute number of the heat dissipating fins will be specified. For this reason, in this case, the number of the heat dissipating surfaces in different directions of the heat dissipating fin shaped like a letter L or C is not regarded as the number of heat dissipating fins, which presents the possibility that the heat dissipating surfaces of the heat dissipating fins will overlap each other excessively depending on the positions of the two faces 1021, 1022 of the base plate 102. Hence, as described above, “the number of the heat dissipating fins is specified to be two or less in an arbitrary section perpendicular to the two faces 1021, 1022 of the base plate 102 (in any section of the heat sink cut at a section in this direction)”.
As to the shape of the plate-shaped heat dissipating fins 103 to 106, examples are shown in
Hereinafter, specific embodiments of the present invention shown in
First Embodiment Shown in
In the plate-shaped heat dissipating fins 103, 104 shown in
In the heat dissipating fins 103, 104 formed on the side of the LED element mounting face 1021, two of them are formed side by side in parallel to each other symmetrically across the LED element 100 as a mode in which the heat dissipating fins 103, 103 on the left and right sides in the drawing and the heat dissipating fins 104, 104 on the up and down sides in the drawing extend in the same direction, respectively. That is, the plate-shaped heat dissipating fins 103, 103 (or 104, 104) opposed to each other are formed on the top surface side of the LED element mounting face 1021 at positions between which the LED element 100 is mounted. Of these heat dissipating fins 103, 104, the number of the heat dissipating fins extending in the same direction is specified to be two or less even in an arbitrary section perpendicular to the faces 1021, 1022 of the base plate 102 (even in any section of the heat sink 101 cut at a section in this direction).
The heat dissipating fins 103, 104, that is, the heat dissipating fins adjacent to each other are formed and arranged in such a way as to be perpendicular to each other (to intersect each other at right angles) and surround a rectangular perimeter in which the LED element 100 is sandwiched (the LED element 100 is arranged at the center), and the respective plate-shaped side faces of the heat dissipating fins 103, 104, which are large in thermal emissivity, are directed to the x direction and to the z direction, respectively. The LED element mounting face 1021 and the other bottom face 1022, which are large in thermal emissivity, of the base plate 102 are directed to the y direction.
In addition, the respective faces 1023, 1024, 1025, 1026 (1023, 1024, 1025, 1026 are on the left side, on the lower side, on the right side, and on the upper side in the drawing, respectively) in the thickness direction of the square perimeter of the base plate 102 are comparatively smaller in area than the respective faces 1021, 1022 but are directed to the x direction and the z direction, respectively, and become the heat radiating surfaces in these directions. This is ditto for the respective faces (top faces, faces of both end portions) in the thickness direction of the respective heat dissipating fins 103, 104: that is, the respective faces are comparatively smaller in area than the plate-shaped side faces but are larger in the number of the faces; and in the top faces and the faces of both end portions, a total of four faces are directed to each of the x, y, z directions and become the heat radiating surfaces in these directions.
Hence, although of the plate-shaped side surfaces of the heat dissipating fins 103, 104, a pair of two side faces opposed to each other on the side in which the LED element 100 is mounted overlap each other, the heat dissipating surfaces of the heat dissipating fins do not overlap each other excessively in any direction of the x, y, and z directions, which results in eliminating the waste of material. For this reason, a high heat radiation efficiency can be acquired by the synergistic effect of the effect of forming the continuous heat transfer faces to which the heat of the LED element 100 is continuously transferred to the bottom face 1022, the side faces surrounding the respective heat dissipating fins 103, 104, and the faces in the thickness direction thereof via the mounting face 1021 of the base plate 102 and the effect of forming the continuous heat dissipating surfaces for continuously radiating heat from the continuous heat transfer faces.
The Number of the Heat Dissipating Fins:
In the case where the number of the heat dissipating fins extending in the same direction is further reduced to only two of a preferable limit even in an arbitrary section perpendicular to the faces 1021, 1022 of the base plate 102, only two of both of the heat dissipating fins 103, 103 on the left and right sides in
In contrast to this, in the case where the number of the plate-shaped heat dissipating fins is increased, the heat dissipating surfaces of the heat dissipating fins overlap each other in any one of the three dimensional directions of the x, y, z directions, which results in causing the waste of material and reducing the heat radiation efficiency of heat (heat dissipation efficiency) for a high spatial occupancy. Hence, the number of the heat dissipating fins to be mounted, that is, the number of the heat dissipating fins on two faces 1021, 1022 of the top and bottom faces of the base plate 102 is specified to be eight or less in total, preferably, within a range from two to eight. However, in
A problem caused in the case where a total number of the plate-shaped heat dissipating fins is increased is caused similarly also in the case where the number of the heat dissipating fins extending in the same direction (in parallel to each other) is too large, as is the case with a comparative example shown in
First Modified Example of the First Embodiment Shown in
Plate-shaped heat dissipating fins shown in
The heat dissipating fins 105, 106 formed on the side of the bottom face 1022 are arranged absolutely similarly to and symmetrically in the up and down direction in the drawing with respect to the four plate-shaped heat dissipating fins 103, 104 formed on the side of the LED element mounting face 1021 of the base plate 102. That is, as a mode in which the heat dissipating fins extend in the same direction, two heat dissipating fins 105, 105 on the left and right sides of the drawing are formed side by side in parallel to each other and symmetrically to each other across the LED element 100, whereas two heat dissipating fins 106, 106 on the up and down sides of the drawing are formed side by side in parallel to each other and symmetrically to each other across the LED element 100. That is, also on the side of the bottom face 1022, the plate-shaped heat dissipating fins 105, 105 and 106, 106 opposed to each other are formed at positions between which a position on the bottom face side, which corresponds to a position on the top face side at which the LED element 100 is mounted, is sandwiched in a similar manner in which the plate-shaped heat dissipating fins 103, 103 and 104, 104 on the top face side of the LED element mounting face 1021 are formed. In other words, the plate-shaped heat dissipating fins are formed at the positions between which the LED element 100 is sandwiched on both of the top and bottom faces of the base plate 102. Of the heat dissipating fins 105, 106, the number of the heat dissipating fins extending in the same direction is specified to be two also in an arbitrary section perpendicular to the face 1022 of the base plate 102 (also at any section of the heat sink 101 cut at a section in this direction).
The heat dissipating fins 105, 106 surround a rectangular perimeter in which a position of the bottom face 1022 corresponding to the position of the top face 1021 at which the LED element 100 is mounted is at the center in a manner in which the heat dissipating fins adjacent to each other are perpendicular to each other (intersect at right angles), and the respective plate-shaped side faces of the heat dissipating fins 105, 106 having a large heat radiation efficiency are directed to the x direction and the z direction, respectively. The LED element mounting face 1021 and the other bottom face 1022, each of which has a large heat radiation efficiency, of the base plate 102 are directed to the y direction.
In addition, not only the respective faces 1023, 1024, 1025, 1026 in the thickness direction of the rectangular perimeter of the base plate 102 and the respective faces (top faces and faces of the end portions) in the thickness direction of the four plate-shaped heat dissipating fins 103, 104 formed on the side of the LED mounting face 1021 of the base plate 102 but also the respective faces (bottom faces and faces of the end portions) in the thickness direction of the respective heat dissipating fins 105, 106 on the side of the bottom face 1022 become the heat radiating surfaces. The respective faces in the thickness direction of the respective heat dissipating fins are comparatively small in area, but the number of faces of both of the top and bottom faces and the faces of the end portions becomes two times the number of those faces in
Hence, also in the case of
Second, Third, and Fourth Modified Examples of the First Embodiment Shown in
The plate-shaped heat dissipating fins of the modified examples shown in
In the second modified example shown in
In the third modified example shown in
The fourth modified example shown in
Fifth and Sixth Modified Examples of the First Embodiment Shown in
A heat sink 101 for LED lighting shown in
In this case, the plate-shaped heat dissipating fins 103 and 104 are integrally formed of the same material by bending the base plate 102 in the y direction (in the up and down direction in the drawing), in which the respective heat dissipating surfaces extend, from the end portion sides of the base plate 102. In the fifth modified example shown in
Principle and Function of Heat Dissipation:
There will be described the principle (function) of heat dissipation in the case where this heat sink 101 of the present invention is set in a space in which the convention of air is not caused to thereby do the LED lighting. When the LED element 100 mounted on the LED mounting face 1021 is made to emit light, the heat (heat flux) Q emitted by the LED element 100 is transferred to the LED element mounting face 1021 of the base plate 102 through a mounting part (not shown) of a bottom portion of the LED element 100. Subsequently, the heat Q transferred to the LED element mounting face 1021 is transferred (conducted) not only to the heat dissipating fins 103, 104 on the side of the LED mounting face 1021 but also to the bottom face 1022 and the heat dissipating fins 105, 106 on the side of the bottom face 1022 speedily (without delay) continuously with the respective heat dissipating surfaces described above and almost uniformly at a high level. For this reason, convection from the heat dissipating surfaces of these heat dissipating fins and, in particular, heat dissipation by radiation are performed uniformly at a given level or more, whereby the heat dissipation efficiency can be increased.
Here, as is specified by the present invention, in the heat dissipating fins 103 to 106, the number of the heat dissipating fins extending in the same direction is specified to be two or less at an arbitrary section perpendicular to the faces 1021, 1022 of the base plate 102 and hence the heat dissipating fins 103 to 106 do not overlap each other excessively in the same direction. Hence, the transferred heat Q is transmitted to the three dimensional directions of the x, y, z directions and is radiated speedily and efficiently to a closed space (heat dissipating space) around them from the surfaces of the LED element mounting face 1021 and the bottom face 1022 of the base plate 102 and the respective heat dissipating surfaces of the heat dissipating fins 103 to 106. Hence, the heat emitted by the LED element 100 is dissipated in all directions of the three dimensional x, y, z directions at a high radiation efficiency in which the amount of heat dissipation is more than a given value. The reasons are as follows: although the heat sink 101 of the present invention is small in the number of the heat dissipating fins 103 to 106, the heat sink 101 is large in a projected area in any direction of the x, y, z directions also in a closed heat dissipating space in a lighting device in which the efficiency of heat dissipation is controlled by heat radiation and in which the convection of air is little caused. The heat sink 101 of the present invention has an excellent characteristic such that although the heat sink 101 has a simple structure in which the number of the heat dissipating fins 103 to 106 is small, the heat sink 101 is excellent in the heat dissipation efficiency per unit heat dissipation area.
Here, in the case of heat dissipation by radiation, which is required in a narrow space or a closed space of a housing for a vehicle-mounted lighting device, the sizes of the projected areas in the x-axis, y-axis, z-axis directions (three dimensional directions) shown in the respective drawings influence the heat radiation efficiency of the vehicle-mounted lighting device, that is, as the total of the projected areas becomes larger, the heat radiation efficiency becomes larger.
In this point, in a heat sink in a conventional example shown in
In other words, in the conventional heat sink shown in
Incidentally, Japanese Patent Application Laid-Open No. 2010-146817 is the same in this point, and the heat radiation efficiency is low for a high spatial occupancy in the direction in which the heat dissipating parts of many ladle parts, each of which is shaped like a letter C, overlap each other and the waste of material is large, in particular, in the x direction in terms of the integrated heat radiation efficiency in three directions of the three dimensional directions. Further, the slit-shaped opening described above is greatly limited in width so as to ensure the size of a heat sink itself and an area on the heat dissipating part side and hence is inevitably made narrow, so that in the case where the heat sink is applied to a closed space, an improvement in the heat dissipation efficiency by the convection of air cannot be actually made as large as desired.
The heat sink of the present invention is most suitable in a usage (installation) state in which a heat dissipating space around the heat sink is closed and is small in volume and is little in the convection of air, that is, in a usage (installation) environment in which heat dissipation by the convection of air is hardly expected. In this usage environment, in order to dissipate heat, heat dissipation by radiation needs to be made main. However, in the heat conventional heat sink structure in which heat dissipation performance is mainly enhanced by an increase in the convection of air which is made by increasing the surface areas of the heat dissipating surfaces of the heat dissipating fins or the like, the heat dissipation by the radiation becomes insufficient and hence heat dissipation cannot be efficiently achieved as a whole. In contrast to this, in the heat sink of the present invention, heat dissipation is mainly done by the radiation of heat from the heat dissipating surfaces of the heat dissipating side surfaces, so that the heat sink of the present invention can be said to be the most suitable heat sink for the usage (setting) environment in which heat dissipation by the convection of air can be hardly expected.
In addition, in the heat sink of the present invention, the respective heat dissipating surfaces including the LED element mounting face 1021 and the heat dissipating fins are of an integral structure in which each of the heat dissipating surfaces does not have a joint face between the LED element mounting face 1021 and the heat dissipating fin and hence do not cause a contact heat resistance caused in the case where the LED element mounting face 1021 and the heat dissipating fins are separately manufactured and then joined to each other. For this reason, heat conduction can be easily developed between the LED element mounting face 1021 and the respective heat dissipating fins, which results in markedly increasing the heat dissipation performance of the whole heat sink. Further, the structure of the heat sink 101 is a structure such that the heat dissipating fins are directed to all directions of the x, y, z directions of the three dimensional directions and hence has high rigidity. For this reason, even in the case of usage in which the heat sink suffers vibrations, for example, in the vehicle-mounted lighting device or the like, the heat sink can hold a shape without using a special reinforcing member and can achieve a maintenance-free heat sink and a long life.
Common Items of the First Embodiment Including the Respective Modified Examples:
The LED element mounting face 1021 and the bottom face 1022 of the base plate 102 and the respective heat dissipating surfaces of the heat dissipating fins 103 to 106, which have been described above, may have a space, a slit, or a partial shape for fixing a component formed in a portion thereof, according to the usage of the heat sink 101 and to a member to which the heat sink 101 is fixed, by cutting out a portion of the face and the surfaces or by three-dimensionally forming a depressed part, a projected part, or a stepped part in the surfaces. In addition, the heat dissipating side surfaces may have a portion thereof omitted or changed in shape according to the need of fixing the component and the like.
The heat sink 101 of the present invention can achieve an excellent heat dissipation effect without complicating the shape and structure of the heat sink, in particular, the shape and structure of the heat dissipating fins and without increasing the number of the heat dissipating fins, on the contrary, by simplifying the structure and by decreasing the number of heat dissipating fins. As a result, various kinds of raw materials, various manufacturing methods, or various manufacturing processes can be selected and hence a heat sink easily manufactured at low cost can be provided. As the raw material can be selected from various kinds of raw materials, for example, aluminum (pure aluminum) or aluminum alloy, copper (pure copper) or copper alloy, a steel plate, resin, or ceramics, and manufacturing methods or manufacturing processes such as drawing or bending of a plate, die casting or casting, forging, or extruding can be selected.
(Aluminum)
In this regard, aluminum (pure aluminum) or an aluminum alloy is desired as a raw material having strength, rigidity, lightness, corrosion resistance, heat transfer capability, heat dissipation capability, and workability which are characteristics require of the heat sink 101. The aluminum (pure aluminum) or the aluminum alloy is especially large in heat transfer characteristics and heat dissipation characteristics required of the heat sink and pure aluminum of 1000 series specified by the AA standard or the JIS standards can be preferably used.
The plate thickness (thickness) of the base plate 102 and the thicknesses of the heat dissipating fins 103 to 106 or a plate thickness (thickness) in the case where a raw material is a metal thin plate can be preferably selected from a range from 0.4 mm to 4 mm in consideration of a reduction in weight, required strength and rigidity, and drawing (forming) capability of the heat sink. When the plate thickness is too thin, the required strength and rigidity or the drawing (forming) capability of the heat sink cannot be ensured. On the other hand, when the plate thickness is too thick, the reduction in weight of the heat sink is sacrificed.
(Surface Emissivity of Heat Dissipating Surface)
In order to make the heat sink of the present invention acquire high heat dissipation capability, the surface emissivity ε of the metal thin plate is desired to be 0.6 or more. For this reason, before drawing the metal thin plate, a pre-coating processing (coating) of paint of black, gray, or white, which is high in heat dissipation rate, may be applied to the entire surface of the metal thin plate of the raw material. Alternatively, after drawing the metal thin plate, a post-coating processing (coating) of the paint which is high in thermal emissivity may be applied to a drawn product. In this way, the amount of heat transfer by radiation as the heat sink can be increased. When the pre-coating processing is previously applied to the metal thin plate of the raw material before the drawing, the coating processing serves as a lubricant in the drawing.
The surface emissivity ε is the ratio of the heat radiation of an actual body to a theoretical value (heat radiation of a black body of an ideal heat radiator) and an actual surface emissivity E may be measured by the method described in Japanese Patent Application Laid-Open No. 2002-234460 or may be measured by the use of a portable thermal emissivity measuring device on the market.
(Mounting Heat Sink of Present Invention in Vehicle-Mounted Lamp)
The mounting of the heat sink of the present invention in a vehicle-mounted LED lamp or the like can be performed in the same way as the mounting of a heat sink generally used, which is also an advantage of the heat sink of the present invention. Usually, the vehicle-mounted LED lamp (lighting device for a vehicle) includes an LED substrate having an LED element as a light source mounted thereon, a reflector for reflecting light from the LED to the front in the direction in which light is emitted, a housing for wrapping the LED substrate and the reflector, an outer lens for closing the open front end of the housing and made of a transparent material, and a heat sink arranged in thermal contact with the LED substrate. The reflector is formed of a resin material and has a parabolic reflecting surface having a focal point near the LED on the LED substrate. Here, the heat sink of the present invention is used as a heat sink arranged on the LED substrate or in thermal contact with the LED substrate. Even in this case, the heat sink of the present invention used for the vehicle-mounted LED lamp is greatly different from the conventional heat sink in the following point: that is, heat dissipation by the convection of air to which heat is transferred to air as in the case of the conventional heat sink is not main but heat dissipation by the thermal radiation of heat is main.
The heat sinks of the respective shapes of the fifth modified example (inventive example) shown in
The heat sinks of the respective shapes of the first modified example shown in
The rectangular shape of the base plate of each example was of the size of 100 mm (z direction)×100 mm (x direction)×thickness 2 mm, and the rectangular shape of the heat dissipating fin was of the size of 70 mm (length in the z direction of the plate-shaped side surface)×30 mm (height in the y direction of the plate-shaped side surface)×thickness 2 mm, which was common to the respective examples. The distance between the heat dissipating fins parallel to each other of the inventive example, that is, between 103 and 103 on the left and right sides and between 104 and 104 on the upper and lower sides was 80 mm or more (the distance from the center of the LED element was 35 mm or more). The distance between the heat dissipating fins in the conventional example and the comparative example was 10 mm. The base plate and the heat dissipating fins had cationic resin coating electrodeposited on the surfaces in the respective examples, the cationic resin coating being commercially available and black. When a surface thermal emissivity was measured for all examples by the use of a commercially available portable thermal emissivity measuring device developed by Japan Aerospace Exploration Agency, the surface thermal emissivity was 0.85 for all examples.
In all examples, the base plate was mounted with a commercially available LED element and then the LED element had an electric current of 3.7 V×0.85 A applied thereto from a direct current power supply to thereby emit light. At this time, the heat sink was set hermetically in a cylindrical wooden case simulating the closed space of a vehicle-mounted LED lamp in which the convection of air was not caused and having the size of 300 mm×300 mm×300 mm, and while monitoring the temperature of the LED element with a thermocouple, the LED element was made to emit light in the atmosphere set at a temperature of 20° C. After a given time passed, the temperature brought into a steady state in which the temperature was neither increased nor decreased was measured. The temperature was measured five times for each of the examples and an average value of the measured temperatures was found and evaluated.
As shown in Table 1, in an inventive example 1 corresponding to the fifth modified example shown in
On the other hand, in the heat sinks of the conventional example 1 shown in
The critical significance of the specifications, in particular, the number and the arrangement of the heat dissipating fins of the heat sink of the present invention can be supported by the facts described above.
As described above, in the heat sinks of the present invention, heat dissipation is done mainly by heat dissipation by heat radiation from the heat dissipating surfaces such as the heat dissipating side surfaces and the like, so that the heat sink of the present invention is most suitable for a narrow usage space (usage, setting environment) in which the convection of air is little caused (heat dissipation by the convection of air is hardly expected). For this reason, the heat sink of the present invention can be used as a heat dissipating component for a vehicular lighting device such as a vehicle-mounted LED lamp.
In various exemplary embodiments, a heat sink for LED lighting according to the present invention includes: a base plate; a first heat-dissipating fin; and a second heat-dissipating fin. In some such embodiments: the base plate, the first fin, and the second fin are formed integrally from aluminum or an aluminum alloy; the base plate comprises a first surface suitable for mounting an LED element and a second surface opposite from the first surface; the first fin extends from the first surface or the second surface of the base plate; the second fin extends from the first surface or the second surface of the base plate; no more than one additional heat-dissipating fin extends from the surface of the base plate from which the first fin extends and is parallel or substantially parallel to the first fin; and no more than one additional heat-dissipating fin extends from the surface of the base plate from which the second fin extends and is parallel or substantially parallel to the second fin.
In further exemplary embodiments, the heat sink according to the present invention includes: a third heat-dissipating fin; and a fourth heat-dissipating fin. In some such embodiments: the first fin is not parallel or substantially parallel to the second fin; the third fin is parallel or substantially parallel to the first fin; and the fourth fin is parallel or substantially parallel to the second fin.
In further exemplary embodiments, in the heat sink according to the present invention, each of the first fin, the second fin, the third fin, and the fourth fin extends from the first surface of the base plate.
In further exemplary embodiments, in the heat sink according to the present invention: the heat sink is formed by bending a blank of the aluminum or aluminum alloy; and each of the first fin, the second fin, the third fin, and the fourth fin is formed by bending the blank such that the base plate joins each of the first fin, the second fin, the third fin, and the fourth fin at a location of a respective bend.
In further exemplary embodiments, the heat sink according to the present invention includes: a fifth heat-dissipating fin; a sixth heat-dissipating fin; a seventh heat-dissipating fin; and an eighth heat-dissipating fin. In some such embodiments: each of the fifth fin, the sixth fin, the seventh fin, and the eighth fin extends from the second surface of the base plate; the fifth fin is not parallel or substantially parallel to the sixth fin; the seventh fin is parallel or substantially parallel to the fifth fin; and the eighth fin is parallel or substantially parallel to the sixth fin.
In further exemplary embodiments, in the heat sink according to the present invention, each of the first fin, the second fin, the third fin, and the fourth fin extends from the second surface of the base plate.
In further exemplary embodiments, the heat sink according to the present invention includes: a third heat-dissipating fin; a fourth heat-dissipating fin; and a fifth heat-dissipating fin. In some such embodiments, each of the first fin, the third fin, and the fourth fin extends from the first surface of the base plate; each of the second fin and the fifth fin extends from the second surface of the base plate; the first fin is not parallel or substantially parallel to the second fin; the third fin is parallel or substantially parallel to the first fin; the fourth fin is not parallel or substantially parallel to the first fin; and the fifth fin is parallel or substantially parallel to the second fin.
In further exemplary embodiments, the heat sink according to the present invention includes: a third heat-dissipating fin; and a fourth heat-dissipating fin. In some such embodiments: each of the first fin and the third fin extends from the first surface of the base plate; each of the second fin and the fourth fin extends from the second surface of the base plate; the first fin is parallel or substantially parallel to the second fin; the third fin is parallel or substantially parallel to the first fin; and the fourth fin is parallel or substantially parallel to the second fin.
In further exemplary embodiments, in the heat sink according to the present invention: each of the first fin and the third fin extends from the first surface of the base plate; and each of the second fin and the fourth fin extends from the second surface of the base plate.
In further exemplary embodiments, in the heat sink according to the present invention: the heat sink is formed by bending a blank of the aluminum or aluminum alloy; and each of the first fin, the second fin, the third fin, and the fourth fin is formed by bending the blank such that the base plate joins each of the first fin, the second fin, the third fin, and the fourth fin at a location of a respective bend.
Specifically, the heat sink 201, as shown in
The base plate part 202 of the heat sink 201 has a side plate part 204 further formed integrally with the end portions on both sides thereof, the side plate part 204 being vertical to the base plate part 202. That is, the vertical front part 221 on the top of the base plate part 202 has a vertical side part 231 and a vertical side part 232 which are continuously arranged on both sides of and at right angles with the vertical front part 221 in such a way as to extend backward. Further, the horizontal plane part 211 of the base plate part 202 has a vertical side part 233 and a vertical side part 234 which are continuously arranged on both sides of and at right angles with the horizontal plane part 211 in such a way as to extend downward. Still further, the vertical front part 222 on the bottom of the base plate part 202 has a vertical side part 235 and a vertical side part 236 which are continuously arranged on both sides of and at right angles with the vertical front part 222 in such a way as to extend forward.
Depending on the whole size of the heat sink 201, it is generally desired that the thickness of the base plate part 202 and the side plate part 204 constructing the heat sink 201 is 0.5 to 5 mm from the viewpoint of rigidity, heat dissipation capability, and weight reduction.
In this regard, although the aluminum material is not limited to a special kind of aluminum, it is desired to use pure aluminum of JIS 1000 series, aluminum alloy of JIS 3000 series, and aluminum alloy of JIS 5000 series, which are excellent in thermal conductivity and formability.
A method for manufacturing the heat sink 201 of the second embodiment will be described below on the basis of
First, one blank 241 which corresponds to a plane shape of a development view matching the three dimensional shape of the heat sink 201 shown in
Next, the LED element mounting part 203, which is formed in a rectangular parallelepiped bulged upward, is formed at the center position of the surface of the blank 241 by coining.
Next, the respective parts of the blank 241 are bent. In the lower figure of
First, a 221 face part of the blank 241 is bent up integrally with a 231 face part and a 232 face part at a right angle with a center on a bend line 243 of a boundary with a 211 face part, and a 222 face part is bent down integrally with a 235 face part and a 236 face part at a right angle with a center on the bend line 243 of a boundary with the 211 face part. In this way, there is formed the base plate part 202, shown in
The manufacturing of the heat sink 201 for LED lighting of the embodiment shown in
In this way, the heat sink 201 for LED lighting of the embodiment shown in
Next, the principle and function of heat dissipation in the case where the heat sink 201 according to the present invention is set in a closed space in which the convection of air is not caused and where the LED lighting is done will be described with reference to
First, when the LED element mounted on the LED element mounting part 203 of the horizontal plane part 211 is made to emit light, heat generated by the LED element is transferred to the horizontal plane part 211 through the LED element mounting part 203. Subsequently, the heat transferred to the horizontal plane part 211 is conducted to the vertical front parts 221, 222 and the vertical side parts 233, 234. Then, the heat Q conducted to the horizontal plane part 211 is radiated in directions at right angles with the horizontal plane part 211 (an arrow of the heat Q radiated from the bottom surface in the up and down direction in the drawing will be omitted), that is, into the surrounding closed space S (heat dissipation space) from the top and bottom surfaces of the horizontal plane part 211. Further, the heat Q conducted to the vertical front parts 221, 222 is radiated in directions at right angles with the vertical front parts 221, 222 (arrows of the heat Q radiated from the bottom surfaces of the vertical front part 222 in the back and forth directions in the drawing will be omitted), that is, into the surrounding closed space S from the top and bottom surfaces of the vertical front parts 221, 222. Still further, the heat Q conducted to the vertical side parts 233, 234 is radiated in directions at right angles with the vertical side parts 233, 234 (arrows of the heat Q radiated from the bottom surfaces of the vertical side parts 233, 234 in the left and right directions in the drawing will be omitted), that is, into the surrounding closed space S from the top and bottom surfaces of the vertical side parts 233, 234.
On the other hand, a part of the heat Q conducted to the vertical front part 221 is conducted to the vertical side parts 231, 232 and is radiated in directions at right angles with the vertical side parts 231, 232 (in the right and left directions in the drawing), that is, into the surrounding closed space S from the top and bottom surfaces of the vertical side parts 231, 232. Further, a part of the heat Q conducted to the vertical front part 222 is conducted to the vertical side parts 235, 236 and is radiated in directions at right angles with the vertical side parts 235, 236 (in the right and left directions in the drawing), that is, into the surrounding closed space S from the top and bottom surfaces of the vertical side parts 235, 236.
In this regard, in the vertical side parts 231 to 236, the vertical side parts 231 and 232, 233 and 234, and 235 and 236 are opposite to each other, respectively, so that the vertical side parts 231 to 236 are smaller in heat dissipation by heat radiation than the horizontal plane part 211 and the vertical front parts 221, 222. This is because as follows: for example, when looking at the vertical side parts 231 and 232, the heat Q from the top face (right face in the drawing) of the vertical side part 231 and the heat Q from the top face (left face in the drawing) of the vertical side part 232 are directly radiated in the directions at right angles with the vertical side parts 231, 232, that is, into the surrounding space S, thereby being sufficiently dissipated; on the other hand, the heat Q radiated in the direction at a right angle with the vertical side part 231 from the bottom face (left face in the drawing) of the vertical side part 231 and the heat Q radiated in the direction at a right angle with the vertical side part 232 from the bottom face (right face in the drawing) of the vertical side part 232 pass each other; so that the vertical side parts 231, 232 absorb the heats Q each other and hence inhibit heat dissipation to the surrounding space S.
In this way, the heat sink 201 shown in
Next, a first modified example of the second embodiment will be described which is common to the second embodiment shown in
The first modified example of the second embodiment will be specifically described with reference to
A blank 241 is a blank which has a rectangular shape as a whole and which has two cutouts respectively on both side portions thereof, that is, a total of four cutouts 242 and which includes a base plate part 202 formed in the center portion and having a thick thickness and side parts 204 formed on both sides and having a thin thickness, that is, a blank whose thickness is varied in a width direction.
When describing a method for manufacturing the blank 241, two kinds of plate-shaped aluminum coil materials produced by rolling and having different thicknesses are prepared, and one thick plate and one thin plate which are acquired by punching or cutting the respective plate-shaped aluminum coil materials are welded to each other, thereby being integrated. A reference numeral 244 designates welded bead portions. Then, cutouts 242 extending in parallel to each other in the shape of a belt from an end side to a center side in a given length are made in the integrated aluminum plate at the positions at which the length is trisected.
By bending the blank 241 in the manner described in the second embodiment, a heat sink 201 according to the first modified example of the second embodiment can be easily manufactured. The heat sink 201 according to the first modified example of the second embodiment has the same three-dimensional shape as shown in
According to the first modified example of the second example, as compared with the second embodiment shown in
Next, a second modified example of the second embodiment which is common to the second embodiment shown in
That is, the blank 241 is formed of an aluminum extruded material having the thick base plate part 202 in the center and the thin side parts 204 on both sides. The blank 241 can be manufactured by extruding an aluminum material by the use of a die corresponding to this sectional shape and then by forming the cutouts 242. Further, by bending the blank 241 in the manner described in the second embodiment, the heat sink 201 according to the second modified example of the second embodiment can be manufactured in the same way.
The heat sink 201 of the second modified example of the second embodiment, as compared with the second embodiment shown in
The heat sink shown in
Further, in
Next, a third modified example of the second embodiment which is different from the second embodiment shown in
Here, a heat sink for LED lighting of the third modified example of the second embodiment is constructed of a base plate part 202 which is formed of a plate-shaped aluminum (including aluminum alloy) having a given uniform thickness and which is formed in the stepped shape as a whole, as is the case with the second embodiment shown in
Next, the heat sink of the third modified example of the second embodiment is greatly different from the heat sink shown in
Still further, the vertical side parts 231 and 232 have overlapping flange parts 251 and 252 arranged at upper and lower positions thereof, respectively, the overlapping flange parts 251 and 252 protruding forward and covering portions of the surfaces of the vertical side parts 2331, 2332, and 2333, 2334 (rear side portions) in such a way as to be in outer contact with the surfaces. Further, the vertical side parts 2333 and 2334 have overlapping flange parts 253, 253 arranged at center positions thereof, respectively, the overlapping flange parts 253, 253 protruding forward and covering portions of the surfaces of the vertical side parts 235, 236 (rear side portions) respectively in such a way as to be in outer contact with the surfaces.
A method for manufacturing the heat sink 201 of the third modified example of the second embodiment will be described below on the basis of
First, one blank 241 which corresponds to a plane shape of a development view matching the three-dimensional shape of the heat sink 201 shown in
Next, an LED element mounting part 203, which is formed in a rectangular parallelepiped and is bulged upward, is formed at the center position of the surface of the blank 241 by the coining process.
Next, the respective parts of the blank 241 are bent. In the lower figure of
First, a 221 face part of the blank 241 is bent up with a 2331 face part, a 2332 face part, a 212 face part, a 231 face part, and a 232 face part at a right angle with a center on the bend line 243 of a boundary with a 211 face part. Further, a 222 face part is bent down integrally with a 235 face part and a 236 face part at a right angle with a center on the bend line 243 of a boundary with the 211 face part. Still further, the 212 face part is bent down (down in
After the stepped base plate part 202 is formed, the 235 face part and the 236 face part are bent forth (up in
By forming the blank 241 in this way, the overlapping flange parts 253 of the 2333 face part and the 2334 face part overlap the surfaces of the 235 face part and the 236 face part and are bonded to the surfaces, respectively. That is, as shown in
Next, the 2331 face part and the 2332 face part are bent forth (up in
Subsequently, the 231 face part and the 232 face part are bent down at a right angle with a center on the bending line 243 of a boundary with the 212 face part and with a center on the bending line 243 of a boundary with the 212 face part, respectively, whereby the vertical side part 231 and the vertical side part 232 which are continuous with the horizontal plane part 212 shown in
By forming the blank 241 in this way, the overlapping flange parts 251 of the 231 face part and the 232 face part are overlaid on the 2331 face part and the 2332 face part in contact with the surfaces thereof, whereas the overlapping flange parts 252 of the 231 face part and the 232 face part are overlaid on the 2333 face part and the 2334 face part in contact with the surfaces thereof. In other words, as shown in
By bending the blank 241 in the above-mentioned way, the manufacturing of the heat sink 201 for LED lighting of the third modified example of the second embodiment shown in
According to the third modified example of the second embodiment, as compared with the heat sink of the second embodiment shown in
In this regard, the third modified example of the second embodiment is an example in which the vertical side parts are overlaid on each other via the overlapping flange parts. However, not only this structure but also a structure such that the vertical side parts and the horizontal plane parts and/or the vertical front parts of the base plate part 202 are overlaid on each other can be also employed.
Further, in the double structure parts of the vertical side parts in the third modified example of the second embodiment, the double materials may be integrally bonded to each other by the use of a bonding method such as screw fastening, rivet fastening, swage fastening, welding, or soldering, whereby the rigidity of the heat sink can be greatly increased.
In various exemplary embodiments, the heat sink for LED lighting according to the present invention includes: a base plate; a first heat-dissipating fin; and a second heat-dissipating fin. In some such embodiments: the base plate, the first fin, and the second fin are formed integrally from aluminum or an aluminum alloy; the base plate comprises a first surface suitable for mounting an LED element and a second surface opposite from the first surface; the first fin comprises a first surface and a second surface opposite from the first surface; the first fin extends from the first surface or the second surface of the base plate; and the second fin extends from the first surface or the second surface of the first fin.
In further exemplary embodiments, the heat sink according to the present invention includes: a third heat-dissipating fin; a fourth heat-dissipating fin; a fifth heat-dissipating fin; a sixth heat-dissipating fin; a seventh heat-dissipating fin; and an eighth heat-dissipating fin. In some such embodiments: the first fin extends from the first surface of the base plate; the second fin extends from the second surface of the first fin; the third fin extends from the second surface of the first fin; the fourth fin extends from the second surface of the base plate; the fifth fin extends from the second surface of the base plate; the sixth fin comprises a first surface and a second surface opposite from the first surface; the sixth fin extends from the second surface of the base plate; the seventh fin extends from the first surface of the sixth fin; and the eighth fin extends from the first surface of the sixth fin.
In further exemplary embodiments, in the heat sink according to the present invention: the heat sink is formed by bending a blank of the aluminum or aluminum alloy; each of the first fin, the fourth fin, the fifth fin, and the sixth fin is formed by bending the blank such that the base plate joins each of the first fin, the fourth fin, the fifth fin, and the sixth fin at a location of a respective bend; each of the second fin and the third fin is formed by bending the blank such that the first fin joins each of the second fin and the third at a location of a respective bend; and each of the seventh fin and the eighth fin is formed by bending the blank such that the sixth fin joins each of the seventh fin and the eighth fin at a location of a respective bend.
In further exemplary embodiments, in the heat sink according to the present invention, the blank comprises a thick portion corresponding to the base plate, the first fin, and the sixth fin and a thin portion corresponding to corresponding to the second fin, the third fin, the fourth fin, the fifth fin, the seventh fin, and the eighth fin.
In further exemplary embodiments, in the heat sink according to the present invention, the blank is prepared by welding sheets of the aluminum or aluminum alloy.
In further exemplary embodiments, in the heat sink according to the present invention, the blank is prepared by coining.
In further exemplary embodiments, the heat sink according to the present invention includes: a third heat-dissipating fin; a fourth heat-dissipating fin; a fifth heat-dissipating fin; a sixth heat-dissipating fin; a seventh heat-dissipating fin; an eighth heat-dissipating fin; a ninth heat-dissipating fin; a tenth heat-dissipating fin; and an eleventh heat-dissipating fin. In some such embodiments: the first fin extends from the first surface of the base plate; the second fin comprises a first surface and a second surface opposite from the first surface; the second fin extends from the second surface of the first fin; the third fin extends from the first surface of the first fin; the fourth fin extends from the first surface of the first fin; the fifth fin extends from the second surface of the surface of the second fin; the sixth fin extends from the second surface of the surface of the second fin; the seventh fin extends from the second surface of the base plate; the eighth fin extends from the second surface of the base plate; the ninth fin comprises a first surface and a second surface opposite from the first surface; the ninth fin extends from the second surface of the base plate; the tenth fin extends from the first surface of the ninth fin; and the eleventh fin extends from the first surface of the ninth fin.
In further exemplary embodiments, in the heat sink according to the present invention: a portion of the fifth fin overlaps and contacts a portion of the fourth fin; a portion of the fifth fin overlaps and contacts a portion of the seventh fin; a portion of the sixth fin overlaps and contacts a portion of the third fin; a portion of the sixth fin overlaps and contacts a portion of the eighth fin; a portion of the seventh fin overlaps and contacts a portion of the eleventh fin; and a portion of the eighth fin overlaps and contacts a portion of the tenth fin.
In further exemplary embodiments, in the heat sink according to the present invention: the heat sink is formed by bending a blank of the aluminum or aluminum alloy; each of the first fin, the seventh fin, the eighth fin, and the ninth fin is formed by bending the blank such that the base plate joins each of the first fin, the seventh fin, the eighth fin, and the ninth fin at a location of a respective bend; each of the second fin, the third fin, and the fourth fin is formed by bending the blank such that the first fin joins each of the second fin, the third fin, and the fourth fin at a location of a respective bend; each of the fifth fin and the sixth fin is formed by bending the blank such that the second fin joins each of the fifth fin and the sixth fin at a location of a respective bend; and each of the tenth fin and the eleventh fin is formed by bending the blank such that the ninth fin joins each of the tenth fin and the eleventh fin at a location of a respective bend.
Specifically, the heat sink 301 of the third embodiment, as shown in
Each of the horizontal plane parts 311, 312 and the vertical front parts 321, 322 is a rectangle having a long side of the same length of the width of the aluminum plate 302 forming the stepped shape and a short side of a width acquired by dividing the length of the aluminum plate 302 into equal quarters.
A reference numeral 300 designates an LED element mounted on the center of the horizontal plane part 312.
Of the horizontal plane parts and the vertical front parts, the horizontal plane part 312 and the vertical front part 321 have vertical side parts 331, 332 arranged on both side ends at a right angle with them, that is, vertically with them. Each of the vertical side parts 331, 332 is a square having a side of the length of the horizontal plane parts 311, 312 and the vertical front parts 321, 322.
Next, the principle and function of heat dissipation in the case where the heat sink 301 having such a stepped shape is set in a space in which the convection of air is not caused and where LED lighting is done will be described. When the LED element 300 mounted on the horizontal plane part 312 is made to emit light, the heat generated by the LED element 300 is conducted to the horizontal plane part 312 through a part having the LED element 300 mounted thereon. Subsequently, the heat conducted to the horizontal plane part 312 is conducted to the vertical front part 321, the vertical front part 322, and the vertical side parts 331, 332. In this way, the heat conducted to the horizontal plane part 312 is conducted to the two or more vertical front parts or the vertical side parts which are continuous with the horizontal plane part 312. Then, the heat Q conducted to the horizontal plane part 312 is radiated at right angles with the horizontal plane part 312 (up and down directions in
Further, a portion of the heat Q conducted to the vertical front part 321 is conducted to the horizontal plane part 311 and is radiated at right angles with the horizontal plane part 311 (up and down directions in
In this way, the heat sink having the stepped shape shown in
Next, a method for manufacturing a heat sink formed in a shape shown in
First, a pure aluminum plate or an aluminum alloy plate (which is simply referred to as an aluminum plate in the present invention) having a given thickness is produced from a raw material of pure aluminum or aluminum alloy by rolling or the like. The aluminum plate produced has a length L of four times a short side of the rectangle of the horizontal plane part 311 (which is the same as the horizontal plane part 312, and vertical front parts 321 and 322) shown in
Next, of four rectangles acquired by dividing the aluminum plate, which is produced by the rolling and has a size of L×W, into four equal quarters in the length direction, three rectangles of the first, second, and fourth quarters except for the third quarter from an end have both side portions thereof cut off by a length corresponding to a side of the square of the vertical side part 331 (which is the same as the vertical side part 332). By cutting the aluminum plate in this way, an aluminum plate 302 can be acquired which has three rectangles having a width (long side) corresponding to the horizontal plane part 311 and the vertical front parts 321 and 322 and one rectangle having a long width (total width) acquired by adding a side of the vertical side part 331 and a side of the vertical side part 332 to a width of the horizontal plane part 312.
In the aluminum plate 302, a short-width rectangular part which is to be the horizontal plane part 311 is bent at a right angle with a rectangular part which is to be the vertical front part 321 with a center on a boundary with the rectangular part which is to be the vertical front part 321; next, a same rectangular part which is to be the horizontal plane part 312 is further bent on a side opposite to the horizontal plane part 311 at a right angle with the rectangular part which is to be the vertical front part 321 with a center on a boundary with the rectangular part which is to be the vertical front part 321; subsequently, a same rectangular part which is to be the vertical front part 322 is still further bent on a side opposite to a same rectangular part of the vertical front part 321, which is bent, at a right angle with the same rectangular part of the horizontal plane part 312 with a center on a boundary with the same rectangular part of the horizontal plane part 312. In this way, a stepped shape of a base shape can be formed.
Then, finally, square parts of the vertical side part 331 and the vertical side part 332 which are positioned on both sides in a width direction of a long-width rectangular part which is to be (the horizontal plane part 312+the vertical side part 331+the vertical side part 332) is bent to the side of the face of the vertical front part 321 at a right angle with the rectangular part of the horizontal plane part 312 with a center on a boundary with the horizontal plane part 312, respectively. In this way, the heat sink 301 of the present invention shown in
A method for manufacturing the aluminum plate 302 has been described by taking the rolling method as an example. However, not only the rolling method but also other working method such as an extruding method can be used.
The heat sink 301 shown in
Further, in
Still further, the vertical side parts 331, 332 shown in
Further, in the heat sink shown in
Here, the thickness of the horizontal plane part 312 except for the part having the LED element 300 mounted thereon is the same as the thickness of the other parts 321, 312, 322, and the part having the LED element 300 mounted thereon has a thicker part 3121 formed on the bottom side thereof in such a way as to bulge downward. In this way, by increasing the thickness of the part having the LED element 300 mounted thereon of the horizontal plane part 312, a large amount of heat generated by the horizontal plane part 312 at the time of lighting is speedily conducted to a surrounding thin part 3122 and is radiated into the upper and lower heat dissipation space from the whole top and bottom surfaces of the horizontal plane part 312 and at the same time is conducted also to the respective face parts 321, 322, 331, 332 adjacent to and continuous with the horizontal plane part 312 and is radiated also from these parts. Hence, the heat sink can further enhance the heat dissipation efficiency and can be easily manufactured in the case where the heat sink is formed in such a shape.
A setting state in the case where the above-mentioned heat sink 301 for an LED light is applied to a headlight for an automobile will be described with reference to
Here, the heat sink 301 is formed of the aluminum plate 302 and has a stepped (two-stepped) shape constructed of the vertical front part 321, the horizontal plane part 311, the vertical front part 322, and the horizontal plane part 312 in this order from the top and has the vertical side parts 331, 332 on both side ends of the horizontal plane part 311 and the vertical front part 322 and has the vertical side parts 333, 334 on both side ends of the horizontal plane part 312 and the vertical front part 322 and has the vertical side parts 333, 334 on both side ends of the horizontal plane part 312 and the vertical front part 322. Further, the heat sink 301 has the vertical side parts 335, 336 extended (protruded) down on both side ends of the horizontal plane part 312 and has vertical side parts 337, 338 extended (protruded) back on both side ends of the vertical front part 321. Here, the vertical side parts 331, 332 are made by bending down extensions of the horizontal plane part 311 at a right angle and are flush with the side surfaces of a housing 340, the extensions being extended to both sides of the horizontal part 311, whereas the vertical side parts 333, 334 are made by bending forth extensions of the vertical front part 322 at a right angle and are arranged in the state where the parts are overlaid on the outside surfaces of the housing 340, the extensions being extended to both sides of the vertical front part 322. The vertical side parts 335, 336 are formed by bending down extensions of the horizontal plane part 312 at a right angle, the extensions being extended to both sides of the horizontal plane part 312. The vertical side parts 337, 338 are formed by bending back extensions of the vertical plane part 321 at a right angle, the extensions being extended to both sides of the vertical plane part 321.
A reference numeral 300 designates an LED element of a light emitting source and the LED elements 300 are mounted on the upper faces of the horizontal plane parts 311, 312. A reference numeral 350 designates reflectors (which is omitted in
The heat sink 301 is set in the housing 340 formed in the shape of a frame body, whose both sides have tope ends formed nearly in the shape of an arc and have bottom ends formed in the stepped shape and whose front portion has a curved opening corresponding to the shape of the arc, in the state where the housing 340 is disposed on the heat sink 301 formed in the stepped shape. The vertical side parts 335, 336 and 337, 338 of the heat sink 301 integrated with the housing 340 are fixed and supported by a fixing part (not shown) of a vehicle body. In the curved opening of the housing 340 is fitted an outer lens 360 formed in the same shape as the curved opening and of transparent glass.
The respective outside surfaces of the vertical front part 321, the horizontal plane part 311, the vertical front part 322, and the horizontal plane part 312 of the heat sink 301 are opposed to the closed space S in a vehicle body and the inside surfaces and outside surfaces of the vertical side parts 331, 332 and 335, 336, and 337, 338 of the heat sink are also opposed to the closed space S.
In the case where the LED element 300 is made to emit light and to do illumination as the headlight of the automobile in this setting state, the heat generated when the LED element 300 emits light is dissipated by radiation to the surrounding closed space (heat dissipation space) S opposite to these parts from the outside surfaces of these face parts 311, 312, 321, and 322 constructing the stepped shape and from the inside surfaces and outside surfaces of the vertical side parts 331 to 338 on both side ends of these face parts. The heat is dissipated by the heat sink having a heat dissipating surface of a very large projected area in the three dimensional directions of the x, y, and z directions and having a high heat radiation efficiency and hence can be dissipated very effectively to a narrow space in which the convection of air is hardly caused.
In various exemplary embodiments, the heat sink for LED lighting according to the present invention includes: a base plate; a first heat-dissipating fin; and a second heat-dissipating fin. In some such embodiments: the base plate, the first fin, and the second fin are formed integrally from aluminum or an aluminum alloy; the base plate comprises a first surface suitable for mounting an LED element and a second surface opposite from the first surface; the first fin comprises a first surface and a second surface opposite from the first surface; the first fin extends from the first surface or the second surface of the base plate; and the second fin extends from the first surface or the second surface of the first fin.
In further exemplary embodiments, the heat sink according to the present invention includes: a third heat-dissipating fin; a fourth heat-dissipating fin; and a fifth heat-dissipating fin. In some such embodiments: the first fin extends from the first surface of the base plate; the second fin extends from the second surface of the first fin; the third fin extends from the first surface of the base plate; the fourth fin extends from the first surface of the base plate; and the fifth fin extends from the second surface of the base plate.
In further exemplary embodiments, in the heat sink according to the present invention: the heat sink is formed by bending a blank of the aluminum or aluminum alloy; each of the first fin, the fourth fin, the fifth fin, and the sixth fin is formed by bending the blank such that the base plate joins each of the first fin, the fourth fin, the fifth fin, and the sixth fin at a location of a respective bend; each of the second fin and the third fin is formed by bending the blank such that the first fin joins each of the second fin and the third at a location of a respective bend; and each of the seventh fin and the eighth fin is formed by bending the blank such that the sixth fin joins each of the seventh fin and the eighth fin at a location of a respective bend.
Specifically, the heat sink 401 for LED lighting of the fourth embodiment (hereinafter simply referred to as the heat sink 401 in some cases) is manufactured by applying a comparatively simple working such as cutting and bending to an aluminum extrusion material made by extruding an aluminum material which is excellent in thermal conductivity and formability, such as pure aluminum of JIS 1000 series and an aluminum alloy of JIS 6000 series. Further, the heat sink 401 may be manufactured by the use of other aluminum alloy material such as an aluminum alloy material of JIS 5000 series. A manufacturing method will be described later.
As shown in
The fin bent piece 403b has the heat dissipating surface in the direction which is perpendicular to the heat dissipating surface of the fin main body 403a and to the heat dissipating surface of the base plate part 402. That is, the heat dissipating surface of the base plate part 402, the heat dissipating surface of the fin main body 403a, and the heat dissipating surface of the fin bent piece 403b are directed in different directions (y-axis direction, x-axis direction, z-axis direction) which are perpendicular to each other.
A plan view, a front view, and a side view of the heat sink 401 of the fourth embodiment will be shown in
In the fourth embodiment shown in
The number and shape of these fin parts 403 do not need to be the same as those of the embodiment shown in
Next, a method for manufacturing the heat sink 401 for LED lighting of the fourth embodiment will be simply described. As described above, the heat sink 401 for LED lighting according to the present invention is manufactured from the aluminum extrusion material formed by extruding a metal material, which is excellent in thermal conductivity and formability, such as pure aluminum of JIS 1000 series and aluminum alloy of JIS 6000 series.
For example, in the case where the heat sink 401 shown in
The heat sink 401 for LED lighting described above is used as the heat sink 401 for vehicle-mounted lighting such as a headlight of an automobile or an embedded lighting of a building. In
In this way, in the case the heat sink 401 for LED lighting of the fourth embodiment is used as the heat sink for LED lighting in a state where the fin parts 403 of the heat sink 401 is protruded into the closed space, the heat generated when the LED light source emits light is dissipated from the heat sink 401 into the closed space in which the convection of air is not caused. The heat sink 401 for LED lighting according to the present invention, as shown in the plan view, the front view, and the side view of
In various exemplary embodiments, the heat sink for LED lighting according to the present invention includes: a base plate; a first heat-dissipating fin; a second heat-dissipating fin; and a third heat-dissipating fin. In some such embodiments: the base plate, the first fin, the second fin, and the third fin are formed integrally from aluminum or an aluminum alloy; the base plate comprises a first surface suitable for mounting an LED element and a second surface opposite from the first surface; the first fin extends from the second surface of the base plate; the second fin comprises a first surface and a second surface opposite from the first surface; the second fin extends from the second surface of the base plate; and the third fin extends from the first surface or the second surface of the second fin.
In further exemplary embodiments, the heat sink according to the present invention includes: a fourth heat-dissipating fin; a fifth heat-dissipating fin; a sixth heat-dissipating fin; a seventh heat-dissipating fin; and an eighth heat-dissipating fin. In some such embodiments: the third fin extends from the first surface of the second fin; the fourth fin extends from the first surface of the second fin; the fifth fin extends from the second surface of the base plate; the sixth fin comprises a first surface and a second surface opposite from the first surface; the sixth fin extends from the second surface of the base plate; the seventh fin extends from the first surface of the sixth fin; and the eighth fin extends from the first surface of the sixth fin.
In further exemplary embodiments, the heat sink according to the present invention includes: a fourth heat-dissipating fin; a fifth heat-dissipating fin; and a sixth heat-dissipating fin. In some such embodiments: the fourth fin extends from the second surface of the base plate; the fifth fin comprises a first surface and a second surface opposite from the first surface; and the sixth fin extends from the first surface or the second surface of the fifth fin.
In further exemplary embodiments, the heat sink according to the present invention includes: a fourth heat-dissipating fin; a fifth heat-dissipating fin; a sixth heat-dissipating fin; a seventh heat-dissipating fin; and an eighth heat-dissipating fin. In some such embodiments: the third fin extends from the first surface of the second fin; the fourth fin extends from the second surface of the second fin; the fifth fin extends from the second surface of the base plate; the sixth fin comprises a first surface and a second surface opposite from the first surface; the sixth fin extends from the second surface of the base plate; the seventh fin extends from the first surface of the sixth fin; and the eighth fin extends from the second surface of the sixth fin.
In further exemplary embodiments, the heat sink according to the present invention includes: a fourth heat-dissipating fin; and a fifth heat-dissipating fin. In some such embodiments: the third fin extends from the first surface of the second fin; the fourth fin extends from the second surface of the second fin; and the fifth fin extends from the second surface of the base plate.
Specifically, the heat sink 501 for LED lighting of the fifth embodiment (hereinafter simply referred to as the heat sink 501 in some cases) is manufactured by applying a comparatively simple working such as cutting and bending to an aluminum extrusion material made by extruding an aluminum material, which is excellent in thermal conductivity and formability, such as pure aluminum of JIS 1000 series and aluminum alloy of JIS 6000 series. Further, the heat sink 501 for LED lighting may be manufactured by the use of other aluminum alloy material such as aluminum alloy material of JIS 5000 series.
As shown in
The base plate part 502 is a plate so-called shaped like a letter L, the plate being bent in a direction perpendicular to the longitudinal direction of the fin parts 503 arranged in parallel to each other. As the base plate part 502 is bent in this manner, there is formed the fin part 503 having a first fin part 503a, which extends in a direction perpendicular to the base plate part 502, and a second fin part 503b, which extends in the direction perpendicular to the base plate part 502 and in a direction intersecting the first fin part 503a. In the present embodiment, the fin part 503 is bent outside along with the base plate part 502 and hence a bent part of the fin part 503 is pulled and extended, which hence is likely to have an effect on the bending of the base plate part 502. Hence, the dimension of protrusion of the fin part 503 needs to be short not to interfere with the bending of the base plate part 502.
Here, the LED light source 500 is made, for example, by mounting a plurality of light emitting diode (LED) elements on a substrate based on an aluminum alloy.
The base plate part 502 is a plate so-called shaped like a letter L, the plate being bent in a direction perpendicular to the longitudinal direction of the fin parts 503 arranged in parallel to each other. In the present embodiment, the fin parts 503 are bent to the inside along with the base plate part 502 and hence the bent parts of the fin parts 503 are compressed, which hence is likely to have an effect on the bending of the base plate part 502. Hence, the fin parts 503 need to be short in the dimension of protrusion not to interfere with the bending of the base plate part 502.
The base plate part 502 is a plate so-called shaped like a letter L, the plate being bent in a direction perpendicular to the longitudinal direction of the fin parts 503 arranged in parallel to each other. In the present embodiment, the fin parts 503 are bent to the outside along with the base plate part 502 and, if the fin parts 503 are bent as they are, the fin parts 503 have an effect on the bending of the base plate part 502, so that before bending the base plate part 502, a linear slit 504 reaching the outside surface of the base plate part 502 is formed in a portion to be bent of each fin part 503. Since the base plate part 502 is bent after the slit is formed in each fin part 503 in this manner, as is the case with the embodiment shown in
The base plate part 502 is a plate so-called shaped like a letter L, the plate being bent in a direction perpendicular to the longitudinal direction of the fin parts 503 arranged in parallel to each other. In the present embodiment, the fin parts 503 are bent to the inside along with the base plate part 502 and, if the fin parts 503 are bent as they are, the fin parts 503 have an effect on the bending of the base plate part 502, so that before bending the base plate part 502, a slit 505 is formed in a portion to be bent of each of the fin parts 503, the slit 505 reaching the outside surface of the base plate part 502 and being shaped like a letter V of an angle of 90 degrees or more. Since the slit 505 shaped like a letter V is formed in each of the fin parts 503 in this manner and then the base plate part 502 is bent, the fin parts 503 do not need to be especially short in the dimension of protrusion as is the case with the embodiment shown in
The heat sink 501 for LED lighting is used as a heat sink 501 for vehicle-mounted lighting such as the headlight of an automobile and the embedded lighting of a building.
In this regard, the heat sink 501 shown in
The heat sink 501 shown in
Here, a reference numeral 520 designates an outer lens fixed to the front of the LED lighting and having transparency, whereas a reference numeral 530 designates a reflector for making light emitted from the LED light source 500 reflect to the outer lens 520.
The heat sink 501 shown in
When the heat sink 501 is fixed in a state where one part of the base plate part 502 constructs a part of the housing 510 of the LED lighting, there is brought about a state in which the other part of the base plate part 502 is protruded to the outside from the LED lighting (in the case of the automobile, inner space in a bonnet) as is the case with the fin parts 503. However, sufficient heat dissipating area can be ensured by the surface area of the base plate part 502 shaped like a letter L and by the surface area of the fin parts 503, so that a sufficient amount of heat can be dissipated.
Here, although a usage state is not shown especially, the heat sinks 501 shown in
In various exemplary embodiments, the heat sink for LED lighting according to the present invention includes: a bent planar base plate; a first heat-dissipating fin; and a second heat-dissipating fin. In some such embodiments: the base plate, the first fin, and the second fin are formed integrally from aluminum or an aluminum alloy; the base plate comprises an inner surface and an outer surface opposite from the inner surface; the first fin extends from the inner surface or the outer surface of the base plate; and the second fin extends from the same surface of the base plate as the first fin.
In further exemplary embodiments, in the heat sink according to the present invention: the inner surface of the base plate is suitable for mounting an LED element; the first fin and the second fin extend from the outer surface; the base plate comprises a first planar region and a second planar region that are joined by a bent region; the first fin extends from the outer surface of the base plate in the first planar region, the second planar region, and the bent region; and the second fin extends from the outer surface of the base plate in the first planar region, the second planar region, and the bent region.
In further exemplary embodiments, in the heat sink according to the present invention: the outer surface of the base plate is suitable for mounting an LED element; the first fin and the second fin extend from the inner surface; the base plate comprises a first planar region and a second planar region that are joined by a bent region; the first fin extends from the inner surface of the base plate in the first planar region, the second planar region, and the bent region; and the second fin extends from the inner surface of the base plate in the first planar region, the second planar region, and the bent region.
In further exemplary embodiments, the heat sink according to the present invention includes: a third heat-dissipating fin; and a fourth heat-dissipating fin. In some such embodiments, the inner surface of the base plate is suitable for mounting an LED element; the first fin, the second fin, the third fin, and the fourth fin extend from the outer surface; the base plate comprises a first planar region and a second planar region that are joined by a bent region; the first fin and the second fin extend from the outer surface of the base plate in the first planar region; and the second fin and the fourth fin extend from the outer surface of the base plate in the second planar region.
In further exemplary embodiments, the heat sink according to the present invention includes: a third heat-dissipating fin; and a fourth heat-dissipating fin. In some such embodiments: the outer surface of the base plate is suitable for mounting an LED element; the first fin, the second fin, the third fin, and the fourth fin extend from the inner surface; the base plate comprises a first planar region and a second planar region that are joined by a bent region; the first fin and the second fin extend from the inner surface of the base plate in the first planar region; and the second fin and the fourth fin extend from the inner surface of the base plate in the second planar region.
These
In the heat sink 601 shown in
Wavy Shape of Heat Dissipating Fin:
In
Here, a width a of the wavy shape 602, a width b of the wavy shape 603, a pitch p of the wavy shapes 602, 602 or the wavy shapes 603, 603, a width w and a height h of the wavy shapes 602, 603 (heat sink 601), and a length l of the continuous wavy shapes 602, 603 (heat sink 601) are designed so as to be tailored to the specifications of the vehicle-mounted LED lamp to which the heat sink 601 is set and to satisfy the required heat dissipation characteristics of the heat sink 601.
When usage ranges of them are described by an example from the specifications of the LED lamp mounted in an ordinary passenger car, the width a of the wavy shape 602 and the width b of the wavy shape 603 are 1 to 20 mm, the pitch p of the wavy shapes 602, 602 or the wavy shapes 603, 603 is 4 to 40 mm, the width w and the height h of the wavy shapes 602, 603 (heat sink 601) are 50 to 250 mm and 10 to 60 mm, respectively, and the length l of the continuous wavy shapes 602, 603 (heat sink 601) is 30 to 250 mm. Further, limit values in the design of these wavy shapes 602, 603 are specified also from the forming limit of the wavy shape when the aluminum alloy thin plate 601a of the raw material is corrugated. That is, in the case where the design values of these wavy shapes 602, 603 are too small or too large, it is impossible to corrugate the aluminum alloy thin plate.
Pre-Coating:
In
Further, the pre-coating serves as a lubricant agent at the time of corrugating the aluminum alloy thin plate 601a of the raw material and hence has an effect on improving the formability of the heat dissipating fins=wavy shapes 602, 603. Hence, in the present invention, before corrugating the aluminum alloy thin plate 601a, the pre-coating of the black paint is previously applied to the aluminum alloy thin plate 601a.
The emissivity ε of the pre-coating (pre-coated film) 610 applied to the surface of the aluminum alloy thin plate 601a of the raw material is made 0.7 or more so as to increase the thermal emissivity of the heat dissipating fins=wavy shapes 602, 603. In the case where the emissivity is less than 0.7, the aluminum alloy thin plate 601a of the raw material having the pre-coating applied thereto has the effect of lubrication but is reduced in the amount of heat transfer or the amount of heat dissipation by radiation and is not much different from a bare aluminum alloy thin plate 601a not having any coating applied thereto.
This emissivity ε is the rate of heat radiation of an actual body to a theoretical value (heat radiation of a black body of an ideal thermal radiator) and the emissivity ε may be actually measured by a method described in Japanese Patent Application Laid-open No. 2002-234460 or by the use of a portable emissivity measurement device developed by Japan Aerospace Exploration Agency. The method described in the Japanese Patent Publication will be described below. The emissivity ε is measured by the use of an emissivity measurement device shown in
[Mathematical equation 1]
Q1=α(T14−T24)/(1/ε1+1/ε2−1) Equation 1
where Q1=amount of heat transfer of an Al alloy heat sink 601, α=Stefan-Boltzmann constant 5.67×10−8 W/m2K4, T1=temperature of black paint layer 622, T2=temperature of heat sink 601, ε1=emissivity of black paint layer 622=0.9, and ε2=emissivity of outer surface of wavy shape 602 of heat sink 601.
Forming of Stepped Part:
In the present invention, as a preferable mode, by crushing the portions of the heat dissipating fins=the wavy shapes 602, 603, stepped parts (steps, depressions and projections) are formed in the wavy shapes 602, 603. The stepped parts become component fixing parts and element fixing parts (mounting face parts) when the heat sink 601 is mounted as a heat sink for a vehicle-mounted LED lamp. Further, these stepped parts provide depressed and projected shapes for increasing rigidity as the heat sink against an external force (bending moment) around an axis vertical to the surface of paper, for example, as shown by arrows on the left and right sides of the heat sink 601 shown in
A heat sink 601 of a second modified example of the sixth embodiment shown in
These stepped parts, including stepped parts to be described later, can be formed by crushing portions, in which these stepped parts in the wavy shapes are to be formed, by the use of a die without using other off-line process after forming the wavy shapes 602, 603 by corrugating, but these stepped parts can be formed by a forming process accompanying the corrugating process in a series of corrugating processes.
The other modes of a reinforcing example like this will be shown in
In a third modified example of the sixth embodiment shown in
In a fourth modified example of the sixth embodiment shown in
In a fifth modified example of the sixth embodiment shown in
In a sixth modified example of the sixth embodiment shown in
a), 44(b), and 44(c) are seventh modified examples of the sixth embodiment and show examples in which a reinforcing bracket 630 is attached to the bottom faces of the wavy shapes 602, 603 (heat sink 601).
Fixing Heat Sink in Vehicle-Mounted LED Lamp:
a) and 45(b) show a mode of fixing a heat sink in a vehicle-mounted LED lamp.
Here, the heat sink 601 having the continuous wavy shapes 602, 603 formed as heat dissipating fins has stepped parts 607a, 607b. Further, the stepped part 607a has the bottom face of the LED substrate 651 thermally connected to the top face thereof via a sheet-shaped heat conducting member 655a. Still further, the stepped part 607b has the top face of the reflector 652 connected to the bottom face thereof.
On the other hand, the LED substrate 651 is arranged in the center portion of the stepped part 607 of the heat sink 601 and has the LED 651a mounted on the top thereof. The reflector 652 is formed of a resin material and has a parabolic reflecting surface having a focal point near the LED 651a on the LED substrate 651.
The housing 653 is opened on the front side (side in which the outer lens 654 is mounted). Further, the housing 653 has an opening 653a on the back side (on the right side in the drawing) and has the heat sink 601 fixed thereto in such a way that the heat sink 601 closes the opening 653a on the back side.
According to the vehicle-mounted LED lamp 650 of this construction, the LED 651a on the LED substrate 651 is driven to emit light and the light emitted from the LED 651a is reflected by the reflector 652 and is radiated forward in the direction in which the light is radiated via the outer lens 654. Here, heat generated from the LED 651a is transferred to the heat sink 601 via heat conducting material 655a from the LED substrate 651 and is dissipated to the outside of the housing 653 from the heat sink 601. In this way, an increase in the temperature of the LED 651a can be suppressed.
Aluminum Alloy as Raw Material:
An aluminum alloy plate as a raw material used for the heat sink of the present invention is a thin plate having a thickness from 2 mm to 0.4 mm, and it is most important that the aluminum alloy plate can be formed into the shape of the heat sink 601 and is excellent in corrugating workability. In addition, in terms of the required characteristics of the heat sink such that heat sink needs to be excellent in heat transfer and corrosion resistance, pure aluminum of 1000 series is preferably selected which has as little amount of alloy element as possible and which is specified or included by the AA standard or the JIS standards. In this regard, in the present invention, an aluminum plate made of pure aluminum is also expressed by an aluminum alloy plate. However, in terms of strength to ensure the rigidity, an aluminum alloy material selected from the 3000 series specified or included by the AA standard or the JIS standards is selected as required. These aluminum alloy plates are manufactured in normal manufacturing processes including casting (DC casting and continuous casting), homogenized heat treatment, hot rolling, process annealing, cold rolling, and thermal refining such as solution heat treatment and quenching heat treatment.
According to the present invention, a heat sink manufactured at high productivity can be provided by using an aluminum alloy plate as a raw material and by corrugating the aluminum alloy plate into the whole shape of heat dissipating fins formed in a continuous wavy shape. For this reason, the heat sink manufactured by the present invention is most suitable for a heat sink for a vehicle-mounted LED lamp.
In various exemplary embodiments, the heat sink for LED lighting according to the present invention includes a corrugated sheet of aluminum or an aluminum alloy. In some such embodiments, at least one ridge of the corrugated sheet comprises a depression comprising a surface suitable for mounting an LED element.
In further exemplary embodiments, in the heat sink according to the present invention: the corrugated sheet comprises a lower step portion and a higher step portion; and the lower step portion and the higher step portion are not coplanar.
In further exemplary embodiments, in the heat sink according to the present invention: the corrugated sheet comprises a narrow pitch portion and a wide pitch portion; and a pitch of ridges of the corrugated sheet in the narrow pitch portion is less than a pitch of ridges of the corrugated sheet in the wide pitch portion.
In further exemplary embodiments, in the heat sink according to the present invention, the corrugated sheet comprises a raised portion extending transverse to ridges of corrugated sheet.
In further exemplary embodiments, in the heat sink according to the present invention, the corrugated sheet comprises a depressed portion extending transverse to ridges of corrugated sheet.
In further exemplary embodiments, in the heat sink according to the present invention, at least one portion of the corrugated sheet is not corrugated.
In various exemplary embodiments, heat sinks according to the present invention include one or more base plates and one or more heat-dissipating fins. Although the base plates and fins are not limited to strictly planar shapes, the base plates and fins may be generally planar and/or may include multiple generally planar portions (e.g., a bent planar structure including two generally planar portions joined at a bent portions). Further, even if the base plates and fins are not strictly planar, they may be said to define planes. Thus, the arrangement of base plates and fins with respect to each other may be defined with reference to the planes defined by such base plates and fins (e.g., the first fin is parallel to the second fin, the first fin is perpendicular to the base plate, the first fin defines a plane that intersects a plane defined by the second fin, etc.). Further, the arrangement of base plates and fins with respect to each other may be defined with reference to angles at which the base plates and fins (or planes defined by the base plates and fins) intersect (e.g., an angle between the first fin and the base plate is 45 degrees, the first fin defines a plane that intersects a plane defined by the second fin at an angle of 45 degrees, etc.). Base plates and fins may be arranged at angles of 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, and/or 85 degrees, with respect to each other, as well as any subranges of angles therein.
A base plate or fin may be said to extend from a surface of another base plate or fin. For example, in the case that a generally planar fin extends from a surface of a generally planar base plate, an edge of the fin may be joined with the surface of the base plate. Such joint may be located at any location on the surface of the base plate. If the fin extends perpendicularly from a central location on the surface of the base plate, the joint between the fin and the base plate may be T-shaped when viewed from an end. If the fin extends perpendicularly from an edge of the surface of the base plate, the joint between the fin and the base plate may be L-shaped when viewed from an end.
In various exemplary embodiments, a fin may be a single unitary body. In alternative embodiments, a fin may be comprised of multiple coplanar or substantially coplanar fins.
In the above detailed description, reference was made by way of non-limiting example to preferred embodiments of the invention. Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-066326 | Mar 2011 | JP | national |
| 2011-066327 | Mar 2011 | JP | national |
| 2011-080432 | Mar 2011 | JP | national |
| 2011-280062 | Dec 2011 | JP | national |
| 2012-065237 | Mar 2012 | JP | national |
This application is a continuation of International Patent Application No. PCT/JP2012/057691, filed Mar. 26, 2012, the disclosure of which is incorporated herein by reference in its entirety. This application claims priority to Japanese Patent Application No. 2011-080432, filed Mar. 31, 2011, Japanese Patent Application No. 2011-066326, filed Mar. 24, 2011, Japanese Patent Application No. 2011-066327, filed Mar. 24, 2011, Japanese Patent Application No. 2011-280062, filed Dec. 21, 2011, and Japanese Patent Application No. 2012-065237, filed Mar. 22, 2012, the disclosures of which are incorporated herein by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2012/057691 | Mar 2012 | US |
| Child | 14034696 | US |
