EGR coolers and vehicle waste heat recovery devices

Abstract

This EGR cooler has a plurality of tubes (11) arrayed in a casing such that an end portion of each of the tubes (11) face a gas inlet portion (20). There are variations in flow velocity of a coolant for cooling the end portion of each of the tubes (11), and the gas inlet portion (20) is provided with a deflection portion (21) for deflecting the flow of an exhaust gas so as to increase the flow rate of the exhaust gas at the end portions of the tubes (11) hit by the high-velocity coolant.

Description

[Technical Field]

[0001] The present disclosure relates to an EGR cooler and a vehicle waste heat recovery device. [Background technology]

[0002] BACKGROUND ART An EGR cooler that cools exhaust gas from an automobile or the like is known from Patent Document 1 and the like. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2014-152626 Summary of the Invention [Problem to be solved by the invention]

[0004] The EGR cooler described in Patent Document 1 improves the cooling performance of the EGR cooler by leveling the flow rate of exhaust gas supplied to the core portion. Incidentally, it is important to prevent the coolant from boiling in an EGR cooler, and we have found that creating a bias in the flow of exhaust gas is an effective way to prevent the coolant from boiling.

[0005] Therefore, the present disclosure provides an EGR cooler and a vehicle waste heat recovery device in which boiling of the coolant is suppressed by causing a bias in the flow of exhaust gas. [Means for solving the problem]

[0006] An EGR cooler according to one aspect of the present disclosure includes: The exhaust gas evaporator has a plurality of tubes through which exhaust gas flows, and a casing that houses the tubes. An EGR cooler that performs heat exchange between the exhaust gas and the cooling water through the tubes by flowing cooling water inside the casing, a gas inlet portion for introducing the exhaust gas into the casing; a plurality of the tubes are arranged in the casing such that an end of each of the tubes faces the gas inlet port; There is a variation in the flow rate of the cooling water that cools the ends of each of the tubes, At the end of the tube where the high-velocity cooling water hits, a deflection portion is provided at the gas inlet portion for deflecting the flow of the exhaust gas so as to increase the flow rate of the exhaust gas.

[0007] A vehicle waste heat recovery device according to one aspect of the present disclosure includes: The exhaust gas evaporator has a plurality of tubes through which exhaust gas flows, and a casing that houses the tubes. A waste heat recovery device for a vehicle, in which heat exchange is performed between the exhaust gas and the cooling water through the tube by flowing cooling water inside the casing, a gas inlet portion for introducing the exhaust gas into the casing; a plurality of the tubes are arranged in the casing such that an end of each of the tubes faces the gas inlet port; There is a variation in the flow rate of the cooling water that cools the ends of each of the tubes, At the end of the tube where the high-velocity cooling water hits, a deflection portion is provided at the gas inlet portion for deflecting the flow of the exhaust gas so as to increase the flow rate of the exhaust gas.

[0008] According to the present disclosure, an EGR cooler and a vehicle waste heat recovery device are provided in which boiling of coolant is suppressed by causing a bias in the flow of exhaust gas. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of an EGR cooler according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is an exploded perspective view of the EGR cooler. [Figure 3] FIG. 2 is a cross-sectional view of the EGR cooler as viewed from above. [Figure 4]FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. [Figure 5] FIG. 3 is a cross-sectional view of the gas inlet portion as viewed from above. [Figure 6] FIG. [Figure 7] FIG. 2 is a cross-sectional view of the gas inlet portion extending in the front-rear and left-right directions. [Figure 8] FIG. 2 is a plan view of the casing as seen from the front. [Figure 9] FIG. 7 is a view corresponding to FIG. 6 of an EGR cooler according to a modified example of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. For the sake of convenience, descriptions of components having the same reference numerals as those already described in the description of the embodiments will be omitted. Furthermore, for the sake of convenience, the dimensions of each component shown in the drawings may differ from the actual dimensions of each component.

[0011] Furthermore, in the description of this embodiment, for convenience of explanation, the terms "left-right direction," "front-rear direction," and "up-down direction" will be referred to as appropriate. Here, the "up-down direction" includes the "upward direction" and the "downward direction." The "front-rear direction" includes the "forward direction" and the "rearward direction." The "left-right direction" includes the "leftward direction" and the "rightward direction." In the drawings described below, the symbol U indicates the upward direction. The symbol D indicates the downward direction. The symbol F indicates the forward direction. The symbol B indicates the rearward direction. The symbol L indicates the leftward direction. The symbol R indicates the rightward direction. Note that when the EGR cooler is installed on a vehicle, these directions do not necessarily match the respective directions set for the vehicle.

[0012] Fig. 1 is a perspective view of an EGR cooler 1 according to an embodiment of the present disclosure. As shown in Fig. 1, the EGR cooler 1 has a heat exchanger 10, a gas inlet 20 for introducing exhaust gas into the heat exchanger 10, a gas outlet 30 for discharging exhaust gas from the heat exchanger 10, a water inlet 40 for introducing cooling water into the heat exchanger 10, and a water outlet 50 (see Fig. 2) for discharging cooling water from the heat exchanger 10.

[0013] 1, hot exhaust gas flows into the heat exchanger 10 from the front through the gas inlet 20, exchanges heat with the cooling water inside the heat exchanger 10, and the cooled exhaust gas is discharged rearward from the heat exchanger 10 through the gas outlet 30. Cold cooling water flows into the heat exchanger 10 from below through the water inlet 40 at the rear of the heat exchanger 10, exchanges heat with the exhaust gas inside the heat exchanger 10, and the heated cooling water is discharged downward through the water outlet 50 at the front of the heat exchanger 10. The illustrated EGR cooler 1 is a so-called counterflow type EGR cooler in which the flow directions of the exhaust gas and the cooling water are opposite to each other in the heat exchanger 10.

[0014] FIG. 2 is an exploded perspective view of the EGR cooler 1. As shown in FIG. 2, the heat exchanger 10 has a plurality of tubes 11 and a casing 12 that houses these tubes 11. The tubes 11 are flat, hollow, plate-like members that are long in the front-rear direction. Exhaust gas flows inside the tubes 11. Cooling water flows through the spaces between the tubes 11 inside the casing 12. Fins 17 are provided inside the tubes 11 to facilitate heat exchange between the exhaust gas and the cooling water. Dimples 13 are provided on the outer surface of the tubes 11 to induce turbulence in the cooling water and promote heat exchange.

[0015] The casing 12 is a rectangular cylindrical member that is long in the front-to-rear direction. A front end plate 14 is attached to the front end of the casing 12. A rear end plate 15 is attached to the rear end of the casing 12. The gas inlet section 20 is attached to the casing 12 via the front end plate 14. The gas outlet section 30 is attached to the casing 12 via the rear end plate 15. The tubes 11 are attached to these front end plate 14 and rear end plate 15.

[0016] FIG. 3 is a cross-sectional view of the EGR cooler 1 as seen from above. FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. 3. As shown in FIGS. 3 and 4, a plurality of tubes 11 are arranged in the left-right direction within the casing 12. Openings 14a are provided in the front end plate 14 at positions corresponding to the openings of the tubes 11, allowing exhaust gas to be taken into the tubes 11. Openings are provided in the rear end plate 15 at positions corresponding to the openings of the tubes 11, allowing exhaust gas to be discharged from the tubes 11. The spaces between the openings 14a in the front end plate 14 and the spaces between the openings in the rear end plate 15 are closed, forming sealed spaces between the casing 12 and the tubes 11 and between the front end plate 14 and the rear end plate 15. Cooling water flows within these sealed spaces.

[0017] Incidentally, the flow rate of the cooling water flowing near the front end of the tube 11 shown in FIG. 4 varies. In the illustrated example, near the front end of the tube 11, the flow rate of the cooling water flowing in the central region in the left-right direction in FIG. 4 is higher than the flow rate of the cooling water flowing in the right and left regions in the left-right direction. The water inlet 40 opens in the central region in the left-right direction, and the water outlet 50 opens in the central region in the left-right direction. This is because the cooling water easily flows through the central region in the left-right direction. Also, this is because the path that the cooling water takes to reach the central region in the left-right direction at the front of the heat exchange unit 10 from the water inlet 40 is shorter than the path that the cooling water takes to reach the right and left regions in the front of the heat exchange unit 10 from the water inlet 40. In addition to the length of the path through which the cooling water flows, the flow rate of the cooling water also varies depending on the shape of the path through which the cooling water flows, the cross-sectional area of ​​the path through which the cooling water flows, and the presence or absence of obstacles on the path (for example, protrusions such as dimples 13).

[0018] As described above, in the EGR cooler 1 of this embodiment, the flow speed of the coolant that cools the front end of each tube 11 varies. Therefore, the coolant flowing near the left end and the right end of the front end of the tube 11 located in the center in the left-right direction is likely to boil. Therefore, in the EGR cooler 1 of this embodiment, to prevent boiling in the areas where boiling is likely to occur, a deflection section 21 is provided in the gas inlet section 20 to deflect the flow of exhaust gas so that high-velocity exhaust gas is introduced into the end of the tube 11 that hits the high-velocity coolant. The structure of the gas inlet section 20 will be described below with reference to FIGS. 5 to 8.

[0019] Figure 5 is a cross-sectional view of the gas inlet section 20 as seen from above. As shown in Figure 5, the gas inlet section 20 is provided with two gas passages through which exhaust gas passes. The two gas passages are provided on the right and left sides. In the following description, the gas passage located on the right side may be referred to as the right gas passage, and the gas passage located on the left side may be referred to as the left gas passage.

[0020] As shown in FIG. 5, exhaust gas flows from the front to the rear. The inner wall of the gas inlet portion 20 is provided with a deflection portion 21 that extends obliquely so as to intersect the front-to-rear direction. The deflection portion 21 is provided in each of the right gas passage and the left gas passage. In the following description, the deflection portion provided in the right gas passage may be referred to as the right deflection portion 21R, and the deflection portion provided in the left gas passage may be referred to as the left deflection portion 21L. Furthermore, since the right gas passage and the left gas passage have a symmetrical shape, only one will be described and the description of the other will be omitted.

[0021] As shown in the figure, the deflection portion 21 makes the opening area of ​​the outlet of the gas inlet portion 20 smaller than the opening area of ​​the inlet of the gas inlet portion 20. In FIG. 5, the dashed line indicates the inner wall of the gas inlet portion of the EGR cooler according to the reference example. In the reference example, the shape of the inner wall of the gas inlet portion is designed with the intention of introducing exhaust gas into the casing at a uniform flow rate, as in Patent Document 1 and the like. The opening area L1 of the outlet of the gas inlet portion of the EGR cooler according to this embodiment is made smaller than the opening area L2 of the outlet of the gas inlet portion of the EGR cooler according to the reference example.

[0022] The right deflection portion 21R is provided on the right inner wall of the right gas passage. The right deflection portion 21R is inclined from right to left as it moves from front to rear. Therefore, exhaust gas entering the right side of the gas inlet portion 20 toward the rear is redirected leftward by the right deflection portion 21R and enters the heat exchanger 10 from the center of the outlet of the gas inlet portion 20 in the left-right direction. In other words, the exhaust gas that would have entered the tubes 11 located in the right region of the heat exchanger 10 without the right deflection portion 21R is now directed toward the center region of the heat exchanger 10 by the right deflection portion 21R. Therefore, the flow rate of exhaust gas introduced into the tubes 11 located in the center region at the front end of the heat exchanger 10 is increased.

[0023] As described above, near the front end of the tube 11, the flow rate of the cooling water flowing in the central region in the left-right direction in FIG. 4 is higher than the flow rate of the cooling water flowing in the right and left regions in the left-right direction. Generally, boiling is less likely to occur in areas where exhaust gas flows at a low flow rate (low flow rate). Furthermore, in areas where the cooling water flows at a high flow rate (high flow rate), the heat capacity of the cooling water is large and the rise in water temperature is small, making boiling less likely to occur. In this embodiment, the deflection section 21 deflects the flow of exhaust gas so that the flow rate of exhaust gas is large in areas where the cooling water flow rate is high. Conversely, to prevent exhaust gas from flowing at a high flow rate into areas where the cooling water flow rate is low, the deflection section 21 directs exhaust gas that would otherwise enter areas where the cooling water flow rate is low into areas where the cooling water flow rate is high (areas where boiling is less likely to occur in the first place). Therefore, in the EGR cooler 1 according to this embodiment, the heat capacity of the cooling water in the central region of the front end portion close to the gas inlet portion 20 of the tube 11, where boiling is more likely to occur, is increased, the rise in water temperature is suppressed, and boiling in the central region is prevented.

[0024] In the EGR cooler 1 according to this embodiment, the flow direction of the exhaust gas flowing inside the tube 11 and the flow direction of the cooling water flowing inside the casing 12 are different. In a counterflow type EGR cooler such as the EGR cooler 1 according to the present embodiment, the vicinity of the gas inlet 20 is downstream of the coolant, and therefore boiling is likely to occur. However, in the EGR cooler 1 according to the present embodiment, the deflection section 21 suppresses boiling in the area where boiling is likely to occur. Therefore, the EGR cooler 1 according to the present embodiment is well suited to counterflow types. However, the EGR cooler 1 according to the present disclosure may also be applied to a parallel flow type EGR cooler.

[0025] 5, in the EGR cooler 1 according to this embodiment, the gas inlet section 20 is provided with a left gas inlet passage 22 through which exhaust gas passes directly from the inlet of the gas inlet section 20 to the heat exchange section 10, and a left deflection section 21L that guides the exhaust gas toward the left gas inlet passage 22. When the gas inlet section 20 is viewed from the direction in which the exhaust gas is introduced into the casing 12 (heat exchange section 10), only a portion of the casing 12 is exposed from the left gas inlet passage 22, and the other portion of the casing 12 is covered by the left deflection section 21L. In the illustrated example, when the gas inlet section 20 is viewed from above in the figure, a region of the casing 12 (front end portion of the tube 11) designated by the symbol A0 is visible through the left gas inlet passage 22, and the other region is covered by the deflection section 21 and is not visible.

[0026] FIG. 6 is a perspective view showing the left gas passage. Only the inner wall of the gas inlet section 20 is shown in FIG. 6 . Also shown in FIG. 6 is a portion of the heat exchange section 10 to which the gas inlet section 20 is attached. The front end plate 14 is not shown in FIG. 6 . As shown in FIG. 6 , the gas inlet section 20 has a high-speed section 60 into which high-speed exhaust gas flows directly toward the heat exchange section 10 (casing 12), and a low-speed section 70. The left deflection section 21L blocks the flow of exhaust gas directly toward the heat exchange section 10, allowing the low-speed section 70 to flow at a lower speed than the exhaust gas flowing through the high-speed section 60. The high-speed section 60 and the low-speed section 70 are separated by a partition wall 23 with a gap. In FIG. 6 , the partition wall 23 is exaggerated by a two-dot chain line. In reality, the partition wall 23 is made up of the “meat” of the gas inlet section 20, and the partition wall 23 does not need to be a plate-shaped portion as shown.

[0027] 7 is a cross-sectional view of the gas inlet section 20 extending in the front-rear and left-right directions. Tubes 11, a front end plate 14, and a casing 12 are also shown in FIG. 7. As shown in FIG. 7, the partition wall 23 faces the casing 12 (front end plate 14) via a gap G. Exhaust gas flows from the high-speed section 60 to the low-speed section 70 via this gap G.

[0028] 6, the low-speed section 70 is made up of a first low-speed section 71, a second low-speed section 72, and a third low-speed section 73. With respect to the direction in which the exhaust gas is introduced into the heat exchange section 10 (casing 12), the first low-speed section 71, the second low-speed section 72, and the third low-speed section 73 are all closed at the inlet side of the gas inlet section 20 and open at the outlet side (casing 12 side) of the gas inlet section 20. The upstream sides of the first low-speed section 71, the second low-speed section 72, and the third low-speed section 73 are closed by the inner wall 24 of the gas inlet section 20. In other words, the exhaust gas does not flow into the low-speed section 70 directly from the inlet of the gas inlet section 20, but rather flows into the low-speed section 70 via the high-speed section 60.

[0029] The upstream side of the low-velocity section 70 is formed by the inner wall 24 of the stepped gas inlet section 20, and multiple spaces (first low-velocity section 71 and second low-velocity section 72) are provided within the low-velocity section 70, with different distances between the stepped gas inlet section 20 and the front end of the tube 11. In the illustrated example, when comparing the front-to-rear dimensions (the distance between the inner wall 24 of the stepped gas inlet section 20 and the front end of the tube 11), the front-to-rear dimension of the first low-velocity section 71 is larger than the front-to-rear dimension of the second low-velocity section 72.

[0030] Most of the exhaust gas passing through the high-speed section 60 enters the tube 11 from the region indicated by symbol A1. The left deflection section 21L is also inclined from bottom to top as it moves from front to rear, causing a portion of the exhaust gas passing through the high-speed section 60 to change direction so that it flows around in a plane extending in the left-right and up-down directions. This portion of the exhaust gas then flows into the first low-speed section 71. Figure 8 shows the exhaust gas flow that flows around in this way. Figure 8 is a plan view of the casing 12 viewed from the front, with the gas inlet section 20 drawn in perspective. Figure 8 shows the downstream end of the left gas passage. As shown in Figure 8, the partition wall 23 separating the high-speed section 60 and the low-speed section 70 extends in the up-down direction. This partition wall 23 does not extend from the top to the bottom of the casing 12, but has a notch 24 at its bottom.

[0031] As shown in FIG. 8, a portion of the exhaust gas flowing through the high-speed section 60 passes through this notch 24 in the partition wall 23 and flows into the first low-speed section 71. A portion of the exhaust gas that flows into the first low-speed section 71 enters the tube 11 from the region indicated by symbol A2 in FIG. 6. The remainder of the exhaust gas that flows into the first low-speed section 71 enters the second low-speed section 72. The exhaust gas that flows into the second low-speed section 72 enters the tube 11 from the region indicated by symbol A3 in FIG. 6. The second low-speed section 72 has a larger internal volume than the third low-speed section 73, and the flow rate of the exhaust gas flowing into it is larger. Therefore, the flow rate of the exhaust gas passing through region A2 is larger than the flow rate of the exhaust gas passing through region A3.

[0032] Incidentally, regions A2 and A3 are located at the left end of the front surface of the casing 12. Region A2 is located more centrally in the vertical direction than region A3, and region A3 is located at the upper end of the front surface of the casing 12. In the front part of the heat exchanger 10, the flow velocity of the cooling water flowing through the central region in the vertical direction is higher than the flow velocity of the cooling water flowing through the upper and lower regions. Therefore, boiling is more likely to occur in region A3 than in region A2. Therefore, in this embodiment, a first low-speed section 71 and a second low-speed section 72 are provided so that more exhaust gas flows into region A2 than region A3. This further suppresses boiling.

[0033] The third low-velocity section 73 is provided to prevent a large amount of exhaust gas from flowing into the lower region A4 of the front ends of the multiple tubes 11. For the same reason as described above, it is more difficult for coolant to flow into the upper and lower regions A4 of the front ends of the multiple tubes 11 than into the central region, so boiling is also more likely to occur in this lower region A4. For this reason, by configuring the exhaust gas to flow in a small amount into the lower region A4 via the third low-velocity section 73, boiling in the lower region A4 is prevented.

[0034] Fig. 9 is a view corresponding to Fig. 6 of an EGR cooler 101 according to a modified example of the present disclosure. As shown in Fig. 9, the cutout 124 of the partition wall 123 may be provided in the center in the up-down direction. In this case, the first low-speed section 171 and the second low-speed section 172 can be provided in the order of increasing distance from the cutout 124 upward and downward.

[0035] In the above-described embodiment, an example in which the present disclosure is applied to an EGR cooler has been described. However, the present disclosure may also be applied to a vehicle waste heat recovery device. A vehicle waste heat recovery device is a component also called a heat collector that is installed in a vehicle. A vehicle waste heat recovery device performs heat exchange between exhaust gas and coolant, and is used to warm the engine with the heated coolant to improve fuel efficiency. Such a vehicle waste heat recovery device also includes a tube, a casing, and the like, and can be configured in a similar manner to the configuration described above.

[0036] This application incorporates by reference the contents disclosed in a Japanese patent application (Patent Application No. 2020-183826) filed on November 2, 2020, as appropriate. [Explanation of symbols]

[0037] 1 EGR cooler 10 Heat exchange section 11 tubes 12 Casing 13 Dimples 14 Front end plate 15 Rear end plate 17 Finn 20 Gas inlet 21 Deflection section 21L Left deflection section 21R Right deflection section 22 Left gas inlet passage 23 Partition Wall 30 Gas outlet 40 Water inlet 50 Water outlet 60 High speed section 70 Low speed section 71 First low speed section 72 Second low speed section 73 Third Low-Speed ​​Section

Claims

1. An exhaust gas turbine engine comprising: a plurality of tubes through which exhaust gas flows; and a casing that houses the tubes; An EGR cooler that performs heat exchange between the exhaust gas and the cooling water through the tubes by flowing cooling water inside the casing, a gas inlet portion for introducing the exhaust gas into the casing; a plurality of the tubes are arranged in the casing such that an end of each of the tubes faces the gas inlet port; There is a variation in the flow rate of the cooling water that cools the ends of each of the tubes, a deflection portion that deflects the flow of the exhaust gas so as to increase the flow rate of the exhaust gas at the end of the tube where the high-speed cooling water hits, and The gas inlet portion a gas inlet passage through which the exhaust gas passes directly into the casing; the deflector portion directing the exhaust gas toward the gas inlet passage, When the gas inlet portion is viewed from the direction in which the exhaust gas is introduced into the casing, only a portion of the casing is exposed from the gas inlet passage, and the other portion of the casing is covered by the deflection portion.

2. The EGR cooler according to claim 1 , wherein a flow direction of the exhaust gas flowing through the tubes is different from a flow direction of the cooling water flowing through the casing.

3. The gas inlet portion has a high-speed section into which the exhaust gas flows at a high speed and directly toward the casing; a low-speed section in which the flow of exhaust gas flowing directly toward the casing is blocked by the deflection section, and the exhaust gas flows at a speed slower than the exhaust gas flowing through the high-speed section, The EGR cooler according to claim 1 , wherein the high speed portion and the low speed portion are separated by a partition wall having a gap therebetween.

4. The EGR cooler according to claim 3 , wherein the partition wall faces the casing via a gap.

5. 5. The EGR cooler according to claim 4, wherein an inlet side of the gas inlet portion is closed and an outlet side of the gas inlet portion is open in a direction in which the exhaust gas in the low-speed portion is introduced into the casing.

6. 6. The EGR cooler according to claim 5, wherein an upstream side of the low speed section is formed by a stepped inner wall of the gas inlet section, and a plurality of spaces having different distances between the stepped gas inlet section and the end of the tube are provided within the low speed section.

7. The exhaust gas evaporator has a plurality of tubes through which exhaust gas flows, and a casing that houses the tubes. A waste heat recovery device for a vehicle, in which heat exchange is performed between the exhaust gas and the cooling water through the tube by flowing cooling water inside the casing, a gas inlet portion for introducing the exhaust gas into the casing; a plurality of the tubes are arranged in the casing such that an end of each of the tubes faces the gas inlet port; There is a variation in the flow rate of the cooling water that cools the ends of each of the tubes, a deflection portion that deflects the flow of the exhaust gas so as to increase the flow rate of the exhaust gas at the end of the tube where the high-speed cooling water hits, and The gas inlet portion a gas inlet passage through which the exhaust gas passes directly into the casing; the deflector portion directing the exhaust gas toward the gas inlet passage, When the gas inlet portion is viewed from the direction in which the exhaust gas is introduced into the casing, only a portion of the casing is exposed from the gas inlet passage, and the other portion of the casing is covered by the deflection portion.

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