Exhaust heat recoverer

Abstract

An exhaust heat recovery device (10) is provided with: a first exhaust pipe (22); a second exhaust pipe (24) forming a gap (46) between the second exhaust pipe (24) and the first exhaust pipe (22); a third exhaust pipe (26) surrounding the second exhaust pipe (24); a heat recovery material (80) that is disposed between the second exhaust pipe (24) and the third exhaust pipe (26) and that exchanges heat with a medium flow path (132) provided on the outer periphery of the third exhaust pipe (26); a valve (161) that opens and closes the second exhaust pipe (24); and a bearing member (163) provided between the second exhaust pipe (24) and the third exhaust pipe (26), in the exhaust heat recovery device (10), in a state in which the valve (161) is closed, the exhaust gas (20) is guided to the heat recovery member (80) through the gap (46), and in a state in which the valve (161) is open, the exhaust gas (20) bypasses the heat recovery member (80) and is guided to the third exhaust pipe (26), and the bearing member (163) is provided between the second exhaust pipe (24) and the third exhaust pipe (26). The bearing member (163) connects and fixes the second exhaust pipe (24) and the third exhaust pipe (26), and seals the space between the rotating shaft (162) of the valve (161) and the second exhaust pipe (24).

Description

Technical Field

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

[0002] WO2021 / 171670A1 discloses a heat exchanger for recovering exhaust heat from waste gas, comprising: a first outer cylinder member fitted to the surface of the outer peripheral wall of a columnar honeycomb structure; an inner cylinder member fitted to the surface of the inner peripheral wall of the columnar honeycomb structure; an upstream cylindrical member having portions arranged radially inward of the inner cylinder member at intervals in a manner constituting a flow path for a first fluid; a cylindrical connecting member connecting the upstream end of the first outer cylinder member to the upstream side of the upstream cylindrical member; a downstream cylindrical member having portions arranged radially outward of the inner cylinder member at intervals in a manner constituting a flow path for the first fluid; and a valve mechanism having an on / off valve disposed at the downstream end of the inner cylinder member. Summary of the Invention

[0003] However, in the heat exchanger described in WO2021 / 171670A1, the shaft of the on / off valve passes through the inner cylinder member and is supported on the outside of the downstream cylindrical member. Therefore, a clearance is required between the shaft of the on / off valve and the inner cylinder member to allow the shaft to rotate. As a result, even when the on / off valve is closed, exhaust gas can still flow out through the clearance, potentially preventing the recovery of heat from the outflowing exhaust gas.

[0004] The purpose of this invention is to improve the heat recovery performance from exhaust gas in an exhaust heat recovery unit.

[0005] According to one aspect of the present invention, an exhaust heat recovery device includes: a first exhaust pipe; a second exhaust pipe into which a downstream end of the first exhaust pipe is inserted, and which forms a gap between the second exhaust pipe and the outer periphery of the first exhaust pipe to allow exhaust gas to flow; a third exhaust pipe disposed to surround the downstream end of the first exhaust pipe and the second exhaust pipe; an annular heat recovery element disposed between the second exhaust pipe and the third exhaust pipe, through which the exhaust gas passes and exchanges heat with a medium flow path disposed on the outer periphery of the third exhaust pipe; a valve for opening and closing the second exhaust pipe at a downstream end of the portion of the second exhaust pipe into which the first exhaust pipe is inserted; and a bearing member of the valve disposed between the second exhaust pipe and the third exhaust pipe. In the exhaust heat recovery device, when the valve is closed, the exhaust gas is guided to the heat recovery element through the gap; when the valve is open, the exhaust gas is guided to the third exhaust pipe by passing around the heat recovery element. The bearing member connects and fixes the second exhaust pipe and the third exhaust pipe, and seals the rotation shaft of the valve with the second exhaust pipe.

[0006] In the above solution, a bearing component located between the second and third exhaust pipes connects and fixes the two exhaust pipes, and seals the valve's rotating shaft with the second exhaust pipe. Therefore, when the valve is closed, exhaust gas is prevented from flowing out between the valve's rotating shaft and the second exhaust pipe. This improves the heat recovery performance from the exhaust gas in the exhaust heat recovery unit. Attached Figure Description

[0007] Figure 1 This is a perspective view of an exhaust heat recovery device according to an embodiment of the present invention.

[0008] Figure 2 yes Figure 1 Sectional view II-II.

[0009] Figure 3A yes Figure 2 The left-hand view near the valve in the image shows the valve in the open state.

[0010] Figure 3B yes Figure 2 The right-hand view near the valve in the diagram shows the valve in the open state.

[0011] Figure 4A yes Figure 2 The left-hand view near the valve in the diagram shows the valve in the closed state.

[0012] Figure 4B yes Figure 2 The right-hand view near the valve in the diagram shows the valve in the closed state.

[0013] Figure 5 This is a cross-sectional view of an exhaust heat recovery unit illustrating the flow of exhaust gas when the valve is in the open state.

[0014] Figure 6 This is a cross-sectional view of an exhaust heat recovery unit illustrating the flow of exhaust gas when the valve is closed. Detailed Implementation

[0015] Hereinafter, the exhaust heat recovery unit 10 according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0016] First, refer to Figure 1 and Figure 2 The overall structure of the exhaust heat recovery unit 10 will be described. Figure 1 This is a three-dimensional view of the exhaust heat recovery unit 10. Figure 2 yes Figure 1 Sectional view II-II.

[0017] An exhaust heat recovery unit 10 is installed, for example, in the exhaust path of an engine (not shown) in a car (not shown), to recover heat from the exhaust gas 20 discharged from the engine. The exhaust heat recovery unit 10 uses the recovered heat, for example, to heat the engine coolant before warm-up.

[0018] like Figure 1 As shown, the exhaust heat recovery unit 10 includes a gas flow section 12, a heat recovery section 14, and a switching mechanism section 16.

[0019] like Figure 2 As shown, the gas flow section 12 includes a first exhaust pipe 22, a second exhaust pipe 24, and a third exhaust pipe 26. Exhaust gas 20 flows through the gas flow section 12.

[0020] Each exhaust pipe 22, 24, and 26 is, for example, a metal pipe formed into a generally cylindrical shape. Examples of the metals constituting each exhaust pipe 22, 24, and 26 include stainless steel. Furthermore, each exhaust pipe 22, 24, and 26 is coaxially arranged with its respective central axis 28 aligned.

[0021] The first exhaust pipe 22 allows exhaust gas 20 to flow from the upstream side to the downstream side. The upper end of the first exhaust pipe 22 is connected to an exhaust pipe (not shown). Exhaust gas 20 from the engine is delivered to the first exhaust pipe 22. The first exhaust pipe 22 has: a first large-diameter portion 30, connected to the upstream exhaust pipe (not shown); a first tapered portion 32, extending from the first large-diameter portion 30, which narrows as it flows downstream in the direction of exhaust gas 20; and a first small-diameter portion 34, extending from the first tapered portion 32 downstream in the direction of flow.

[0022] Exhaust gas 20 passing through the first exhaust pipe 22 is supplied to the second exhaust pipe 24. The second exhaust pipe 24 is inserted into the downstream end of the first exhaust pipe 22, forming an annular channel 46 between it and the outer periphery of the first exhaust pipe 22, serving as a gap for the exhaust gas 20 to flow through. The second exhaust pipe 24 has an upstream end, i.e., a second large diameter portion 40, arranged to surround the downstream end, i.e., the first small diameter portion 34, of the first exhaust pipe 22. Furthermore, the second exhaust pipe 24 has: a second tapered portion 42 extending from the second large diameter portion 40, which narrows as it moves downstream in the flow direction; and a second small diameter portion 44 extending from the second tapered portion 42 in the downstream direction of the flow direction.

[0023] The inner diameter of the second large diameter portion 40 in the second exhaust pipe 24 is larger than the outer diameter of the first small diameter portion 34 in the first exhaust pipe 22. As a result, an annular channel 46 is formed between the outer periphery of the first small diameter portion 34 in the first exhaust pipe 22 and the inner periphery of the second large diameter portion 40 in the second exhaust pipe 24.

[0024] The welded portion 44a of the second small-diameter portion 44, which is welded to the bearing member 163 described later, is formed flat, while the other parts of the second small-diameter portion 44 are formed in a cylindrical shape. Thus, the flow path cross-section of the inner circumference of the second small-diameter portion 44 is formed into a generally D-shape by the flat welded portion 44a and the other cylindrical parts. A valve 161, described later, is provided inside the second small-diameter portion 44 of the second exhaust pipe 24 to switch the flow of exhaust gas 20 flowing in the second exhaust pipe 24.

[0025] The third exhaust pipe 26 is configured to surround the downstream end of the first exhaust pipe 22 and the second exhaust pipe 24. Specifically, the third exhaust pipe 26 surrounds the outer periphery of the following portions: a portion of the first exhaust pipe 22 extending downstream of the first large-diameter portion 30 to the first small-diameter portion 34; and the entirety of the second exhaust pipe 24. The third exhaust pipe 26 has: a third large-diameter portion 60 disposed on the outer periphery of the second exhaust pipe 24; a third tapered portion 62 extending from the third large-diameter portion 60 and decreasing in diameter towards the downstream side in the flow direction; and a third small-diameter portion 64 extending from the third tapered portion 62 towards the downstream side in the flow direction. The upstream portion of the third large-diameter portion 60 in the flow direction is formed by a cylindrical member 66 as another component.

[0026] The inner diameter of the third largest diameter portion 60 in the third exhaust pipe 26 is larger than the outer diameter of the second largest diameter portion 40 in the second exhaust pipe 24, forming an annular gap between the second largest diameter portion 40 in the second exhaust pipe 24 and the third largest diameter portion 60 in the third exhaust pipe 26. As a result, a bypass flow path 68 is formed on the outer periphery of the second largest diameter portion 40 in the second exhaust pipe 24 for the exhaust gas 20 passing through the annular channel 46 to circulate.

[0027] The third exhaust pipe 26 has a flange 61 that protrudes radially outward from the outer periphery of the third large diameter portion 60 of the third exhaust pipe 26. The flange 61 is disposed on the outer periphery of a hole that passes radially through the third exhaust pipe 26 and into which the bearing member 163, described later, is inserted. The flange 61 is formed into a generally cylindrical shape having an inner circumferential surface that abuts against the outer circumferential surface of the bearing member 163.

[0028] A collar 70 is arranged circumferentially between the end of the third large diameter portion 60 in the third exhaust pipe 26 and the first large diameter portion 30 of the first exhaust pipe 22.

[0029] The collar 70 has an inner peripheral wall 72 and an outer peripheral wall 74, forming a generally U-shaped cross-sectional shape. The collar 70 is fixed to the first large diameter portion 30 of the first exhaust pipe 22 with its inner peripheral wall 72 in close contact with the first large diameter portion 30. Furthermore, the collar 70 is fixed to the third large diameter portion 60 of the third exhaust pipe 26 with its outer peripheral wall 74 in close contact with the third large diameter portion 60. Thus, the end of the flow path 68 is closed by the collar 70.

[0030] An annular heat recovery element 80 is disposed between the second large diameter portion 40 of the second exhaust pipe 24 and the third large diameter portion 60 of the third exhaust pipe 26. The heat recovery element 80 allows exhaust gas 20 to pass through it internally, and heat exchange occurs between it and cooling water, which serves as the medium, flowing in the medium flow path 132 (described later) located on the outer periphery of the third exhaust pipe 26. The heat recovery element 80 is formed in an annular shape surrounding the second exhaust pipe 24, recovering heat from the exhaust gas 20 flowing in the surrounding flow path 68.

[0031] The heat recovery component 80 is formed, for example, of a material primarily composed of ceramic. The thermal expansion coefficient of the ceramic-based heat recovery component 80 differs from that of the metal exhaust pipes 22, 24, and 26. The heat recovery component 80 is constructed of a honeycomb structure. Specifically, the heat recovery component 80 includes a cylindrical inner cylinder portion 84 forming the inner circumferential surface, a cylindrical outer cylinder portion 88 forming the outer circumferential surface, and a honeycomb portion 90 disposed between the inner cylinder portion 84 and the outer cylinder portion 88.

[0032] The honeycomb section 90 is made of a honeycomb-shaped core material. The longitudinal and transverse walls constituting the honeycomb section 90 extend along the flow direction of the exhaust gas 20 flowing in the bypass flow path 68. Thus, the honeycomb section 90 has multiple channels running through it in the flow direction, allowing the exhaust gas 20 to flow through and recovering heat from the exhaust gas 20 passing through each channel.

[0033] A gasket 100, serving as a pressing member, is disposed between the heat recovery component 80 and the second large diameter portion 40 of the second exhaust pipe 24.

[0034] The gasket 100 is formed from a plate-shaped component that is cylindrical. The plate-shaped component constituting the gasket 100 is, for example, made of a metal plate. The gasket 100 is sized to be externally fitted into the second large-diameter portion 40 of the second exhaust pipe 24.

[0035] A gasket 100 is disposed between the second exhaust pipe 24 and the heat recovery member 80, pressing the two together radially. Specifically, the gasket 100 is inserted into the inner circumferential surface of the inner cylinder portion 84 of the heat recovery member 80, for example, in a reduced-diameter state, and then fixed by expanding the second large-diameter portion 40 of the second exhaust pipe 24. Thus, the gasket 100 is configured to be inserted between the second large-diameter portion 40 of the second exhaust pipe 24 and the heat recovery member 80.

[0036] In its installed state, where it is positioned between the second large-diameter portion 40 of the second exhaust pipe 24 and the heat recovery member 80, the gasket 100 is capable of radial elastic deformation. In the installed state, the gasket 100 presses against the heat recovery member 80 such that the outer peripheral surface of the outer cylinder portion 88 is in close contact with the inner peripheral surface of the third exhaust pipe 26. The heat recovered by the heat recovery member 80 is transferred to the cylindrical member 66 constituting the third large-diameter portion 60 of the third exhaust pipe 26.

[0037] The gasket 100 is configured to slide relative to the second exhaust pipe 24 along its length (along the direction of the central axis 28). Thus, the gasket 100 allows for relative thermal deformation of the second exhaust pipe 24 and the heat recovery member 80 along the length of the second exhaust pipe 24. The specific function will be detailed in the description of its function and effect.

[0038] The heat recovery unit 14 uses the heat from the waste gas 20 to heat the cooling water. The heat recovery unit 14 has a cylindrical component 130, a supply pipe 140, and a recovery pipe 142.

[0039] A cylindrical member 130 is disposed on the outer periphery of the cylindrical member 66, which constitutes the third large-diameter portion 60 of the third exhaust pipe 26, in a manner that surrounds the cylindrical member 66 throughout its entire circumference. The cylindrical member 130 includes: a container-shaped member body 134 protruding outwards, which forms a medium flow path 132 between itself and the cylindrical member 66; and a pair of fixing flanges 136 extending from the edges of the member body 134. The cylindrical member 130 is fixed in a state where each fixing flange 136 is in close contact with the cylindrical member 66. A supply pipe 140 and a recovery pipe 142 (see reference) are connected to the member body 134. Figure 1 ).

[0040] Supply piping 140 supplies cooling water to medium flow path 132. Recovery piping 142 recovers cooling water from medium flow path 132. Supply piping 140 and recovery piping 142 are respectively located at circumferentially separated parts of the main body 134.

[0041] The heat recovered by the heat recovery unit 80 from the exhaust gas 20 is transferred to the cooling water flowing in the medium flow path 132 via the cylindrical member 66 of the third exhaust pipe 26. Thus, a heat recovery unit 14 is constructed that uses the heat of the exhaust gas 20 to heat the cooling water.

[0042] Next, refer to Figures 3A to 4B The switching mechanism section 16 will be explained. Figure 3A yes Figure 2 The left-hand view near valve 161 is a diagram showing the open state of valve 161. Figure 3B yes Figure 2 The right-side view near valve 161 is a diagram showing the open state of valve 161. Figure 4A yes Figure 2 The left-hand view near valve 161 in the figure is a diagram showing the closed state of valve 161. Figure 4B yes Figure 2 The right-hand view near valve 161 is a diagram showing the valve 161 in the closed state. It should be noted that... Figures 3A to 4BIn order to make it easier to understand the state of valve 161, valve 161 is marked with a shading line.

[0043] like Figure 2 As shown, the switching mechanism 16 includes a valve 161, a main shaft 162 serving as a rotation axis, a bearing member 163 for the valve 161, a sealing member 164, an actuator 169, and a fixing member 170. The switching mechanism 16 switches the flow of exhaust gas 20 within the gas flow section 12.

[0044] like Figure 3A and Figure 3B As shown, valve 161 is formed as a flat plate having a front surface 161a and a rear surface 161b. Valve 161 is formed in a shape corresponding to the flow path cross-section of the second small-diameter portion 44 in the second exhaust pipe 24. That is, valve 161 is formed in a roughly D-shape corresponding to the roughly D-shaped flow path cross-section of the second small-diameter portion 44 (see reference). Figure 4A and Figure 4B Valve 161 is rotatable and is supported by spindle 162. Valve 161 is located downstream of the portion of the second exhaust pipe 24 where the first exhaust pipe 22 is inserted, and opens and closes the connecting channel 48 that connects the second exhaust pipe 24 to the third exhaust pipe 26 without passing through the annular channel 46.

[0045] The valve 161 is in an open state configured on the front surface 161a and the rear surface 161b along the flow direction. Figure 3A and Figure 3B In the state shown, exhaust gas 20 from the first exhaust pipe 22 flows downstream of the second exhaust pipe 24. Valve 161 is in a closed state with its front surface 161a facing upstream in the flow direction and its rear surface 161b facing downstream in the flow direction. Figure 4A and Figure 4B In the state shown, the flow of exhaust gas 20 to the downstream side of the second exhaust pipe 24 is suppressed, and the flow of exhaust gas 20 to the annular channel 46 is promoted.

[0046] That is, when the connecting channel 48 is closed, the exhaust gas 20 is guided to the heat recovery unit 80 through the annular channel 46; when the connecting channel 48 is open, the exhaust gas 20 is allowed to flow around the heat recovery unit 80. It should be noted that the switching of the exhaust gas 20's flow will be detailed in the description of its function and effects.

[0047] Here, as Figure 3A and Figure 3BAs shown, arc-shaped stops 45a and 45b are respectively provided on the inner circumference of the second small diameter portion 44 in the second exhaust pipe 24. Stop 45a is configured to protrude into the connecting channel 48 covering approximately half a circumference of the inner circumference of the second small diameter portion 44. Stop 45b is configured to protrude into the connecting channel 48 covering approximately the remaining half circumference of the inner circumference of the second small diameter portion 44 where stop 45a is not provided. Stops 45a and 45b are respectively positioned opposite each other across valve 161. Stop 45b is located downstream of the valve 161 in the direction of flow of exhaust gas 20 (along the direction of the central axis 28).

[0048] like Figure 4A and Figure 4B As shown, when valve 161 switches from the open state to the closed state, the front surface 161a of valve 161 abuts against the downstream side of the flow direction of a stop 45a, and the rear surface 161b of valve 161 abuts against the upstream side of the flow direction of another stop 45b. This effectively suppresses the outflow of exhaust gas 20 from the connecting passage 48 when valve 161 is closed.

[0049] like Figure 2 As shown, the main shaft 162 is formed in a generally cylindrical shape. The main shaft 162 extends from the outside of the third exhaust pipe 26 into the interior of the second exhaust pipe 24. A valve 161 is provided at one end of the main shaft 162. An actuator 169 is mounted at the other end of the main shaft 162. The rotation of the main shaft 162 is controlled by the actuator 169. The main shaft 162 has a tapered portion 162a formed in a manner that narrows from one end to the other. One end of the main shaft 162 is configured to have a larger diameter than the other end.

[0050] The bearing member 163 is formed in a cylindrical shape (generally cylindrical). The bearing member 163 is disposed between the second exhaust pipe 24 and the third exhaust pipe 26, and extends through the third exhaust pipe 26 to the outside. The bearing member 163 connects and fixes the second exhaust pipe 24 and the third exhaust pipe 26. The bearing member 163 has a sealing member 164 that seals the space between the main shaft 162 of the valve 161 and the second exhaust pipe 24.

[0051] The bearing component 163 has a recess 163a, a first welded portion 163c, a second welded portion 163d, and a sliding portion 163e. The bearing component 163 is formed of a metal that can be welded to the second exhaust pipe 24 and the third exhaust pipe 26. The bearing component 163 is, for example, made of stainless steel.

[0052] The recess 163a is formed in a concave shape along the central axis direction from the end of the bearing member 163 on the side of the second exhaust pipe 24. The diameter of the recess 163a is larger than that of the sliding part 163e. A sealing member 164 is provided in the recess 163a.

[0053] The first weld portion 163c fixes and seals the end face of the bearing member 163 to the second exhaust pipe 24 by welding. Specifically, the first weld portion 163c is formed by welding the welded portion 44a, which is formed flatly on the second small diameter portion 44 of the second exhaust pipe 24, to the end face of the bearing member 163.

[0054] At this time, since the welded portion 44a is formed flat, it forms a surface contact with the annular end face of the bearing member 163, which is also formed flat. As a result, the welding of the bearing member 163 to the second exhaust pipe 24 can be easily performed, and the quality of the first welded portion 163c can be stabilized.

[0055] The second welded portion 163d fixes and seals the outer peripheral surface of the bearing member 163 to the third exhaust pipe 26 by welding. Specifically, the second welded portion 163d is formed by welding the inner peripheral surface of the flange portion 61, which protrudes from the third large diameter portion 60 of the third exhaust pipe 26 toward the outer peripheral surface, to the outer peripheral surface of the bearing member 163.

[0056] At this time, since a flange 61 is provided in the third exhaust pipe 26, the contact area (contact length) between the flange 61 and the outer peripheral surface of the bearing member 163 can be increased. As a result, the welding of the bearing member 163 and the third exhaust pipe 26 can be easily performed, and the quality of the second weld 163d can be stabilized.

[0057] The sliding portion 163e is a circular hole for sliding on the outer peripheral surface of the main shaft 162. The sliding portion 163e is formed along the central axis of the bearing member 163. The sliding portion 163e is formed with a diameter approximately the same as the outer diameter of the main shaft 162.

[0058] A sealing member 164 is disposed within the recess 163a of the bearing member 163. The sealing member 164 is disposed in a compressed state between the bottom surface of the recess 163a and the tapered portion 162a of the spindle 162. The sealing member 164 seals the spindle 162 and the end of the sliding portion 163e of the spindle 162.

[0059] Actuator 169 is driven by electricity supplied from a power supply unit (not shown). Actuator 169 is controlled by electrical signals from a controller (not shown). Actuator 169 drives spindle 162 to rotate.

[0060] The fixing member 170 is a cup-shaped metal member that supports the actuator 169. The fixing member 170 is mounted at multiple locations on the outer surface of the third exhaust pipe 26 and the cylindrical member 130 via multiple brackets 171 (see reference). Figure 1 ).

[0061] Next, refer to Figure 5 and Figure 6 The function of the exhaust heat recovery unit 10 will be explained. Figure 5 This is a cross-sectional view of the exhaust heat recovery unit 10, which illustrates the flow of exhaust gas 20 when valve 161 is in the open state. Figure 6 This is a cross-sectional view of the exhaust heat recovery unit 10, which illustrates the flow of exhaust gas 20 when valve 161 is in the closed state.

[0062] First, refer to Figure 5 The following explanation addresses the situation where valve 161 is open and the heat from exhaust gas 20 is not recovered by the cooling water flowing in the heat recovery section 14.

[0063] like Figure 5 As shown, exhaust gas 20 from the engine flows into the first exhaust pipe 22 via an upstream exhaust pipe (not shown). The exhaust gas 20 flowing from the first exhaust pipe 22 into the exhaust heat recovery unit 10 is directly guided into the second exhaust pipe 24.

[0064] At this time, since valve 161 is open and connecting passage 48 is open, the exhaust gas 20 flowing into the second exhaust pipe 24 is guided through connecting passage 48 to the third exhaust pipe 26 and flows out to the downstream exhaust pipe (not shown). That is, the exhaust gas 20 flows in the exhaust heat recovery unit 10 by bypassing the superheat recovery unit 80.

[0065] As a result, the exhaust gas 20 is not guided to the heat recovery unit 80, and therefore the heat of the exhaust gas 20 is not recovered by the cooling water flowing in the heat recovery unit 14.

[0066] If, from this state, actuator 169 drives spindle 162 to rotate and closes valve 161, then it will become Figure 6 The state shown.

[0067] Next, refer to Figure 6 The following describes the situation where valve 161 is closed and the heat of exhaust gas 20 is recovered by cooling water flowing in the heat recovery section 14.

[0068] like Figure 6 As shown, exhaust gas 20 from the engine flows into the first exhaust pipe 22 via an upstream exhaust pipe (not shown). The exhaust gas 20 flowing from the first exhaust pipe 22 into the exhaust heat recovery unit 10 is directly guided into the second exhaust pipe 24. At this time, since valve 161 is closed and connecting passage 48 is shut off, the exhaust gas 20 flowing into the second exhaust pipe 24 is guided to the bypass flow path 68 via the annular passage 46. The exhaust gas 20 guided to the bypass flow path 68 passes through the heat recovery unit 80, thus heat is transferred to the cooling water flowing in the heat recovery section 14. Afterwards, the exhaust gas 20 is guided from the bypass flow path 68 into the third exhaust pipe 26 and flows out to a downstream exhaust pipe (not shown).

[0069] Thus, the exhaust gas 20 is guided to the heat recovery unit 80, and the heat of the exhaust gas 20 is recovered to the cooling water flowing in the heat recovery unit 14.

[0070] At this time, the bearing member 163, located between the second exhaust pipe 24 and the third exhaust pipe 26, is fixed and sealed to the second exhaust pipe 24 via the first welding part 163c, and fixed and sealed to the third exhaust pipe 26 via the second welding part 163d. That is, the bearing member 163 connects and fixes the second exhaust pipe 24 and the third exhaust pipe 26, and seals the space between the main shaft 162 of the valve 161 and the second exhaust pipe 24. Therefore, when the valve 161 is closed, exhaust gas 20 is prevented from flowing out between the main shaft 162 of the valve 161 and the second exhaust pipe 24.

[0071] Furthermore, a sealing member 164 is provided on the bearing member 163 to seal the ends of the main shaft 162 and the sliding part 163e within the recess 163a. ​​Therefore, exhaust gas 20 that flows out from the gap around the outer periphery of the main shaft 162 can be guided to the outside of the bypass flow path 68 and the third exhaust pipe 26.

[0072] Therefore, almost all of the exhaust gas 20 flowing in from the upstream exhaust pipe (not shown) is guided to the heat recovery unit 80, thereby improving the heat recovery performance of the exhaust heat recovery unit 10 from the exhaust gas 20.

[0073] A gasket 100 is provided between the second exhaust pipe 24 and the heat recovery component 80 to press the two together radially. The gasket 100 allows for relative thermal deformation of the second exhaust pipe 24 and the heat recovery component 80 along the length of the second exhaust pipe 24.

[0074] Here, the bearing member 163 is connected and fixed to the second exhaust pipe 24 and the third exhaust pipe 26 via a first weld 163c and a second weld 163d. That is, the second exhaust pipe 24 is supported by the third exhaust pipe 26 via the bearing member 163, and its position is constrained. On the other hand, the heat recovery member 80 is embedded in the third exhaust pipe 26 (cylindrical member 66), and its position is constrained. Furthermore, the heat recovery member 80 is mainly composed of ceramic, and its coefficient of thermal expansion is different from that of the metal exhaust pipes 22, 24, and 26. Therefore, if the two are heated, a difference in thermal expansion will occur. In such a structure, a seal is required between the second exhaust pipe 24 and the heat recovery member 80 to prevent the exhaust gas 20 from bypassing. However, if the two are constrained by a sealing structure, stress will be generated due to the difference in thermal expansion. That is, assuming that the second exhaust pipe 24 is constrained at one end by the bearing member 163 and at the other end by the heat recovery member 80, stress will be generated in the second exhaust pipe 24.

[0075] In contrast, in the exhaust heat recovery unit 10, the gasket 100 is configured to slide relative to the second exhaust pipe 24 along its length (along the direction of the central axis 28). That is, by providing the gasket 100, relative thermal deformation of the second exhaust pipe 24 and the heat recovery unit 80 along the length of the second exhaust pipe 24 is permitted. Therefore, even if the second exhaust pipe 24 is heated by the exhaust gas 20 and undergoes thermal deformation starting from the position where it is welded to the bearing member 163, the force caused by the thermal deformation will not be transmitted to the heat recovery unit 80 because the gasket 100 slides relative to the second exhaust pipe 24. Thus, for example, compared to the case where the heat recovery unit 80 is fixed to the second exhaust pipe 24 and the third exhaust pipe 26 by brazing or the like, durability against thermal fatigue can be improved.

[0076] Furthermore, when the dimensions of the second exhaust pipe 24 increase due to the heat from the exhaust gas 20, the elastic deformation of the gasket 100 can suppress the positional displacement of the heat recovery component 80 caused by the thermal expansion of the second exhaust pipe 24. In particular, in hybrid vehicles where the temperature change of the exhaust heat recovery unit 10 increases due to switching between engine drive and electric motor drive, the positional displacement of the heat recovery component 80 can also be suppressed.

[0077] The above implementation method achieves the following effects.

[0078] The exhaust heat recovery unit 10 includes: a first exhaust pipe 22; a second exhaust pipe 24, into which the downstream end of the first exhaust pipe 22 is inserted, and forming an annular channel 46 between the second exhaust pipe 24 and the outer periphery of the first exhaust pipe 22 for the flow of exhaust gas 20; a third exhaust pipe 26, configured to surround the downstream end of the first exhaust pipe 22 and the second exhaust pipe 24; an annular heat recovery element 80, disposed between the second exhaust pipe 24 and the third exhaust pipe 26, allowing the exhaust gas 20 to pass through from the inside and exchange heat with a medium flow path 132 disposed on the outer periphery of the third exhaust pipe 26; and a valve 161 inserted into the second exhaust pipe 24. The downstream portion of the first exhaust pipe 22 opens and closes the second exhaust pipe 24; and the bearing component 163 of the valve 161 is disposed between the second exhaust pipe 24 and the third exhaust pipe 26. In the exhaust heat recovery unit 10, when the valve 161 is closed, the exhaust gas 20 is guided to the heat recovery component 80 through the annular channel 46. When the valve 161 is open, the exhaust gas 20 is guided to the third exhaust pipe 26 by passing around the heat recovery component 80. The bearing component 163 connects and fixes the second exhaust pipe 24 and the third exhaust pipe 26, and seals the main shaft 162 of the valve 161 with the second exhaust pipe 24.

[0079] In this configuration, a bearing member 163, located between the second exhaust pipe 24 and the third exhaust pipe 26, connects and fixes the second exhaust pipe 24 and the third exhaust pipe 26, and seals the space between the main shaft 162 of the valve 161 and the second exhaust pipe 24. Therefore, when the valve 161 is closed, exhaust gas 20 is prevented from flowing out between the main shaft 162 of the valve 161 and the second exhaust pipe 24. This improves the heat recovery performance from the exhaust gas 20 in the exhaust heat recovery unit 10.

[0080] The embodiments of the present invention have been described above. However, the above embodiments only illustrate a part of the application examples of the present invention and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

[0081] For example, the exhaust heat recovery unit 10 of the above embodiment has been described as using the recovered heat to heat cooling water, but each embodiment is not limited to this. For example, the exhaust heat recovery unit 10 may also use the recovered heat to heat gear oil, etc.

[0082] Furthermore, in the above embodiments, the case of applying the exhaust heat recovery device 10 to a car has been described, but the above embodiments are not limited to this, and the exhaust heat recovery device 10 may also be applied to vehicles.

[0083] This application claims priority based on Japanese Patent Application No. 2023-082327, filed on May 18, 2023, with the Japan Patent Office. The entire contents of this application are incorporated herein by reference.

Claims

1. An exhaust heat recovery unit, comprising: First exhaust pipe; The second exhaust pipe is inserted into the downstream end of the first exhaust pipe and forms a gap between it and the outer periphery of the first exhaust pipe to allow exhaust gas to flow. The third exhaust pipe is configured to surround the downstream end of the first exhaust pipe and the second exhaust pipe; An annular heat recovery element is disposed between the second exhaust pipe and the third exhaust pipe, allowing the exhaust gas to pass through from the inside and exchange heat with the medium flow path disposed on the outer periphery of the third exhaust pipe; A valve, located downstream of the portion of the second exhaust pipe into which the first exhaust pipe is inserted, opens and closes the second exhaust pipe; and The bearing component of the valve is disposed between the second exhaust pipe and the third exhaust pipe; In the exhaust heat recovery unit, With the valve closed, the exhaust gas is guided to the heat recovery unit through the gap; with the valve open, the exhaust gas bypasses the heat recovery unit and is guided to the third exhaust pipe. The bearing component connects and fixes the second exhaust pipe to the third exhaust pipe, and seals the valve's rotating shaft with the second exhaust pipe.

2. The exhaust heat recovery unit according to claim 1, wherein, It also includes a pressing component, which is disposed between the second exhaust pipe and the heat recovery component, and presses the two together radially. The pressing member allows for relative thermal deformation of the second exhaust pipe and the heat recovery member along the length of the second exhaust pipe.

3. The exhaust heat recovery unit according to claim 1 or 2, wherein, The bearing component is cylindrical with a sliding portion for sliding on the outer circumferential surface of the rotating shaft. The bearing component also includes: The first welding part fixes and seals the end face of the bearing component to the second exhaust pipe by welding; The second welding part fixes and seals the outer peripheral surface of the bearing component to the third exhaust pipe by welding. as well as A sealing member that seals the ends of the rotating shaft and the sliding part within the bearing member.

4. The exhaust heat recovery unit according to claim 1 or 2, wherein, The second exhaust pipe also has a first welded portion that is welded to the bearing component. The first welded portion is formed flat. The valve is shaped to correspond to the flow path cross-section of the second exhaust pipe.

5. The exhaust heat recovery unit according to claim 1, wherein, The bearing components are made of stainless steel.

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