JP2019011717A - Thermoelectric device - Google Patents

Abstract

To provide a thermoelectric device capable of improving mountability on a vehicle while securing flexible controllability.SOLUTION: A thermoelectric device includes: an exhaust gas passage allowing inflow of exhaust gas from an internal combustion engine; and an exhaust gas after-treatment section which has a thermoelectric conversion section which is provided along a first passage extending in a first direction and allowing inflow of exhaust gas from the exhaust gas passage and an exhaust emission control section which is provided in parallel to the first passage in the first direction and purifies exhaust gas in-flowing from the exhaust gas passage. A flow passage of exhaust gas in-flowing from the exhaust gas passage in the exhaust gas after-treatment section is configured to be selectable between a first flow passage passing only the exhaust emission control section and a second flow passage passing the exhaust emission control section after passing the thermoelectric conversion section or selectable between the first flow passage passing only the exhaust emission control section and a third flow passage passing the thermoelectric conversion section after passing the exhaust emission control section.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a thermoelectric device.

    For the purpose of temperature management of exhaust gas discharged from the engine and recovery of waste heat contained in the exhaust gas, a thermoelectric conversion unit including a thermoelectric generator (TEG) provided in series with the engine and the exhaust gas purification device is provided. Thermoelectric devices are known. For example, in Patent Document 1, a thermoelectric generator provided in the exhaust passage generates power using waste heat contained in the exhaust gas, cools the exhaust gas, and supplies power to the thermoelectric generator from a power storage device such as a battery. It is described that the exhaust gas can be kept in a desired temperature range by functioning as a heat pump that heats the exhaust gas by heating.

JP 2012-82828 A

  In such a thermoelectric device, a bypass circuit that bypasses the thermoelectric conversion unit is provided in the exhaust system in which the thermoelectric conversion unit is provided, and the bypass valve installed on the bypass circuit is controlled to open and close, thereby protecting the thermoelectric conversion unit and fuel consumption. Flexible operation to improve the effect, exhaust gas purification performance, etc. can be considered. For example, when the exhaust gas becomes excessively hot, the thermoelectric conversion unit can be protected by switching the bypass valve so that the exhaust gas bypasses the thermoelectric conversion unit. In addition, when the temperature of the exhaust gas is low, such as when starting the engine, the exhaust valve is switched so that the exhaust gas bypasses the thermoelectric conversion section, thereby promoting warming of the exhaust gas and purifying the exhaust gas of the exhaust gas purification device. The time to reach the required temperature with respect to the rate can be shortened, and the purification performance can be improved. Even when the operation of the thermoelectric conversion unit is unnecessary or when the thermoelectric conversion efficiency is lowered, the fuel consumption performance can be improved by switching the bypass valve so that the exhaust gas bypasses the thermoelectric conversion unit.

  In flexible control employing such a bypass circuit, mountability becomes a problem due to the complexity of the system and the size of components. In particular, this problem becomes prominent when employed in commercial vehicles such as trucks and buses.

  As described above, at least one embodiment of the present invention has been made in view of the above-described circumstances, and provides a thermoelectric device that can improve mountability to a vehicle while ensuring flexible controllability. Objective.

In order to solve the above problems, a thermoelectric device according to at least one embodiment of the present invention includes an exhaust gas path through which exhaust gas from an internal combustion engine flows,
A thermoelectric conversion unit provided along a first path extending in a first direction and into which the exhaust gas flows from the exhaust gas path; and provided in parallel with the first path in the first direction; An exhaust gas purification unit that purifies the exhaust gas flowing in from the exhaust gas path, and an exhaust gas aftertreatment unit,
The flow path of the exhaust gas flowing from the exhaust gas path in the exhaust gas aftertreatment section passes through the exhaust gas purification section after passing through the first flow path that passes only the exhaust gas purification section and the thermoelectric conversion section. Between the first flow path that passes only the exhaust gas purification section and the exhaust gas purification section, and then passes through the thermoelectric conversion section. It is configured to be selectable between the third flow path.

According to the above configuration, the exhaust gas post-processing section is provided along the first path extending in the first direction, the thermoelectric conversion section into which exhaust gas flows from the exhaust gas path, and the first path in the first direction. And an exhaust gas purification unit that purifies the exhaust gas flowing in from the exhaust gas path. As a result, the exhaust gas aftertreatment unit can be reduced in size, so that mounting on a vehicle is improved.
Further, according to the above configuration, the exhaust gas flow path flowing from the exhaust gas path in the exhaust gas post-processing section passes through the first flow path that passes only the exhaust gas purification section and the thermoelectric conversion section, and then the exhaust gas purification. Between the first flow path and the exhaust gas purification section after passing through only the exhaust gas purification section, and after passing through the thermoelectric conversion section. It is configured to be selectable between the third flow path. As a result, it is possible to select whether or not the exhaust gas flowing from the exhaust gas path is guided to the thermoelectric conversion unit. it can. Therefore, the durability of the thermoelectric conversion part can be improved while improving the fuel efficiency.

  According to at least one embodiment of the present invention, it is possible to improve the mounting property of a thermoelectric device on a vehicle and improve the durability of the thermoelectric conversion unit while improving fuel efficiency.

It is a mimetic diagram showing the whole thermoelectric device composition concerning one embodiment. It is typical sectional drawing which shows the structure of the exhaust-gas post-processing part of one Embodiment, (a) shows the state which the bypass valve closed, (b) shows the state which the bypass valve opened. It is the figure which simplified and represented the direction of the flow of the exhaust gas in an exhaust-gas aftertreatment part, (a) represents the direction of the flow of the exhaust gas in the exhaust-gas aftertreatment part of one Embodiment, (b) is others The direction of the flow of the exhaust gas in the exhaust gas aftertreatment part of the embodiment is shown.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent.
For example, expressions expressing relative or absolute arrangements such as “in a certain direction”, “along a certain direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial” are strictly In addition to such an arrangement, it is also possible to represent a state of relative displacement with an angle or a distance such that tolerance or the same function can be obtained.
For example, an expression indicating that things such as “identical”, “equal”, and “homogeneous” are in an equal state not only represents an exactly equal state, but also has a tolerance or a difference that can provide the same function. It also represents the existing state.
For example, expressions representing shapes such as quadrangular shapes and cylindrical shapes represent not only geometrically strict shapes such as quadrangular shapes and cylindrical shapes, but also irregularities and chamfers as long as the same effects can be obtained. A shape including a part or the like is also expressed.
On the other hand, the expressions “comprising”, “comprising”, “comprising”, “including”, or “having” one constituent element are not exclusive expressions for excluding the existence of the other constituent elements.

FIG. 1 is a schematic diagram showing an overall configuration of a thermoelectric device 1 according to an embodiment of the present invention.
The thermoelectric device 1 is an apparatus that collects heat energy (waste heat) of exhaust gas discharged from an internal combustion engine 2 mounted on a vehicle as a driving power source and generates electric power. The internal combustion engine 2 is a prime mover that works by burning fossil fuel in a cylinder. In this embodiment, a four-cylinder diesel engine that uses light oil as fuel is exemplified as the internal combustion engine 2.
The application target of the present invention may include a gasoline engine that uses gasoline as a fuel.

In the internal combustion engine 2, air (outside air) taken from the intake gas path 4 is supplied to each cylinder via the intake manifold 5, and is compressed and heated in each cylinder according to the piston cycle. In each cylinder, fuel is injected from the injector to the compressed and heated air, and combustion is performed by self-ignition of the fuel. In the present embodiment, the internal combustion engine 2 includes a turbocharger 6 for supercharging. The turbocharger 6 includes a turbine 8 that is driven by exhaust gas, and a compressor 10 that operates in conjunction with the turbine 8.
An intercooler 12 for cooling the intake air compressed by the compressor 10 is installed on the downstream side of the compressor 10 in the intake gas path 4.

  The internal combustion engine 2 is equipped with a common rail system (not shown), and fuel supplied to each cylinder is increased in pressure by a supply pump and stored in a rail (accumulation chamber). It is controlled so that a predetermined amount is injected.

Exhaust gas generated in each cylinder is discharged to the outside from the exhaust gas path 16 via the exhaust manifold 14. An exhaust gas aftertreatment unit 60 is provided on the downstream side of the turbine 8 constituting the turbocharger 6 in the exhaust gas path 16. The exhaust gas aftertreatment unit 60 includes an exhaust gas purification unit 620 that is a DPF (Diesel Particulate Filter) as described later, and particulate matter contained in the exhaust gas is collected by the exhaust gas purification unit 620. Details of the exhaust gas aftertreatment unit 60 will be described later.
The exhaust gas purification unit 620 has a regeneration function of burning the collected particulate matter in order to improve the reduction in the collection performance when the collected amount of the particulate matter exceeds a predetermined amount. Also good.

A catalyst 20 for purifying the exhaust gas is provided on the downstream side of the exhaust gas after-treatment unit 60 in the exhaust gas path 16. In the present embodiment, a selective catalytic reduction denitration device (SCR: Selective Catalytic Reduction) is used as the catalyst 20 for purifying nitrogen oxides (NO _x ) contained in the exhaust gas. For example, urea water is used as a reducing agent in the selective catalytic reduction denitration apparatus. The reducing agent is hydrolyzed in a high-temperature atmosphere of exhaust gas, and the generated ammonia chemically reacts with nitrogen oxide (NO _x ) in the exhaust gas, so that nitrogen (N ₂ ), water (H ₂ O), and Purification is performed by reducing it to

The internal combustion engine 2 also includes an EGR system 22 for reducing nitrogen oxide (NO _x ) in the exhaust gas and improving fuel efficiency at partial load by recirculating a part of the exhaust gas to the intake side. The EGR system 22 adjusts the recirculation amount of the exhaust gas, the EGR path 24 formed between the exhaust manifold 14 and the intake manifold 5, the EGR cooler 26 for cooling the exhaust gas passing through the EGR path 24, and the exhaust gas recirculation amount. And an EGR valve 28. The opening degree of the EGR valve 28 is controlled by a control unit (not shown), and the recirculation amount of the exhaust gas by the EGR system 22 is adjusted.

  The cylinder block or the like of the internal combustion engine 2 is provided with a water jacket (not shown), and the internal combustion engine 2 is cooled by flowing cooling water through the water jacket. The cooling water circulates in the circulation path 30. The circulation path 30 includes a cooling water pump 32 for pumping the cooling water, and a radiator 34 for exchanging heat with the outside air to dissipate heat. The cooling water whose temperature has been increased by cooling the internal combustion engine 2 is sent to the radiator 34 by the cooling water pump 32, cooled by heat exchange with the outside air, and then sent to the internal combustion engine 2 again.

  Heat dissipation in the radiator 34 is promoted by blowing air from a radiator fan 35 disposed so as to face the radiator 34. The radiator fan 35 is driven by using a part of the power of the internal combustion engine 2, and the amount of air blown is controlled according to the temperature of the cooling water sent to the radiator 34, for example, so that the temperature of the cooling water is appropriate. Cooled to range.

  The cooling water pump 32 is a mechanical pump that is driven by using a part of the power of the internal combustion engine 2 by being mechanically connected to the internal combustion engine 2 via a transmission mechanism such as a belt. It may be an electric pump driven using electric power stored in the battery 42 or electric power generated by the alternator 36 or a thermoelectric conversion unit 610 described later.

The power generated in the internal combustion engine 2 is mainly transmitted to the traveling wheel side of the vehicle via an output shaft (not shown), but a part of the power is transmitted to the alternator 36 for power generation via a transmission mechanism such as a belt. Communicated. The alternator 36 is an AC generator that generates AC power by being rotated by power transmitted from the internal combustion engine 2. The AC power generated by the alternator 36 is DC converted by the inverter 38 and then supplied to the in-vehicle load 40, and the surplus is stored in the battery 42.
The alternator 36 can be used for power generation as described above, and can also assist the internal combustion engine 2 by consuming electric power stored in the battery 42 and driving it as an electric motor (motor).

(Exhaust gas aftertreatment section 60)
With reference to FIG. 2, the exhaust-gas post-processing part 60 of one Embodiment is demonstrated. FIG. 2 is a schematic cross-sectional view showing the structure of the exhaust gas aftertreatment unit 60 according to an embodiment. FIG. 2A shows a state in which a bypass valve 607, which will be described later, is closed, and FIG. ) Shows a state in which the bypass valve 607 is opened.
The exhaust gas post-processing unit 60 is provided along a first path 601 extending in a first direction which is the left-right direction in the drawing, and a thermoelectric conversion unit 610 into which exhaust gas flows from the exhaust gas path 16, and a first in the first direction. An exhaust gas purifying unit 620 is provided so as to be parallel to the one path 601 and purifies the exhaust gas flowing from the exhaust gas path 16.

The thermoelectric conversion unit 610 includes a heat exchanger 611 formed in a cylindrical shape so as to surround the exhaust gas purification unit 620, a thermoelectric element 612 attached to the outer periphery of the heat exchanger 611, and an outer periphery of the thermoelectric element 612. And an attached cooling device 613.
The heat exchanger 611 is provided in the first path 601 and contacts exhaust gas flowing in the first path 601. In other words, the first path 601 is an exhaust gas flow path formed in a cylindrical shape so as to surround the periphery of the exhaust gas purification unit 620, and a heat exchanger 611 having a cylindrical shape is provided in the first path 601. Has been placed.
The thermoelectric element 612 is an element that utilizes the Seebeck effect in which an electromotive force is generated when two ends of two kinds of different metals (or semiconductors) are connected and a temperature difference is provided between the two ends.
The cooling device 613 is a cooling device formed in a cylindrical shape so as to surround the outer periphery of the thermoelectric element 612, and low-temperature cooling water is introduced through a cooling water introduction line 46 branched from the circulation path 30. Cooling water from the cooling device 613 is returned to the circulation path 30 via the cooling water return line 48.

  A heat exchanger 611 is attached to the inner peripheral surface that is one surface of the thermoelectric element 612, and a cooling device 613 is attached to the outer peripheral surface that is the other surface. The heat exchanger 611 is configured to heat the inner peripheral surface of the thermoelectric element 612 with the heat of the exhaust gas flowing in the first path 601. The cooling device 613 is configured to cool the outer peripheral surface of the thermoelectric element 612 with low-temperature cooling water introduced via the cooling water introduction line 46.

  Between the thermoelectric conversion unit 610 and the exhaust gas purification unit 620, the exhaust gas that has passed through the first path 601 is disposed upstream of the exhaust gas purification unit 620 on the left side of the exhaust gas purification unit 620 inside the first path 601 having a cylindrical shape. A leading inner path 603 is provided. A downstream side on the right side of the exhaust gas purification unit 620 in the figure is connected to the catalyst 20 shown in FIG.

In the following description, the left upstream region of the exhaust gas purification unit 620 is referred to as a DPF upstream region 605. The DPF upstream region 605 is connected to the downstream side of the inner path 603. Further, the upstream side of the heat exchanger 611 in the first path 601 is referred to as a first path upstream portion 601a.
The first path upstream portion 601 a and the DPF upstream region 605 are separated by a partition wall 606. The partition wall 606 has an opening 606a that allows the first path upstream portion 601a and the DPF upstream region 605 to communicate with each other, and a bypass valve 607 that opens and closes the opening 606a is provided in the opening 606a. The bypass valve 607 is a butterfly valve type valve that opens and closes the opening 606a by, for example, rotation of a plate-shaped valve body, and is driven by an actuator (not shown). As shown in FIG. 2A, when the bypass valve 607 closes the opening 606a, the first path upstream portion 601a and the DPF upstream region 605 are separated by a partition wall 606. As shown in FIG. 2B, when the bypass valve 607 opens the opening 606a, the first path upstream portion 601a and the DPF upstream region 605 communicate with each other through the opening 606a.

  The flow of the exhaust gas in the exhaust gas aftertreatment unit 60 of the embodiment configured as described above will be described.

(When the bypass valve 607 closes the opening 606a)
As shown in FIG. 2A, when the bypass valve 607 closes the opening 606a, the exhaust gas flowing into the first path upstream portion 601a as shown by the arrow a from the exhaust gas path 16 on the left side of the figure is After flowing through the first path 601 downstream and passing through the heat exchanger 611 in the first path 601, the direction of the flow is reversed as indicated by the arrow b, and the flow passes through the inner path 603, and the arrow c As shown, the DPF upstream region 605 is reached.
When the exhaust gas passes through the heat exchanger 611 in the first path 601, the heat exchanger 611 transmits the heat of the exhaust gas to the thermoelectric element 612 to heat the inner peripheral surface of the thermoelectric element 612. Further, the outer peripheral surface of the thermoelectric element 612 is cooled by the cooling device 613.
In this manner, a temperature difference is generated between the inner peripheral surface and the outer peripheral surface of the thermoelectric element 612. Therefore, the thermoelectric element 612 performs thermoelectric generation (TEG).

The exhaust gas that has reached the DPF upstream region 605 passes through the exhaust gas purification unit 620 from the DPF upstream region 605. At that time, as described above, the particulate matter in the exhaust gas is captured by the exhaust gas purification unit 620.
The exhaust gas after passing through the DPF 602 flows to the catalyst 20 shown in FIG. 1 via the exhaust gas path 16 connected to the downstream side on the right side of the exhaust gas purification unit 620 as shown by the arrow d. The catalyst 20 purifies NO _x .

(When the bypass valve 607 opens the opening 606a)
As shown in FIG. 2B, when the bypass valve 607 opens the opening 606a, the exhaust gas flowing in from the exhaust gas passage 16 on the left side of the drawing does not flow toward the downstream side in the first passage 601. Then, as shown by an arrow e, it flows into the DPF upstream region 605 through the opening 606a. That is, the exhaust gas flowing into the first path upstream portion 601a bypasses the thermoelectric converter 610 and flows into the DPF upstream region 605.
Exhaust gas that has flowed into the DPF upstream region 605 passes through the DPF 602 and is passed through the exhaust gas path 16 connected to the downstream side on the right side of the exhaust gas purification unit 620 as shown by the arrow f in FIG. It flows to the catalyst 20 shown.

  Thus, in the above-described embodiment, the flow path of the exhaust gas flowing from the exhaust gas path 16 in the exhaust gas post-processing section 60 is the flow path that passes through the exhaust gas purification section 620 after passing through the thermoelectric conversion section 610. And a flow path that passes only through the exhaust gas purifying unit 620 can be selected.

(About thermoelectric power generation in the thermoelectric element 612)
As described above, when the bypass valve 607 closes the opening 606a and the exhaust gas passes through the heat exchanger 611 in the first path 601, the thermoelectric element 612 performs thermoelectric power generation.
Since the electric power generated by the thermoelectric element 612 is a direct current having a voltage corresponding to the temperature difference, it is transformed to a predetermined voltage by the converter 49 shown in FIG. The output of the converter 49 is supplied to the in-vehicle load 40 and the surplus is stored in the battery 42.
In the present embodiment, the power generated by the alternator 36 and the supply destination (the vehicle load 40 and the battery 42) of the power generated by the thermoelectric element 612 are shared. May be provided independently.

(Regarding opening / closing control of the bypass valve 607)
In the exhaust gas aftertreatment unit 60 of one embodiment, the opening and closing of the bypass valve 607 is controlled as follows, for example. The thermoelectric device 1 according to an embodiment includes a control unit 50 and a temperature sensor 45 a and a pressure sensor 45 b installed in the exhaust gas path 16, for example, upstream of the exhaust gas post-processing unit 60.
The amount of power generated in the alternator 36 and the thermoelectric element 612 is controlled by the control unit 50 that is a control unit. The control unit 50 is configured as a part of an ECU (Engine Control Unit) composed of an electronic arithmetic unit or the like, and executes control according to a predetermined program installed in advance.
The detection results of the temperature sensor 45a and the pressure sensor 45b are sent to the control unit 50 as electrical signals.

The control unit 50 detects that the temperature of the exhaust gas detected by the temperature sensor 45a is within a predetermined temperature range in which the temperature-power generation characteristics of the thermoelectric element 612, that is, the conversion efficiency is equal to or higher than a certain value, and If the detected pressure of the exhaust gas is equal to or lower than a predetermined pressure, a drive signal is output to an actuator (not shown) of the bypass valve 607 so as to close the opening 606a. As a result, as shown in FIG. 2A, the opening 606 a is closed by the bypass valve 607, so that the exhaust gas passes through the thermoelectric converter 610. Therefore, thermoelectric power generation is performed by the thermoelectric element 612, and the electric power generated by the thermoelectric element 612 is supplied to the in-vehicle load 40 and the battery 42 via the converter 49.
Further, the control unit 50 controls the amount of power generated by the alternator 36 so as to reduce the driving load of the alternator 36 of the internal combustion engine 2 according to the amount of power generated by the thermoelectric element 612.
Thereby, the thermal energy of the exhaust gas can be recovered as electric energy, so that energy efficiency is improved.

  In addition, the control unit 50 determines that the temperature of the exhaust gas detected by the temperature sensor 45a is outside the predetermined temperature range described above, or the pressure of the exhaust gas detected by the pressure sensor 45b exceeds the predetermined pressure described above. If so, a drive signal is output to an actuator (not shown) of the bypass valve 607 so as to open the opening 606a. Thereby, as shown in FIG. 2B, the opening 606 a is opened by the bypass valve 607, so that the exhaust gas bypasses the thermoelectric conversion unit 610. Therefore, thermoelectric power generation is not performed in the thermoelectric element 612.

Therefore, when the temperature of the exhaust gas detected by the temperature sensor 45a falls below the above-described predetermined temperature range, the exhaust gas bypasses the thermoelectric conversion unit 610 and the exhaust resistance in the exhaust gas path 16 can be suppressed. The performance degradation of the internal combustion engine 2 due to the installation of the part 610 can be suppressed.
Further, when the temperature of the exhaust gas detected by the temperature sensor 45a exceeds the above-described predetermined temperature range, it is possible to suppress the thermoelectric element 612 from being overheated by bypassing the thermoelectric conversion unit 610, and the thermoelectric conversion. The durability of the part 610 can be improved.
When the pressure of the exhaust gas detected by the pressure sensor 45b exceeds the above-described predetermined pressure, the exhaust gas bypasses the thermoelectric conversion unit 610 and the exhaust resistance in the exhaust gas path 16 can be suppressed. Reduction can be suppressed.

As described above, the exhaust gas post-processing unit 60 described above is provided along the first path 601 extending in the first direction which is the left-right direction in the figure, and the thermoelectric conversion unit 610 into which the exhaust gas flows from the exhaust gas path 16; An exhaust gas purification unit 620 is provided to be parallel to the first path 601 in the first direction and purifies the exhaust gas flowing in from the exhaust gas path 16. Thereby, since the exhaust gas post-processing part 60 can be reduced in size, the mounting property to a vehicle improves.
Further, in the exhaust gas aftertreatment unit 60 described above, the flow path of the exhaust gas flowing in from the exhaust gas path 16 in the exhaust gas aftertreatment unit 60 is a flow that passes through the exhaust gas purification unit 620 after passing through the thermoelectric conversion unit 610. It is configured to be selectable between a path and a flow path that passes only through the exhaust gas purification unit 620. Thus, since it is possible to select whether or not the exhaust gas flowing in from the exhaust gas path 16 is guided to the thermoelectric conversion unit 610, whether or not to operate the thermoelectric conversion unit 610 is determined as described above, for example, the temperature of the exhaust gas, It can be controlled according to the pressure of the exhaust gas. Therefore, the durability of the thermoelectric conversion unit 610 can be improved while improving the fuel efficiency.

The present invention is not limited to the above-described embodiments, and includes forms obtained by modifying the above-described embodiments and forms obtained by appropriately combining these forms.
For example, in the exhaust gas aftertreatment unit 60 of the above-described embodiment, the heat exchanger 611 of the thermoelectric conversion unit 610 is formed in a cylindrical shape so as to surround the exhaust gas purification unit 620. That is, in the exhaust gas aftertreatment unit 60 of the above-described embodiment, the thermoelectric conversion unit 610 is formed in a cylindrical shape so as to surround the exhaust gas purification unit 620. However, the thermoelectric conversion part 610 does not necessarily need to be formed in a cylindrical shape. For example, the thermoelectric conversion unit 610 may be formed so as to extend partly in the circumferential direction on the outer peripheral side of the exhaust gas purification unit 620. Further, a plurality of thermoelectric conversion units 610 may be provided so as to sandwich the exhaust gas purification unit 620 from the outer peripheral side. For example, a pair of thermoelectric conversion units 610 are arranged so as to sandwich the exhaust gas purification unit 620 from the outer peripheral side. May be.

For example, when the pair of thermoelectric conversion units 610 are arranged so as to sandwich the exhaust gas purification unit 620 from the outer peripheral side, the first path 601 of the exhaust gas post-processing unit 60 is the first horizontal direction shown in FIG. The two thermoelectric conversion units 610 are arranged in one of the two channels, and the other of the pair of thermoelectric conversion units 610 is arranged in the other of the two channels. May be.
In this case, a butterfly valve type flow control valve is provided in each of the first path upstream portion 601a in the two flow paths of the first path 601, and the exhaust gas is converted into the thermoelectric conversion unit 610 and the exhaust gas purification by the flow control valve. It may be configured to be able to switch between passing the part 620 or passing only the exhaust gas purification part 620.

In the exhaust gas aftertreatment unit 60 of the above-described embodiment, as shown in FIGS. 2A and 3A, the exhaust gas that has flowed into the first path upstream portion 601a from the exhaust gas path 16 on the left side of the drawing. Flows through the first path 601 toward the downstream side on the right side in the figure, passes through the heat exchanger 611 in the first path 601, and then reverses the direction of the flow to move the inner path 603 upstream of the DPF on the left side in the figure. The air flowed toward the side region 605, and the flow direction was further reversed to flow in the exhaust gas purification unit 620 toward the right in the figure. FIG. 3 is a diagram showing the flow direction of the exhaust gas in the exhaust gas aftertreatment unit 60 in a simplified manner. FIG. 3A shows the inside of the exhaust gas aftertreatment unit 60 according to the embodiment described above. 3 (b) shows the direction of the exhaust gas flow in the exhaust gas aftertreatment unit 60 of another embodiment described below.
That is, as in the exhaust gas aftertreatment unit 60 according to another embodiment shown in FIG. 3B, the exhaust gas flowing into the first path upstream portion 601a from the exhaust gas path 16 on the left side of the drawing is the first. After flowing through the path 601 toward the right downstream side in the figure and passing through the heat exchanger 611 in the first path 601, the direction of the flow is reversed to flow in the exhaust gas purification unit 620 toward the left in the figure. You may do it.

In the above-described embodiment, when the bypass valve 607 closes the opening 606a, the exhaust gas passes through the exhaust gas purification unit 620 after passing through the thermoelectric conversion unit 610. That is, in the above-described embodiment, the flow path of the exhaust gas flowing from the exhaust gas path 16 in the exhaust gas post-processing unit 60 is a flow path that passes through the exhaust gas purification unit 620 after passing through the thermoelectric conversion unit 610; It is configured to be selectable between a flow path that passes only through the exhaust gas purification unit 620.
However, when the bypass valve 607 closes the opening 606a, the exhaust gas may pass through the thermoelectric conversion unit 610 after passing through the exhaust gas purification unit 620. That is, the flow path of the exhaust gas flowing in from the exhaust gas path 16 in the exhaust gas aftertreatment section 60 includes only a flow path that passes through the thermoelectric conversion section 610 after passing through the exhaust gas purification section 620 and only the exhaust gas purification section 620. You may be comprised so that it can select between the flow paths which pass.

In the exhaust gas post-processing unit 60 of the above-described embodiment, thermoelectric power generation is performed by the thermoelectric element 612. For example, when the temperature of the exhaust gas is low, the electric power from the alternator 36 and the battery 42 is supplied to the thermoelectric element 612. The exhaust gas passing through the thermoelectric converter 610 may be heated by causing the thermoelectric element 612 to generate heat. For example, the exhaust gas passing through the thermoelectric conversion unit 610 may be heated by causing the thermoelectric element 612 to generate heat during regeneration of the exhaust gas purification unit 620.
In the above-described embodiment, a selective catalytic reduction denitration apparatus is used as the catalyst 20. However, in such a selective catalytic reduction denitration apparatus, the reaction rate of hydrolysis of urea water depends on the ambient temperature. When the exhaust gas is at a relatively low temperature, such as during cold start, the consumption of reducing agent required to produce a predetermined amount of ammonia increases. Therefore, the consumption of the reducing agent in the catalyst 20 can be effectively suppressed by promoting the temperature rise of the exhaust gas by causing the thermoelectric conversion unit 610 to function as a heater as described above. As a result, since the capacity of the storage tank for the reducing agent can be reduced, it is possible to achieve good mountability with respect to a vehicle having a limited space and to achieve economics by reducing the consumption of the reducing agent.

  In the above-described embodiment, the exhaust gas purification unit 620 and the thermoelectric conversion unit 610 are integrally configured as the exhaust gas post-processing unit 60. However, the structure is the same as that in the exhaust gas post-processing unit 60 of the above-described embodiment. The catalyst 20 and the thermoelectric conversion unit 610 may be integrally configured depending on the structure. That is, an exhaust gas flow path is provided around the catalyst 20, and the thermoelectric conversion unit 610 is disposed in the flow path, whereby the thermal energy of the exhaust gas passing through the catalyst 20 is converted into electrical energy by the thermoelectric conversion unit 610. You may make it do.

DESCRIPTION OF SYMBOLS 1 Thermoelectric device 2 Internal combustion engine 16 Exhaust gas path | route 20 Catalyst 60 Exhaust gas post-processing part 601 1st path | route 607 Bypass valve 610 Thermoelectric conversion part 620 Exhaust gas purification | cleaning part

Claims (1)

An exhaust gas path through which exhaust gas from the internal combustion engine flows,
A thermoelectric conversion unit provided along a first path extending in a first direction and into which the exhaust gas flows from the exhaust gas path; and provided in parallel with the first path in the first direction; An exhaust gas purification unit that purifies the exhaust gas flowing in from the exhaust gas path, and an exhaust gas aftertreatment unit,
The flow path of the exhaust gas flowing from the exhaust gas path in the exhaust gas aftertreatment section passes through the exhaust gas purification section after passing through the first flow path that passes only the exhaust gas purification section and the thermoelectric conversion section. Between the first flow path that passes only the exhaust gas purification section and the exhaust gas purification section, and then passes through the thermoelectric conversion section. A thermoelectric device configured to be selectable with the third flow path.

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