JP7221853B2 - Exhaust heat recovery device - Google Patents

Description

The present disclosure relates to an exhaust heat recovery device applied to, for example, an exhaust system of an internal combustion engine.

2. Description of the Related Art Conventionally, an exhaust heat recovery device is known that recovers exhaust heat by exchanging heat between an exhaust gas of an internal combustion engine and a heat exchange medium such as cooling water. Patent Document 1 discloses a structure in which a shell is provided in which an exhaust gas flow path passing through a heat exchanger and a bypass flow path merge, and an opening end of the bypass flow path is curved toward an opening on the downstream side of the shell. ing.

JP-A-2008-25380

In the configuration of Patent Document 1, when the valve closes the open end of the bypass flow path, a large amount of exhaust gas flows into the exhaust gas flow path passing through the heat exchanger. On the other hand, when the valve opens the open end, although the proportion of the exhaust gas flowing through the bypass channel increases, part of the exhaust gas flows through the exhaust gas channel and exchanges heat with the heat exchanger. There is

An object of the present disclosure is to propose a technique for suppressing the occurrence of unnecessary heat exchange.

One aspect of the present disclosure is an exhaust heat recovery device that includes a heat exchanger that exchanges heat between an exhaust gas and a heat exchange medium, and includes a piping section, a shell member, and a valve. The piping part constitutes a first flow path that does not exchange heat between the exhaust gas and the heat exchanger, and a second flow path that performs the heat exchange. The shell member is configured to join the exhaust gas discharged from the first outlet, which is the outlet of the first flow path, and the exhaust gas discharged from the second outlet, which is the outlet of the second flow path. . A valve is disposed within the shell member and is configured to be movable between first and second positions. The first position is a position in which the first outlet is closed to increase the flow rate of the exhaust gas to the second flow path compared to before the closure. The second position is a position in which the first outlet is opened to reduce the flow rate of the exhaust gas to the second flow path compared to before opening. The valve is also configured to direct at least a portion of exhaust gases discharged from the first outlet toward the second outlet when in the second position.

With such a configuration, when the valve is in the second position, the exhaust gas discharged from the first outlet is guided to the second outlet, thereby reducing the flow rate of the exhaust gas flowing through the second flow path. be able to. The reason for this is thought to be that the concentration of the exhaust gas at the second outlet causes the pressure at the second outlet to rise and the difference from the pressure at the inlet of the second flow path to decrease. Since the flow rate of the exhaust gas flowing through the second flow path is reduced, heat exchange occurring in the heat exchanger arranged in the second flow path can be suppressed.

In the above exhaust heat recovery device, the valve may have a recessed portion. Also, the valve may be positioned such that the concave opening side is upstream when the valve is in the first position. The second position may be a position where at least part of the exhaust gas discharged from the first outlet flows into the recess.

With such a configuration, since the valve has the concave portion, the exhaust gas that has reached the valve is likely to move and gather inside the concave portion. Therefore, more exhaust gas can be guided to the second outlet, and the flow rate of the exhaust gas flowing through the second flow path can be further reduced.

In the above exhaust heat recovery device, when the valve is in the second position, at least a part of the valve may be positioned in the discharge direction of the exhaust gas discharged from the second outlet. With such a configuration, since the distance between the valve and the second outlet is short, the above-described effects of guiding the exhaust gas to the second outlet can be highly exhibited. Also, the valve itself can impede the flow of exhaust gases discharged from the second outlet.

In the exhaust heat recovery device described above, the second outlet may be provided at a position along the wall surface of the pipe forming the first flow path. Moreover, the second outlet may be provided at a position offset in the circumferential direction of the pipe. With such a configuration, since the second outlet is provided at a biased position, the proportion of the area affected by the exhaust gas guided by the valve at the second outlet increases. If the above ratio is small, the effect of suppressing the flow rate of the exhaust gas flowing through the second flow path is reduced. In the above configuration, by increasing the above ratio, it is possible to effectively suppress the flow rate of the exhaust gas flowing through the second flow path.

In the above exhaust heat recovery device, the second flow path may include a flow path along the pipe forming the first flow path downstream of the heat exchanger, and a second outlet may be formed in the flow path. .
With such a configuration, the adjustment of the position of the second outlet can be set to an arbitrary position in the vicinity of the pipe described above. Thereby, the position of the second outlet can be set at a position where the effect of reducing the flow rate of the second flow path by the valve is high.

It is a perspective view showing an exhaust heat recovery device of an embodiment. 2A is a front view showing the exhaust heat recovery device of the embodiment, FIG. 2B is a plan view showing the exhaust heat recovery device, and FIG. 2C is a left side view showing the exhaust heat recovery device. 2C is an end view according to the III-III section of FIG. 2B; FIG. It is a perspective view showing the stay plate of the embodiment. It is a perspective view which shows the valve|bulb of embodiment. It is a figure explaining the flow of the exhaust gas in the exhaust heat recovery apparatus of embodiment. It is a schematic diagram which shows the exhaust heat recovery apparatus of a modification. It is a perspective view which shows the exhaust-gas-heat recovery apparatus of a modification.

Embodiments of the present disclosure will be described below with reference to the drawings.
[1. embodiment]
[1-1. overall structure]
An exhaust heat recovery device 1 of this embodiment shown in FIGS. 1 to 3 is a device used in an exhaust system of a vehicle having an internal combustion engine. In the following description, upstream and downstream mean upstream and downstream in the flow direction of the exhaust gas discharged from the internal combustion engine.

The exhaust heat recovery device 1 includes a pipe section 10 and an outer shell 30 as elements that form a flow path for exhaust gas. Further, as shown in FIG. 3, the exhaust heat recovery device 1 includes a heat exchanger 20 that exchanges heat between the exhaust gas and a heat exchange medium. The exhaust heat recovery device 1 also includes a valve 40 for controlling the flow of exhaust gas.

The piping section 10 includes an inner pipe 11 and a housing 12 .
The inner pipe 11 is a hollow cylindrical member with both ends open. An inlet 11A is formed on the upstream side of the inner pipe 11 (left side in FIG. 3). A first outlet 11B is formed on the downstream side of the inner pipe 11 (on the right side in FIG. 3). The inner pipe 11 guides the exhaust gas discharged from the internal combustion engine (not shown) from the inlet 11A on the upstream side to the first outlet 11B on the downstream side by passing through the inside thereof. A plurality of branch openings 13 are formed in a predetermined range in the axial direction of the inner pipe 11 and are dispersed in the circumferential direction of the inner pipe 11 . A part of the exhaust gas flowing inside the inner pipe 11 can flow out of the inner pipe 11 through the branch port 13 .

The housing 12 is an annular member arranged to surround the inner pipe 11 . The housing 12 includes an outer peripheral plate 14 , an upstream lid 15 and a stay plate 16 . The outer peripheral plate 14 is a tubular plate member that surrounds the outer side of the inner pipe 11 . Also, the upstream lid 15 and the stay plate 16 are members arranged between the outer peripheral plate 14 and the inner pipe 11 .

The upstream lid 15 has a plate-like portion that spreads radially around the inner pipe 11, as shown in FIG. A tubular first lid opening 15A and a tubular second lid opening 15B are formed at two spaced apart portions of the plate-like portion. The first lid opening 15A is a portion that serves as an inlet for supplying heat exchange medium to the heat exchanger 20 . The second lid opening 15B is a portion that serves as an outlet through which the heat exchange medium that has exchanged heat with the exhaust gas is discharged.

As shown in FIGS. 3 and 4, the stay plate 16 includes a cylindrical tubular portion 16A and a flange portion 16B radially extending from one end of the tubular portion 16A. The tubular portion 16A has an inner diameter larger than the outer diameter of the inner pipe 11, and a gap is formed between the inner pipe 11 and the tubular portion 16A. A second outlet 16C, which is an opening, is formed in a part of the tubular portion 16A in the circumferential direction. The second outlet 16</b>C is provided along the wall surface of the inner pipe 11 . The other end 16D of the tubular portion 16A has a reduced diameter and is in close contact with the outer peripheral surface of the inner pipe 11. As shown in FIG.

The heat exchanger 20 is arranged outside the inner pipe 11 and inside the housing 12 . The heat exchanger 20 has a plurality of ring-shaped disk members 21 each having an internal space through which a heat exchange medium flows. The disk members 21 are arranged so as to surround the inner pipe 11 and spaced apart from each other in the axial direction of the inner pipe 11 . The heat exchanger 20 also has a first connection channel 22 and a second connection channel 23 . The first connection channel 22 is connected to the first lid opening 15A and communicates with the inner space of each disc member 21 . The second connection channel 23 is connected to the second lid opening 15B and communicates with the inner space of each disc member 21 . The first lid opening 15A and the second lid opening 15B are connected to a cooling water circulation system (not shown). Cooling water, which is an example of a heat exchange medium, flows into the first connecting channel 22 of the heat exchanger 20 from the cooling water circulation system through the first lid opening 15A. The cooling water exchanges heat with the exhaust gas while flowing through the inner space of the disk member 21 toward the second connection flow path 23, flows out through the second lid opening 15B, and returns to the cooling water circulation system. Thus, heat exchange by the heat exchanger 20 is performed.

The outer shell 30 is a hollow thin-walled member that is open upstream and downstream. The upstream side of the outer shell 30 is connected to the outer peripheral plate 14 . An exhaust port 31 is formed downstream of the outer shell 30 and connected to an exhaust path (not shown). This outer shell 30 is configured to cover the first outlet 11B and the second outlet 16C. A valve 40 is arranged inside the outer shell 30 . The outer shell 30 is an example of a shell member.

Bulb 40 is generally concave and has a bowl shape, as shown in FIG. The valve 40 includes a substantially flat circular bottom plate 41 and an edge portion 42 formed around the bottom plate 41 . The bottom plate 41 and edge portion 42 are examples of the concave portion.

Valve 40 is configured to be movable between a first position and a second position inside outer shell 30 . The first position is the position indicated by the dashed line in FIG. 3, where the valve 40 covers and closes the first outlet 11B. The second position is the position indicated by the solid line in FIG. 3, where the valve 40 opens the first outlet 11B. The valve 40 is arranged such that when it is in the first position, the recessed opening side is positioned upstream and the downstream side is swollen. Further, when the valve 40 is in the second position, a portion of the valve 40 is positioned in the discharge direction of the exhaust gas discharged from the second outlet 16C. For example, the valve 40 may be arranged such that the concave opening side faces the downstream end side of the inner pipe 11 in the second position. More preferably, when the valve 40 is in the second position, the portion of the bottom plate 41 and the edge portion 42 closest to the second outlet 16C covers the second outlet 16C from the radially outer side of the inner pipe 11, and the bottom plate 41 and edge 42 , the farthest part from second outlet 16</b>C may be positioned on the downstream extension line of inner pipe 11 . However, as will be described later, the configuration is not limited to this. Movement of the valve 40 between the first position and the second position is realized by rotating the valve 40 about a rotating shaft 43 . A detailed configuration of the rotating shaft 43 and a supporting mechanism for the valve 40 and the rotating shaft 43 are omitted.

[1-2. Flow path of exhaust gas]
As shown in FIG. 6, the exhaust gas flowing through the piping portion 10 is first introduced into the inner pipe 11 through the inlet 11A. The inner pipe 11 branches into a first flow path 61 that goes straight toward the first outlet 11</b>B and a second flow path 62 that flows from the branch port 13 via the heat exchanger 20 . That is, the first flow path 61 is a flow path in which heat exchange between the exhaust gas and the heat exchanger 20 is not performed, and the second flow path 62 is a flow path in which the heat exchange is performed. In FIG. 6, the arrows schematically indicating the flow of the exhaust gas flowing through each flow path are given the reference numerals (61, 62) of each flow path. In the piping section 10 , a portion of the inner pipe 11 downstream of the branch port 13 constitutes a first flow path 61 , and the wall surface of the inner pipe 11 and the housing 12 constitute a second flow path 62 . The inner pipe 11 is an example of piping that constitutes the first flow path 61 .

When the valve 40 is in the first position, shown in dashed lines in FIG. 3, the valve 40 blocks the first outlet 11B. Therefore, as a result of suppressing the exhaust gas from flowing into the first flow path 61, the flow rate of the exhaust gas to the second flow path 62 increases compared to before the blockage. The exhaust gas entering the second flow path 62 from the branch port 13 contacts the heat exchanger 20 and exchanges heat. Since the exhaust gas is a high-temperature gas, it raises the temperature of the cooling water in the heat exchanger. After that, it passes through the space between the inner pipe 11 and the flange portion 16B and is discharged into the outer shell 30 from the second outlet 16C.

On the other hand, when the valve 40 is in the second position shown in FIG. 6 (or shown in solid lines in FIG. 3), the first outlet 11B is open. As a result, the flow rate of the exhaust gas flowing through the first passage 61 increases compared to before it is opened, and most of the exhaust gas is discharged into the outer shell 30 through the first outlet 11B. Accordingly, the flow rate of exhaust gas to the second flow path 62 is relatively reduced compared to when the valve 40 is in the first position.

In the outer shell 30, the exhaust gas discharged from the first outlet 11B, which is the outlet of the first flow path 61, and the exhaust gas discharged from the second outlet 16C, which is the outlet of the second flow path 62, join together. , is discharged from the discharge port 31 . The outer shell 30 guides the exhaust gas introduced into the piping section 10 downstream.

[1-3. Action by valve]
The operation of the valve 40 will be described with reference to FIGS. 5 and 6. FIG. As shown in FIG. 6, when the valve 40 is in the second position, most of the exhaust gas is discharged through the first outlet 11B and directed straight to the outlet 31. As shown in FIG. However, some of the exhaust gas hits the valve 40 . When a part of the valve 40 is positioned on the extension line of the inner pipe 11, the valve 40 is likely to be exposed to the exhaust gas. However, since the exhaust gas discharged from the first outlet 11B also diffuses sideways, the valve 40 does not necessarily have to be positioned on the extension line of the inner pipe 11 . Since the valve 40 is concavely formed by the bottom plate 41 and the edge 42 , the exhaust gas flows into the concave valve 40 . That is, the second position is a position where at least part of the exhaust gas discharged from the first outlet 11B flows into the concave portion.

Valve 40 guides the exhaust gas as indicated by arrow 63 in FIG. Since the valve 40 is bowl-shaped as shown in FIG. 5, once the exhaust gas enters the inside, it is difficult to escape from the side, and a large amount of exhaust gas flows to the opposite side. Then, for example, when the bottom plate 41 is circular and the edge 42 is provided along the circular edge, the opposite end is narrow, so the exhaust gas concentrates and the pressure increases. The pressure is particularly high in the region 64 shown in FIG.

A portion of the valve 40 in the second position is positioned in the discharge direction of the exhaust gas discharged from the second outlet 16C. Therefore, the valve 40 guides at least part of the exhaust gas discharged from the first outlet 11B toward the second outlet 16C. As a result, as the pressure in region 64 rises, the pressure in and near the second outlet 16C also rises.

If the influence of the exhaust gas flow by the valve 40 is not taken into consideration, the pressure at the branch port 13 is higher than that at the second outlet 16C when comparing the pressures at the branch port 13 and the second outlet 16C. Therefore, part of the exhaust gas flows through the second flow path 62 even if the first outlet 11B is open. However, when the pressure at the second outlet 16C increases, the pressure gradient between the branch port 13 and the second outlet 16C decreases, and the flow rate of the exhaust gas flowing through the second flow path 62 decreases. Thus, the valve 40 is configured to regulate the flow of exhaust gas discharged from the first outlet 11B to increase the gas pressure at the second outlet 16C.

[1-4. effect]
According to the embodiment detailed above, the following effects are obtained.
(1a) In the exhaust heat recovery device 1 described above, when the valve 40 is at the second position, the exhaust gas discharged from the first outlet 11B is guided to the second outlet 16C. As a result, the pressure of the second outlet 16C increases, and the flow rate of the exhaust gas flowing through the second flow path 62 can be reduced. As a result, heat exchange that occurs in the heat exchanger 20 arranged in the second flow path 62 can be suppressed, and troubles related to temperature control of the vehicle and damage to equipment caused by unexpected heat exchange can be suppressed. .

(1b) The valve 40 has a bowl-shaped concave portion. Therefore, the exhaust gas that has reached the valve 40 is less likely to disperse than in the case of a flat-type or convex-type valve. In addition, the exhaust gas concentrates at the end opposite to the portion where the exhaust gas enters the concave portion, and the pressure increases. Therefore, more exhaust gas can be efficiently guided to the second outlet 16C, and the flow rate of the exhaust gas flowing through the second flow path 62 can be reduced to a higher degree.

(1c) When the valve 40 is in the second position, a portion of the valve 40 is located in the discharge direction of the exhaust gas discharged from the second outlet 16C. Therefore, the valve 40 itself can block the flow of the exhaust gas discharged from the second outlet 16C. Further, since the distance between the valve 40 and the second outlet 16C is short, the effect of guiding the exhaust gas to the second outlet 16C can be enhanced.

(1d) The second outlet 16</b>C is provided along the wall surface of the inner pipe 11 forming the first flow path 61 and is offset in the circumferential direction of the inner pipe 11 . Therefore, compared to a configuration in which the second outlets 16C are widely distributed, the proportion of the area affected by the exhaust gas guided by the valve 40 at the second outlets 16C is high. Therefore, it is possible to highly reduce the flow rate of the second flow path by increasing the pressure of the second outlet 16C. Incidentally, if the second outlet 16C were arranged widely in the circumferential direction, the valve 40 would increase the pressure in a part of the second outlet 16C, and the exhaust gas would be discharged smoothly from the other part. Therefore, the effect of reducing the flow rate of the exhaust gas flowing through the second flow path is smaller than in the present embodiment.

(1e) The second flow path 62 includes a flow path along the outer wall of the inner pipe 11 composed of the cylindrical portion 16A and the inner pipe 11 downstream of the heat exchanger 20 . A second outlet 16C is formed in the flow path. Therefore, the position of the second outlet 16</b>C can be sufficiently downstream of the heat exchanger 20 . If the second outlet 16C were provided at a position far away from the first outlet 11B, the flow velocity and flow rate of the exhaust gas guided by the valve 40 would easily decrease. In the present embodiment, the second outlet 16C is brought closer to the vicinity of the first outlet 11B by the cylindrical portion 16A, so that the flow velocity and flow rate of the exhaust gas guided by the valve 40 are sufficiently high, and the second outlet 16C The effect of increasing pressure can be improved.

[2. Other embodiments]
Although the embodiments of the present disclosure have been described above, the present disclosure is by no means limited to the above-described embodiments, and needless to say, can take various forms as long as they fall within the technical scope of the present disclosure.

(2a) In the above embodiment, the inner pipe 11, that is, the configuration in which the second flow path 62 is provided coaxially around the first flow path 61 was exemplified. However, the first flow path and the second flow path do not have to be arranged coaxially. For example, as shown in FIG. 7, the second flow path 102 may be configured non-coaxially with the first flow path 101 . That is, the exhaust heat recovery device constitutes the first flow path and the second flow path, and if the configuration is such that when the first flow path is opened, the pressure at the outlet of the second flow path can be increased by the valve. For example, the specific shapes of the piping portion, shell, valve, etc. are not particularly limited.

(2b) In the above-described embodiment, the valve 40 has a round bowl-shaped concave shape, but may have other shapes. For example, the bulb may be flat or convex (ie, bulging toward the upstream side). Further, it may be concave, elliptical bowl-shaped, or may have an additional configuration other than the concave portion.

(2c) In the above embodiment, when the valve 40 is in the second position, the valve 40 is located in the discharge direction of the exhaust gas discharged from the second outlet 16C so as to cover the second outlet 16C. However, the second position may be any other position as long as the pressure at the outlet of the second channel can be increased.

Further, the valve 40 may be configured so that the opening degree of the valve can be finely adjusted. For example, as shown in FIG. 8, an actuator 111 that adjusts the valve opening may be provided. By configuring in this way, the pressure rise of the second outlet 16C can be more finely controlled, and the flow rate of the second flow path 62 can be finely controlled.

(2d) In the above embodiment, the cylindrical portion 16A of the stay plate 16 separates the second outlet 16C downstream of the heat exchanger 20 and is positioned closer to the first outlet 11B. However, the position of the second outlet 16C is not particularly limited. For example, the second outlet 16C may be provided on the flange portion 16B or may be provided at a position radially away from the inner pipe 11 .

(2e) In the above embodiment, the configuration in which the second outlet 16C is one opening was exemplified. However, the second outlet 16C may have a plurality of openings, and the shape of the openings may be round, elliptical, polygonal, or the like. Note that the second outlet 16C is provided at a position offset in the circumferential direction of the cylindrical portion 16A, so that the effect of reducing the flow rate of the second flow path can be improved as described in (1d) above. . When the openings are a plurality of holes, it is sufficient that the openings have a biased distribution. For example, in a portion of the cylindrical portion 16A in the circumferential direction, more holes may be arranged or larger holes may be formed than in other portions. Note that the biased position referred to here may be, for example, a position within a range of about one-third in the circumferential direction. The offset position may also be a position that is greatly influenced by the exhaust gases guided by the valve 40 . This position is the position covered by at least a portion of the valve 40 when the valve 40 is in the second position. For example, it is preferable that the position is closest to the rotating shaft 43 of the valve 40 in the circumferential direction of the tubular portion 16A, but the position is not limited to this position.

(2f) A plurality of functions possessed by one component in the above embodiment may be realized by a plurality of components, or a function possessed by one component may be realized by a plurality of components. . Also, a plurality of functions possessed by a plurality of components may be realized by a single component, or a function realized by a plurality of components may be realized by a single component. Also, part of the configuration of the above embodiment may be omitted. Moreover, at least part of the configuration of the above embodiment may be added or replaced with respect to the configuration of the other above embodiment.

REFERENCE SIGNS LIST 1 Exhaust heat recovery device 10 Piping portion 11 Inner pipe 11A Inlet 11B First outlet 12 Housing 13 Branch port 14 Peripheral plate 15 Upstream lid 15A First Lid Opening 15B Second Lid Opening 16 Stay Plate 16A Cylindrical Part 16B Flange 16C Second Outlet 16D Other End 20 Heat Exchanger 21 Disk member 22 First connection channel 23 Second connection channel 30 Outer shell 31 Discharge port 40 Valve 41 Bottom plate 42 Edge 43 Rotating shaft 61, 101... First channel, 62, 102... Second channel, 64... Region, 111... Actuator

Claims (5)

An exhaust heat recovery device comprising a heat exchanger that exchanges heat between an exhaust gas and a heat exchange medium,
a piping part that constitutes a first flow path that does not exchange heat between the exhaust gas and the heat exchanger, and a second flow path that performs heat exchange;
configured to merge the exhaust gas discharged from a first outlet that is an outlet of the first flow path and the exhaust gas that is discharged from a second outlet that is an outlet of the second flow path a shell member;
a valve disposed inside the shell member in a first position for closing the first outlet to increase the flow rate of the exhaust gas to the second flow path compared to before closing; a valve configured to be movable to a second position that opens an outlet to reduce the flow rate of the exhaust gas to the second flow path compared to before opening;
The exhaust heat recovery device, wherein the valve is configured to direct at least a portion of the exhaust gas discharged from the first outlet toward the second outlet when the valve is in the second position. The exhaust heat recovery device according to claim 1,
the valve has a recessed portion that is recessed, and an opening side of the recessed portion is positioned upstream when the valve is in the first position;
The exhaust heat recovery device, wherein the second position is a position where at least part of the exhaust gas discharged from the first outlet flows into the concave portion. The exhaust heat recovery device according to claim 1 or 2,
The exhaust heat recovery device, wherein when the valve is in the second position, at least a part of the valve is positioned in a discharge direction of the exhaust gas discharged from the second outlet. The exhaust heat recovery device according to any one of claims 1 to 3,
The exhaust heat recovery device, wherein the second outlet is provided at a position along the wall surface of the pipe forming the first flow path, and at a position offset in the circumferential direction of the pipe. The exhaust heat recovery device according to any one of claims 1 to 4,
The exhaust heat recovery device, wherein the second flow path includes a flow path along a pipe forming the first flow path downstream of the heat exchanger, and the second outlet is formed in the flow path. .

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