JP2021088981A - Exhaust heat recovery device - Google Patents

Abstract

To provide a small exhaust heat recovery device having excellent mountability to a vehicle.SOLUTION: An exhaust heat recovery device 10 connected to respective exhaust pipes on the upstream and downstream sides in which exhaust gas G flows includes: a heat exchange part 30 having a cooling medium flow passage 32 in which a cooling medium W exchanging heat with the exhaust gas G circulates and a heat exchange flow passage 33 of the exhaust gas G; a main exhaust gas flow passage part 20 forming a main exhaust gas flow passage 23 for preventing the exhaust gas G from flowing from an exhaust pipe 18 on the upstream side to the heat exchange part 30 and causing the exhaust gas G to flow from an exhaust pipe 19 on the downstream side; EGR piping 50 forming a recirculation flow passage 51 for causing the exhaust gas G to flow from the heat exchange flow passage 33 to an exhaust gas recirculation device 55 side on the intake side; and a changeover valve 60 distributing the exhaust gas G to the heat exchange flow passage 33 and the main exhaust gas flow passage 23. A cooling medium inlet pipe 34 and a cooling medium outlet pipe 35 are provided in the heat exchange part 30. The cooling medium inlet pipe 34, the cooling medium outlet pipe 35 and the EGR piping 50 are disposed on the exhaust pipe side on the upstream side.SELECTED DRAWING: Figure 2

Description

The present invention relates to an exhaust heat recovery device used in an internal combustion engine of an automobile, and more particularly to an exhaust heat recovery device suitable for use in an internal combustion engine provided with an exhaust gas recirculation device (EGR).

As an exhaust heat recovery device of this type, there is one disclosed in Patent Document 1. The exhaust heat recovery device disclosed in Patent Document 1 includes a main exhaust flow path for introducing the exhaust gas of an internal combustion engine, a detour flow path that branches from the main exhaust flow path and joins the main exhaust flow path, and the detour flow path. A heat exchanger that is interposed in the bypass flow path and introduces exhaust gas in the bypass flow path to exchange heat with the cooling medium, and opens and closes the main exhaust flow path and the bypass flow path on the downstream side of this heat exchanger. The valve member is provided, and the detour flow path between the valve member and the heat exchanger is configured to be communicatively connected to the exhaust gas recirculation device (EGR) via the recirculation flow path. Further, the valve device is driven by an actuator.

Japanese Unexamined Patent Publication No. 2016-446666

In the conventional exhaust heat recovery device, the flow of exhaust gas in the main exhaust flow path and the bypass flow path is performed by a single valve member, but the member that controls the flow of exhaust gas in the bypass flow path enters the bypass flow path. Therefore, space is indispensable on the detour flow path side, and the entire device becomes large accordingly.

Further, since the main exhaust flow path and the detour flow path including the heat exchanger are arranged in parallel, the dimension in the front-rear direction of the vehicle becomes large, the entire device becomes large, and the mountability of the vehicle becomes an issue.

Therefore, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a compact exhaust heat recovery device having excellent vehicle mountability.

According to the present invention, in an exhaust heat recovery device connected to an upstream exhaust pipe and a downstream exhaust pipe through which exhaust gas flows, a cooling medium flow path through which a cooling medium that exchanges heat with the exhaust gas circulates, and the exhaust gas. A heat exchange section having a heat exchange flow path and a main exhaust flow path portion that forms a main exhaust flow path in which the exhaust gas does not flow from the exhaust pipe on the upstream side to the heat exchange section but flows from the exhaust pipe on the downstream side. The EGR pipe forming a recirculation flow path for flowing the exhaust gas from the heat exchange flow path to the exhaust gas recirculation device side on the intake side, and switching to distribute the exhaust gas to the heat exchange flow path and the main exhaust flow path. A valve is provided, and a cooling medium inlet pipe and a cooling medium outlet pipe for connecting the cooling medium flow path are provided in the heat exchange section, respectively, and the cooling medium inlet pipe, the cooling medium outlet pipe, and the EGR pipe are provided. It is characterized in that it is arranged on the exhaust pipe side on the upstream side, respectively.

According to the present invention, the total length of the apparatus can be shortened and the size can be reduced by arranging the cooling medium inlet pipe, the cooling medium outlet pipe, and the EGR pipe of the heat exchange section on the upstream exhaust pipe side, respectively. It is possible to improve the mountability of the vehicle.

It is a perspective view which shows the exhaust heat recovery device of one Embodiment of this invention. It is a top view of the exhaust heat recovery device. It is a cross-sectional view of the exhaust heat recovery device in the exhaust heat recovery mode, (a) is a cross-sectional view taken along the line AA in FIG. 2, and (b) is a cross-sectional view taken along the line BB in FIG. .. It is a cross-sectional view of the exhaust gas recovery device in the exhaust gas recirculation mode, (a) is a cross-sectional view taken along the line AA in FIG. 2, and (b) is a cross-sectional view taken along the line BB in FIG. .. It is a cross-sectional view of the exhaust heat recovery device in the exhaust heat non-recovery mode, (a) is a cross-sectional view taken along the line AA in FIG. 2, and (b) is a cross-sectional view taken along the line BB in FIG. is there.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing an exhaust heat recovery device according to an embodiment of the present invention, FIG. 2 is a plan view of the exhaust heat recovery device, and FIG. 3 is a cross-sectional view of the exhaust heat recovery device in the exhaust heat recovery mode. 3 (a) is a cross-sectional view taken along the line AA in FIG. 2, FIG. 3 (b) is a cross-sectional view taken along the line BB in FIG. 2, and FIG. 4 is a cross-sectional view of the exhaust heat recovery device in the exhaust gas recirculation mode. 4A is a sectional view taken along the line AA in FIG. 2, FIG. 4B is a sectional view taken along the line BB in FIG. 2, and FIG. 5 is an exhaust heat of the exhaust heat recovery device. It is a cross-sectional view in the non-collection mode, FIG. 5A is a cross-sectional view taken along the line AA in FIG. 2, and FIG. 5B is a cross-sectional view taken along the line BB in FIG.

As shown in FIG. 1, the exhaust heat recovery device 10 includes an upstream exhaust pipe 18 and a downstream exhaust pipe through which exhaust gas G discharged from an engine (internal engine) 55 equipped with an exhaust gas recirculation device (EGR) flows. An apparatus main body 11 connected to each of 19 for recovering the heat of the exhaust gas G and recirculating the exhaust gas G to the engine 55, and exhaust heat for recovering the heat of the exhaust gas G shown in FIG. It has a recovery mode, an exhaust gas recirculation mode in which the exhaust gas G shown in FIG. 4 is recirculated to the engine 55, and an exhaust heat non-recovery mode in which heat recovery is not performed as shown in FIG.

As shown in FIGS. 1 to 5, the device main body 11 of the exhaust heat recovery device 10 forms a main exhaust flow path portion 20 that forms an exhaust gas main exhaust flow path 23 that allows exhaust gas G to flow from the gas introduction port 21 to the gas discharge port 22. A heat exchanger that forms the cooling medium flow path 32 of the cooling medium and the heat exchange flow path 33 of the exhaust gas G in which the exhaust gas G branches from the main exhaust flow path portion 20 and exchanges heat with the cooling water (cooling medium) W. A heat exchange section 30 having a 31 and a confluence section 40 forming a gas flow path 41 on the downstream side of the heat exchange section 30 connecting the downstream side of the heat exchange flow path 33 of the heat exchange section 30 and the main exhaust flow path 23. An EGR pipe 50 forming a recirculation flow path 51 for flowing the exhaust gas G flowing through the confluence 40 to the engine 55 on the intake side, and a switching valve 60 for distributing the exhaust gas G to the main exhaust flow path 23 and the heat exchange flow path 33. , Is equipped.

The flow mode of the exhaust gas G is switched between the switching valve 60 and the valve provided on the exhaust gas recirculation device side (not shown) as follows.

In the exhaust heat non-recovery mode, the main exhaust flow path 23 and the heat exchange flow path 33 are opened, and the gas flow path 41 and the recirculation flow path 51 on the downstream side of the heat exchange section 30 are closed. In the exhaust heat recovery mode, the main exhaust flow path 23 and the recirculation flow path 51 are closed, and the heat exchange flow path 3 and the gas flow path 41 on the downstream side of the heat exchange section 30 are opened. In the exhaust gas recirculation mode, the main exhaust flow path 23 and the gas flow path 41 on the downstream side of the heat exchange unit 30 are closed, and the heat exchange flow path 33 and the recirculation flow path 51 are opened.

As shown in FIGS. 1 and 2, the apparatus main body 11 is located on the lower side of one side surface and forms the main exhaust flow path 23, and on the first housing 12 (upper stage on one side surface). The second housing 13 which is located on the side) and forms the merging portion 40, and the third housing which is attached to the first housing 12 and the second housing 13 and is located on the other side surface side and forms the heat exchange portion 30. The upper lid portion 15 (note that the second housing 13 and the upper lid portion 15) cover the body 14, the upper surface opening side of the second housing 13 and the third housing 14, and assemble the housings 13 and 14 in a block shape. The lower lid portion 16 (note that the lower lid portion 16 is 2) and the lower lid portion 16 (note that the lower lid portion 16 is 2) to cover the lower surface opening side of the first housing 12 and the third housing 14 and assemble the housings 12 and 14 in a block shape. It may be divided). An actuator mounting housing 17 for fastening and fixing the actuator 65, which will be described later, via bolts 66 and nuts 67 is mounted on the side surface of the third housing 14.

As shown in FIG. 1, the gas introduction port 21 and the gas discharge port 22 of the main exhaust flow path 23 are formed in a cylindrical shape, and the main exhaust flow path 23 other than the gas introduction port 21 and the gas discharge port 22 is square. It is formed in a tubular shape or a cylindrical shape. An upstream exhaust pipe 18 is connected to the gas introduction port 21, and a downstream exhaust pipe 19 is connected to the gas discharge port 22.

As shown in FIGS. 3 (b), 4 (b), and 5 (b), the heat exchange flow path 32 of the cooling medium flow path 32 in which the cooling water (cooling medium) W of the heat exchange unit 30 circulates and the heat exchange flow path of the exhaust gas G. The heat exchanger 31 is formed by 33.

Further, as shown in FIGS. 1 to 5, the heat exchange section 30 is connected to the cooling medium inlet pipe 34 connected to the upstream end side of the cooling medium flow path 32 and to the downstream end side of the cooling medium flow path 32. Each cooling medium outlet pipe 35 is provided. The heat exchanger 31 is configured in a laminated arrangement from a plurality of metal plates such as aluminum materials, and is arranged vertically in the heat exchange unit 30 with respect to the flow direction of the exhaust gas G of the housing 12. Then, as shown in FIG. 3B, the cooling water (cooling medium) W flowing in from the cooling medium inlet pipe 34 flows into the heat exchange section 30 in the flow direction of the exhaust gas G (from the lower side of the heat exchanger 31). It exchanges heat with the exhaust gas G while flowing from the lower side to the upper side of the heat exchanger 31 in the same flow direction as the arrow pointing to the upper side), and flows out from the cooling medium outlet pipe 35. The cooling medium inlet pipe 34, the cooling medium outlet pipe 35, and the EGR pipe 50 are arranged on the upstream side exhaust pipe 18 side, which is the front side of the apparatus main body 11, respectively. Further, the EGR pipe 50 is arranged on the downstream side of the exhaust gas G from the heat exchange unit 30. That is, when viewed from the front side of the apparatus main body 11, the cooling medium inlet pipe 34 and the cooling medium outlet pipe 35 are arranged vertically on the right side of the inlet portion of the housing 12, and the EGR pipe 50 is arranged in the housing 12. It is arranged above the gas inlet 12. More specifically, when the apparatus main body 11 is viewed from the flow direction of the exhaust gas G of the main exhaust flow path 23, the heat exchange unit 30 has a U-shape having a horizontal region and a vertical region so as to surround the main exhaust flow path portion 20. The connection position of the confluence 40 of the EGR pipe 50 is vertically arranged with the main exhaust flow path 20 in a U-shaped horizontal region, and the cooling medium inlet pipe 34 and the cooling medium outlet pipe are connected. The connection positions of the 35 with the heat exchange unit 30 are vertically arranged with each other and are in a U-shaped vertical region.

Further, as shown in FIG. 3B, in the heat exchange section 30, the exhaust gas G exchanges heat with the heat exchange section gas inflow section 37 in which the exhaust gas G flows from the main exhaust flow path 23 into the heat exchange flow path 33. A heat exchange section gas outflow section 38 that flows out from the flow path 33 to the confluence section 40 is provided, respectively. The heat exchange section gas inflow section 37 is arranged on the cooling medium inlet pipe 34 side (lower side), and the heat exchange section gas outflow section 38 is arranged on the cooling medium outlet pipe 35 side (upper side). As shown in FIGS. 3A and 3B, a part of the heat exchange section 30 extends to the lower side of the main exhaust flow path 23, and the inlet portion of the heat exchange section gas inflow section 37 of the heat exchange section 30. The 36 and the opening 24 formed on the lower side of the main exhaust flow path 23 communicate with each other. Further, the upper portion of the heat exchange section 30 communicates with the confluence section 40 via the heat exchange section gas outflow section 38.

As shown in FIGS. 1 and 3 to 5, an EGR pipe 50 forming a recirculation flow path 51 is provided on the front surface of the second housing 13 forming the main exhaust flow path portion 20. A mounting flange 52 for connecting an exhaust pipe 53 extending from the engine 55 is attached to the tip of the EGR pipe 50.

Further, as shown in FIGS. 3 (a), 4 (a), and 5 (a), the communication port 25 is located at the confluence position on the downstream side of the gas flow path 41 of the main exhaust flow path 23 and the confluence portion 40. , 45 are provided respectively. By opening and closing each of the communication ports 25 and 45 and the main exhaust flow path 23 by the switching valve 60, the exhaust gas G is distributed to the main exhaust flow path 23 and the heat exchange flow path 33.

As shown in FIGS. 3 (a), 4 (a), and 5 (a), the switching valve 60 includes a butterfly valve portion 61 that opens and closes the main exhaust flow path 23, and a main exhaust flow path 23 and a confluence portion 40. It has a shutter valve portion 62 that opens and closes the communication ports 25 and 45 of the gas flow path 41 of the above. The butterfly valve portion 61 and the shutter valve portion 62 are provided in parallel with a predetermined interval by bending or the like. Further, the butterfly valve portion 61 is formed to be larger than the shutter valve portion 62. When the shutter valve portion 62 smaller than the butterfly valve portion 61 closes the communication ports 25 and 45 of the gas flow path 41 of the main exhaust flow path 23 and the confluence portion 40, the large butterfly valve portion 61 becomes the main exhaust flow path. It is designed to open 23. Then, the drive shaft 63 fixed to the center of the butterfly valve portion 61 is rotated by the actuator 65, so that the switching valve 60 swings. Due to the swing of the switching valve 60, as shown in FIG. 3A, when the main exhaust flow path 23 is closed in the butterfly valve portion 61, the shutter valve portion 62 joins the main exhaust flow path 23 and the confluence portion 40. When the communication ports 25 and 45 of the gas flow path 41 are opened, and as shown in FIGS. 4 (a) and 5 (a), the main exhaust flow path 23 is opened in the butterfly valve portion 61. In addition, the shutter valve portion 62 switches the communication ports 25 and 45 of the main exhaust flow path 23 and the gas flow path 41 of the merging portion 40 to the closed state.

According to the exhaust heat recovery device 10 of the above embodiment, as shown in FIGS. 3A and 3B, in the exhaust heat recovery mode, the main exhaust flow path 23 is fully closed at the butterfly valve portion 61 of the switching valve 60. Then, at the shutter valve portion 62 of the switching valve 60, the communication ports 25 and 45 of the main exhaust flow path 23 and the gas flow path 41 of the merging portion 40 are fully opened. In this state, the exhaust gas G discharged from the engine 55 and flowing from the exhaust pipe 18 on the upstream side flows from the opening 24 on the lower side of the main exhaust flow path 23 to the heat exchange section gas inflow section 37 to exchange heat. The gas flow path 41 of the merging section 40 passes from the gas inflow section 37 through the heat exchanger 31 and the gas outflow section 38 of the heat exchange section, and from the gas outflow section 38 of the heat exchange section via the gas flow path 41 of the merging section 40. And flows from the communication ports 45 and 25 of the main exhaust flow path 23 to the exhaust pipe 19 on the downstream side through the main exhaust flow path 23. Then, when the exhaust gas G discharged from the engine 55 passes through the heat exchange flow path 33 of the heat exchanger 31, heat exchange with the cooling water W passing through the cooling medium flow path 32 of the heat exchanger 31 is performed and discharged. The heat is recovered.

Further, as shown in FIGS. 4A and 4B, in the exhaust gas recirculation mode, the main exhaust flow path 23 is fully opened at the butterfly valve portion 61 of the switching valve 60, and the shutter valve portion 62 of the switching valve 60 is the main. The communication ports 25 and 45 of the exhaust flow path 23 and the gas flow path 41 of the confluence 40 are fully closed. In this state, the exhaust gas G discharged from the engine 55 and flowing from the exhaust pipe 18 on the upstream side flows to the exhaust pipe 19 on the downstream side through the main exhaust flow path 23 fully opened by the butterfly valve portion 61. .. At this time, when a valve (not shown) provided in the exhaust pipe 53 connecting the EGR pipe 50 and the engine 55 is opened, a part of the exhaust gas G1 is under the main exhaust flow path 23 due to the negative pressure on the exhaust pipe 53 side. It flows from the opening 24 on the side to the gas inflow section 37 of the heat exchange section, passes through the heat exchanger 31 and the gas outflow section 38 of the heat exchange section from the gas inflow section 37 of the heat exchange section, and joins from the gas outflow section 38 of the heat exchange section to the confluence section 40. It flows into the recirculation flow path 51 of the EGR pipe 50 via the gas flow path 41 of the above. As a result, the heat exchanger 31 exchanges heat with the cooling water W to recover the exhaust heat, and the exhaust gas G1 is recirculated to the engine 55 to improve fuel efficiency.

Further, as shown in FIGS. 5A and 5B, in the exhaust heat non-recovery mode, the main exhaust flow path 23 is fully opened in the butterfly valve portion 61 of the switching valve 60, and the shutter valve portion 62 of the switching valve 60. The communication ports 25 and 45 of the main exhaust flow path 23 and the gas flow path 41 of the confluence 40 are fully closed. In this state, the exhaust gas G discharged from the engine 55 and flowing from the exhaust pipe 18 on the upstream side flows to the exhaust pipe 19 on the downstream side through the main exhaust flow path 23 fully opened by the butterfly valve portion 61. .. At this time, since the exhaust gas G does not pass through the heat exchange flow path 33 of the heat exchanger 31, the exhaust heat is not recovered. Further, since the valve provided in the exhaust pipe 53 is in the closed state, the exhaust gas G does not recirculate from the recirculation flow path 51 of the EGR pipe 50 to the engine 55.

Further, according to the exhaust heat recovery device 10, as shown in FIG. 1, the cooling medium inlet pipe 34, the cooling medium outlet pipe 35, and the EGR pipe 50 of the heat exchange unit 30 are arranged on the upstream exhaust pipe 18 side, respectively. Further, by attaching the actuator 65 for driving the switching valve 60 to the side surface of the third housing 14 forming the heat exchange portion 30 of the apparatus main body 11, the total length and width of the apparatus can be shortened and the size can be reduced. It is possible to improve the mountability of the vehicle.

Further, since the opening area of the heat exchange flow path 33 of the heat exchange unit 30 can be widened, the ventilation resistance can be lowered. Further, since the switching valve 60 has the butterfly valve portion 61 and the shutter valve portion 62, the space can be effectively utilized, and it is possible to deal with only the main exhaust flow path 23.

Further, by arranging the heat exchange unit 30 and the actuator 65 adjacent to each other, it can be mounted even at a position directly under the exhaust manifold having high exhaust gas energy and high temperature. Further, the portion where the exhaust gas temperature is high can be efficiently cooled, and the boiling resistance of the heat exchanger 31 can be improved.

According to the above embodiment, the cooling water is used as the cooling medium, but the cooling medium may be other than the cooling water.

10 Exhaust heat recovery device 11 Equipment main body 18 Upstream side exhaust pipe 19 Downstream side exhaust pipe 20 Main exhaust flow path 21 Gas introduction port 22 Gas discharge port 23 Main exhaust flow path 24 Opening 25 Communication port 30 Heat exchange section 32 Cooling medium flow path 33 Heat exchange flow path 34 Cooling medium inlet pipe 35 Cooling medium outlet pipe 37 Heat exchange part Gas inflow part 38 Heat exchange part Gas outflow part 40 Confluence part 41 Heat exchange part downstream gas flow path 45 Communication port 50 EGR Piping 51 Recirculation flow path 55 Engine (internal engine) equipped with exhaust gas recirculation device (EGR)
60 Switching valve 61 Butterfly valve part 62 Shutter valve part 63 Drive shaft G, G1 Exhaust gas W Cooling water (cooling medium)

Claims (5)

In an exhaust heat recovery device having a gas inlet and a gas discharge port installed in an exhaust pipe from which exhaust gas from an internal combustion engine equipped with an exhaust gas recirculation device is guided.
A main exhaust flow path portion having a main exhaust flow path through which the exhaust gas flows from the gas introduction port to the gas discharge port, and
A heat exchange section that is attached to the main exhaust flow path and has a heat exchange flow path in which the exhaust gas diverted from the main exhaust flow path exchanges heat with the cooling medium.
With
The heat exchange section includes a heat exchanger having a cooling medium flow path through which the cooling medium flows, and a confluence section that divides the exhaust gas from the heat exchange flow path into the main exhaust flow path section and the exhaust gas recirculation device. Being done
An EGR pipe for introducing the exhaust gas from the confluence into the exhaust gas recirculation device is provided at the end of the confluence in the flow direction of the exhaust gas in the main exhaust flow path.
A cooling medium inlet pipe and a cooling medium outlet pipe constituting the cooling medium flow path are provided at the end of the heat exchange portion in the direction in which the exhaust gas of the main exhaust flow path flows.
When the main body of the device is viewed from the flow direction of the exhaust gas in the main exhaust flow path, the heat exchange portion has a U-shape having a horizontal region and a vertical region so as to surround the main exhaust flow path portion.
The connection position of the confluence portion of the EGR pipe is vertically arranged with the main exhaust flow path portion and is located in the U-shaped horizontal region.
An exhaust heat recovery device characterized in that the connection positions of the cooling medium inlet pipe and the heat exchange portion of the cooling medium outlet pipe are vertically arranged with each other and are in the U-shaped vertical region. The exhaust heat recovery device according to claim 1.
In the heat exchange section, the exhaust gas flows into the heat exchange flow path from the main exhaust flow path to the heat exchange section gas inflow section, and the exhaust gas flows from the heat exchange flow path to the gas flow path downstream of the heat exchanger. A heat exchange section and a gas outflow section are provided, respectively.
An exhaust heat recovery device, wherein the heat exchange section gas inflow section is arranged on the cooling medium inlet pipe side, and the heat exchange section gas outflow section is arranged on the cooling medium outlet pipe side. The exhaust heat recovery device according to claim 1.
The merging portion is provided with a communication port for returning the exhaust gas from the merging portion to the main exhaust flow path.
The main exhaust flow path portion is provided with an opening through which the exhaust gas is diverted to the heat exchange portion.
There is a switching valve provided on the downstream side of the main exhaust flow path from the opening to open and close the main exhaust flow path and the heat exchange flow path.
The switching valve has a butterfly valve portion that opens and closes the main exhaust flow path and a shutter valve portion that opens and closes the communication port, and the main exhaust can be rotated by a drive shaft provided in the butterfly valve portion. Fixed to the flow path,
An exhaust heat recovery device for distributing the exhaust gas into the heat exchange flow path and the main exhaust flow path. The exhaust heat recovery device according to claim 1.
An EGR pipe for introducing the exhaust gas from the confluence into the exhaust gas recirculation device is provided at an upstream end of the confluence of the confluence in the flow direction of the exhaust gas in the main exhaust flow path.
An exhaust heat recovery device characterized in that the cooling medium inlet pipe and the cooling medium outlet pipe are provided at an upstream end of the heat exchange portion in the direction of exhaust gas flow in the main exhaust passage. The exhaust heat recovery device according to any one of claims 1 to 4.
An exhaust heat recovery device characterized in that the EGR pipe is arranged on the downstream side of the exhaust gas from the heat exchange unit.

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