JP2016102446A - Exhaust heat recovery device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust heat recovery device enabling selection of each flow passage and flow rate control and capable of attaining efficient heat recovery and thermoelectric generation, by a simple flow passage constitution and a single control valve.SOLUTION: An exhaust heat recovery device of an internal combustion engine includes a main exhaust flow passage 2 introducing exhaust gas, a detour flow passage 3 branching from the main exhaust flow passage 2 and made confluent at a confluence part 5, and a valve device 10 opening/closing the main exhaust flow passage 2 and the detour flow passage 3 at the confluence part 5. In the detour flow passage 3, a heat exchanger 7 performing heat exchange with exhaust gas and a thermoelectric generation device 6 are included. The valve device 10 is a single valve member that consecutively the area of one flow passage of the main exhaust flow passage 2 and the detour flow passage 3 in a state of closing the other flow passage.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exhaust heat recovery device for an internal combustion engine of an automobile.

  Conventionally, in order to improve the overall thermal efficiency of an automobile running on an internal combustion engine, an exhaust heat recovery device that collects exhaust heat of the internal combustion engine with a heat exchanger and heats the cooling medium to promote warm-up and improve heating performance It is often used to interpose the exhaust pipe. In addition, it has also been proposed that a thermoelectric power generator for directly converting exhaust heat into electricity and driving an auxiliary machine or charging a battery is provided in the exhaust pipe. Therefore, from the viewpoint of further effective use of exhaust heat, an integrated exhaust heat recovery device in which both the heat exchanger and the thermoelectric generator are interposed in the exhaust pipe can be considered, but the operation areas required for each other are different. However, since there is an operation region (bypass region) that does not require both, it is necessary to well control the supply of exhaust gas and cooling medium to each device, which is difficult to realize.

  Ideally, (α) a flow path interposing a thermoelectric generator, (β) a flow path interposing a heat exchanger, and (γ), (α), and a bypass flow path that bypasses both (β) It is preferable to have an exhaust heat recovery device that is provided with three flow paths independently and that can selectively switch the three flow paths and that can continuously distribute and control the flow rate ratio in the selected multiple flow paths. The large system having the independent flow path and the switching valve is difficult to control, and the vehicle mounting in terms of weight and space is remarkably limited.

  As a solution to such a problem, in Patent Document 1, a heat exchanger, a thermoelectric power generation device (thermoelectric power generation element), and a plate valve body (open / close valve) are provided in a single housing, and the exhaust in the housing is exhausted. By changing the direction of the gas flow according to the posture of the plate-like valve body, the way the exhaust gas hits the heat exchanger and the thermoelectric power generation element is changed, and the above (α), (β), and (γ) are simulated. In addition, an exhaust heat recovery device that makes each of the flow paths appear is disclosed. Patent Document 2 states that “in an exhaust system of an internal combustion engine having at least two flow paths constituting an exhaust flow path connected to the internal combustion engine, the flow path is switched by a single valve member and each An “exhaust device capable of appropriately adjusting the flow path area” is disclosed (described in paragraph [0014] of Patent Document 2).

Japanese Patent No. 3767509 Japanese Patent No. 4486963

  However, in the exhaust heat recovery apparatus disclosed in Patent Document 1, an independent flow path such as the above (α) (β) (γ) cannot be secured, and gas flow distribution in each flow path is only roughly. The request cannot be met because it cannot be adjusted.

  In an actual vehicle operation state, when the internal combustion engine is operated at a high load, the exhaust gas is not brought into contact with the heat exchanger and the thermoelectric power generation element, but is allowed to flow only in the main exhaust passage (bypass passage). We want to ensure output performance and avoid excessive heat recovery and thermoelectric generation. However, depending on the exhaust heat recovery device of Patent Document 1, since a high-temperature and large-flow gas hits the heat exchanger and the thermoelectric power generation element even at a high load of the internal combustion engine, boiling of the cooling water occurs in the heat exchanger. In the thermoelectric generator, there is a concern about heat damage to the thermoelectric generator. Of course, the original purpose of achieving the output performance of the internal combustion engine by minimizing the channel resistance cannot be achieved.

  Further, in the low load to medium load operation region of the internal combustion engine, exhaust gas corresponding to the amount of heat necessary for heat recovery and thermoelectric power generation is brought into contact with both, and unnecessary exhaust gas beyond that flows to the main exhaust flow path. Such flow rate adjustment (distribution control) in each flow path is necessary, but cannot be realized by flow direction control in a single space like the exhaust heat recovery device of Patent Document 1. Furthermore, it is not possible to realize control in which the main exhaust flow path is throttled according to the operating state of the internal combustion engine to prioritize the silencing requirement.

  Therefore, the present invention provides an exhaust heat recovery device that enables flow control as well as selection of each flow path by a simple flow path configuration and a single control valve, and can realize efficient heat recovery and thermoelectric generation. Is an issue.

  In order to achieve the above object, an exhaust heat recovery apparatus according to the present invention includes a main exhaust passage for introducing exhaust gas of an internal combustion engine, a branch from the main exhaust passage, and a junction at the junction with the main exhaust passage. And a valve device that opens and closes the main exhaust passage and the bypass passage at the junction, and the bypass passage has heat exchange for exchanging heat with the exhaust gas in the bypass passage. And the valve device is constituted by a single valve member that continuously sets the other flow passage area while closing one of the main exhaust flow passage and the bypass flow passage. It is what.

  In the exhaust heat recovery apparatus, the single valve member is driven in accordance with an operating state of the internal combustion engine, and the main exhaust passage and the bypass passage are switched, and the main exhaust passage And it is good to provide the control apparatus which adjusts each channel area of the said bypass channel.

  The heat exchanger and the thermoelectric device may include a cooling medium flow path, and heat exchange may be performed by introducing the cooling medium of the internal combustion engine.

  Since this invention is comprised as mentioned above, there exist the following effects. That is, in the exhaust heat recovery apparatus of the present invention, the merging portion is provided with a valve device that continuously sets the area of the other flow path in a state where one of the main exhaust flow path and the detour flow path is completely closed. Since the heat exchanger and the thermoelectric element are arranged in the flow path before and after the internal combustion engine, when the internal combustion engine is at a high load, the exhaust gas does not contact the heat exchanger and the thermoelectric power generation element without flowing into the internal combustion engine. Output performance can be secured, and excessive heat recovery and thermoelectric generation can be avoided. Further, since the flow passage area of the bypass flow passage can be arbitrarily set while closing the main exhaust flow passage, the heat recovery amount and the thermoelectric power generation amount can be set according to the operation state of the internal combustion engine. Furthermore, since the distribution can be arbitrarily set while simultaneously flowing to the bypass flow path and the main exhaust flow path, it becomes possible to cope with a request state according to the operation state of the internal combustion engine.

  In the exhaust heat recovery apparatus, the single valve member is driven in accordance with the operating state of the internal combustion engine, and the main exhaust passage and the bypass passage are switched, and the main exhaust passage and the bypass passage are switched. If a control device that adjusts the flow area of each channel is provided, a trade according to the priority of every moment in heat recovery and thermoelectric generation requirements, output performance requirements of internal combustion engines, noise reduction requirements by flow passage restriction, etc. Off control is possible

It is sectional drawing which shows the warming-up state of the exhaust heat recovery apparatus which concerns on one Embodiment of this invention. It is sectional drawing which shows the normal driving | running state after warming-up of the exhaust heat recovery apparatus which concerns on one Embodiment of this invention. It is sectional drawing which shows the heat recovery of the exhaust heat recovery apparatus which concerns on one Embodiment of this invention, and a thermoelectric power generation state. It is sectional drawing which shows the silencing requirement priority state of the exhaust heat recovery apparatus which concerns on one Embodiment of this invention. It is sectional drawing which shows the bypass state of the exhaust heat recovery apparatus which concerns on one Embodiment of this invention. It is sectional drawing which shows the warming-up state of the exhaust heat recovery apparatus which concerns on other embodiment of this invention. It is sectional drawing which shows the normal driving | running state of the exhaust heat recovery apparatus which concerns on other embodiment of this invention. It is sectional drawing which shows the bypass state of the exhaust heat recovery apparatus which concerns on other embodiment of this invention. It is sectional drawing which shows the warming-up state of the exhaust heat recovery apparatus which concerns on further another embodiment of this invention. It is sectional drawing which shows the normal driving | running state of the exhaust heat recovery apparatus which concerns on further another embodiment of this invention. It is sectional drawing which shows the normal driving | running state of the exhaust heat recovery apparatus which concerns on further another embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. 1 to 5 show an exhaust heat recovery apparatus according to an embodiment of the present invention. An exhaust heat recovery device 1 is connected between an upstream exhaust pipe EP1 connected to an internal combustion engine (not shown) and a downstream exhaust pipe EP2 extending rearward of the vehicle. About these connection methods, it is good also as connecting directly by welding etc. in the connection parts J1 and J2 like this embodiment, and good also as connecting detachably via a flange or a coupling apparatus. The left side of the drawing is the upstream side of the exhaust gas, and the exhaust gas flows down from the internal combustion engine (not shown) through the catalytic converter and the like through the exhaust pipe EP1. The right side of the figure is the downstream side of the exhaust gas.

  A branch section 4 connected to the exhaust pipe EP1 branches into a main exhaust flow path 2 and a bypass flow path 3, and both flow paths merge at a downstream junction section 5. A single valve member 10, which is a valve device that can select the flow of both flow paths and control the flow rate distribution, is disposed in the merge portion 5. In the detour channel 3, a thermoelectric generator 6 is interposed upstream and a heat exchanger 7 is interposed in series downstream. That is, the exhaust heat recovery apparatus according to the present invention is composed of two flow paths, a bypass flow path that interposes the thermoelectric generator 6 and the heat exchanger 7 and a main exhaust flow path that does not interpose both, in all the embodiments. Is done.

  The thermoelectric generator 6 has a structure in which a heat exchange fin 6b is sandwiched between a plurality of thermoelectric generators 6a, and a cooling medium passage 6c is provided on the outer surface of the thermoelectric generator 6a. The exhaust gas flowing through the bypass channel 3 exchanges heat when passing through the heat exchange fins 6b, and the heat is transmitted to the inner surface of the thermoelectric generator 6a. On the other hand, the outer surface of the thermoelectric generator 6a also exchanges heat with the cooling medium flowing in the cooling medium flow path 6c. Here, as the temperature difference ΔT between the heat transfer from the exhaust gas and the heat transfer to the cooling medium increases, The power generation amount is large. In the heat exchanger 7, a plurality of cooling fins 7a and a plurality of cooling medium flow paths 7b are alternately stacked to form a heat exchanger, and the exhaust gas passing through the cooling fins 7a exchanges heat with the cooling medium. . As the cooling medium, it is preferable to introduce the coolant liquid used in the vehicle cooling system for cooling the internal combustion engine as it is, but other cooling media may be used. As a thermoelectric power generation element, one using the Seebeck effect is generally used, but the thermoelectric power generation element 6a is not limited to this, and any element may be used as long as it generates power by a temperature difference. Further, since the temperature of the exhaust gas decreases as it passes through the heat exchange fins 6b, more efficient power generation can be achieved by arranging thermoelectric power generation elements having different corresponding temperatures from the upstream side to the downstream side according to the temperature change. Is possible.

  The cooling medium flow path 6 c of the thermoelectric generator 6 and the cooling medium flow path 7 b of the heat exchanger 7 are communicated with each other via a communication pipe 8. The cooling medium entering the cooling medium flow path 6c from the introduction pipe 6a is discharged to the communication pipe 8 through heat exchange, flows into the cooling medium flow path 7b through the communication pipe 8, and further from the outlet pipe 7c through heat exchange. It is discharged and supplied to a cooling water flow path of a vehicle (not shown). Note that the direction in which the cooling medium flows, that is, which of the cooling medium flow path 6c and the cooling medium flow path 7b of the heat exchanger 7 first passes the cooling medium is not limited to this embodiment, and may be set as appropriate. As in this embodiment, in order to ensure a large temperature difference ΔT, a low-temperature cooling medium is first passed through the thermoelectric generator 6 where it is desired to introduce the cooling medium. The order of flowing heat into the heat exchanger 7 where it is desired to recover is reasonable.

  The valve member 10 is fan-shaped in cross section, and its main part is pivotally supported by a pivot shaft 9 so that the outer peripheral wall surface of the valve member 10 slides on the inner wall surface of the detour channel 3 and the inner wall surface of the main exhaust channel. It is arranged freely. The valve member 10 is connected to an actuator ACT, and is driven and controlled according to the operating state of the internal combustion engine by the electronic control unit ECU via the actuator ACT. The actuator ACT has, for example, a step motor (not shown), which is precisely rotated or held and fixed by the electronic control unit ECU. In the electronic control unit ECU, based on detection signals of various sensors (oxygen sensor, pressure sensor, water temperature sensor, rotation sensor, accelerator opening sensor, etc.), the operating status of the internal combustion engine, the operating status of the driver's accelerator pedal, In addition, the vehicle posture and the braking situation are monitored, and in a predetermined cycle, the optimum position of the valve member 10 at that time is calculated and rotated to that position or stopped at that position. A drive signal is output. Thus, a control device is configured by the actuator ACT and the electronic control unit ECU, and the flow switching between the main exhaust flow path 2 and the bypass flow path 3 (opening and closing of each flow path) is performed. The flow area adjustment of each of the exhaust flow path 2 and the bypass flow path 3 is performed. The electronic control unit ECU may be installed exclusively for this system, or may be integrated with the electronic control unit of a vehicle or an internal combustion engine. In addition, regarding the specific setting and driving details of the valve member 10, the valve member disclosed in the above-mentioned Patent Document 2 can be referred to.

  In FIG. 1, the main exhaust passage 2 is fully closed by the valve member 10, and the exhaust passage is switched to the bypass passage 3 side. Therefore, all of the exhaust gas a is introduced into the bypass flow path 3, and heat exchange is performed between the thermoelectric generator 6 and the heat exchanger 7, and then exhausted as the exhaust gas b to the main exhaust flow path 2 at the junction 5. . Further, in the present embodiment, the flow path of the bypass flow path 3 is adapted to meet the output requirements and the silencing requirements by the swing drive of the valve member 10 with the main exhaust flow path 2 maintained in the fully closed state. The area is adjusted sequentially. For example, when the amount of the exhaust gas b flowing through the gap between the valve member 10 and the bypass flow path 3 is adjusted, the “flow adjustment function” is exhibited by the “throttle function” of the valve member 10. Since the valve member 10 can be driven steplessly, the flow passage area of the bypass flow passage 3 can be arbitrarily adjusted with the main exhaust flow passage 2 maintained in a fully closed state.

  The mode of FIG. 1 shows a so-called warm-up state when the internal combustion engine and the cooling medium are not warmed immediately after the internal combustion engine is started. In the warm-up period until the cooling medium reaches a constant temperature, The requirement to improve the cooling medium temperature is given top priority. Accordingly, priority is given to heat recovery in the heat exchanger 7, so that the main exhaust passage 2 is fully closed by the valve member 10 located in the recess 11 as described above, and the exhaust passage is the bypass passage 3. It has been switched to the side. Then, all of the exhaust gas is introduced into the bypass flow path 3, heat exchanged by the thermoelectric generator 6 and the heat exchanger 7, and then discharged to the main exhaust flow path 2 at the junction 5. At this time, the exhaust gas heat-exchanged in the thermoelectric generator 6 flows into the heat exchanger 7, but the thermoelectric generator element itself has a low heat conductivity, so the heat recovery amount is very small, and the adverse effect is Absent. In the warm-up process, it is preferable that the main exhaust passage 2 is fully closed by the valve member 10, but since it is not essential to completely shut off the exhaust gas, only the exhaust flow rate of the main exhaust passage 2 is necessary. If it is narrowed down, it is not necessarily required to be in the fully closed state, and it may be in a slightly opened state.

  The mode of FIG. 2 shows a normal operation state after completion of warm-up, and implements appropriate thermoelectric power generation and heat recovery in a state of medium to high rotation speed of the internal combustion engine. In this state, the valve member 10 is swung within a range in which the exhaust gas can flow in both the main exhaust flow path 2 and the bypass flow path 3, and receives an instruction from the electronic control unit ECU according to the priority requirement from time to time. The ratio (distribution) that flows to each channel is determined. That is, the amount e flowing through the main exhaust passage 2 is determined by the gap g, and the amount d flowing through the bypass passage 3 is determined by the gap f. Therefore, by adjusting the size of both the gaps, The amount of heat recovery, the silence level, or the output of the internal combustion engine can be selected as appropriate.

  As described above, according to the exhaust heat recovery apparatus of the present invention, the above-described three independent flow paths (α), (β), and (γ) are not required, and in particular (α: a thermoelectric power generation element is interposed). The conventional problem can be solved with a simple overall configuration including only two flow paths and a single valve body. Furthermore, it is also possible to perform integrated trade-off control on thermoelectric power generation and heat recovery requirements, noise reduction requirements, and internal combustion engine output requirements according to priority requests from the vehicle side.

  3 and FIG. 4 does not allow exhaust gas to flow through both flow paths as in FIG. 2 even during normal operation after warming up, but it preferentially requires only flowing through one flow path. To meet. For example, in the embodiment of FIG. 3, the flow rate of the exhaust gas flowing through the thermoelectric generator 6 and the heat exchanger 7 is slowed down by restricting the exhaust gas flow rate h flowing through the bypass flow path 3, so that the thermoelectric power generation amount and the heat recovery are positively performed. It is a control form that increases the amount. In the embodiment of FIG. 4, the exhaust gas is allowed to flow only in the main exhaust flow path 2 and the exhaust gas flow rate i is reduced. By doing in this way, it can give priority to the silencing requirement in the state where thermoelectric generation and heat recovery are unnecessary.

  The mode of FIG. 5 shows the state of the internal combustion engine during medium to high rotation or high load, and the main exhaust passage 2 is fully opened and the bypass passage 3 is fully closed. The That is, this is an aspect corresponding to the above-described (γ). As a result, the exhaust gas at a high temperature and high flow rate is not brought into contact with the heat exchanger and the thermoelectric power generation element, so that excessive heat recovery and boiling of the cooling water are performed in the heat exchanger, and excessive power generation and Heat damage to the elements can be prevented respectively. Of course, it is also possible to ensure the output performance of the internal combustion engine by flowing the exhaust gas without resistance only in the main exhaust passage 2 (bypass passage).

  6 to 8 show an exhaust heat recovery apparatus 1x according to the second embodiment of the present invention. The arrangement of the thermoelectric generator 6 and the heat exchanger 7 is different from that of the first embodiment. The order is reversed. That is, the heat exchanger 7 is arranged on the upstream side in the bypass flow path 3 and the thermoelectric generator 6 is arranged on the downstream side. With such an arrangement, the exhaust gas flowing down from the internal combustion engine is directly introduced into the heat exchanger 7, which contributes to an early temperature rise of the cooling medium during warm-up. As for the order of introduction of the cooling medium, the order in which the cooling medium after passing through the thermoelectric generator 6 and heated by the thermoelectric generator 6 flows into the heat exchanger 7 is the same as in the first embodiment. Reasonable, but you can change the order as needed

  The mode of FIG. 6 shows the same state as the mode of FIG. 1 in the first embodiment, and is a state in which the internal combustion engine is warming up. Since the exhaust gas flowing down from the internal combustion engine is directly introduced into the heat exchanger 7, it is effective for an early temperature rise of the cooling medium during warm-up.

  The mode of FIG. 7 shows the same state as the mode of FIG. 2 in the first embodiment, that is, the state at the time of medium to high rotation of the internal combustion engine after completion of warm-up, and appropriate thermoelectric power generation and heat recovery. Is a state in which In this state, the valve member 10 is swung within a range in which the exhaust gas can flow in both the main exhaust flow path 2 and the bypass flow path 3, and receives an instruction from the electronic control unit ECU according to the priority requirement from time to time. The ratio (distribution) that flows to each channel is determined. Even in this case, it is effective as a structure capable of positively recovering heat rather than thermoelectric power generation.

  The mode of FIG. 8 shows the same state as the mode of FIG. 3 in the first embodiment, that is, the state at the time of middle to high rotation of the internal combustion engine or at the time of high load. In addition, the bypass flow path 3 is fully closed. In this case, the order of the thermoelectric generator 6 and the heat exchanger 7 is irrelevant. However, in the heat exchanger, excessive heat recovery and boiling of the cooling water occur in the thermoelectric generator, as in the embodiment of FIG. Excessive power generation and thermal damage to the elements can be prevented, respectively, and the output performance of the internal combustion engine can be ensured by flowing the exhaust gas without resistance only in the main exhaust passage 2 (bypass passage).

  FIGS. 9 to 11 show an exhaust heat recovery apparatus 1y according to a third embodiment of the present invention. The flow path and control of the cooling medium are different from those of the first embodiment. In FIG. 9, a cooling medium pipe 210 branched from a cooling medium passage of a vehicle (not shown) is divided into a first introduction pipe 212 and a second introduction pipe 213 at a branch 211, and the first introduction pipe 212 is connected to the thermoelectric generator 6. The second introduction pipes 213 are connected to the heat exchanger 7 respectively. The first lead-out pipe 214 connected to the thermoelectric generator 6 and the second lead-out pipe 215 connected to the heat exchanger 7 are connected to the switching valve 217. The switching valve 217 that switches the flow of the cooling medium is a so-called three-way valve that can select the flow of the cooling medium flowing in the first outlet pipe 214 and the second outlet pipe 215. One or both of the medium and the cooling medium flow from the second outlet pipe 215 can be selected. Therefore, with respect to the thermoelectric generator 6 and the heat exchanger 7, it is possible to flow the cooling medium only to either one or both. In addition, since the structure of a three-way valve is known, illustration is abbreviate | omitted.

  The mode of FIG. 9 is the same state as the mode of FIG. 1 in the first embodiment, and is a state in which the internal combustion engine is warming up. Prioritizing the request to heat up the vehicle coolant early in the warm-up process, the switching valve 217 is operated to allow the coolant to flow only to the heat exchanger 7 and not to the thermoelectric generator 6. . As a result, the heat of the cooling water is not taken away by the thermoelectric generator 6, so that an early temperature rise of the cooling medium is promoted.

  The mode of FIG. 10 is the same state as the mode of FIG. 2 in the first embodiment, and performs moderate thermoelectric generation and heat recovery in the middle to high rotation state of the internal combustion engine. In this state, the switching valve 217 is operated to allow the cooling medium to flow through both the thermoelectric generator 6 and the heat exchanger 7. The thermoelectric generator 6 that wants to directly introduce a low-temperature cooling medium is not affected by the heat exchanger 7, and the power generation efficiency can be increased. Particularly in cold districts, there is a need to provide heating assistance by constantly recovering heat in the heat exchanger 7, and according to this embodiment, thermoelectric power generation and always recovering heat can be efficiently made compatible.

  On the other hand, when there is no need to recover heat in the middle to high rotation state of the internal combustion engine and it is desired to actively perform thermoelectric generation, the switching valve 217 is operated as shown in the embodiment of FIG. Thus, it is preferable to flow the cooling water only to the thermoelectric generator 6 and stop the flow into the heat exchanger 7. However, since there is a concern that the exhaust gas flows into the heat exchanger 7 and the cooling medium in the heat exchanger 7 boils, it is preferable to monitor the cooling medium temperature in the heat exchanger 7 by some means. .

DESCRIPTION OF SYMBOLS 1, 1x, 1y Exhaust heat recovery apparatus 2 Main exhaust flow path 3 Detour flow path 4 Branch part 5 Junction part 6 Thermoelectric generator 6a Thermoelectric element 6b Heat exchange fin 6c Cooling medium flow path 6d Induction pipe 7 Heat exchanger 7a Heat exchange Fin 7b Cooling medium flow path 7c Lead pipe 8 Communication pipe 9 Pivot shaft 10 Valve device 11 Recess 210, 216 Cooling medium pipe 211 Branch 212 First inlet pipe 213 Second inlet pipe 214 First outlet pipe 215 Second outlet pipe 217 Switching valve

Claims (3)

  A main exhaust passage that introduces exhaust gas of the internal combustion engine, a bypass passage that branches from the main exhaust passage and joins at the junction with the main exhaust passage, and the main exhaust passage and the bypass at the junction In the exhaust heat recovery device comprising a valve device that opens and closes the flow path, the bypass flow path includes a heat exchanger and a thermoelectric generator that exchange heat with the exhaust gas in the bypass flow path, The exhaust heat recovery apparatus is a single valve member that continuously sets the area of the other flow path in a state where one of the main exhaust flow path and the bypass flow path is closed.   The single valve member is driven according to the operating state of the internal combustion engine, and the main exhaust passage and the bypass passage are switched, and each of the main exhaust passage and the bypass passage is switched. The exhaust heat recovery apparatus according to claim 1, further comprising a control device that adjusts a flow path area.   The exhaust heat recovery apparatus according to claim 1 or 2, wherein the heat exchanger and the thermoelectric generator are provided with a cooling medium flow path to perform heat exchange by introducing the cooling medium of the internal combustion engine.

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