Patent Application
20180076374
The present invention relates to a thermoelectric generator, specifically, to an improvement in a sealing structure of the thermoelectric generator.
There has been typically known a thermoelectric generator including a heat-receiving plate, a cooling plate, and a plurality of thermoelectric generation modules interposed between the heat-receiving plate and the cooling plate (see, for instance, Patent Literature 1: JP-A-2013-080883). In the thermoelectric generator of Patent Literature 1, in order to prevent occurrence of migration and the like caused by adherence of moisture to thermoelectric elements in the thermoelectric generation modules, a resin-made O-ring having an excellent heat resistance seals a space between the heat-receiving plate and the cooling plate, thereby preventing moisture from entering the thermoelectric generation modules.
Although the sealing structure uses such a heat-resistant O-ring, heat resistance of the O-ring has a limitation. In view of this, a thermoelectric generator having a sealing structure capable of further suppressing deterioration of the O-ring by heat has been proposed (see, for instance, Patent Literature 2: JP-A-2007-258298). In the thermoelectric generator of Patent Literature 2, a metallic frame having more excellent heat resistance is used in place of the resin-made O-ring and is bonded to the heat-receiving plate and the cooling plate with an adhesive agent and the like.
However, when the metallic frame is used in place of the resin-made O-ring as described in the thermoelectric generator of Patent Literature 2, heat received in the heat-receiving plate is transferred to the cooling plate through the metallic frame, so that the heat amount transferred to the thermoelectric generation modules is decreased to significantly decrease an electric power generation efficiency.
An object of the invention is to provide a thermoelectric generator capable of maintaining a favorable sealing performance even when the thermoelectric generator is exposed to a high heat, and preventing a decrease in an electric power generation efficiency.
According an aspect of the invention, a thermoelectric generator includes: a heat-receiving plate configured to receive heat; a cooling plate configured to be kept at a lower temperature than a temperature of the heat-receiving plate; and a thermoelectric generation module interposed between the heat-receiving plate and the cooling plate, in which the thermoelectric generation module includes: a plurality of thermoelectric elements; an outer sealing frame surrounding the thermoelectric elements; and a film sheet continuously entirely covering at least a first side facing the heat-receiving plate of the thermoelectric elements and the outer sealing frame; and a first heat insulation layer formed in a space that is defined between the heat-receiving plate and the thermoelectric generation module and that corresponds to the outer sealing frame.
In the above arrangement, it is preferable that the thermoelectric generator further includes a heat transfer layer formed between the heat-receiving plate and the thermoelectric generation module in a manner to circumvent the first heat insulation layer.
In the above arrangement, it is preferable that the thermoelectric generator further includes a fastener inserted through the heat-receiving plate, the cooling plate and the thermoelectric generation module to fasten the heat-receiving plate, the cooling plate and the thermoelectric generation module with each other, in which the thermoelectric generation module includes an inner sealing frame surrounding the fastener; and a second heat insulation layer formed in a space that is defined between the heat-receiving plate and the thermoelectric generation module and that corresponds to the inner sealing frame.
In the above arrangement, it is preferable that the thermoelectric generator further includes a heat transfer layer formed between the heat-receiving plate and the thermoelectric generation module in a manner to circumvent the first heat insulation layer and the second heat insulation layer, when the first heat insulation layer and the second heat insulation layer are formed between the heat-receiving plate and the thermoelectric generation module.
In the above arrangement, it is preferable that the thermoelectric generation module is interposed between the heat-receiving plate and the cooling plate while being pressed by the heat-receiving plate and the cooling plate, and the fastener includes a coil spring configured to apply a pressing force to the thermoelectric generation module through the heat-receiving plate and the cooling plate.
In the above arrangement, it is preferable that the outer sealing frame and/or the inner sealing frame is bonded to the film sheet.
In the above arrangement, it is preferable that the film sheet is in a form of a laminated sheet a first surface made of an electrically insulative material and a second surface made of a low gas (moisture) permeable material, more specifically, the film sheet includes film sheets each including a polyimide film and a copper film entirely covering one surface of the polyimide film, and the film sheets are respectively provided on the first side facing the heat-receiving plate and a second side facing the cooling plate of the thermoelectric elements and the outer sealing frame with the respective copper films facing the heat-receiving plate and the cooling plate.
According to the above aspect of the invention, with use of the outer sealing frame (e.g., metallic frame) in place of the typical resin-made O-ring, the thermoelectric generator can be further improved in heat resistance to maintain a favorable sealing performance even when the thermoelectric generator is exposed to high heat. Moreover, since a first heat insulation layer is formed in a space that is defined between the heat-receiving plate and the thermoelectric generation module and that corresponds to the outer sealing frame, the heat received in the heat-receiving plate is prevented from being transferred to the outer sealing frame, so that the heat amount to be transferred to the cooling plate through the outer sealing frame can be significantly reduced to improve the electric power generation efficiency.
A first exemplary embodiment of the invention will be described below with reference to the attached drawings.
Overall Description of Thermoelectric Generator
As shown in
The heat-receiving plate 10 is, for instance, made of iron, copper or aluminum and is heated to about 280 degrees C. by flame and the like.
The cooling plate 20 is, for instance, made of aluminum and includes a cooling circuit 20A in which a cooling liquid (e.g., cooling water) flows therein. The cooling plate 20 is entirely cooled and kept at about 20 to 40 degrees C. by the cooling liquid. The cooling circuit 20A is connected to a feed pipe 20B and a return pipe 20C of the cooling liquid on an outside of the cooling plate 20.
The thermoelectric generation module 30 will be described later.
A plurality of bolt holes 11 each having an internal thread are provided at and near a center and near a periphery of the heat-receiving plate 10. A plurality of through holes 21 penetrating the cooling plate 20 from a front side to a rear side are provided at and near a center and near a periphery of the cooling plate 20 in a manner corresponding to the bolt holes 11. A plurality of through holes 31 are provided at and near a center of the thermoelectric generation module 30 in a manner corresponding to the bolt holes 11 and the through holes 21.
With use of the bolt holes 11 and the through holes 21, 31, the heat-receiving plate 10 and the cooling plate 20 are fastened together while the thermoelectric generation module 30 is held between the heat-receiving plate 10 and the cooling plate 20. At this time, a first fastener 40 and a second fastener 50 are used as a fastening means.
Five first fasteners 40 are provided to the through holes at and near the center of the thermoelectric generation module 30 in the thermoelectric generator 1. Each of the first fasteners 40 includes: a bolt 41 inserted into each of the bolt holes 11A and the through holes 21A at and near the center among the bolt holes 11 and the through holes 21 and the through holes 31 of the thermoelectric generation module 30; a receiving member 42 having a cylindrical portion in which the bolt 41 is inserted and a flange integrated with the cylindrical portion and having an inverse T-shaped cross section; and a coil spring 43 in which the bolt 41 is inserted and that is interposed between a lower surface of the cooling plate 20 and a spring seat surface of the flange of the receiving member 42, the coil spring 43 being configured to apply a pressing force to the thermoelectric generation module 30 through the heat-receiving plate 10 and the cooling plate 20.
The second fastener 50 includes a pair of second fasteners 50 on each of sides of the thermoelectric generator 1, namely, eight second fasteners 50 (only two of those are shown in
Herein, a wire diameter and an outer diameter of the coil spring 53 of the second fastener 50 are smaller than a wire diameter and an outer diameter of the coil spring 43 of the first fastener 40. A spring force of the coil spring 53 is smaller than a spring force of the coil spring 43. The second fasteners 50 having a smaller spring force are provided in a pair close to each other on each of the sides of the thermoelectric generator 1 in order to uniform a holding force to be applied to the thermoelectric generation module 30, the holding force being generated when the thermoelectric generation module 30 is held between the heat-receiving plate 10 and the cooling plate 20.
As shown in
In
As shown in
Moreover, a bonding pattern 35C similar to those of the heat-receiving electrode 35A and the cooling electrode 35B is formed on the inner surface of each of the film sheets 35, corresponding to the outer sealing frame 33 and the inner sealing frame 34. By bonding the sealing frames 33, 34 to the bonding pattern 35C by soldering and the like, the sealing frames 33, 34 are firmly bonded to the film sheets 35. A bonding portion of each of the outer sealing frame 33 and the inner sealing frame 34 has a simple square cross section.
In
As shown in
Next, a manufacturing procedure of the thermoelectric generator 1 will be described.
First, the thermoelectric elements 32N, 32P, the outer sealing frame 33, and the inner sealing frames 34 are bonded by soldering and the like between the film sheets 35 in which the heat-receiving electrode 35A, cooling electrode 35B, and bonding pattern 35C are formed by a known circuit pattern forming method, thereby assembling the thermoelectric generation module 30. One of the film sheets 35 of the thermoelectric generation module 30 is disposed on the cooling plate 20 while the heat transfer sheet 70 is disposed on the other of the film sheets 35. Further, the heat-receiving plate 10 is disposed on the heat transfer sheet 70. Thus, the thermoelectric generation module 30 is held between the heat-receiving plate 10 and the cooling plate 20. Subsequently, the heat-receiving plate 10, cooling plate 20, and thermoelectric generation module 30 are mutually fastened by the first and second fasteners 40, 50. Description of treatment of other components such as the lead wire will be omitted.
According to the exemplary embodiment, since the thermoelectric generation module 30 is sealed with use of the metallic outer sealing frame 33 and inner sealing frame 34, heat resistance is further improvable, so that a favorable sealing performance is maintainable even when the thermoelectric generator 1 is exposed to high heat. Moreover, since the first heat insulation layer 61 is formed in the space corresponding to the outer sealing frame 33 and the second heat insulation layers 62 are formed in the space corresponding to the inner sealing frames 34 between the heat-receiving plate 10 and the thermoelectric generation module 30, the heat received in the heat-receiving plate 10 is prevented from being transferred to the sealing frames 33, 34, so that the heat amount to be transferred to the cooling plate through the sealing frames 33, 34 can be significantly reduced to improve the electric power generation efficiency.
In
The same effects as in the first exemplary embodiment can be obtained also in the second exemplary embodiment.
The scope of the invention is not restricted to the above exemplary embodiments, but includes modifications and improvements as long as an object of the invention can be achieved.
For instance, the cross section of each of the sealing frames 33, 34 is a simple square in the above exemplary embodiments, but not limited to the square. As represented by the outer sealing frame 33 in
Moreover, in order to obtain the same effects, a thickness of each of the sealing frames may be sufficiently increased. In this arrangement, when the thickness of each of the sealing frames is larger than a thickness of each of the thermoelectric elements, a step may be formed in the heat-receiving plate and the cooling plate, whereby a position of the bonding portion of each of the thermoelectric elements is differentiated from a position of the bonding portion of each of the sealing frames to absorb a dimensional difference between the thermoelectric elements and the sealing frames.
In the above exemplary embodiments, the heat transfer layer 71 is exemplified by a layer formed of the heat transfer sheet 70 (e.g., carbon sheet), but may be formed from heat conductive grease. In this arrangement, the surrounding first and second heat insulation layers are desirably a solid material (e.g., sheet) instead of the air layer. With this arrangement, the first and second heat insulation layers function as a barrier against the heat conductive grease to enable to prevent the heat conductive grease from leaking out between the heat-receiving plate and the cooling plate.
In the above exemplary embodiments, the thermoelectric generation module 30 of the thermoelectric generator 1 is exemplified by one including a single thermoelectric element unit 32. However, the thermoelectric generation module may include a plurality of thermoelectric element units.
Moreover, as for the first and second fasteners 40, 50 described in the first exemplary embodiment, any suitable structure may be employed for implementation and is not limited to the structure in the above exemplary embodiments.
Further, in the above exemplary embodiments, the second side facing the cooling plate 20 of the thermoelectric elements 32N, 32P and the sealing frames 33, 34 is also covered with the film sheet 35. However, the film sheet may be provided as needed on the second side facing the cooling plate. The film sheet may be omitted as long as electrical insulation between the thermoelectric elements and the cooling plate is maintained.
In the above exemplary embodiments, the sealing frames 33, 34 are soldered to the film sheets 35, but may be bonded by an adhesive agent (e.g., polyimide varnish) usable at a high temperature.
In the above exemplary embodiments, since the first fastener 40 is used, the inner sealing frames 34 each surrounding the bolt 41 of the first fastener 40 are also used and the second heat insulation layers 62 are formed. However, when only the second fastener 50 is used, such an inner sealing frame and second heat insulation layer are unnecessary.
