Exhaust gas heat recovery device

Abstract

An exhaust gas heat recovery device (1) is provided with: a first flow path member (10) having a first flow path through which exhaust gas flows; a second flow path member (20) that is adjacent to the first flow path member (10), has a heat exchange unit (30), and has a second flow path; and a valve mechanism (40) that opens and closes the first flow path and blocks or blocks the flow of the exhaust gas from the second flow path, and the first flow path member (10) is provided with a double-wall section (19) having an inner wall section (17) facing the first flow path and an outer wall section (18) positioned on the opposite side of the first flow path on at least a part of the upstream side in the flow direction of the exhaust gas from the valve mechanism (40).

Description

Technical Field

[0001] This invention relates to an exhaust heat recovery device. Background Technology

[0002] JP2021-188567A discloses a waste gas heat recovery device comprising: a first flow path component having a first flow path for waste gas to flow through; a second flow path component being disposed adjacent to the first flow path and having a second flow path bypassing (bypassing) the first flow path; and a heat exchange section for exchanging heat between the waste gas and a refrigerant.

[0003] The waste gas heat recovery device described in JP2021-188567A includes a valve mechanism for switching the flow path of waste gas to a first flow path or a second flow path. The valve mechanism includes: a butterfly valve that opens and closes the first flow path under the action of a rotating shaft orthogonal to the flow direction of the waste gas in the first flow path; and a gate portion that closes the outlet of the second flow path, which serves as a bypass flow path, when the butterfly valve opens the first flow path, and opens the outlet when the butterfly valve closes the first flow path. Summary of the Invention

[0004] In the waste gas heat recovery device disclosed in JP2021-188567A, for example, when the waste gas is bypassed from the first flow path to the second flow path and heat exchanged in the heat exchange section, if the first flow path is closed by a butterfly valve, the waste gas will be retained in the closed space formed by the butterfly valve and the first flow path components, and then flow into the second flow path.

[0005] However, if the exhaust gas remains trapped, its heat will be conducted to the first flow path component and released to the outside, resulting in heat loss. Therefore, there is a risk that the temperature of the exhaust gas flowing in the heat exchange section will decrease, leading to a reduction in heat recovery efficiency.

[0006] The purpose of this invention is to prevent the temperature of the waste gas flowing in the heat exchange section from dropping, thereby avoiding a decrease in heat recovery efficiency.

[0007] According to one aspect of the present invention, an exhaust gas heat recovery device for recovering heat from exhaust gas discharged from an engine by heat exchange with a fluid comprises: a first flow path component having a first flow path for exhaust gas flow formed therein; a second flow path component disposed adjacent to the first flow path component, having a second flow path formed therein that bypasses a portion of the first flow path, and having a heat exchange section for heat exchange between the exhaust gas flowing in the second flow path and the fluid; and a valve mechanism disposed in the first flow path, the valve mechanism opening the first flow path or closing the first flow path to guide the exhaust gas to the second flow path, wherein at least a portion of the first flow path component upstream of the valve mechanism in the direction of exhaust gas flow has a double wall portion, the double wall portion having: an inner wall portion facing the first flow path, and an outer wall portion located on the side of the inner wall portion opposite to the first flow path.

[0008] According to the present invention, the temperature of the exhaust gas flowing into the heat exchange section can be prevented from decreasing, thereby preventing a decrease in heat recovery efficiency. Attached Figure Description

[0009] Figure 1 This is a perspective view illustrating the waste gas heat recovery device according to an embodiment of the present invention.

[0010] Figure 2 A front view showing a portion of the waste gas heat recovery device involved in this embodiment.

[0011] Figure 3 This is a side view, taken from the upstream side of the first flow path, used to illustrate the heat recovery state of the waste gas heat recovery device according to this embodiment.

[0012] Figure 4 This is a perspective view illustrating the valve mechanism of the waste gas heat recovery device according to this embodiment.

[0013] Figure 5 A front view showing a portion of the waste gas heat recovery device involved in this embodiment.

[0014] Figure 6 This is a side view, taken from the upstream side of the first flow path, illustrating the non-recovery state of the waste gas heat recovery device according to this embodiment. Detailed Implementation

[0015] Hereinafter, with reference to the accompanying drawings, the waste gas heat recovery device 1 according to the embodiments of the present invention will be described.

[0016] Figure 1 This is a perspective view illustrating the waste gas heat recovery device 1 according to an embodiment of the present invention. Figure 2A front view showing a portion of the waste gas heat recovery unit 1 being removed. Furthermore, Figure 3 To observe from the upstream side of the first flow path 14 Figure 2 The side view of the waste gas heat recovery device 1 in the heat recovery state.

[0017] like Figure 1 As shown, the waste gas heat recovery device 1 includes: a first flow path component 10, a second flow path component 20, and a heat exchange section 30.

[0018] The first flow path component 10 has a body portion 11, a first inflow portion 12, and a first outflow portion 13. The body portion 11 has a hollow structure, and a first flow path 14 for the flow of exhaust gas is formed inside the body portion 11.

[0019] The first inlet 12 is an opening on one side of the main body 11 and is connected to the flow path of exhaust gas from the engine. The first outlet 13 is an opening on the other side of the main body 11 and is connected to the flow path of exhaust gas. In the exhaust gas flow, the first inlet 12 is located upstream of the first outlet 13.

[0020] The main body 11 is formed with a structure that supplies exhaust gas from the first flow path 14 to the second flow path 24 (see...). Figure 2 The first upstream opening 15 of the outlet and the first downstream opening 16 of the inlet for the flow of exhaust gas from the second flow path 24 to the first flow path 14.

[0021] The first flow path component 10 includes a butterfly valve 41 located at a position relative to the first flow path 14 for opening and closing ( Figure 2 The double wall portion 19 is located upstream of the flow direction of the exhaust gas. The double wall portion 19 has an inner wall portion 17 facing the first flow path 14 and an outer wall portion 18 located on the side of the inner wall portion 17 opposite to the first flow path 14.

[0022] In this embodiment, the waste gas heat recovery device 1 has an inner component 50 that covers at least a portion of the inner surface of the first flow path component 10.

[0023] In this embodiment, the inner component 50 forms the inner wall portion 17, and the first flow path component 10 forms the outer wall portion 18. That is, the first flow path component 10 and the inner component 50 form a double wall portion 19.

[0024] The double-walled portion 19 has a gap S1 between the inner wall portion 17 and the outer wall portion 18, which is isolated from the first flow path 14.

[0025] The inner component 50 has a joint 53 with the first flow path component 10 on a portion of its upstream or downstream side in the direction of exhaust gas flow. In this embodiment, the first flow path component 10 and the inner component 50 are connected by spot welding at the joint 53 located on the downstream side in the direction of exhaust gas flow.

[0026] In this embodiment, the inner component 50 has a first upright portion 51 that stands upright toward the inner side of the first flow path 14. The first upright portion 51 is located upstream of the first downstream opening 16 in the first flow path 14 and is formed along the direction of the first downstream opening 16 that is orthogonal to the flow direction of the exhaust gas.

[0027] Furthermore, the inner component 50 has a second upright portion 52 on its inner surface opposite to the first upright portion 51, which stands upright toward the inner side of the first flow path 14. This second upright portion 52 is formed on the upstream side of the butterfly valve 41 (valve body 43) when the valve mechanism 40 is in the heat recovery state, and is formed in a direction orthogonal to the flow direction of the exhaust gas.

[0028] The first erected part 51 is formed in the non-heat recovery state of the valve mechanism 40 ( Figure 5 The height H1 of the lower part from the inner surface of the first flow path component 10 is greater than the gap D1 generated in the separation direction between the first downstream opening 16 and the valve mechanism 40 (gate part 42). Furthermore, the second upright part 52 is formed such that, in the heat recovery state ( Figure 2 The height H2 of the lower part of the first flow path component 10 is greater than the gap D2 between the inner surface of the first flow path component 10 and the valve mechanism 40 (valve body 43) in the separation direction.

[0029] The second flow path component 20 is disposed adjacent to the first flow path component 10. The second flow path component 20 has: a body portion 21, a second upstream side opening portion 22, and a second downstream side opening portion 23.

[0030] The main body 21 has a hollow structure, and a second flow path 24 is formed inside the main body 21 for the flow of exhaust gas that bypasses a part of the first flow path 14.

[0031] The second upstream opening 22 is located on the upstream side of the second flow path 24 and collects the exhaust gas bypassing a portion of the first flow path 14 into the interior of the main body 21. The second downstream opening 23 allows the exhaust gas flowing through the interior of the main body 21 to flow into the first flow path 14.

[0032] The second upstream opening 22 is connected to the first upstream opening 15 formed in the first flow path component 10 via the first connecting portion 25. Furthermore, the second downstream opening 23 is connected to the first downstream opening 16 formed in the first flow path component 10 via the second connecting portion 26.

[0033] The inner side of the first connecting portion 25, the interior of the second flow path component 20, and the inner side of the second connecting portion 26 constitute the second flow path 24.

[0034] The first flow path component 10 and the second flow path component 20 described above allow exhaust gas to bypass from the first flow path 14 to the second flow path component 20 via the first connecting portion 25. Furthermore, exhaust gas flowing through the second flow path component 20 can flow into the first flow path 14 via the second connecting portion 26.

[0035] The second flow path component 20 includes a heat exchange section 30. The heat exchange section 30 includes a refrigerant inlet section 31, a heat exchange section body 32, and a refrigerant outlet section 33, and is supplied with cooling water, which is the refrigerant. The heat exchange section 30 performs heat exchange between the exhaust gas and the refrigerant flowing in the second flow path 24.

[0036] The refrigerant inlet 31 is a hollow tube-shaped portion that connects the flow path (not shown) for supplying cooling water before cooling the engine to the interior of the heat exchanger body 32. The refrigerant inlet 31 allows cooling water, which is the refrigerant, supplied from the aforementioned flow path, to flow into the interior of the heat exchanger body 32.

[0037] The refrigerant outlet 33 is a hollow tube-shaped portion that connects the interior of the heat exchanger body 32 to the flow path (not shown) that supplies cooling water to the engine. The refrigerant inlet 31 allows the cooling water flowing through the interior of the heat exchanger body 32 to flow out through the aforementioned flow path.

[0038] When exhaust gas flows within the portion of the body 21 of the second flow path component 20 surrounded by the heat exchange section body 32 (the portion of the second flow path 24 surrounded by the heat exchange section body 32), the heat exchange section 30 can perform heat exchange between the exhaust gas and the cooling water flowing inside the heat exchange section body 32, transferring the heat of the exhaust gas to the cooling water and recovering that heat. Furthermore, the state in which the valve mechanism 40 closes the first flow path 14 and the exhaust gas flows through the second flow path 24 for this heat exchange, as described later, is called the heat recovery state. On the other hand, the state in which the valve mechanism 40 opens the first flow path 14 and the exhaust gas does not flow through the second flow path 24 is called the heat non-recovery state.

[0039] like Figure 2 As shown, the waste gas heat recovery device 1 has a valve mechanism 40 inside the first flow path component 10.

[0040] Figure 4 For illustrative purposes Figure 1 A perspective view of the valve mechanism 40 of the waste gas heat recovery device 1 shown.

[0041] The valve mechanism 40 includes: a butterfly valve 41 for opening and closing the first flow path 14; a gate portion 42 for intercepting or blocking exhaust gas flowing from the second flow path 24 into the first flow path 14; and a valve body 43 for opening and closing the first flow path 14.

[0042] The valve mechanism 40 is located downstream of the inner component 50 in the direction of exhaust gas flow. That is, the valve mechanism 40 is located further downstream than the double-walled portion 19.

[0043] The valve body 43 is connected to a rotating shaft 44 and is supported rotatably within the first flow path 14. The rotating shaft 44 is connected to a drive shaft of an actuator, which is a drive unit (not shown).

[0044] The valve body 43 in the butterfly valve 41 is a plate-shaped component that can close the length and width of the first flow path 14. The valve body 43 can switch the opening or closing of the first flow path 14 by the rotation of the rotating shaft 44.

[0045] A gate portion 42 is provided on the valve body 43. The gate portion 42 has a plate-shaped gate body portion 42a and a pair of connecting portions 42b. The gate body portion 42a opens or closes the first downstream opening portion 16.

[0046] The connecting part 42b supports the gate body part 42a in such a way that the gate body part 42a and the valve body 43 are kept at a distance that prevents the gate body part 42a from contacting the inner wall part (first downstream opening 16) of the first flow path component 10 and can close the first downstream opening 16.

[0047] The gate portion 42 has a protrusion 45 that protrudes outward in the direction of the rotation radius of the rotating valve mechanism 40. In the non-heat recovery state of the valve mechanism 40 ( Figure 5 and Figure 6 When the protrusion 45 abuts against the inner surface of the first flow path component 10 on the downstream side of the first downstream side opening 16 in the direction of exhaust gas flow.

[0048] The end 43a of the valve body 43 upstream of the flow direction of the exhaust gas in the non-heat recovery state of the valve body 43 is configured to abut or approach the first upright part 51 in the heat recovery state of the valve mechanism 40, that is, in the state where the valve body 43 closes the first flow path 14.

[0049] Furthermore, the end 43b of the valve body 43 downstream of the flow direction of the exhaust gas in the non-heat recovery state of the valve body 43 is configured to abut or approach the second upright portion 52 in the heat recovery state of the valve mechanism 40, that is, in the state where the valve body 43 closes the first flow path 14.

[0050] In this embodiment, the first erected portion 51 is formed in a state greater than that of the valve mechanism 40 in the non-heat recovery state. Figure 5The gap D1 generated in the separation direction between the first downstream side opening 16 and the gate portion 42. Furthermore, the second upright portion 52 is formed to be larger than the gap in the heat recovery state of the valve mechanism 40. Figure 2 The gap D2 between the inner surface of the first flow path component 10 and the valve body in the separation direction.

[0051] <Valve mechanism operation and exhaust gas flow>

[0052] Next, the operation of the valve mechanism 40 and the flow of waste gas in the waste gas heat recovery device 1 according to this embodiment will be explained.

[0053] Figure 5 A front view showing a portion of the waste gas heat recovery unit 1 being removed. Additionally, Figure 6 To observe from the upstream side of the first flow path 14 Figure 5 The side view of the waste gas heat recovery device 1 in the non-recovery state.

[0054] The valve mechanism 40 in the waste gas heat recovery device 1 can be in the heat recovery state ( Figure 2 and Figure 3 ) and heat non-recovery state ( Figure 5 and Figure 6 The flow path 14 is switched between the two states: the heat recovery state is when the first downstream opening 16 is opened through the gate 42 while the first flow path 14 is closed through the butterfly valve 41; the heat non-recovery state is when the first downstream opening 16 is closed through the gate 42 while the first flow path 14 is opened through the butterfly valve 41.

[0055] In this embodiment, such as Figure 5 and Figure 6 As shown, if it becomes a non-heat recovery state, the valve mechanism 40 rotates in such a way that the main surface of the valve body 43 of the valve mechanism 40 is parallel to the flow direction of the exhaust gas. At the same time, the front end 42e of the gate portion 42 abuts against the downstream surface of the first upright portion 51 in the flow direction of the exhaust gas, and the protrusion 45 formed on the gate portion 42 abuts against the inner surface of the first flow path component 10 on the downstream side of the first downstream opening 16 in the flow direction of the exhaust gas.

[0056] In this state, the exhaust gas flows from the first inlet 12 into the first flow path component 10, flows through the first flow path 14 formed inside the first flow path component 10, and flows out from the first outlet 13.

[0057] On the other hand, the valve mechanism 40 rotates and switches to the heat recovery state, so that when the heat non-recovery state, the end 43a of the valve body 43 located upstream in the flow direction rotates toward the first upright part 51, while the end 43b of the valve body 43 located downstream in the flow direction rotates toward the second upright part 52, so that the main surface of the valve body 43 of the valve mechanism 40 is orthogonal to the flow direction of the exhaust gas.

[0058] like Figure 2 and Figure 3 As shown, if the valve mechanism is in a heat recovery state, the upstream surface of the first upright portion 51 in the flow direction abuts against the downstream surface of the end portion 43a of the valve body 43 in the flow direction. Furthermore, the downstream surface of the second upright portion 52 in the flow direction abuts against the upstream surface of the end portion 43b of the valve body 43 in the flow direction.

[0059] In this state, if exhaust gas flows from the first inlet 12 into the first flow path component 10, the exhaust gas will remain in the space S2 formed by the valve body 43 and the first flow path component 10, and will flow into the second flow path 24 from the first upstream side opening 15.

[0060] The exhaust gas flows through the second flow path 24 inside the second flow path component 20 and exchanges heat with the refrigerant flowing in the heat exchange section 30. After passing through the second flow path 24, the exhaust gas flows back to the first flow path 14 from the first downstream opening 16, and flows through the first flow path and out from the first outlet 13.

[0061] <Effects>

[0062] The waste gas heat recovery device 1 according to this embodiment includes: a first flow path component 10, which has a first flow path 14 for waste gas to flow through it; a second flow path component 20, which is disposed adjacent to the first flow path component 10, and has a second flow path 24 that bypasses a part of the first flow path 14, and has a heat exchange section 30 for heat exchange between the waste gas flowing through the second flow path 24 and the refrigerant; and a valve mechanism 40, which is disposed in the first flow path component 10, and has a butterfly valve 41 for opening and closing the first flow path 14 and a gate section 42 for intercepting or blocking the flow of waste gas from the second flow path 24.

[0063] The first flow path component 10 has a first upstream opening 15 as an outlet for exhaust gas to flow out from the first flow path 14 to the second flow path 24 and a first downstream opening 16 as an inlet for exhaust gas to flow in from the second flow path 24 to the first flow path 14.

[0064] The valve mechanism 40 is configured to switch between a heat recovery state and a heat non-recovery state by rotating a rotating shaft 44 orthogonal to the flow direction of the exhaust gas in the first flow path 14. As described above, in the heat non-recovery state, the first downstream opening 16 is closed by the gate 42 while the first flow path 14 is opened by the butterfly valve 41. In the heat recovery state, the first downstream opening 16 is opened by the gate 42 while the first flow path 14 is closed by the butterfly valve 41.

[0065] In this embodiment, the first flow path component 10 has a double wall portion 19 located upstream of the butterfly valve 41 used to open and close the first flow path 14 in the direction of exhaust gas flow. The double wall portion 19 has an inner wall portion 17 facing the first flow path 14 and an outer wall portion 18 located on the side opposite to the first flow path 14 of the inner wall portion 17.

[0066] The double-walled portion 19 has a gap S1 formed between the inner wall portion 17 and the outer wall portion 18 and isolated from the first flow path 14.

[0067] When the exhaust gas undergoes heat exchange in the heat exchange section 30, it will remain in the space S2 of the first flow path component 10 formed by the closed butterfly valve 41, and flow into the second flow path 24 from the first upstream opening 15 (see Figure 2 (The arrow in the image).

[0068] In this case, in the double wall portion 19, the heat of the exhaust gas flowing in the first flow path 14 is conducted from the inner wall portion 17 to the outside via the outer wall portion 18. Therefore, in the double wall portion 19, heat loss caused by heat dissipation from the outer wall portion 18 to the outside of the first flow path component 10 can be suppressed.

[0069] Therefore, according to the waste gas heat recovery device 1, the temperature of the waste gas flowing to the heat exchange section 30 can be prevented from dropping, thus preventing a decrease in heat recovery efficiency.

[0070] In this embodiment, the double wall portion 19 has a gap portion S1, so the gap portion S1 can be used to block the conduction of heat of the exhaust gas flowing in the first flow path 14 formed by the inner side of the inner wall portion 17.

[0071] Therefore, it is possible to improve the effect of suppressing heat loss caused by heat dissipation from the first flow path member 10 constituting the outer side wall portion 18 to the outside of the first flow path member 10.

[0072] In this embodiment, the inner component 50 is disposed inside the first flow path component 10 and covers the inner surface of the first flow path component 10. The inner component 50 forms an inner wall portion 17, and the first flow path component 10 forms an outer wall portion 18.

[0073] In this way, by forming the inner wall portion 17 with the inner component 50, the manufacture of the double wall portion 19 can be made easier.

[0074] In this embodiment, the inner component 50 is connected to the first flow path component 10 and the inner component 50 by spot welding at the joint 53 on the downstream side of the exhaust gas flow direction.

[0075] Thus, in this embodiment, the inner component 50 is engaged with the first flow path component 10 at one of the upstream or downstream sides in the flow direction of the exhaust gas, and the other unengaged part on the upstream or downstream side can serve as a free end for thermal expansion and contraction of the inner wall portion 17.

[0076] In particular, the outer wall portion 18 of the first flow path component 10 is connected to the second flow path component 20 at two points. More specifically, the first connecting portion 25 of the second flow path component 20 is connected to the first upstream opening portion 15 of the first flow path component 10, and the second connecting portion 26 of the second flow path component 20 is connected to the first downstream opening portion 16 of the first flow path component 10. In the non-heat recovery state, high-temperature exhaust gas flows within the first flow path 14, and therefore the first flow path component 10 tends to expand under the influence of the heat of the exhaust gas. However, in the first flow path component 10, as described above, the portion between the second flow path component 20 and the two connection points is constrained by the second flow path component 20, thus generating thermal stress. In contrast, in the waste gas heat recovery device 1, a double-walled portion 19 is disposed between the first upstream opening 15 and the first downstream opening 16 (i.e., the double-walled portion 19 is disposed between two connection points), and an inner wall portion 17 (inner component 50) that bears the heat of the waste gas is partially welded, with at least one end of it being a free end, thereby allowing thermal expansion of the inner wall portion 17. This improves the heat resistance of the waste gas heat recovery device 1.

[0077] [Other Implementation Methods]

[0078] The above describes the embodiments of the present invention. However, the above embodiments are only a part of the application examples of the present invention, and their purpose is not to limit the technical scope of the present invention to the specific structure of the above embodiments.

[0079] In the first embodiment, the fluid used for cooling the exhaust gas is not limited to cooling water, but may also be a medium such as a liquid or gas suitable for heat exchange.

[0080] In this embodiment, the valve mechanism 40 is a structure in which a pair of connecting portions 42b support both ends of the gate body portion 42a. Alternatively, for example, one connecting portion 42b may be provided at the center of the gate body portion 42a. Furthermore, it may be a so-called louver structure in which multiple connecting portions 42b are arranged in parallel.

[0081] The inner component 50 disposed inside the first flow path component 10 can be a structure divided along a horizontal plane that includes the axis of the rotation shaft portion 44 of the valve mechanism 40. Alternatively, the inner component 50 can be a structure divided along a plane perpendicular to the axis of the rotation shaft portion 44 of the valve mechanism 40.

[0082] This application claims priority to Japan Patent Application No. 2023-117582, filed on July 19, 2023 with the Japan Patent Office, the entire contents of which are incorporated herein by reference.

Claims

1. An exhaust gas heat recovery device that recovers heat from exhaust gas discharged from an engine by exchanging heat with a fluid, wherein, The waste gas heat recovery device includes: The first flow path component has a first flow path formed inside for the flow of exhaust gas; The second flow path component is disposed adjacent to the first flow path component, and has a second flow path that bypasses a part of the first flow path inside, and has a heat exchange section for heat exchange between the exhaust gas flowing in the second flow path and the fluid. as well as The valve mechanism is located in the first flow path. The valve mechanism can either open the first flow path or close the first flow path and guide the exhaust gas to the second flow path. The first flow path component has at least a double wall portion on the upstream side of the exhaust gas flow direction, which is closer to the valve mechanism than the valve mechanism. The double wall portion has an inner wall portion facing the first flow path and an outer wall portion located on the opposite side of the inner wall portion to the first flow path.

2. The waste gas heat recovery device according to claim 1, wherein, The double-walled portion has a gap formed between the inner wall portion and the outer wall portion and isolated from the first flow path.

3. The waste gas heat recovery device according to claim 1, wherein, The first flow path component has an inner component that covers at least a portion of the inner surface of the first flow path component. The inner component forms the inner wall portion, and the first flow path component forms the outer wall portion.

4. The waste gas heat recovery device according to claim 3, wherein, The first flow path component is connected to the second flow path component at two points. The double-walled portion is disposed in the first flow path component between two connection points with the second flow path component. The inner component has a joint on one of the upstream or downstream sides in the direction of exhaust gas flow, and the other of the upstream or downstream sides without a joint is a free end.

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