JP2013110825A - Thermoelectric generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation efficiency of a thermoelectric conversion module from being degraded while positioning the thermoelectric conversion module.SOLUTION: In the thermoelectric generator, thermoelectric conversion modules 27 are arranged through clearances 41 along the exhaust direction of exhaust gas passing through a heat receiving passage and interposed with heat conduction plates 42 between the thermoelectric conversion modules 27 so that the thermoelectric conversion module 27 is in contact with an upstream end 29a and a downstream end 29b of a heat receiving substrate 29.

Description

  The present invention relates to a thermoelectric power generator, and more particularly to a thermoelectric power generator that performs thermoelectric power generation using exhaust gas discharged from an internal combustion engine.

  Conventionally, since exhaust gas or the like discharged from an internal combustion engine of a vehicle such as an automobile contains thermal energy, if the exhaust gas is discarded as it is, the thermal energy is wasted. Therefore, the thermal energy contained in the exhaust gas is recovered by the thermoelectric generator and converted into electrical energy, and for example, the battery is charged.

  As this type of conventional thermoelectric power generation device, one side surface of the thermoelectric conversion module is opposed to the outer peripheral portion of the exhaust pipe into which exhaust gas discharged from the internal combustion engine is introduced, and the low temperature side of the thermoelectric conversion module is arranged. The other side is known to face a cooling water pipe through which cooling water flows.

  This thermoelectric conversion module is configured to include a thermoelectric conversion element such as a semiconductor, an electrode, a heat receiving substrate on the high temperature side, a heat radiating substrate on the low temperature side, and the like. Due to the low cooling water, power is generated by generating a temperature difference between the high temperature side and the low temperature side of the thermoelectric conversion module.

  By the way, in the exhaust gas flowing through the exhaust pipe, much of the heat amount of the exhaust gas is taken away by the thermoelectric conversion module on the upstream side of the exhaust pipe, and the temperature of the exhaust gas is lowered on the downstream side of the exhaust pipe.

  For this reason, the exhaust gas temperature varies between the upstream side of the exhaust pipe and the downstream side of the heat shield space, and the power generation efficiency of the downstream thermoelectric conversion module is lower than that of the upstream thermoelectric conversion module. As a result, there arises a problem that the overall power generation efficiency of the thermoelectric conversion module is lowered.

Conventionally, as a thermoelectric power generation apparatus capable of improving the power generation efficiency, the one shown in Patent Document 1 is known.
This thermoelectric power generation device includes a plurality of thermoelectric conversion modules arranged with a certain gap in the direction of the exhaust gas flowing in the exhaust pipe, and is arranged on the upstream side and on the downstream side Between the thermoelectric conversion modules, a connecting portion in which a depression is formed is provided.

  A heat transfer plate meshes with the recess so as to be able to come into contact with the connecting portion. When the heat transfer plate comes into contact with the connecting portion, the heat supplied to the upstream thermoelectric conversion module is transferred via the heat transfer plate. By transmitting to the thermoelectric conversion module, the power generation efficiency of the downstream thermoelectric conversion module is prevented from being lower than that of the upstream thermoelectric conversion module.

  For this reason, it can suppress that the temperature added to the upstream thermoelectric conversion module and the downstream thermoelectric conversion module varies, and it can prevent that the power generation efficiency of a thermoelectric conversion module falls.

  Further, the heat transfer power generation device shown in Patent Document 1 includes a leaf spring member that presses the cooling water pipe against the exhaust pipe via the thermoelectric conversion module, and positions the thermoelectric conversion module in the exhaust direction by the spring force of the leaf spring. ing.

JP 2005-130558 A

  However, in such a conventional thermoelectric generator, a connecting plate that engages with the recess of the connecting portion and can contact the connecting portion is provided, and this connecting plate is connected to the upstream end of the thermoelectric power generation conversion module. Since it is not in contact with the downstream end, heat can be transferred to the thermoelectric generation conversion module only from the direction perpendicular to the exhaust direction.

  That is, since a gap is formed between the connecting plate and the upstream end and the downstream end of the thermoelectric conversion module, the heat of the exhaust gas flows to the cooling water side from this gap, and the heat of the exhaust gas is converted to thermoelectric conversion. The heat cannot be transmitted from the exhaust direction of the module to the thermoelectric conversion module, and the heat transfer efficiency is not sufficient.

  In addition, the conventional thermoelectric power generator positions the thermoelectric conversion module because the thermoelectric conversion module is positioned in the exhaust direction by the spring force of the leaf spring member that presses the cooling water pipe against the exhaust pipe via the thermoelectric conversion module. Therefore, a leaf spring is required, the number of parts of the thermoelectric generator increases, and the manufacturing cost of the thermoelectric generator increases.

  The present invention has been made to solve the above-described conventional problems, and provides a thermoelectric power generation apparatus that can prevent the power generation efficiency of the thermoelectric conversion module from being lowered while positioning the thermoelectric conversion module. The purpose is to do.

  In order to achieve the above object, the thermoelectric generator according to the present invention is (1) provided with an exhaust pipe into which exhaust gas discharged from an internal combustion engine is introduced, coaxially with the exhaust pipe, and circulating cooling water. A cooling water pipe, and a plurality of thermoelectric conversion modules that perform thermoelectric power generation according to a temperature difference between the one side surface and the other side surface, with one side surface facing the exhaust pipe and the other side surface facing the cooling water pipe. The thermoelectric conversion module is a thermoelectric generator arranged with a gap along the exhaust direction of the exhaust gas flowing through the exhaust pipe, and contacts the upstream end and the downstream end in the exhaust direction of the thermoelectric module. Thus, it is comprised from what was provided with the heat conduction means by which the heat conduction part was interposed between the said thermoelectric conversion modules.

  In this thermoelectric generator, the heat conduction part is interposed between the thermoelectric conversion modules so as to come into contact with the upstream end and the exhaust direction downstream end of the thermoelectric conversion module. The heat flowing through the cooling water pipe can be transmitted to the upstream end and the downstream end of the thermoelectric conversion module through the heat conducting portion.

  For this reason, it is possible to effectively utilize the heat of the exhaust gas flowing through the gap between the thermoelectric conversion modules and to prevent the temperature applied to the upstream thermoelectric conversion module and the downstream thermoelectric conversion module from varying in the exhaust direction. It can prevent that the power generation efficiency of a conversion module falls.

  Moreover, since the heat conduction part is interposed between the thermoelectric conversion modules so that the exhaust direction upstream end and the exhaust direction downstream end of the thermoelectric conversion module are in contact, the thermoelectric conversion module is positioned in the exhaust direction by the heat conduction part. can do. For this reason, it can prevent that the number of parts of a thermoelectric power generating device increases, and can reduce the manufacturing cost of a thermoelectric power generating device.

  In the thermoelectric generator according to (1) above, (2) the heat conducting means includes a high-temperature side heat conducting sheet continuously interposed between the plurality of thermoelectric conversion modules and the exhaust pipe, The heat conduction part is configured to protrude from the high temperature side heat conduction sheet toward the cooling water pipe so as to contact the exhaust direction upstream end and the exhaust direction downstream end of the thermoelectric conversion module adjacent to the exhaust direction. Has been.

  Since this thermoelectric power generator includes a high-temperature side heat conduction sheet continuously interposed between a plurality of thermoelectric conversion modules and the exhaust pipe, it improves the adhesion between the thermoelectric conversion module and the exhaust pipe. Thus, the heat transfer efficiency of the exhaust gas can be improved.

  In addition, since the heat conducting portion is provided so as to protrude from the high temperature side heat conduction sheet toward the cooling water pipe so as to be in contact with the exhaust direction upstream end and the exhaust direction downstream end of the thermoelectric conversion module adjacent in the exhaust direction, Heat can be transmitted to the thermoelectric conversion module adjacent in the exhaust direction via the conductive sheet, and the temperature difference between the thermoelectric conversion modules adjacent in the exhaust direction can be reduced.

  For this reason, it can prevent that the electric power generation amount of the upstream thermoelectric conversion module falls. Specifically, when the temperature difference between the upstream thermoelectric conversion module and the downstream thermoelectric conversion module is large, the power generation amount differs between the upstream thermoelectric conversion module and the downstream thermoelectric conversion module.

In this case, a reverse voltage is applied from the thermoelectric conversion module having a high power generation amount to the thermoelectric conversion module having a low power generation amount, and heat transfer occurs in a direction in which the temperature difference is reduced by the Peltier effect.
Therefore, if the temperature difference between the upstream thermoelectric conversion module and the downstream thermoelectric conversion module is large, the reverse voltage from the upstream thermoelectric conversion module to the downstream thermoelectric conversion module increases, and the upstream thermoelectric conversion module The phenomenon that the amount of power generation decreases.

  In the present invention, since the temperature difference between the upstream thermoelectric conversion module and the downstream thermoelectric conversion module can be reduced, the reverse voltage applied to the downstream thermoelectric conversion module from the upstream thermoelectric conversion module is reduced. It is possible to prevent the power generation efficiency of the upstream thermoelectric conversion module from being lowered.

  In the thermoelectric generator according to (1) or (2), (3) the thermoelectric conversion module includes a plurality of N-type thermoelectric conversion elements and P-type thermoelectric conversion elements, and the N-type thermoelectric conversion elements and P-type thermoelectric elements. A heat receiving substrate provided on one side surface of the conversion element and facing the exhaust pipe, and a heat dissipation substrate provided on the other side surface of the N-type thermoelectric conversion element and the P-type thermoelectric conversion element and facing the cooling water pipe. The heat conducting portion is configured to be in contact with at least the exhaust direction upstream end and the exhaust direction downstream end of the heat receiving substrate of the adjacent thermoelectric conversion module.

  In this thermoelectric power generator, the heat conduction part contacts at least the upstream end and the downstream end of the heat receiving board of the adjacent thermoelectric conversion module, so that heat flowing from the gap between the thermoelectric conversion modules to the cooling water pipe is heated. The heat can be transmitted to the upstream end and the downstream end of the heat receiving substrate of the thermoelectric conversion module via the conductive portion.

  For this reason, it is possible to effectively utilize the heat of the exhaust gas flowing through the gap between the thermoelectric conversion modules and to prevent the temperature applied to the upstream thermoelectric conversion module and the downstream thermoelectric conversion module from varying in the exhaust direction. It can prevent that the power generation efficiency of a conversion module falls.

  (1) In the thermoelectric generators according to (1) to (3), (4) the heat conduction portion includes a relief portion extending along an exhaust direction, and the thermoelectric power source adjacent to the escape portion in the exhaust direction. It is comprised from what the wiring which connects conversion modules is provided.

  In this thermoelectric generator, the heat conduction part has an escape part extending along the exhaust direction, and an electric wire connecting the thermoelectric conversion modules adjacent in the exhaust direction to the escape part is provided. Adjacent thermoelectric conversion modules can be reliably connected.

  In the thermoelectric generators according to (2) to (4) above, (5) the heat conduction means is a low temperature side heat conduction that is continuously interposed between the plurality of thermoelectric conversion modules and the cooling water pipe. It is composed of a sheet.

  Since this thermoelectric power generator is provided with a low-temperature side heat conductive sheet continuously interposed between the thermoelectric conversion module and the cooling water pipe, it improves the adhesion between the thermoelectric conversion module and the cooling water pipe and reduces the exhaust gas. Heat transfer efficiency can be improved.

  For this reason, the heat conduction efficiency between one side and the other side of the thermoelectric conversion module can be improved, and the temperature difference between the one side and the other side of the thermoelectric conversion module can be increased, improving the power generation efficiency of the thermoelectric conversion module. Can be made.

In the thermoelectric generators according to (1) to (5) above, (6) the heat conducting means is made of expanded graphite.
Expanded graphite has a thermal conductivity several tens of times in the direction perpendicular to the layer direction. For this reason, if expanded graphite is used for the heat conduction part and this expanded graphite is interposed between the thermoelectric conversion modules so that the heat conduction in the exhaust direction is higher than the direction perpendicular to the exhaust direction, The transferred heat can be efficiently transmitted to the upstream end and the downstream end of the thermoelectric conversion module in the exhaust direction, and the temperature variation between the upstream thermoelectric conversion module and the downstream thermoelectric conversion module can be suppressed. it can.

  Moreover, if a high temperature side heat conductive sheet and a low temperature side heat conductive sheet are comprised from expanded graphite, the heat conduction efficiency of the exhaust direction of a high temperature side heat conductive sheet and a low temperature side heat conductive sheet can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, it can prevent that the electric power generation efficiency of a thermoelectric conversion module falls, positioning a thermoelectric conversion module.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows 1st Embodiment of the thermoelectric power generator which concerns on this invention, and is a schematic block diagram of the exhaust system of an engine provided with a thermoelectric power generator. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows 1st Embodiment of the thermoelectric power generating apparatus which concerns on this invention, and is side surface sectional drawing of a thermoelectric power generating apparatus. It is a figure which shows 1st Embodiment of the thermoelectric generator which concerns on this invention, and is AA arrow sectional drawing of FIG. It is a figure which shows 1st Embodiment of the thermoelectric power generation apparatus which concerns on this invention, and is a perspective view of a thermoelectric power generation module. It is a figure which shows 1st Embodiment of the thermoelectric power generation apparatus which concerns on this invention, and is principal part side surface sectional drawing of a thermoelectric power generation apparatus. It is a figure which shows 1st Embodiment of the thermoelectric generator which concerns on this invention, and is a top view of a heat conductive plate. It is a figure which shows 2nd Embodiment of the thermoelectric power generation apparatus which concerns on this invention, and is side surface sectional drawing of a thermoelectric power generation apparatus. It is a figure which shows 2nd Embodiment of the thermoelectric power generating apparatus which concerns on this invention, and is BB direction sectional drawing of FIG. It is a figure which shows 2nd Embodiment of the thermoelectric generator which concerns on this invention, and is a top view of a heat conductive sheet. It is a figure which shows 2nd Embodiment of the thermoelectric generator which concerns on this invention, and is principal part side sectional drawing of a thermoelectric generator. It is a figure which shows 2nd Embodiment of the thermoelectric power generating apparatus which concerns on this invention, and is principal part side surface sectional drawing of the thermoelectric power generating apparatus which has the heat conductive sheet of another structure. It is a figure which shows 2nd Embodiment of the thermoelectric power generating apparatus which concerns on this invention, and is principal part side surface sectional drawing of the thermoelectric power generating apparatus which has the heat conductive sheet of another structure. It is a figure which shows 2nd Embodiment of the thermoelectric power generating apparatus which concerns on this invention, and is principal part side surface sectional drawing of the thermoelectric power generating apparatus which has the heat conductive sheet of another structure.

Hereinafter, embodiments of a thermoelectric generator according to the present invention will be described with reference to the drawings. In the present embodiment, a case where the thermoelectric generator is applied to a water-cooled multi-cylinder internal combustion engine mounted on a vehicle such as an automobile, for example, a four-cycle gasoline engine (hereinafter simply referred to as an engine) will be described. Yes. The engine is not limited to a gasoline engine.
(First embodiment)
FIGS. 1-6 is a figure which shows 1st Embodiment of the thermoelectric power generating apparatus which concerns on this invention.
First, the configuration will be described.
As shown in FIG. 1, an engine 1 as an internal combustion engine mounted on a vehicle such as an automobile is formed by mixing air supplied from an intake system and fuel supplied from a fuel supply system at an appropriate air-fuel ratio. After the air-fuel mixture is supplied to the combustion chamber and combusted, the exhaust gas generated with this combustion is discharged from the exhaust system to the atmosphere.

  The exhaust system includes an exhaust manifold 2 attached to the engine 1 and an exhaust pipe 4 connected to the exhaust manifold 2 via a spherical joint 3. The exhaust manifold 2 and the exhaust pipe 4 An exhaust passage is formed.

  The spherical joint 3 allows moderate swinging of the exhaust manifold 2 and the exhaust pipe 4 and functions so as not to transmit the vibration and movement of the engine 1 to the exhaust pipe 4 or to attenuate and transmit them.

  Two catalysts 5 and 6 are installed in series on the exhaust pipe 4, and the exhaust gas is purified by the catalysts 5 and 6.

  Among the catalysts 5 and 6, the catalyst 5 installed upstream in the exhaust gas exhaust direction in the exhaust pipe 4 is a so-called start catalyst (S / C). The catalyst 6 installed downstream in the exhaust direction is a so-called main catalyst (M / C) or underfloor catalyst (U / F).

  These catalysts 5 and 6 are constituted by, for example, a three-way catalyst. This three-way catalyst exhibits a purifying action in which carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx) are collectively changed to harmless components by a chemical reaction.

  A water jacket is formed inside the engine 1, and the water jacket is filled with a coolant called long life coolant (LLC) (hereinafter simply referred to as coolant).

  The cooling water is led out from the outlet pipe 8 attached to the engine 1 and then supplied to the radiator 7, and is returned from the radiator 7 to the engine 1 through the cooling water reflux pipe 9.

  The radiator 7 cools the cooling water circulated by the water pump 10 by heat exchange with the outside air.

A bypass pipe 12 is connected to the reflux pipe 9, and a thermostat 11 is interposed between the bypass pipe 12 and the reflux pipe 9, and the amount of cooling water flowing through the radiator 7 and the bypass are bypassed by the thermostat 11. The amount of cooling water flowing through the pipe 12 is adjusted.
For example, during the warm-up operation of the engine 1, the amount of cooling water on the bypass pipe 12 side is increased to promote warm-up.

  A heater pipe 13 is connected to the bypass pipe 12, and a heater core 14 is provided in the middle of the heater pipe 13. The heater core 14 is a heat source for heating the passenger compartment using the heat of the cooling water.

  The air heated by the heater core 14 is introduced into the vehicle interior by the blower fan 15. A heater unit 16 is configured by the heater core 14 and the blower fan 15.

  The heater pipe 13 is provided with an upstream pipe 18 a for supplying cooling water to a thermoelectric generator 17 described later, and between the thermoelectric generator 17 and the reflux pipe 9, the thermoelectric generator 17 to the reflux pipe 9 are provided. A downstream pipe 18b for discharging the cooling water is provided.

  For this reason, when the exhaust heat recovery operation (details of this exhaust heat recovery operation will be described later) is performed in the thermoelectric generator 17, the cooling water flowing through the downstream pipe 18b flows through the upstream pipe 18a. It becomes higher than the temperature of the cooling water.

  On the other hand, the exhaust system of the engine 1 is provided with a thermoelectric power generation device 17 that recovers the heat of the exhaust gas discharged from the engine 1 and converts the heat energy of the exhaust gas into electrical energy. It is supposed to convert.

  As shown in FIGS. 2 and 3, the thermoelectric generator 17 is provided between the inner pipe 21 into which the exhaust gas G exhausted from the engine 1 is introduced and the inner pipe 21. And an outer pipe 23 as an exhaust pipe forming the heat receiving passage 22.

  An upstream end of the inner pipe 21 is connected to the exhaust pipe 4, and an exhaust passage 25 into which the exhaust gas G is introduced from the exhaust pipe 4 is formed inside the inner pipe 21. The inner tube 21 is fixed to the outer tube 23 via a support member 24, and the downstream end of the outer tube 23 is connected to the tail pipe 19.

  Therefore, the exhaust gas G discharged from the engine 1 through the exhaust pipe 4 to the exhaust passage 25 of the inner pipe 21 is discharged to the tail pipe 19 through the exhaust passage 25 and then discharged from the tail pipe 19 to the outside air.

A heat radiating fin 23A is formed on the inner peripheral portion of the outer tube 23 toward the inner tube 21, and the exhaust gas flowing through the heat receiving passage 22 is transmitted to the outer tube 23 through the heat radiating fin 23A.
Further, the thermoelectric generator 17 includes a thermoelectric conversion module 27 and a cylindrical cooling water pipe 28 provided coaxially with the outer pipe 23.

  As shown in FIG. 4, the thermoelectric conversion module 27 includes an insulating ceramic heat receiving substrate 29 constituting a high temperature side heat receiving portion and an insulating ceramic heat radiating substrate 30 constituting a low temperature side heat receiving portion. A plurality of N-type thermoelectric conversion elements 31 and P-type thermoelectric conversion elements 32 that generate thermoelectromotive force according to a temperature difference by the Seebeck effect are installed, and the N-type thermoelectric conversion elements 31 and the P-type thermoelectric conversion elements 32 are electrodes. They are alternately connected in series via 33a and 33b. Further, the thermoelectric conversion modules 27 adjacent in the exhaust direction are electrically connected via the wiring 35.

  In FIG. 2, the thermoelectric conversion modules 27 are arranged via gaps 41 having a certain length in the exhaust direction. Between the thermoelectric conversion module 27 and the outer peripheral portion 23a of the outer tube 23, a heat conduction plate 42 serving as a heat conduction portion constituting heat conduction means is interposed. The heat conduction plate 42 is made of, for example, expanded graphite. It is configured.

  As shown in FIG. 5, the heat conducting plate 42 includes an exhaust direction upstream end (hereinafter simply referred to as an upstream end) 29 a and an exhaust direction downstream end (hereinafter simply referred to as a downstream end) of the heat receiving substrate 29 of the adjacent thermoelectric conversion module 27. It is interposed between the thermoelectric conversion modules 27 so as to come into contact with 29b. In FIG. 5, the electrodes 33a and 33b are omitted. In addition, the heat receiving substrate 29 constitutes one side surface of the thermoelectric conversion module 27, and the heat dissipation substrate 30 constitutes the other side surface of the thermoelectric conversion module 27.

  As shown in FIG. 6, a rail groove 42 </ b> A is formed in the heat conducting plate 42 as a relief portion extending along the exhaust direction, and the thermoelectric conversion modules 27 adjacent to each other in the exhaust direction are formed in the rail groove 42 </ b> A. Is provided. For this reason, the wiring 35 can reliably connect the thermoelectric conversion modules 27 without being obstructed by the heat conducting plate 42.

  Since the thermoelectric conversion module 27 has a substantially square plate shape and needs to be in close contact between the outer pipe 23 and the cooling water pipe 28, the outer pipe 23 and the cooling water pipe 28 are as shown in FIG. It is formed into a polygon.

  Further, the outer tube 23 and the cooling water tube 28 may be circular. In this case, the heat receiving substrate 29 and the heat radiating substrate 30 of the thermoelectric conversion module 27 may be curved.

As shown in FIGS. 2 and 3, the cooling water pipe 28 includes a cooling water introduction part 28a connected to the upstream side pipe 18a and a cooling water discharge part 28b connected to the downstream side pipe 18b.
The cooling water pipe 28 has a cooling water discharge part 28b with respect to the cooling water introduction part 28a so that the cooling water introduced into the cooling water pipe 28 from the cooling water introduction part 28a flows in the same direction as the exhaust direction of the exhaust gas G. It is provided downstream in the exhaust direction. For this reason, the cooling water flows in the same direction as the flow of the exhaust gas G flowing in the heat receiving passage 22.

  As shown in FIG. 2, a plurality of communication holes 36 are formed in the inner tube 21, and the communication holes 36 communicate the inside of the inner tube 21 and the heat receiving passage 22. The communication holes 36 are formed at equal intervals in the circumferential direction of the inner tube 21 and are arranged along the exhaust direction of the exhaust gas G flowing through the inner tube 21, that is, the extending direction of the inner tube 21. ing. The communication holes 36 are not limited to those formed at regular intervals.

  The support member 24 has communication holes 24a formed at equal intervals in the circumferential direction of the support member 24. The heat receiving passage 22 communicates with the tail pipe 19 through the communication holes 24a. The communication holes 24a are not limited to those formed at regular intervals.

  The inner pipe 21 is provided with an on-off valve 26. The on-off valve 26 is provided at the downstream end of the inner pipe 21, and is rotatably attached to the outer pipe 23 so as to open and close the inner pipe 21. ing. The on-off valve 26 automatically opens and closes according to the pressure level of the exhaust gas G flowing through the exhaust passage 25.

  That is, the on-off valve 26 is introduced into the inner pipe 21 by closing the inner pipe 21 as shown by the solid line in FIG. 2 during idling or low load running of the engine 1 where the pressure of the exhaust gas G is low. Exhaust gas G is introduced into the heat receiving passage 22.

  Further, the on-off valve 26 releases the inner pipe 21 as shown by a broken line in FIG. For this reason, the thermoelectric generator 17 can prevent the exhaust gas G from increasing in back pressure and prevent the exhaust performance from deteriorating.

Next, the operation will be described.
When the engine 1 is cold started, the catalysts 5 and 6 and the cooling water of the engine 1 are all at a low temperature (about the outside temperature).

  When the engine 1 is started from this state, an exhaust gas G of, for example, 300 to 400 ° C. is discharged from the engine 1 to the exhaust pipe 4 through the exhaust manifold 2 as the engine 1 starts. 5 and 6 are heated by the exhaust gas G.

  Further, the cooling water is returned to the engine 1 through the bypass pipe 12 without passing through the radiator 7, so that the warm-up operation is performed.

  When the engine 1 is cold started, for example, the idling of the engine 1 is performed and the pressure of the exhaust gas G is low, so that the on-off valve 26 is closed. Therefore, the exhaust gas G introduced from the exhaust pipe 4 into the exhaust passage 25 of the inner pipe 21 is introduced into the heat receiving passage 22, and the cooling water W flowing through the cooling water pipe 28 is increased by the exhaust gas G passing through the heat receiving passage 22. Warm-up of the engine 1 is promoted.

  Further, when the engine 1 after warming up the engine 1 is traveling at a low load, the on-off valve 26 is closed because the pressure of the exhaust gas G is low even if the temperature of the exhaust gas G becomes high. For this reason, the exhaust gas G introduced from the exhaust pipe 4 into the exhaust passage 25 of the inner pipe 21 is introduced into the heat receiving passage 22. At this time, the thermal energy of the exhaust gas G is efficiently converted into pressure energy by the thermoelectric conversion module 27.

  Further, it is necessary to improve the cooling performance of the engine 1 when the engine 1 is traveling at a high load. When the engine 1 travels at a high load, for example, the pressure of the exhaust gas G increases because the engine 1 rotates at a high speed, so the pressure of the exhaust gas G introduced into the inner pipe 21 increases, and the on-off valve 26 is released. The

  When the on-off valve 26 is released, the exhaust passage 25 and the tail pipe 19 communicate with each other, and the exhaust gas G is discharged directly from the exhaust passage 25 to the tail pipe 19 without flowing through the heat receiving passage 22. For this reason, the temperature of the cooling water W flowing through the cooling water pipe 28 is not increased by the high-temperature exhaust gas G.

  At this time, since the thermostat 11 blocks communication between the bypass pipe 12 and the reflux pipe 9, the cooling water led out from the engine 1 through the lead-out pipe 8 is led out to the reflux pipe 9 through the radiator 7.

  For this reason, low-temperature cooling water is supplied to the engine 1, and the cooling performance of the engine 1 can be enhanced.

  Further, since the on-off valve 26 is released when the engine 1 is traveling at a high load, the back pressure of the exhaust gas G flowing through the exhaust passage 25 is not increased, and the exhaust performance of the exhaust gas G is prevented from deteriorating. Can do.

  Next, the operation of the thermoelectric generator 17 during low-load running of the engine 1 after the warm-up will be described.

  When the pressure of the exhaust gas G is small, the inner pipe 21 is closed by the on-off valve 26 and the communication between the exhaust passage 25 and the tail pipe 19 is blocked.

  In the thermoelectric power generation device 17 of the present embodiment, the thermoelectric conversion module 27 is arranged via the gap 41 along the exhaust direction of the exhaust gas flowing through the heat receiving passage 22, and the upstream end 29 a of the heat receiving substrate 29 of the thermoelectric conversion module 27 and A heat conducting plate 42 was interposed between the thermoelectric conversion modules 27 so as to contact the downstream end 29b.

  For this reason, heat flowing from the gap 41 between the thermoelectric conversion modules 27 to the cooling water pipe 28 can be transmitted to the upstream end 29a and the downstream end 29b of the heat receiving substrate 29 of the thermoelectric conversion module 27 via the heat conduction plate 42. it can.

  Therefore, it is possible to suppress the temperature applied to the upstream side thermoelectric conversion module 27 and the downstream side thermoelectric conversion module 27 from effectively varying heat flowing from the gap 41 of the thermoelectric conversion module 27 in the exhaust direction. It can prevent that the power generation efficiency of the conversion module 27 falls.

  Further, since the heat conduction plate 42 is interposed between the thermoelectric conversion modules 27 so as to be in contact with the upstream end 29 a and the downstream end 29 b of the heat receiving substrate 29 of the thermoelectric conversion module 27, the thermoelectric conversion is performed by the heat conduction plate 42. The module 27 can be positioned in the exhaust direction. For this reason, it is possible to prevent an increase in the number of parts of the thermoelectric generator 17 and reduce the manufacturing cost of the thermoelectric generator 17.

  Moreover, in this Embodiment, since the heat conductive plate 42 is comprised from the expanded graphite, the heat transmitted to the expanded graphite can be efficiently transmitted to the upstream end and the downstream end of the thermoelectric conversion module 27 in the exhaust direction. it can.

  Specifically, the expanded graphite has a hexagonal plate-like crystal structure and is configured in a layered manner, and in the plane of the layer, carbons are connected by a covalent bond, which is strong and easily moves with electrons. Therefore, the layer direction has high electrical conductivity and thermal conductivity.

In expanded graphite, an organic component is added to graphite and expanded in a direction perpendicular to the layer direction, so that the interlayer distance is widened. Therefore, a space exists in a direction perpendicular to the layer direction. For this reason, it can be made to change with respect to compressive force.
In addition, expanded graphite has a thermal conductivity that is one order of magnitude higher than the direction perpendicular to the layer direction. Therefore, even if the temperature in the direction perpendicular to the layer direction is uniform, the expanded graphite is heated in the direction perpendicular to the layer direction. Move.

  In the present embodiment, the heat conductive plate 42 is made of expanded graphite, and the heat conductive plate 42 is interposed between adjacent thermoelectric conversion modules 27 so that the direction perpendicular to the layer direction of the heat conductive plate 42 is the exhaust direction. By mounting, the heat transmitted to the heat conduction plate 42 can be efficiently transmitted to the upstream end 29a and the downstream end 29b of the heat receiving substrate 29 of the thermoelectric conversion module 27, and the upstream thermoelectric conversion module 27 and the downstream It is possible to further suppress the variation in temperature with the thermoelectric conversion module 27 on the side.

(Second Embodiment)
FIGS. 7-13 is a figure which shows 2nd Embodiment of the thermoelectric power generating apparatus which concerns on this invention, The same number is attached | subjected to the structure same as 1st Embodiment, and description is abbreviate | omitted.
6 to 9, a heat conduction sheet 51 as a high temperature side heat conduction sheet constituting a heat conduction means is interposed between the thermoelectric conversion module 27 and the outer peripheral portion 23 a of the outer tube 23. The sheet 51 is made of expanded graphite. The heat conductive sheet 51 is a single heat conductive sheet that is continuously interposed between the plurality of thermoelectric conversion modules 27 and the outer tube 23.

  A heat conduction sheet 52 as a low temperature side heat conduction sheet constituting a heat conduction means is interposed between the thermoelectric conversion module 27 and the inner peripheral portion 28c of the cooling water pipe 28. It is composed of expanded graphite. The heat conductive sheet 52 is a single heat conductive sheet continuously interposed between the plurality of thermoelectric conversion modules 27 and the cooling water pipe 28.

  Further, a fitting groove 51B is formed in the heat conductive sheet 51, and the thermoelectric conversion module 27 is fitted into the fitting groove 51B so that the periphery of the thermoelectric conversion module 27 is surrounded. Yes.

  Further, the heat conductive sheet 51 is integrally provided with a convex portion 51A as a heat conductive portion, and this convex portion 51A is provided at the upstream end 29a and the downstream end 29b of the heat receiving substrate 29 of the adjacent thermoelectric conversion module. It protrudes from the heat conductive sheet 51 toward the cooling water pipe 28 so as to come into contact.

  In the present embodiment, the heat conduction sheet 51, the convex portion 51A, and the heat conduction sheet 52 constitute a heat conduction means. In FIG. 9, the electrodes 33a and 33b are omitted.

  As shown in FIGS. 9 and 10, a rail groove 51a as a relief portion is formed in the convex portion 51A of the heat conductive sheet 51, and the thermoelectric conversion modules 27 adjacent to each other in the exhaust direction are formed in the rail groove 51a. A wiring 35 to be connected is provided. Therefore, the wiring 35 can reliably connect the thermoelectric conversion modules 27 without being obstructed by the convex portion 51A.

  In the present embodiment, a heat conductive sheet 51 continuously provided between the plurality of thermoelectric conversion modules 27 and the outer tube 23 and made of expanded graphite is provided, and the heat conductive sheet 51 is provided in the exhaust direction. Since the convex portion 51A that protrudes from the heat conductive sheet 51 toward the cooling water pipe 28 is formed so as to contact the upstream end 29a and the downstream end 29b of the heat receiving substrate 29 of the adjacent thermoelectric conversion module 27, thermoelectric conversion is performed by the convex portion 51A. The module 27 can be positioned in the exhaust direction. For this reason, it is possible to prevent an increase in the number of parts of the thermoelectric generator 17 and reduce the manufacturing cost of the thermoelectric generator 17.

  Moreover, in this Embodiment, heat can be transmitted to the thermoelectric conversion module 27 adjacent to an exhaust direction via the heat conductive sheet 51, and the temperature difference of the thermoelectric conversion module 27 adjacent to an exhaust direction can be made small. .

  For this reason, it can prevent that the electric power generation amount of the upstream thermoelectric conversion module 27 falls. Specifically, when the temperature difference between the upstream thermoelectric conversion module 27 and the downstream thermoelectric conversion module 27 is large, the power generation amount differs between the upstream thermoelectric conversion module 27 and the downstream thermoelectric conversion module 27. In this case, a reverse voltage is applied from the thermoelectric conversion module 27 with a high power generation amount to the thermoelectric conversion module 27 with a low power generation amount, and heat transfer occurs in a direction in which the temperature difference decreases due to the Peltier effect.

  Therefore, if the temperature difference between the upstream thermoelectric conversion module 27 and the downstream thermoelectric conversion module 27 is large, the reverse voltage from the upstream thermoelectric conversion module 27 to the downstream thermoelectric conversion module 27 increases, and the upstream side Of the thermoelectric conversion module 27 is reduced.

  In the present embodiment, the thermoelectric conversion module 27 has a heat conductive sheet 51 interposed between the thermoelectric conversion module 27 and the upstream end 29a of the heat receiving substrate 29 of the thermoelectric conversion module 27 adjacent to the convex portion 51A of the heat conductive sheet 51. Therefore, the temperature difference between the upstream thermoelectric conversion module 27 and the downstream thermoelectric conversion module 27 can be reduced.

  As a result, the reverse voltage applied from the upstream thermoelectric conversion module 27 to the downstream thermoelectric conversion module 27 can be reduced, and the power generation efficiency of the upstream thermoelectric conversion module 27 can be prevented from decreasing.

  In the present embodiment, in particular, the heat conductive sheet 51 is made of expanded graphite. As described above, this expanded graphite has a thermal conductivity that is an order of magnitude higher than the direction perpendicular to the layer direction, so that the temperature perpendicular to the layer direction is perpendicular to the layer direction even if the temperature in the direction perpendicular to the layer direction becomes uniform. Heat in any direction.

  In the present embodiment, the heat conductive sheet 51 is interposed between the thermoelectric conversion module 27 and the outer tube 23 so that the direction perpendicular to the layer direction of the heat conductive sheet 51 is the exhaust direction. The heat can be efficiently moved in the exhaust direction via 51, and variations in temperature between the upstream thermoelectric conversion module 27 and the downstream thermoelectric conversion module 27 can be suppressed.

  In addition, as described above, expanded graphite adds an organic component to graphite and expands in a direction perpendicular to the layer direction, so that the interlayer distance is widened, so there is a space in the direction perpendicular to the layer direction. Therefore, it can be deformed with respect to the compressive force.

  For this reason, even if there are irregularities on the surfaces of the outer tube 23 and the heat receiving substrate 29, the adhesion between the thermoelectric conversion module 27 and the outer tube 23 can be improved by the heat conductive sheet 51.

  Further, in the present embodiment, since the heat conductive sheet 52 continuously provided between the plurality of thermoelectric conversion modules 27 and the cooling water pipe 28 is provided, the cooling water pipe 28 and the surface of the heat dissipation substrate 30 are provided. Even if there are irregularities, the heat conductive sheet 52 can improve the adhesion between the thermoelectric conversion module 27 and the cooling water pipe 28.

  Therefore, the heat conduction efficiency between the heat receiving substrate 29 of the thermoelectric conversion module 27 and the heat radiating substrate 30 can be improved, and the temperature difference between the heat receiving substrate 29 and the heat radiating substrate 30 of the thermoelectric conversion module 27 can be increased. The power generation efficiency of the module 27 can be improved.

  In the present embodiment, as shown in FIG. 11, thin metal plates 53 and 54 made of aluminum, copper, stainless steel or the like are incorporated in the heat conductive sheets 51 and 52, and the rigidity of the heat conductive sheets 51 and 52 is increased. You may make it raise.

  Also, as shown in FIG. 12, thin metal foils 54a, 54b, 55a, 55b made of aluminum, copper, stainless steel, or the like are provided on both surfaces of the heat conductive sheets 51, 52 to increase the rigidity of the heat conductive sheets 51, 52. You may do it.

  Moreover, in this Embodiment, although the convex part 51A is provided in the heat conductive sheet 51, you may provide the convex part 52A in the heat conductive sheet 52 as shown in FIG. If it does in this way, positioning of thermoelectric conversion module 27 can be performed by convex parts 51A and 52A.

  As described above, the thermoelectric power generation device according to the present invention has an effect of preventing the power generation efficiency of the thermoelectric conversion module from being lowered while positioning the thermoelectric conversion module, and is discharged from the internal combustion engine. It is useful as a thermoelectric power generation apparatus that performs thermoelectric power generation using exhaust gas.

1 engine (internal combustion engine)
17 Thermoelectric generator 23 Outer pipe (exhaust pipe)
23a outer peripheral part 27 thermoelectric conversion module 28 cooling water pipe 28c inner peripheral part 29 heat receiving substrate (one side)
29a Exhaust direction upstream end 29b Exhaust direction downstream end 30 Heat dissipation board (other side)
31 N-type thermoelectric conversion element 32 P-type thermoelectric conversion element 35 Wiring 41 Crevice 42 Heat conduction plate (heat receiving part, heat conduction means)
42A, 51a Rail groove (flank)
51 Heat conduction sheet (high temperature side heat conduction sheet, heat conduction means)
51A Convex part (heat conduction part)
52 Heat conduction sheet (low temperature side heat conduction sheet, heat conduction means)

Claims (6)

An exhaust pipe into which exhaust gas discharged from the internal combustion engine is introduced, a cooling water pipe provided coaxially with the exhaust pipe and through which cooling water flows, one side facing the exhaust pipe and the other side facing the cooling pipe A plurality of thermoelectric conversion modules facing the water pipe and performing thermoelectric power generation according to a temperature difference between the one side surface and the other side surface, and the thermoelectric conversion module is along an exhaust direction of the exhaust gas flowing through the exhaust pipe A thermoelectric generator arranged through a gap,
A thermoelectric generator comprising heat conduction means having a heat conduction portion interposed between the thermoelectric conversion modules so as to come into contact with an upstream end and an exhaust direction downstream end of the thermoelectric conversion module.   The heat conduction means includes a high-temperature side heat conduction sheet continuously interposed between the plurality of thermoelectric conversion modules and the exhaust pipe, and the heat conduction portion is adjacent to the exhaust direction in the thermoelectric conversion module. 2. The thermoelectric generator according to claim 1, wherein the thermoelectric generator is provided so as to protrude from the high-temperature-side heat conductive sheet toward the cooling water pipe so as to come into contact with an upstream end in the exhaust direction and a downstream end in the exhaust direction.   The thermoelectric conversion module includes a plurality of N-type thermoelectric conversion elements and P-type thermoelectric conversion elements, a heat receiving substrate provided on one side of the N-type thermoelectric conversion elements and the P-type thermoelectric conversion elements, and facing the exhaust pipe; An exhaust direction of the heat receiving substrate of the adjacent thermoelectric conversion module, which is provided on the other side surface of the N-type thermoelectric conversion element and the P-type thermoelectric conversion element and is configured from a heat dissipation substrate facing the cooling water pipe. The thermoelectric power generator according to claim 1 or 2, wherein the thermoelectric generator contacts the upstream end and the downstream end in the exhaust direction.   The heat conduction part has an escape part extending along an exhaust direction, and wiring for connecting the thermoelectric conversion modules adjacent to the escape part in the exhaust direction is provided. The thermoelectric power generator according to claim 3.   5. The heat conduction means includes a low-temperature side heat conduction sheet continuously interposed between the plurality of thermoelectric conversion modules and the cooling water pipe. The thermoelectric power generator according to claim 1.   The thermoelectric generator according to any one of claims 1 to 5, wherein the heat conducting means is made of expanded graphite.

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