JP2006214350A - Thermoelectric generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoelectric power generator capable of improving power generation efficiency.
A thermoelectric generator (1) electrically converts a plurality of heat exchangers (5) having a heat exchange fin portion (8) for collecting heat of exhaust gas passing through an exhaust passage (2) and heat collected by the heat exchange fin portion (8). A plurality of thermoelectric conversion modules 6 for conversion are provided. In the exhaust passage 2, an introduction pipe member 17 that forms a passage 16 for introducing exhaust gas is disposed. The introduction tube member 17 includes an outer tube portion 18 and an inner tube portion 19 disposed inside the outer tube portion 18, and an inner surface of the end portion 18 a of the outer tube portion 18 and an end portion 19 a of the inner tube portion 19. A spring 20 that changes the relative position of the inner tube portion 19 with respect to the outer tube portion 18 according to the engine load is provided between the outer surface and the outer surface. The outer pipe part 18 is provided with gas supply windows 21A to 21C and a gas bypass window 22, and the inner pipe part 19 is provided with gas supply windows 23A to 23C and a gas bypass window 24.
[Selection] Figure 1

Description

  The present invention relates to a thermoelectric power generation apparatus that generates power using heat of exhaust gas discharged from an internal combustion engine.

As a conventional thermoelectric power generation device, for example, as described in Patent Document 1, a plurality of thermoelectric conversion modules and one thermoelectric conversion module are arranged on one surface side, and the heat of exhaust gas passing through the exhaust passage is recovered. A heat exchanging unit and a cooling unit that is disposed on the other side of each thermoelectric conversion module and cools the thermoelectric conversion module, and includes one side (high temperature side) and the other side (low temperature side) of the thermoelectric conversion module. One that generates power by a thermoelectric effect according to a temperature difference is known.
Japanese Patent Laid-Open No. 2004-21660

  However, all the thermoelectric conversion modules cannot be used efficiently depending on the engine load (exhaust gas energy) simply by flowing the exhaust gas uniformly from the upstream side to the downstream side of the exhaust passage. Obtaining efficiency can be difficult.

  An object of the present invention is to provide a thermoelectric power generator capable of improving power generation efficiency.

  The present invention relates to a thermoelectric generator that generates power using heat of exhaust gas discharged from an internal combustion engine, a first passage through which exhaust gas passes, and a heat exchange unit that recovers heat of the exhaust gas through the first passage. A plurality of thermoelectric conversion units that convert the heat recovered by the heat exchange unit into electricity, an introduction pipe member that is disposed in the first passage and that forms a second passage for introducing exhaust gas from the internal combustion engine, Gas flow path control means for controlling to selectively supply the exhaust gas introduced into the second passage to a position corresponding to each thermoelectric conversion section in the heat exchange section is provided.

  In such a thermoelectric generator, for example, when the load of the internal combustion engine is low and the temperature of the exhaust heat is low, the exhaust gas introduced into the second passage by the gas flow path control means is the minimum necessary in the heat exchange section. It is made to supply to the position corresponding to the thermoelectric conversion part. At this time, the exhaust heat recovered by the heat exchange unit is conducted to the minimum necessary thermoelectric conversion unit, and electric power is generated by the thermoelectric conversion unit. On the other hand, when the load of the internal combustion engine is high and the temperature of the exhaust heat is high, the exhaust gas introduced into the second passage by the gas flow path control means is placed at a position corresponding to many thermoelectric conversion units in the heat exchange unit. To be supplied. At this time, the exhaust heat recovered by the heat exchange unit is conducted to many thermoelectric conversion units, and power is generated by the thermoelectric conversion units. As described above, for example, the flow of exhaust gas to the heat exchange unit is controlled according to the load (exhaust heat temperature) of the internal combustion engine, and the number of thermoelectric conversion units contributing to power generation is changed. The thermoelectric converter can be used efficiently. Thereby, it becomes possible to improve the power generation efficiency of the thermoelectric power generator.

  Preferably, the introduction pipe member has an outer pipe part and an inner pipe part arranged inside the outer pipe part, and the gas flow path control means is an inner pipe with respect to the outer pipe part according to the load of the internal combustion engine. According to the relative setting position of the inner tube portion relative to the outer tube portion, the displacement setting means for changing the relative position of the portion, the plurality of first gas supply windows provided at positions corresponding to the thermoelectric conversion portions in the outer tube portion, A plurality of second gas supply windows provided in the inner pipe portion so as to selectively overlap each first gas supply window.

  In such a configuration, the first gas supply window of the outer tube portion overlaps the second gas supply window of the inner tube portion by changing the relative position of the inner tube portion with respect to the outer tube portion according to the load of the internal combustion engine. Then, the exhaust gas introduced into the inner pipe part flows out of the outer pipe part through the second gas supply window and the first gas supply window. Therefore, by appropriately determining the positions and dimensions of the first gas supply window and the second gas supply window, the exhaust gas can be easily and reliably supplied to the position corresponding to the thermoelectric conversion unit in the heat exchange unit.

  At this time, when the gas flow path control means is in the initial position with respect to the outer tube portion and the first gas bypass window provided at a position on the exhaust pipe downstream side of the heat exchange portion in the outer tube portion. And a second gas bypass window provided in the inner tube portion so as to overlap the first gas bypass window, and the plurality of second gas supply windows have an inner tube portion with respect to the outer tube portion. When in the initial position, it is preferably provided so as to be located upstream of the corresponding first gas supply window.

  In this case, in a state where the load of the internal combustion engine is extremely low and the relative position of the inner tube portion with respect to the outer tube portion hardly changes from the initial position, the exhaust gas introduced into the inner tube portion is the second gas supply window and the first Instead of being supplied to the heat exchange section through the gas supply window, the gas flows downstream through the second gas bypass window and the first gas bypass window. For this reason, the heat of the exhaust gas is not taken away by the heat exchanging section, so that the exhaust gas flows downstream while maintaining the temperature. Therefore, for example, when the exhaust purification catalyst is disposed downstream of the heat exchange section, the exhaust purification catalyst can be warmed early by the heat of the exhaust gas.

  The displacement setting means is preferably a spring provided between the inner surface of the exhaust pipe downstream end portion of the outer pipe portion and the outer surface of the exhaust pipe downstream end portion of the inner pipe portion, and contracts in accordance with the load of the internal combustion engine. . In this case, as the load on the internal combustion engine increases, the energy (exhaust pressure) of the exhaust gas increases, and this exhaust pressure moves the inner pipe part while contracting the spring downstream of the outer pipe part. Will come to do. Thereby, it is possible to change the relative position of the inner tube portion with respect to the outer tube portion according to the load of the internal combustion engine with an extremely simple structure in which only one spring is provided.

  The displacement setting means may include an actuator that moves the inner tube portion relative to the outer tube portion, and a device that controls the actuator according to the load of the internal combustion engine. In this case, the load of the internal combustion engine is detected, and the actuator is controlled so that the inner pipe moves to the exhaust downstream side with respect to the outer pipe as the detected value increases. Thereby, when the inner tube portion moves relative to the outer tube portion, no extra force such as a spring reaction force is applied to the exhaust gas, which is advantageous in terms of exhaust pressure loss.

  Furthermore, it is preferable that a region where the first gas supply window and the second gas supply window overlap is smaller than a region corresponding to the thermoelectric conversion unit in the heat exchange unit. Thereby, when the exhaust gas introduced into the inner pipe part is supplied to the heat exchange part through the second gas supply window and the first gas supply window, the flow of the exhaust gas becomes faster. The heat recovery rate of the heat exchange unit is increased, and the heat transfer rate to the thermoelectric conversion unit is increased. Therefore, the power generation efficiency of the thermoelectric power generator is further improved.

  Preferably, the gas flow path control means controls the flow of the exhaust gas so that the number of locations where the exhaust gas is supplied in the heat exchange section increases as the load on the internal combustion engine increases. Thus, as the load on the internal combustion engine increases, the number of thermoelectric conversion units contributing to power generation increases, so that all thermoelectric conversion units can be used reliably and efficiently regardless of the load on the internal combustion engine. .

  Furthermore, preferably, a plurality of thermoelectric converters are arranged along the flow direction of the exhaust gas introduced into the second passage. In this case, when the exhaust gas is supplied from the second passage to the positions corresponding to the plurality of thermoelectric conversion units located on the exhaust upstream side and the exhaust downstream side in the heat exchange unit, the exhaust gas is supplied to each position of the heat exchange unit. Since the temperature of the exhaust gas to be produced is substantially uniform, the temperature at each position of the heat exchanging portion becomes substantially uniform. For this reason, since the thermal expansion difference of the heat exchange part produced by the temperature difference of the upstream area | region and downstream area of a heat exchange part becomes small, the dispersion | variation in the pressing load of each thermoelectric conversion part with respect to a heat exchange part is suppressed. Accordingly, heat is transferred from the heat exchange part to each thermoelectric conversion part almost evenly, and the high temperature side (heat exchange part side) temperature of each thermoelectric conversion part is made uniform, thereby preventing the occurrence of power generation failure. it can.

  Preferably, a plurality of thermoelectric converters are arranged around the flow direction of the exhaust gas introduced into the second passage. For example, when the load of the internal combustion engine is high and the temperature of the exhaust heat is high, the exhaust heat is distributed to a plurality of thermoelectric conversion units. Even in this state, the high temperature side (heat exchange unit side) of each thermoelectric conversion unit ) Is maintained at a high temperature, so that desired power generation can be obtained. On the other hand, for example, when the load of the internal combustion engine is low and the temperature of the exhaust heat is low, the temperature on the high temperature side of the thermoelectric conversion unit due to the distribution of exhaust heat is reduced by, for example, only one thermoelectric conversion unit contributing to power generation Since the decrease is prevented, sufficient power generation can be performed.

  According to the present invention, since the power generation efficiency of the thermoelectric power generator is increased, the performance of the thermoelectric power generator can be improved.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a preferred embodiment of a thermoelectric generator according to the present invention will be described in detail with reference to the drawings.

  First, a first embodiment of a thermoelectric generator according to the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view showing the thermoelectric generator of this embodiment, and FIG. 2 is a cross-sectional view taken along the line II-II in FIG.

  In each figure, the thermoelectric generator 1 of the present embodiment is disposed at an arbitrary position of an exhaust system of an engine (internal combustion engine) in an automobile or the like, for example, an upstream portion of an exhaust purification catalyst. The thermoelectric generator 1 includes an exhaust pipe 3 that forms an exhaust passage 2 through which exhaust gas discharged from an engine (not shown) passes, and a plurality of thermoelectric units 4 that generate power using the heat of the exhaust gas that passes through the exhaust passage 2. It has.

  A plurality (six in this case) of the thermoelectric units 4 are arranged around the exhaust gas flow direction in the exhaust passage 2. In addition, a plurality of thermoelectric unit groups including these thermoelectric units 4 are arranged along the exhaust gas flow direction (here, three rows). Each thermoelectric unit 4 includes a heat exchanger 5, a thermoelectric conversion module 6, and a cooling water case 7.

  The heat exchanger 5 is provided on both sides of the heat exchange fin portion 8 for recovering the heat of the exhaust gas passing through the exhaust passage 2, and a partition that divides the exhaust passage 2 for each thermoelectric unit 4. Wall 9. The plurality of fins constituting the heat exchange fin portion 8 are provided so as to extend in parallel with a predetermined interval. The heat exchanger 5 is made of a material having good thermal conductivity such as aluminum, copper, stainless steel or the like.

  The heat exchangers 5 adjacent to each other in the exhaust gas flow direction are coupled to each other, and the heat exchangers 5 adjacent to each other around the exhaust gas flow direction are also coupled to each other. At this time, for example, a heat insulating material is interposed between the adjacent heat exchangers 5 so that the heat of the exhaust gas recovered by the heat exchange fins 8 of the heat exchanger 5 is not transmitted to the adjacent heat exchangers 5. It is desirable to couple the heat exchangers 5 together. The heat exchanger 5 located on the most exhaust upstream side of the exhaust passage 2 and the heat exchanger 5 located on the most exhaust downstream side are coupled to the exhaust pipe 3.

The thermoelectric conversion module 6 converts heat recovered by the heat exchange fin portion 8 of the heat exchanger 5 into electricity, and is placed on the heat exchanger 5. The thermoelectric conversion module 6 has a plurality of thermoelectric conversion elements (for example, a p-type semiconductor and an n-type semiconductor made of Bi ₂ Te ₃ or the like). The thermoelectric conversion module 6 has a temperature difference between an end face on the heat exchanger 5 side (high temperature side end face) and an end face on the opposite side of the heat exchanger 5 (cooling water case 7 side) (low temperature side end face). Generates electromotive force due to the Seebeck effect.

  The cooling water case 7 is placed on the low temperature side end face of the thermoelectric conversion module 6. The cooling water case 7 is provided with a cooling water passage 10 through which cooling water for cooling the low temperature side end face of the thermoelectric conversion module 6 passes. A cooling water pipe 11 connected to a radiator (not shown) is connected to the cooling water passage 10 of the cooling water case 7 located on the most upstream side of the exhaust passage 2 and the cooling water passage 10 of the cooling water case 7 located on the most downstream side of the exhaust. Are connected, and the cooling water passages 10 of the cooling water cases 7 adjacent to each other in the flow direction of the exhaust gas are connected by a cooling water pipe (not shown). As a result, the cooling water circulates inside each cooling water case 7. The cooling water case 7 is made of, for example, aluminum.

  Further, the thermoelectric generator 1 includes bands 13 a and 13 b arranged for each row so as to surround each thermoelectric unit 4. These bands 13a and 13b press and fix each part (the heat exchanger 5, the thermoelectric conversion module 6 and the cooling water case 7) of the thermoelectric unit 4 through the pressing block 12 placed on each cooling water case 7. It is. These bands 13 a and 13 b are fixed to each other by two sets of bolts 14 and nuts 15.

  In the exhaust passage 2, an introduction pipe member 17 that forms a passage 16 for introducing exhaust gas from the engine is disposed. The introduction tube member 17 includes an outer tube portion 18 having a cylindrical shape, and a cylindrical inner tube portion 19 disposed inside the outer tube portion 18. The outer pipe portion 18 is joined to the exhaust pipe 3 on the exhaust upstream side of each thermoelectric unit 4 and extends to the exhaust downstream side of each thermoelectric unit 4 through the central portion of the exhaust pipe 3. ing.

  The outer pipe portion 18 has a closed end 18a on the exhaust downstream side, and the inner pipe portion 19 has a closed end 19a on the exhaust downstream side. A spring 20 is provided between the inner surface of the end portion 18a of the outer tube portion 18 and the outer surface of the end portion 19a of the inner tube portion 19 to be biased to the opposite side of the exhaust gas introduction direction. When exhaust gas is introduced into the introduction pipe member 17, the inner pipe portion 19 moves toward the exhaust downstream side while contracting the spring 20 against the biasing force of the spring 20 due to the flow (pressure) of the exhaust gas. It becomes like this. That is, the spring 20 constitutes a displacement setting means that contracts according to the energy of the exhaust gas and changes the relative position of the inner tube portion 19 with respect to the outer tube portion 18. By using the spring 20 in this way, the displacement of the inner tube portion 19 according to the energy of the exhaust gas can be easily and inexpensively performed. The urging force of the spring 20 is appropriately determined according to the engine displacement and the like.

  In the outer pipe portion 18, gas supply windows 21 </ b> A to 21 </ b> A through which exhaust gas introduced into the introduction pipe member 17 flows out of the introduction pipe member 17 and is supplied to the heat exchange fin portions 8 of the heat exchangers 5. 21C and a gas bypass window 22 for allowing the exhaust gas introduced into the introduction pipe member 17 to flow out of the introduction pipe member 17 by bypassing the heat exchangers 5 are provided. The gas supply windows 21A to 21C and the gas bypass window 22 have a rectangular shape as shown in FIG. The dimensions of the gas supply windows 21A to 21C and the gas bypass window 22 are all the same, for example.

  A plurality (six in this case) of gas supply windows 21 </ b> A to 21 </ b> C are formed in the outer pipe portion 18 in correspondence with the thermoelectric units 4 in the first to third rows from the exhaust upstream side (see FIG. 6). The gas supply windows 21 </ b> A to 21 </ b> C are formed at positions corresponding to the exhaust upstream side end portions of the respective heat exchangers 5 in the outer pipe portion 18. As a result, the exhaust gas flowing out from the gas supply windows 21A to 21C is supplied to the exhaust upstream end of each heat exchange fin portion 8, and the exhaust gas further moves toward the exhaust downstream side through the heat exchange fin portion 8. Since it flows, the heat of the exhaust gas can be efficiently recovered by the heat exchange fin portion 8. A plurality (six in this case) of gas bypass windows 22 are formed at positions on the exhaust pipe downstream side of the heat exchanger 5 in the outer pipe portion 18 (see FIG. 6).

  The inner pipe portion 19 includes gas supply windows 23A to 23C for causing the exhaust gas introduced into the introduction pipe member 17 to flow out of the introduction pipe member 17 in cooperation with the gas supply windows 21A to 21C. A gas bypass window 24 is provided for allowing exhaust gas introduced into the pipe member 17 to flow out of the introduction pipe member 17 in cooperation with the gas bypass window 22. The gas supply windows 23A to 23C and the gas bypass window 24 have a rectangular shape as shown in FIG. A plurality of (here, six) gas supply windows 23A to 23C are formed in the inner pipe portion 19 corresponding to the thermoelectric units 4 in the first to third rows from the exhaust upstream side (see FIG. 6). The number of gas bypass windows 24 is the same as the number of gas bypass windows 22, for example.

  In a state where the inner tube portion 19 is in an initial position with respect to the outer tube portion 18 (a state where the spring 20 does not expand and contract), the gas supply windows 23A to 23C are more than the gas supply windows 21A to 21C in the inner tube portion 19. It is formed at a position upstream of the exhaust.

In this state, the position of the edge of the gas supply window 23C on the exhaust downstream side substantially coincides with the position of the edge of the gas supply window 21C on the exhaust upstream side. Further, as shown in FIG. 3, the distance _{D 1} of the from the gas supply window 21A to the gas supply window 23A is longer than the distance _{D 2} from the gas supply window 21B to the gas supply window 23B. W ₁ (length along the axial direction of the inner tube portion 19) width of the gas supply window 23A is (length along the axial direction of the outer tube portion 18) width of the gas supply window 21A~21C greater than W It has become. The width _{W 2} of the gas supply window 23B is larger than the width _{W 1} of the gas supply window 23A, further the width _{W 3} of the gas supply window 23C is larger than the width _{W 2} of the gas supply window 23B.

  Further, in a state where the inner tube portion 19 is in the initial position with respect to the outer tube portion 18, the gas bypass window 24 is formed at a position such that it overlaps with each gas bypass window 22 in the inner tube portion 19. Yes.

  As shown in FIG. 4, when the inner tube part 19 moves relative to the outer tube part 18, the gas supply windows 23A to 23C and the gas supply windows 21A to 21C overlap each other in the region P (in FIG. 4A). The maximum area of the hatched portion is smaller than the area of the formation region Q of the heat exchange fin portion 8 in the heat exchanger 5 (the portion surrounded by the one-dot chain line in FIG. 5B). 4A is a view of a portion including the gas supply windows 21C and 23C in the introduction pipe member 17 as viewed from the heat exchanger 5 side, and FIG. 4B is a view of the heat exchanger 5. It is a figure when it sees from the gas supply windows 21C and 23C side. With this configuration, the exhaust gas introduced into the introduction pipe member 17 is supplied to the heat exchange fin portion 8 through the gas supply windows 23A and 21A, the gas supply windows 23B and 21B, and the gas supply windows 23C and 21C. The flow velocity during

  Next, the operation of the thermoelectric generator 1 configured as described above will be described. During operation of the engine, exhaust gas from the engine is introduced into the introduction pipe member 17 and cooling water flows through the cooling water passage 10 of the cooling water case 7 in each thermoelectric unit 4.

  Here, when the engine load is in an extremely low load state immediately after the cold start, the energy (pressure) of the exhaust gas is sufficiently low, so that even if the exhaust gas is introduced into the outer pipe portion 18, the spring 20 hardly contracts. The inner tube portion 19 remains almost in the initial position with respect to the outer tube portion 18. In this case, as shown in FIG. 3, the exhaust gas introduced into the inner pipe portion 19 is guided to the outside of the introduction pipe member 17 through the gas bypass windows 24 and 22, and further exhausted on the downstream side. It flows toward the purification catalyst.

  In this operating region, the exhaust gas flows by bypassing all the heat exchangers 5, and the heat of the exhaust gas (exhaust heat) does not contribute to power generation. At this time, since exhaust gas does not pass through the heat exchanger 5 at all, exhaust pressure loss does not increase. Further, since the exhaust heat is not lost to the heat exchanger 5, the exhaust gas flows to the exhaust purification catalyst with almost no decrease in the exhaust temperature. For this reason, since the exhaust purification catalyst is quickly warmed, the exhaust purification performance is improved.

  When the engine load increases slightly, the energy of the exhaust gas slightly increases. As shown in FIG. 5, the exhaust pipe introduced into the outer pipe section 18 pushes the inner pipe section 19 to the exhaust downstream side. The spring 20 contracts. For this reason, the overlap of the gas bypass windows 22 and 24 is released, and the gas supply windows 21C and 23C are overlapped. In this case, as shown in FIG. 5 and FIG. 6, the exhaust gas introduced into the inner pipe portion 19 passes through the gas supply windows 23C and 21C, and each heat exchange in the third row from the exhaust upstream side. It is supplied to the heat exchange fin portion 8 of the vessel 5. Then, the exhaust gas flows through between the fins of the heat exchange fin portion 8.

  At this time, the high-temperature exhaust heat is recovered by the heat exchange fin portion 8 and further transmitted to the high-temperature side end face of the thermoelectric conversion module 6. For this reason, the high temperature side end surface of the thermoelectric conversion module 6 is maintained in a high temperature state. On the other hand, the low-temperature side end surface of the thermoelectric conversion module 6 is cooled because heat is taken away by the cooling water flowing in the cooling water case 7. Thereby, a temperature difference arises between the high temperature side end surface and the low temperature side end surface of the thermoelectric conversion module 6, and electric power according to this temperature difference is generated.

  When the engine load further increases, the energy of the exhaust gas further increases, and as shown in FIG. 7, the inner pipe portion 19 is further pushed to the exhaust downstream side by the exhaust gas introduced into the outer pipe portion 18, In addition to the gas supply windows 21C and 23C, the gas supply windows 21B and 23B overlap each other. In this case, the exhaust gas introduced into the inner pipe portion 19 passes through the gas supply windows 23B and 21B and the gas supply windows 23C and 21C, and performs heat exchange in the second and third rows from the exhaust upstream side. It is supplied to the heat exchange fin portion 8 of the vessel 5. Thus, power is generated by the thermoelectric conversion modules 6 in the second and third rows from the exhaust upstream side.

  When the engine load is further increased to a high load state, the energy of the exhaust gas becomes sufficiently high. Therefore, as shown in FIG. 8, the exhaust gas introduced into the outer tube portion 18 causes the inner tube portion 19 to further exhaust. Pushed downstream, the gas supply windows 21A and 23A overlap in addition to the gas supply windows 21B and 23B and the gas supply windows 21C and 23C. In this case, the exhaust gas introduced into the inner pipe portion 19 passes through the gas supply windows 23A and 21A, the gas supply windows 23B and 21B, and the gas supply windows 23C and 21C, and the heat of all the heat exchangers 5 It is supplied to the exchange fin unit 8. As a result, all the thermoelectric conversion modules 6 generate power completely.

  In the above, the gas supply windows 21A to 21C and the gas bypass window 22 formed in the outer pipe portion 18, the gas supply windows 23A to 23C and the gas bypass window 24 formed in the inner pipe portion 19, and the spring 20 are A gas flow path control unit is configured to control the exhaust gas introduced into the passage 16 so as to be selectively supplied to the heat exchange fin portion 8 of each heat exchanger 5.

  FIG. 9 is a cross-sectional view showing a typical example of a thermoelectric conversion device having a conventional structure as a comparative example, and FIG. 10 is a cross-sectional view taken along the line XX of FIG. In the figure, the same reference numerals are given to the same or equivalent members as in the present embodiment.

  In each figure, the thermoelectric conversion device 100 includes an integrated heat exchanger 101 having a hexagonal cross section. The heat exchanger 101 includes six partition walls 103 that form six exhaust passages 102 through which exhaust gas passes, and six heat exchange fin portions 104 that are provided so as to be accommodated in the respective exhaust passages 102. Yes. Each heat exchange fin section 104 has three rows of thermoelectric regions along the flow direction of the exhaust gas, and the thermoelectric conversion module 6 and the cooling water case 7 are arranged at positions corresponding to the thermoelectric regions of each row.

  In such a thermoelectric conversion device 100, the exhaust gas from the engine is introduced into all the exhaust passages 102 and flows downstream through the fins of all the heat exchange fin portions 104. At this time, exhaust heat is taken in order from the thermoelectric region on the exhaust upstream side of each heat exchange fin section 104 and power is generated by the corresponding thermoelectric conversion module 6, so that the exhaust temperature decreases toward the exhaust downstream side. For this reason, the temperature of the heat exchange fin unit 104 and the thermoelectric conversion module 6 decreases in order of the first, second, and third rows from the exhaust upstream side.

  In this case, it is difficult to use all the thermoelectric conversion modules 6 at the most efficient temperature, and the temperature of the thermoelectric conversion modules 6 in the first row from the exhaust upstream side may exceed the heat resistance temperature. In addition, due to a temperature difference between the exhaust upstream region and the exhaust downstream region of the heat exchange fin portion 104, a radial thermal expansion difference is generated between the regions of the heat exchange fin portion 104. As a result, each thermoelectric conversion module 6 is pressed. There is a possibility that the load is non-uniform, an uneven load is applied to the elements, electrodes, etc. in the thermoelectric conversion module 6 and power generation failure occurs.

  Further, when the engine state is low and the exhaust heat is low, power is generated only by the first row of thermoelectric conversion modules 6 from the exhaust upstream side, and the second and third rows of thermoelectric conversion modules 6 from the exhaust upstream side. May not contribute to power generation. However, even in that case, since the exhaust gas passes through the heat exchange fin portion 104, it is disadvantageous in terms of exhaust pressure loss.

  In contrast, in the thermoelectric conversion device 1 of the present embodiment, the outer pipe portion 18 having the gas supply windows 21A to 21C and the gas bypass window 22, the gas supply windows 23A to 23C, and the gas bypass window 24 are provided inside the exhaust pipe 3. Since the introduction pipe member 17 including the inner pipe portion 19 is disposed and the spring 20 is provided to change the relative position of the inner pipe portion 19 with respect to the outer pipe portion 18 according to the engine load, the above problem is solved. can do.

  That is, when the engine is in a high load state, the exhaust gas from the engine is supplied to the heat exchange fin portions 8 of many heat exchangers 5, but the exhaust gas is first introduced into the introduction pipe member 17. From there, it is directly supplied to each heat exchange fin portion 8 via the gas supply windows 23A to 23C and gas supply windows 21A to 21C, so that the temperature of the exhaust gas supplied to each heat exchange fin portion 8 is substantially uniform. Become. For this reason, since the temperature difference of the heat exchanger 5 hardly arises between each row | line | column, the thermal expansion difference of the heat exchanger 5 between each row | line | column is almost eliminated, and the variation of the pressing load concerning each thermoelectric conversion module 6 is suppressed. The Thereby, the transfer rate of the exhaust heat from each heat exchanger 5 to each thermoelectric conversion module 6 is improved, and the amount of power generated by each thermoelectric conversion module 6 is made uniform. Further, the temperature of the thermoelectric conversion modules 6 in the first row from the exhaust upstream side is prevented from exceeding the heat resistance temperature. On the other hand, when the engine is in a low load state, the energy of the exhaust gas is low, so that the heat exchange fin portion 8 to which the exhaust gas is supplied is reduced, and the power generation is effectively performed by the minimum necessary thermoelectric conversion module 6. The

  Thus, since the flow of the exhaust gas to each heat exchange fin part 8 is controlled according to the load of the engine, the thermoelectric conversion device 1 uses the thermoelectric conversion module 6 in an efficient state, thereby generating power efficiency. Can be increased.

  Further, the exhaust gas is supplied to the heat exchange fin portion 8 by making the maximum area of the region where the gas supply windows 23A to 23C and the gas supply windows 21A to 21C overlap with each other smaller than the area of the heat exchange fin portion 8 formation region. Since the flow rate at the time is increased, the heat recovery amount of the heat exchange fin portion 8 is increased, and the power generation amount generated in the thermoelectric conversion module 6 is increased. Thereby, the power generation efficiency can be further improved.

  Furthermore, when the engine is in a low load state, the exhaust gas introduced into the inner pipe portion 19 is caused to flow out from the gas supply windows 23C and 21C, and the heat exchange fins of the heat exchangers 5 in the third row from the exhaust upstream side. Since the gas is supplied to the section 8, the exhaust gas does not pass through the heat exchangers 5 in the first row and the second row from the exhaust upstream side. Therefore, power generation can be performed without increasing the exhaust pressure loss.

  A second embodiment of a thermoelectric generator according to the present invention will be described with reference to FIG. In the figure, the same or equivalent members as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In the figure, a thermoelectric power generation apparatus 30 of the present embodiment has an electric actuator 31 and a controller 32 that controls the electric actuator 31 instead of the spring 20 in the first embodiment.

  The electric actuator 31 has a rod portion 31 a that can reciprocate in the axial direction (longitudinal direction) of the introduction tube member 17. The rod portion 31 a is introduced into the exhaust pipe 3 through a bearing 33 provided in the exhaust pipe 3, and further, the exhaust of the inner pipe portion 19 is inserted in the exhaust pipe downstream end 18 a of the outer pipe portion 18. It is connected to the end 19a on the downstream side.

  The controller 32 detects the flow rate and temperature of the exhaust gas from the engine, obtains the load of the engine from the detection result, and controls the stroke of the rod portion 31a of the electric actuator 31 based on this, thereby the outer pipe portion 18. The relative position of the inner tube portion 19 with respect to the is set. Specifically, the controller 32 controls the electric actuator 31 so that the inner pipe portion 19 moves to the exhaust downstream side as the engine load increases. The flow rate of the exhaust gas can be estimated from, for example, the engine speed and the throttle valve opening, and the temperature of the exhaust gas can be estimated from, for example, the temperature of the catalyst.

  In the present embodiment, unlike the case of using the spring 20 described above, the force for pushing back the spring is not applied to the inner tube portion 19, so that it is possible to prevent the exhaust pressure loss corresponding to the spring reaction force from occurring.

  A third embodiment of the thermoelectric generator according to the present invention will be described with reference to FIGS. In the figure, the same or equivalent members as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In FIG. 12, in the thermoelectric power generation device 40 of the present embodiment, a thermoelectric unit group including a plurality (here, six) of thermoelectric units 4 is arranged in only one row along the exhaust gas flow direction.

  The introduction pipe member 17 of the thermoelectric generator 40 includes an outer pipe part 41 and an inner pipe part 42 instead of the outer pipe part 18 and the inner pipe part 19 in the first embodiment. The outer pipe portion 41 is provided with a plurality of gas supply windows 43 and a plurality of gas bypass windows 44. The number of gas supply windows 43 and gas bypass windows 44 is the same as the number of thermoelectric units 4. Each gas supply window 43 is formed at a position corresponding to the exhaust upstream side end of each heat exchanger 5 in the outer pipe portion 41. The gas bypass window 44 is formed at a position on the exhaust pipe downstream side of each heat exchanger 5 in the outer pipe portion 41.

  The inner pipe portion 42 is provided with a plurality of gas supply windows 45 and a plurality of gas bypass windows 46. The number of gas supply windows 45 and gas bypass windows 46 is the same as the number of thermoelectric units 4. In a state where the inner pipe portion 42 is in the initial position with respect to the outer pipe portion 41, each gas supply window 45 is formed at a position upstream of the above gas supply windows 43 in the inner pipe portion 42. . Further, the positions of the edges on the exhaust upstream side of the gas supply windows 45 are the same, and the positions of the edges on the exhaust downstream side of the gas supply windows 45 are different. That is, the width (length along the axial direction of the inner tube portion) H of each gas supply window 45 is different (see FIG. 13).

  In such a thermoelectric power generation apparatus 40, when the engine load is slightly high and low from the cold start, as shown in FIG. 13, the inner pipe portion 42 is exhausted by the exhaust gas introduced into the introduction pipe member 17. Is pushed to the exhaust downstream side with respect to the outer pipe portion 41, and the gas supply window 45 having the largest width and the corresponding gas supply window 43 are overlapped with each other. In this case, as shown in FIGS. 13 and 14, the exhaust gas introduced into the inner pipe portion 42 passes through a pair of gas supply windows 45, 43, and corresponds to one corresponding heat exchanger 5. It is supplied to the heat exchange fin unit 8. Then, power generation is performed by only one thermoelectric conversion module 6 corresponding to the heat exchanger 5.

  From this state, when the engine load increases, as shown in FIG. 15, the inner pipe portion 42 is pushed further to the exhaust downstream side by the exhaust gas, and in addition to the pair of gas supply windows 43 and 45, second. The large gas supply window 45 and the corresponding gas supply window 43 overlap each other. In this case, as shown in FIGS. 15 and 16, the exhaust gas introduced into the inner pipe portion 42 passes through the two gas supply windows 45, 43 and flows through the two corresponding heat exchangers 5. It is supplied to the heat exchange fin unit 8. The two thermoelectric conversion modules 6 corresponding to these heat exchangers 5 generate power.

  When the engine load further increases, as shown in FIG. 17, the exhaust pipe pushes the inner pipe portion 42 further to the exhaust downstream side, and in addition to the two sets of gas supply windows 43 and 45, the third width is reached. The large gas supply window 45 and the corresponding gas supply window 43 overlap each other. In this case, as shown in FIGS. 17 and 18, the exhaust gas introduced into the inner pipe portion 42 passes through the three gas supply windows 45 and 43, and corresponds to the corresponding three heat exchangers 5. It is supplied to the heat exchange fin unit 8. Then, power is generated by the three thermoelectric conversion modules 6 corresponding to these heat exchangers 5.

  Although not described below, as the engine load further increases, the number of gas supply windows 45 that overlap with the gas supply window 43 increases, so the number of heat exchange fin portions 8 to which exhaust gas is supplied increases, and accordingly, power generation is performed. More thermoelectric conversion modules 6 contribute.

  By the way, when exhaust gas is supplied to the heat exchange fin portions 8 of all the heat exchangers 5 in a state where the load of the engine is low and the exhaust heat is small, the exhaust heat recovered in each heat exchange fin portion 8 is Since it is distributed to the thermoelectric conversion modules 6, it becomes difficult to ensure the high temperature side end surfaces of the thermoelectric conversion modules 6 in a high temperature state, which may cause a decrease in power generation efficiency. However, in this embodiment, when the engine is in a low load state, there are few thermoelectric conversion modules 6 that contribute to power generation, so the high temperature side end face of the thermoelectric conversion module 6 is maintained in a high temperature state. Thereby, since the thermoelectric conversion module 6 is always used in an efficient state regardless of the engine load, the power generation efficiency can be improved.

  In the present embodiment, the thermoelectric unit group including the plurality of thermoelectric units 4 is only one row, but it goes without saying that such a thermoelectric unit group may be arranged in a plurality of rows along the flow direction of the exhaust gas. Yes. In this case, for example, the configuration of the present embodiment is adopted in combination with the first embodiment, and the exhaust gas flow path is controlled for each thermoelectric unit 4 to perform fine and optimal power generation control. It becomes possible.

  Although several embodiments of the thermoelectric generator according to the present invention have been described above, the present invention is not limited to the above-described embodiments.

  For example, in the above embodiment, a rectangular gas supply window is provided in the inner tube portion of the introduction tube member 17, but the shape of the gas supply window in the inner tube portion is triangular as shown in FIG. May be. In this case, when the inner tube portion 19 is moved relative to the outer tube portion 18, the area of the region where the inner tube portion 19 and the outer tube portion 18 overlap depends on the amount of movement of the inner tube portion 19. It will change nonlinearly. Depending on the displacement of the vehicle, the operating condition, etc., such a configuration may finely and optimally tune the exhaust gas flow rate to the heat exchanger 5 and increase the degree of freedom in controlling the exhaust gas flow rate. it can. In addition, as a shape of the gas supply window of the inner tube portion, a circular shape or the like may be used. Further, the shape of the gas supply window of the outer tube portion and the gas bypass window of the outer tube portion and the inner tube portion are not particularly limited to a rectangular shape.

  Moreover, in the said embodiment, although it was set as the structure which provides the heat exchanger 5 of the same number as the thermoelectric conversion module 6, a heat exchanger is good also as an integrated structure as shown in FIG.9 and FIG.10. In this case, the flow path of the exhaust gas is controlled so as to selectively supply the exhaust gas to a position corresponding to each thermoelectric conversion module 6 in the heat exchange fin portion of the heat exchanger according to the engine load. .

It is sectional drawing which shows 1st Embodiment of the thermoelectric power generating apparatus concerning this invention. It is the II-II sectional view taken on the line of FIG. It is a figure which shows the positional relationship etc. with the gas supply window and gas bypass window of an outer side pipe part, and the gas supply window and gas bypass window of an inner side pipe part. It is a figure which shows the relationship between the area of the area | region where the gas supply window of an outer side pipe part and the gas supply window of an inner side pipe part overlap, and the area of the formation area of the heat exchange fin part in a heat exchanger. FIG. 4 is a schematic diagram showing a state of an introduction pipe member and an exhaust gas flow path when an engine load increases from the state shown in FIG. 3. FIG. 4 is a cross-sectional view showing an exhaust gas flow path when the engine load is increased from the state shown in FIG. 3. FIG. 6 is a schematic diagram showing the state of the introduction pipe member and the exhaust gas flow path when the engine load is increased from the state shown in FIG. 5. FIG. 8 is a schematic view showing the state of the introduction pipe member and the exhaust gas flow path when the engine load increases from the state shown in FIG. 7. It is sectional drawing which shows an example of the thermoelectric conversion apparatus of conventional structure. FIG. 10 is a sectional view taken along line XX in FIG. 9. It is a block diagram which shows 2nd Embodiment of the thermoelectric power generating apparatus concerning this invention. It is sectional drawing which shows 3rd Embodiment of the thermoelectric power generating apparatus concerning this invention. It is the schematic which shows the state of the introductory pipe member at the time of an engine low load, and the flow path of exhaust gas. It is sectional drawing which shows the flow path of the exhaust gas at the time of an engine low load. It is the schematic which shows the state of an introductory pipe member when an engine load goes up from the state shown in FIG. 13, and the flow path of exhaust gas. It is sectional drawing which shows the flow path of exhaust gas when engine load rises from the state shown in FIG. FIG. 16 is a schematic diagram showing the state of the introduction pipe member and the exhaust gas flow path when the engine load increases from the state shown in FIG. 15. It is sectional drawing which shows the flow path of exhaust gas when an engine load rises from the state shown in FIG. It is the schematic which shows the modification of the gas supply window of an inner side pipe part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Thermoelectric power generation device, 2 ... Exhaust passage (1st passage), 5 ... Heat exchanger, 6 ... Thermoelectric conversion module (thermoelectric conversion part), 8 ... Heat exchange fin part (heat exchange part), 16 ... Passage (1st 2 passages), 17 ... introducing pipe member, 18 ... outer pipe part, 18a ... exhaust downstream end part, 19 ... inner pipe part, 19a ... exhaust downstream end part, 20 ... spring (displacement setting means, gas flow path control) Means), 21A-21C ... gas supply window (first gas supply window, gas flow path control means), 22 ... gas bypass window (first gas bypass window, gas flow path control means), 23A-23C ... gas supply window (Second gas supply window, gas flow path control means), 24 ... gas bypass window (second gas bypass window, gas flow path control means), 30 ... thermoelectric generator, 31 ... electric actuator (displacement setting means, gas flow) Road control means), 31a ... rod part, 32 ... control LA (displacement setting means, gas flow path control means), 40 ... thermoelectric generator, 41 ... outer pipe section, 42 ... inner pipe section, 43 ... gas supply window (first gas supply window, gas flow path control means), 44 ... Gas bypass window (first gas bypass window, gas flow path control means), 45 ... Gas supply window (second gas supply window, gas flow path control means), 46 ... Gas bypass window (second gas bypass window, Gas flow path control means).

Claims (9)

In a thermoelectric generator that generates power using the heat of exhaust gas discharged from an internal combustion engine,
A first passage through which the exhaust gas passes;
A heat exchanging portion that recovers heat of the exhaust gas passing through the first passage;
A plurality of thermoelectric conversion units that convert the heat recovered by the heat exchange unit into electricity;
An introduction pipe member disposed in the first passage and forming a second passage for introducing the exhaust gas from the internal combustion engine;
Gas flow path control means for controlling to selectively supply the exhaust gas introduced into the second passage to a position corresponding to each thermoelectric conversion unit in the heat exchange unit. Thermoelectric generator. The introduction pipe member has an outer pipe part and an inner pipe part arranged inside the outer pipe part,
The gas flow path control means includes a displacement setting means for changing a relative position of the inner pipe part with respect to the outer pipe part according to a load of the internal combustion engine, and positions corresponding to the thermoelectric conversion parts in the outer pipe part. A plurality of first gas supply windows provided on the inner pipe portion so as to selectively overlap each first gas supply window according to a relative position of the inner tube portion with respect to the outer pipe portion. The thermoelectric generator according to claim 1, further comprising a plurality of second gas supply windows. The gas flow path control means includes a first gas bypass window provided at a position on the exhaust pipe downstream side of the heat exchange section in the outer pipe section, and the inner pipe section at an initial position with respect to the outer pipe section. And a second gas bypass window provided in the inner pipe portion so as to overlap the first gas bypass window.
The plurality of second gas supply windows are provided to be located upstream of the corresponding first gas supply window when the inner tube portion is in an initial position with respect to the outer tube portion. The thermoelectric power generator according to claim 2, wherein   The displacement setting means is a spring that is provided between the inner surface of the exhaust downstream end of the outer tube and the outer surface of the exhaust downstream end of the inner tube, and contracts according to the load of the internal combustion engine. The thermoelectric generator according to claim 2 or 3, wherein the thermoelectric generator is provided.   The displacement setting means includes an actuator for moving the inner pipe portion relative to the outer pipe portion, and means for controlling the actuator according to a load of the internal combustion engine. 3. The thermoelectric generator according to 3.   The region where the first gas supply window and the second gas supply window overlap is smaller than the region corresponding to the thermoelectric conversion unit in the heat exchange unit. The thermoelectric generator as described.   The said gas flow path control means controls the flow of the said exhaust gas so that the location where the said exhaust gas is supplied in the said heat exchange part increases as the load of the said internal combustion engine becomes high. Item 7. The thermoelectric generator according to any one of Items 1 to 6.   The thermoelectric generator according to any one of claims 1 to 7, wherein a plurality of the thermoelectric conversion units are arranged along a flow direction of the exhaust gas introduced into the second passage. 9. The thermoelectric generator according to claim 1, wherein a plurality of the thermoelectric converters are arranged around a flow direction of the exhaust gas introduced into the second passage. .

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