Patent Application
20070289621
Various other objects, features, and many of the attendant advantages of the present invention will be readily appreciated as the same becomes better understood with reference to the following detailed description of the preferred embodiments when considered in connection with the accompanying drawings, in which:
Embodiments of the present invention will next be described with reference to the drawings.
The illumination unit 10 includes a reflection plate 11 and an electric bulb 12 (light source). The reflection plate 11 has a generally dome-like shape and is made of aluminum. The reflection plate 11 is supported by the support member 51 via attachment members 13 provided on the outer circumferential surface of the plate 11. The inner circumferential surface of the reflection plate 11 is coated with a reflective film (e.g., aluminum deposition film), and light from the electric bulb 12 is reflected downward by the reflective film.
The electric bulb 12 is located generally at the center of the interior of the reflection plate 11, and is attached to a socket 14 at the back of the center of the reflection plate 11 in such a manner that electricity can be supplied to the electric bulb 12. The attachment members 13 are formed of, for example, ceramic chains having low thermal conductivity, and are provided between the reflection plate 11 and the support member 51 so that a predetermined tensile force is applied to the members 13.
The heat transfer member 21, which is formed of an aluminum block, has a horizontal top surface generally perpendicular to the vertical direction, and a bottom surface which curbs along the outer circumferential surface of the reflection plate 11. The bottom surface of the heat transfer member 21 is fixed to the reflection plate 11 such that the member 21 and the plate 11 are united together. The outer surface of the heat transfer member 21 and the outer circumferential surface of the reflection plate 11, which surfaces are exposed to air, are coated with a heat insulation material 22.
The heat insulation material 22 is, for example, a coating material capable of forming a ceramic coating film exhibiting low thermal conductivity. The heat insulation material 22 is applied to the reflection plate 11 and the heat transfer member 21 so that the area of a region coated with the material 22 is about 80% the total area of the air-exposed outer circumferential surface of the plate 11 and the air-exposed outer surface (exclusive of the top surface) of the member 21. The greater the area of a region coated with the heat insulation material 22, the smaller the amount of heat radiated from the reflection plate 11 and the heat transfer member 21 to air. However, the thus-accumulated heat may adversely affect durability of the electric bulb 12. Therefore, the coating area is determined as described above, so as to suppress radiation of heat to air and to maintain durability of the electric bulb 12.
As shown in
Each of the lower electrodes 32A and the upper electrodes 32B has such a size that end surfaces of two thermoelectric elements 33 can be bonded thereto. The lower electrodes 32A are attached to the top surface of the lower substrate 31A at predetermined positions, and the upper electrodes 32B are attached to the bottom surface of the upper substrate 31B at predetermined positions. The lower electrodes 32A and the upper electrodes 32B are provided in a staggered fashion such that they are shifted form one another by a distance generally equal to the size of one thermoelectric element 33 in the longitudinal direction of the lower substrate 31A and the upper substrate 31B (i.e., in a forward-backward direction as viewed in
The thermoelectric elements 33, which assume a rectangular parallelepiped shape, are formed of P-type and N-type elements made of, for example, a bismuth-tellurium alloy. The P-type and N-type thermoelectric elements 33 are alternately provided in left-right and forward-backward directions as viewed in
As shown in
The bottom surface of the substrate-engaging section 41a is fixed to the top surface of the upper substrate 31B of the thermoelectric conversion module 30. The substrate-engaging section 41a is formed such that the bottom surface thereof has an area somewhat larger than that of the top surface of the upper substrate 31B. The connection section 41b has such a size that it has at least a predetermined cross-sectional area so as to reduce its thermal resistance to a predetermined level or less. The support-member-engaging section 41c has a through-hole 41c1 into which a bolt 42 can be inserted in the vertical direction.
As shown by thick solid lines in
The support member 51 (heat absorber), which supports the illumination unit 10, is formed of an iron rod, and is mounted to a building structure (not illustrated). The support member 51 has an inverted T-shaped cross section such that a predetermined surface area can be attained, and a step section 51a of the support member 51 has a screw hole 51b which penetrates therethrough in the vertical direction. When the bolt 42 is screwed into the screw hole 51b, with the support-member-engaging section 41c being engaged with the step section 51a, the heat releasing path member 41 is united with the support member 51.
In the indoor downlight illumination system according to the first embodiment, which has the aforementioned configuration, heat from the electric bulb 12 of the illumination unit 10 is conducted through the reflection plate 11 to the thermoelectric conversion module 30. Subsequently, heat is conducted, through the lower substrate 31A (on the high-temperature side) of the thermoelectric conversion module 30, the lower electrodes 32A, the thermoelectric elements 33, and the upper electrodes 32B, to the upper substrate 31B (on the low-temperature side), and then heat is conducted through the heat releasing path member 41 to the support member 51.
Iron constituting the support member 51 has a thermal conductivity at room temperature (300 K) of about 80.3 W/(m·K), which is considerably higher than the thermal conductivity of air (i.e., about 0.026 W/(m·K)). Therefore, heat is distributed in the support member 51 without being accumulated therein, and is radiated through the outer surface of the support member 51 and the outer surface of the building structure, and thus heat is always efficiently conducted from the heat releasing path member 41 to the support member 51.
With this configuration, even when a cooling fan is not employed, the temperature of the upper substrate 31B of the thermoelectric conversion module 30 can be maintained at a low level, and a predetermined temperature difference can be maintained between the substrates 31A and 31B. Therefore, since no cooling fan is required for maintaining a predetermined temperature difference between the substrates 31A and 31B, electric power generated by the thermoelectric conversion module 30 can be utilized with sufficient effectiveness. This configuration, which does not require installation of a cooling fan or a like device on the ceiling, is also advantageous in that maintenance for such an apparatus is not required.
In the first embodiment, the heat releasing path member 41 is made of aluminum. Since aluminum has a thermal conductivity of about 236 W/(m·K), which is considerably higher than that of air, the heat releasing path member 41 can efficiently conduct heat transferred to the upper substrate 31B to the support member 51. In addition, the weight of the heat releasing path member 41 can be reduced, and thus the total weight of the illumination system can be reduced.
In the first embodiment, the top surface of the heat transfer member 21 is a horizontal surface generally perpendicular to the vertical direction, and the top surface is in almost close contact with the lower substrate 31A of the thermoelectric conversion module 30. Therefore, by virtue of the property of heat (i.e., heat generally transfers upward), heat can be effectively conducted from the heat transfer member 21 to the lower substrate 31A of the thermoelectric conversion module 30.
In the first embodiment, the heat transfer member 21 is made of aluminum. Therefore, the heat transfer member 21 can efficiently conduct heat from the reflection plate 11 to the lower substrate 31A of the thermoelectric conversion module 30. In addition, the weight of the heat transfer member 21 can be reduced, and thus the total weight of the illumination system can be reduced.
In the first embodiment, the outer surface of the heat transfer member 21 and the outer circumferential surface of the reflection plate 11, which surfaces are exposed to air, are coated with the heat insulation material 22, and the heat insulation material 22 is applied to the reflection plate 11 and the heat transfer member 21 so that the area of a region coated with the material 22 is about 80% the total area of the air-exposed outer circumferential surface of the plate 11 and the air-exposed outer surface (exclusive of the top surface) of the member 21. Therefore, the amount of heat radiated through the outer circumferential surface of the reflection plate 11 and the outer surface of the heat transfer member 21 to air is reduced, and the amount of heat which passes through the thermoelectric conversion module 30 is increased, whereby electric power generation efficiency of the thermoelectric conversion module 30 can be increased.
In the first embodiment, as shown in
According to this modification, since the area of engagement of the support member 51 with the support-member-engaging section 41c of the heat releasing path member 41 is increased, as compared with the case of the first embodiment, heat is further efficiently conducted from the heat releasing path member 41 to the support member 51, and thus a predetermined temperature difference can be readily maintained between the substrates 31A and 31B.
In the first embodiment and the modification thereof (hereinafter may be referred to as “the first embodiment, etc.”), the illumination system of the present invention is applied to an indoor downlight illumination system. However, the present invention is not necessarily limited thereto, and, for example, as shown in
The outdoor nighttime illumination system includes an illumination unit 10 which is attached to a railing 161 via an attachment member 113. The illumination unit 10 includes a reflection plate 11 which is in contact, via a heat transfer member 21, a thermoelectric conversion module 30, and a heat releasing path member 141, with flowing river water 151. The attachment member 113 includes a nut 113a, a bracket 113b, and a bolt 113c. The bracket 113b is made of, for example, ceramic material having low thermal conductivity so that when the reflection plate 11 of the illumination unit 10 is attached via the bracket 113b to the railing 161, heat does not easily move from the reflection plate 11 to the railing 161.
The heat releasing path member 141 is formed of a generally L-shaped aluminum rod. The heat releasing path member 141 includes a substrate-engaging section 141a which extends in a horizontal direction, and a connection section 141b which extends downward from one end of the substrate-engaging section 141a in the vertical direction. A lower end portion of the connection section 141b serves as a water-contacting section 141d which is in contact with the flowing river water 151 (heat absorber). The connection section 141b has such a size that it has at least a predetermined cross-sectional area (e.g., a square cross section having a size of 30 mm×30 mm) so as to reduce its electric resistance to a predetermined level or less.
In the nighttime illumination system according to the second embodiment, which has the aforementioned configuration, heat conducted from the reflection plate 11 of the illumination unit 10 to the thermoelectric conversion module 30 is transferred through the heat releasing path member 141 to the flowing river water 151.
Water has a thermal conductivity of about 0.6 W/(m·K), and, in general, the temperature of river water is lower than air temperature. Therefore, heat is distributed in the flowing river water 151 without being accumulated therein, and thus heat is always efficiently conducted from the heat releasing path member 141 to the flowing water river 151. With this configuration, similar to the case of the first embodiment, etc., even when a cooling fan is not employed, a predetermined temperature difference can be maintained between the substrates 31A and 31B of the thermoelectric conversion module 30, and electric power generated by the thermoelectric conversion module 30 can be utilized with sufficient effectiveness.
In the second embodiment, similar to the case of the first embodiment, etc., the weight of the heat releasing path member 141 can be reduced, and thus the total weight of the illumination system can be reduced. In addition, since the air-exposed outer surface of the heat transfer member 21 and the air-exposed outer circumferential surface of the reflection plate 11 are coated with a heat insulation material 22, electric power generation efficiency of the thermoelectric conversion module 30 can be increased.
Specific examples of the aforementioned embodiments will next be described. In each of the examples, generated electric power was measured.
In Example 1, the present invention was applied to a downlight illumination instrument in the interior of a shop. In Example 1, the electric bulb 12 of the illumination unit 10 was a 180 W incandescent lamp. The size of the thermoelectric conversion module 30 was determined to be 35 mm×35 mm×3.5 mm, and 190 pairs of the P-type and N-type thermoelectric elements 33 made of a bismuth-tellurium alloy were employed. The area of the top surface of the heat transfer member 21 was determined to be 14 cm2, and the volume of the heat transfer member 21 was determined to be 30 cm3. The air-exposed outer circumferential surface of the reflection plate 11 and the air-exposed outer surface (exclusive of the top surface) of the heat transfer member 21 were coated with a ceramic coating film (i.e., the heat insulation material 22) so that the area of a region coated with the material 22 accounted for about 80% of the total area of these outer surfaces. When the temperature of the lower substrate 31A (on the high-temperature side) was 130° C., and the temperature of the upper substrate 31B (on the low-temperature side) was 45° C.; i.e., when the temperature difference between the substrates 31A and 31B was 85 degrees in Celsius, an electric power of 4.4 W was generated. The thus-generated electric power was charged in a storage battery, and was used as electric power for another illumination instrument intermittently used in the shop.
In Example 2, similar to the case of Example 1, the present invention was applied to a downlight illumination instrument in the interior of a shop. In Example 2, the electric bulb 12 of the illumination unit 10 was a 150 W incandescent lamp. The size of the thermoelectric conversion module 30 was determined to be 28 mm×28 mm×3 mm, and 127 pairs of the P-type and N-type thermoelectric elements 33 made of a bismuth-tellurium alloy were employed. The area of the top surface of the heat transfer member 21 was determined to be 10.5 cm2, and the volume of the heat transfer member 21 was determined to be 21 cm3. The air-exposed outer circumferential surface of the reflection plate 11 and the air-exposed outer surface (exclusive of the top surface) of the heat transfer member 21 were coated with a ceramic coating film (i.e., the heat insulation material 22) so that the area of a region coated with the material 22 accounted for about 80% of the total area of these outer surfaces. When the temperature of the lower substrate 31A (on the high-temperature side) was 120° C., and the temperature of the upper substrate 31B (on the low-temperature side) was 40° C.; i.e., when the temperature difference between the substrates 31A and 31B was 80 degrees in Celsius, an electric power of 3.8 W was generated. The thus-generated electric power was employed as electric power for a drive motor of an electrically driven small fan for advertisement.
In Example 3, the present invention was applied to a nighttime illumination instrument provided on a railing of a bridge spanning a river. In Example 3, the electric bulb 12 of the illumination unit 10 was a 200 W incandescent lamp. The size of the thermoelectric conversion module 30 was determined to 40 mm×40 mm×3.3 mm, and 98 pairs of the P-type and N-type thermoelectric elements 33 made of a bismuth-tellurium alloy were employed. The area of the top surface of the heat transfer member 21 was determined to be 18 cm2, and the volume of the heat transfer member 21 was determined to be 36 cm3. The air-exposed outer circumferential surface of the reflection plate 11 and the air-exposed outer surface (exclusive of the top surface) of the heat transfer member 21 were coated with a ceramic coating film (i.e., the heat insulation material 22) so that the area of a region coated with the material 22 accounted for about 60% of the total area of these outer surfaces. When the temperature of the lower substrate 31A (on the high-temperature side) was 110° C., and the temperature of the upper substrate 31B (on the low-temperature side) was 20° C.; i.e., when the temperature difference between the substrates 31A and 31B was 90 degrees in Celsius, an electric power of 5.2 W was generated. Ten sets of such illumination instruments were provided, and the thus-generated electric power was charged in a storage battery. The electric power was used for driving a music player during the day, or employed as electric power for another type of an illumination instrument.
In Example 3, temperature of the lower substrate 31A (on the high-temperature side) of the thermoelectric conversion module 30 was measured with varying the area of a region coated with the heat insulation material 22. The results are shown in Table 1.
As used herein, the expression “heat insulation material coating area ratio” refers to the ratio of the area of a region coated with the heat insulation material 22 to the total area of the air-exposed outer circumferential surface of the reflection plate 11 and the air-exposed outer surface (exclusive of the top surface) of the heat transfer member 21. As shown in Table 1, when the heat insulation material coating area ratio is 50% or more, a desired temperature difference is attained between the substrates 31A and 31B.
In the aforementioned embodiments, the ratio of the area of a region coated with the heat insulation material to the total area of the air-exposed outer circumferential surface of the reflection plate 11 and the air-exposed outer surface (exclusive of the top surface) of the heat transfer member 21; i.e., the heat insulation material coating area ratio, is determined to be 80%. However, as is clear from Table 1, the heat insulation material coating area ratio may be appropriately changed so as to fall within a range of 50% or more and less than 80%. When durability of the electric bulb 12 is well maintained, the heat insulation material coating area ratio may be appropriately changed so as to fall within a range of 80% or more and 100% or less.
In the aforementioned embodiments, the heat insulation material 22 employed is a ceramic-containing coating material having low thermal conductivity. However, the heat insulation material 22 is not necessarily limited to such a coating material, and may be a heat insulation material such as glass fiber, felt, or plastic foam.
In the aforementioned embodiments, the heat transfer member 21 or the heat releasing path member 41 or 141 is made of aluminum. However, such a member is not necessarily made of aluminum, and may be made of, for example, a metal such as an aluminum alloy or copper.
In the aforementioned embodiments, the illumination system employs a single heat transfer member 21, a single thermoelectric conversion module 30, and a single heat releasing path member 41 or 141. However, the illumination system may employ a plurality of sets, each including the heat transfer member, thermoelectric conversion module, and heat releasing path member.
In the first embodiment, the attachment member 13 is formed of a ceramic chain, and, in the second embodiment, the attachment member 113 is formed by making use of the ceramic bracket 113b. However, the attachment member 13 or 113 may be formed of a variety of materials, so long as heat is not easily conducted from the reflection plate 11 through the attachment member 13 or 113.
In the second embodiment, the top surface of the heat transfer member 21 is a horizontal surface generally perpendicular to the vertical direction, and the top surface is in almost close contact with the lower substrate 31A of the thermoelectric conversion module 30. However, the heat transfer member may be formed to have a horizontal bottom surface generally perpendicular to the vertical direction, and the thermoelectric conversion module may be provided so that the upper substrate of the module is in almost close contact with the bottom surface of the heat transfer member. In this case, a voltage of reverse polarity is generated.
The illumination system of the present invention is not limited to the aforementioned embodiments, and may be applied to, for example, an illumination instrument installed at seashore, lakeshore, park, etc., or a light of an automobile, a motorcycle, or the like.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-166492 | Jun 2006 | JP | national |
