EGR coolers and vehicle waste heat recovery devices

Abstract

To provide an EGR cooler which enables adjustment of water conduction resistance and achieves reduction of influence on internal flow of the EGR cooler and a vehicular waste heat recovery device, and to provide the vehicular waste heat recovery device.SOLUTION: An EGR cooler has: a casing in which a coolant for cooling exhaust gas flows and which has a square tube shape; and an adapter connected to the casing at the downstream side of a coolant passage. The adapter has: an introduction port which introduces the coolant in the casing into the adapter; a cylindrical bridge part which is continuous with the introduction port and has an inner diameter φ; and a contraction part which is provided at the downstream side of the coolant passage relative to the bridge part and configured to be processed so that its inner diameter becomes any diameter smaller than φ, which adjusts water conduction resistance of the EGR cooler. A distance a from an opening of the introduction port to the contraction part is over 0.15 times of the inner diameter φ of the bridge part.SELECTED DRAWING: Figure 6

Description

[Technical field]

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

[0002] 2. Description of the Related 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] JP 2008-128611 A Summary of the Invention [Problem to be solved by the invention]

[0004] Coolant flows through the internal combustion engine and its auxiliary devices. The flow rate of the coolant flowing through the internal combustion engine and its auxiliary devices is determined by the flow resistance of each component. In recent years, there has been a demand for replacing the EGR cooler that was installed at the time of vehicle development with a different EGR cooler at the mass production stage. However, since the water flow resistance of EGR coolers usually differs depending on the product, simply replacing the EGR cooler could disrupt the flow balance of the cooling water flowing through the internal combustion engine and auxiliary equipment. In order to achieve the same water flow resistance as the EGR cooler at the beginning of the vehicle's development, it is possible to provide an orifice at the outlet of the EGR cooler. However, providing an orifice at the outlet may affect the flow inside the EGR cooler in some cases.

[0005] Therefore, the present invention provides an EGR cooler and a vehicle waste heat recovery device that can adjust the water flow resistance and reduce the effect on the internal flow of the EGR cooler and the vehicle waste heat recovery device. [Means for solving the problem]

[0006] An EGR cooler according to one aspect of the present invention includes: A rectangular tubular casing through which cooling water flows to cool the exhaust gas; An adapter connected to the casing on a downstream side of a cooling water flow path, The adapter comprises: an inlet for introducing cooling water from within the casing into the adapter; A cylindrical transfer portion having an inner diameter φ and connected to the inlet; a throttle portion provided downstream of the cooling water flow path with respect to the transfer portion and configured to be machined to an arbitrary inner diameter smaller than φ for adjusting the water flow resistance of the EGR cooler, A distance a from the opening of the introduction port to the narrowed portion is 0.15 times or more the inner diameter φ of the transfer portion.

[0007] A vehicle waste heat recovery device according to one aspect of the present invention includes: A rectangular tubular casing through which cooling water flows to cool the exhaust gas; An adapter connected to the casing on a downstream side of a cooling water flow path, The adapter comprises: an inlet for introducing cooling water from within the casing into the adapter; A cylindrical transfer portion having an inner diameter φ and connected to the inlet; a throttle portion provided downstream of the flow path of the cooling water with respect to the transfer portion and configured to be machined to an arbitrary inner diameter smaller than φ for adjusting the water flow resistance of the vehicle waste heat recovery device; A distance a from the opening of the introduction port to the narrowed portion is 0.15 times or more the inner diameter φ of the transfer portion.

[0008] According to the present invention, there is provided an EGR cooler and a vehicle waste heat recovery device that can adjust the water flow resistance and reduce the effect on the internal flow of the EGR cooler and the vehicle waste heat recovery device. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of an EGR cooler according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an exploded perspective view of the EGR cooler. [Diagram 3] FIG. 2 is a cross-sectional view of the EGR cooler as viewed from above. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Diagram 5] 4 is a cross-sectional view taken along line VV in FIG. 3. [Figure 6] FIG. 6 is an enlarged view of a portion VI in FIG. [Figure 7] FIG. 7 is an enlarged view of part VII in FIG. [Figure 8] FIG. 2 is a schematic cross-sectional view of an analysis model in Example 1. [Figure 9] FIG. 1 is a diagram for explaining an analysis result in the first embodiment. [Figure 10] FIG. 11 is a schematic cross-sectional view of an analysis model in Example 2. [Figure 11] FIG. 13 is a diagram for explaining the analysis results in the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. For the sake of convenience, the description of the components having the same reference numbers as those already described in the description of the embodiment will be omitted. Also, for the sake of convenience, the dimensions of each component shown in the drawings may differ from the actual dimensions of each component.

[0011] In addition, in the description of this embodiment, for convenience of explanation, the "left-right direction," "front-rear direction," and "up-down direction" will be mentioned as appropriate. Here, the "up-down direction" is a direction that includes the "upward direction" and the "downward direction." The "front-rear direction" is a direction that includes the "forward direction" and the "rearward direction." The "left-right direction" is a direction that includes the "leftward direction" and the "rightward direction." In the figures 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 invention. 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 exchange section 10 from the front through the gas inlet 20, exchanges heat with cooling water inside the heat exchange section 10, and the cooled exhaust gas is discharged rearward from the heat exchange section 10 through the gas outlet 30. Cold cooling water flows into the heat exchange section 10 from below through the water inlet 40 at the rear of the heat exchange section 10, exchanges heat with the exhaust gas inside the heat exchange section 10, and the heated cooling water is discharged downward through the water outlet 50 at the front of the heat exchange section 10. The illustrated EGR cooler 1 is a so-called counterflow type EGR cooler in which the flow direction of the exhaust gas and the flow direction of the cooling water are opposite to each other in the heat exchange section 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 spaces between the tubes 11 inside the casing 12. Fins 17 are provided inside the tubes 11 to aid in heat exchange between the exhaust gas and the cooling water. Dimples 13 are provided on the outer surface of the tubes 11 to promote heat exchange by causing turbulence in the cooling water.

[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. A gas inlet section 20 is attached to the casing 12 via the front end plate 14. A gas outlet section 30 is attached to the casing 12 via the rear end plate 15. The tubes 11 are attached to the front end plate 14 and the 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 in the casing 12. Openings 14a are provided in the front end plate 14 at positions corresponding to the openings of the tubes 11, and exhaust gas can 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, and exhaust gas can be discharged from the tubes 11 to the outside. The spaces between the openings of the front end plate 14 and the openings of the rear end plate 15 are closed, and sealed spaces are formed between the casing 12 and the tubes 11 and between the front end plate 14 and the rear end plate 15. Cooling water flows in this sealed space.

[0017] Fig. 5 is a cross-sectional view taken along the line VV in Fig. 3. In this embodiment, a water inlet 40 and a water outlet 50 are provided on the lower surface of the casing 12. Fig. 6 is an enlarged view of a portion VI in Fig. 5. As shown in Figs. 5 and 6, in this embodiment, the water outlet 50 is formed as an adapter 51 attached to an opening of the casing 12. A cooling water passage through which cooling water passes is provided inside the adapter 51. The adapter 51 is fitted into an opening provided in the casing 12 and fixed to the casing 12 by joining the opening edge by welding or the like.

[0018] The adapter 51 has an inlet 52, a transfer section 53, a throttle section 54, and a connection section 55. The inlet 52 is configured to allow the cooling water in the casing to flow into the inside of the adapter. The transfer section 53 is a cooling water flow path provided continuously with the inlet 52.

[0019] The throttle portion 54 is a cooling water flow passage having an inner diameter smaller than that of the transfer portion 53. The smaller the inner diameter of the throttle portion 54, the higher the water flow resistance of the EGR cooler 1. The inner diameter of the throttle portion 54 is adjusted to an arbitrary size by machining or the like. By adjusting the throttle portion 54 to an arbitrary inner diameter, the water flow resistance of the EGR cooler 1 can be adjusted. Note that the inner diameter φ of the throttle portion 54 is O is preferably 40% to 90% of the inner diameter φ of the connecting portion 53.

[0020] The connection part 55 is connected to a pipe 2 that guides the cooling water to equipment downstream of the EGR cooler 1. In this embodiment, the connection part 55 and the pipe 2 are connected by inserting a part of the pipe 2 into the inside of the connection part 55. An O-ring 3 may be provided between the connection part 55 and the pipe 2 to prevent leakage of the cooling water.

[0021] In this embodiment, a portion of the pipe 2 is inserted inside the connection portion 55, but the connection portion and the pipe may be connected by inserting the connection portion into the inside of the pipe. Also, instead of a pipe, the connection part may be directly connected to a device downstream of the EGR cooler 1, such as an internal combustion engine. As another example, a rubber hose may be placed to cover the outer wall surface of the connection part or the adapter, and the connection may be made with a hose band or the like.

[0022] Furthermore, the connecting portion does not necessarily have to be provided, and the adapter may be configured so that the outer wall surface and the pipe are connected. In this case, a throttle portion 54 is provided at the downstream end of the adapter.

[0023] Next, the relationship between the distance from the opening of inlet 52 to throttle portion 54 and the inner diameter of bridge portion 53 will be described. As shown in Fig. 6, the distance from the opening of inlet 52 to throttle portion 54 is designated as a. Here, the opening refers to the upstream end of the cooling water flow path provided inside adapter 51. In other words, the opening of inlet 52 refers to the upstream end of the cooling water in inlet 52.

[0024] At this time, the ratio b of the distance a from the opening of the introduction port 52 to the throttle portion 54 to the inner diameter φ of the transfer portion 53 is configured to satisfy the following formula.

number

[0025] If the adapter has a throttle portion with an arbitrary inner diameter that adjusts the water flow resistance of the EGR cooler, the water flow resistance of the EGR cooler can be freely set by adjusting the inner diameter of the throttle portion. However, simply providing a throttle portion can cause inconveniences such as uneven flow inside the casing, which can change the cooling performance of the EGR cooler due to the influence of the throttle portion, or changing the flow pattern of the entire cooling water circulation path including the EGR cooler. The inventor has found that in the EGR cooler having the above-mentioned configuration, when the ratio b of the distance a from the opening of the inlet 52 to the throttling section 54 to the inner diameter φ of the transfer section 53 is 0.15 or more, the cooling water can flow out uniformly from inside the casing 12 and the effect on the flow inside the EGR cooler can be reduced.

[0026] 7 is an enlarged view of the adapter 51. The inlet 52 is provided with a tapered portion 520 that is chamfered at the opening. In a cross-sectional view taken along a line passing through the central axis Ax of the connecting portion 53, the length of the tapered portion 520 (chamfered length) is defined as c. The length of the front-rear direction component of the tapered portion 520 is defined as c1, and the length of the up-down direction component is defined as c2. Furthermore, the angle formed between an extension line of the tapered portion 520 and the central axis Ax of the connecting portion 53 is defined as θ.

[0027] In this case, the chamfered area S, which is the area lost by providing the chamfer at the inlet 52, is obtained by the following formula.

number

[0028] Here, the EGR cooler according to the present embodiment is configured such that the relationship between the inner diameter φ of the connecting portion 53 and the chamfered area S satisfies the following formula.

number

[0029] In the EGR cooler having the above-mentioned configuration, the inlet 52 of the adapter 51 is provided with the chamfered tapered portion 520, so that the inlet 52 can suck in a wider range of cooling water inside the casing 12. In this case, the inventors have found that, in a cross section passing through the center line of the cross section of the transfer portion 53, if the number obtained by dividing the chamfered area A by the 1.8th power of the inner diameter φ of the transfer portion is greater than 0.001, the influence of the flow inside the casing 12 can be further reduced.

[0030] Furthermore, the tapered portion 520 is provided at its upstream end and downstream end with R-chamfered portions R1 and R2. In the EGR cooler configured as described above, the R-chamfered portions R1 and R2 are provided at both ends of the tapered portion 520, so that the chamfered area S can be made even larger than when no R-chamfered portion is provided. Furthermore, the R-chamfered portions R1 and R2 make the flow path smooth, so that the cooling water inside the casing 12 can be introduced more smoothly into the adapter 51. This can further reduce the effect of the flow inside the casing 12.

[0031] Example 1 An analysis was performed using an analytical model to investigate the flow of cooling water flowing through the EGR cooler and the adapter. FIG. 8 is a schematic cross-sectional view of the analytical model used in Example 1. As shown in FIG. 8, the analytical model is formed by connecting three cylinders of different sizes. In the analytical model, the cylinder on the most upstream side with the largest inner diameter mimics the casing 12 in this embodiment (casing cylinder). The second largest cylinder, which is connected to the downstream side of the casing cylinder, mimics the transfer section 53 in this embodiment (transfer section cylinder, inner diameter is φ). The smallest cylinder, which is connected to the downstream side of the transfer section cylinder, mimics the throttle section 54 in this embodiment (throttle section cylinder, inner diameter φ). O ). Moreover, the length a of the cylinder of the transfer portion in the longitudinal direction corresponds to the distance from the opening of the introduction port 52 to the throttle portion 54 in this embodiment.

[0032] At this time, the flow velocity distribution at cross section Z 5 mm upstream from the upstream end of the cylindrical transfer section in the cylindrical casing was examined, and the standard deviation SD of the flow velocity distribution was calculated. A larger standard deviation SD indicates a more non-uniform flow in the cylindrical casing, and a smaller standard deviation SD indicates a more uniform flow in the cylindrical casing.

[0033] The standard deviation SD at cross section Z was investigated by changing the longitudinal length of the cylinder at the transfer section with the inner diameter φ of 20, 30, and 50 mm. Figure 9 shows the results obtained by analysis. When the ratio b of the longitudinal length a of the cylinder at the transfer section to the inner diameter φ of the cylinder at the transfer section is 0.15 or more, the standard deviation SD is approximately 0.35 even if the inner diameter φ of the transfer section or ratio b changes. On the other hand, when ratio b is less than 0.15, the standard deviation SD exceeds 0.35 by more than 10%. Therefore, since the standard deviation SD can be reduced when ratio b is 0.15 or more, it was confirmed that the effects of the flow inside the casing can be suppressed in an adapter with ratio b of 0.15 or more.

[0034] Example 2 Next, the effect of chamfering was analyzed using an analytical model. Fig. 10 is a schematic cross-sectional view of the analytical model used in Example 2. As shown in Fig. 10, the analytical model used in Example 2 differs from the analytical model used in Example 1 in that it has a tapered portion at the upstream end of the transfer cylinder. In a cross section passing through the central axis of the transfer cylinder, if the length of the tapered portion is c and the angle between the extension line of the tapered portion and the central axis is θ, the chamfer area S can be obtained by the following formula.

number

[0035] The chamfer area S was changed and the standard deviation SD at the cross section Z was investigated for the inner diameter φ of the cylinder at the transfer section = 20, 30, and 50 mm. The inventors found that the results could be meaningfully organized by dividing the chamfer area S by the 1.8th power of the inner diameter φ of the cylinder at the transfer section. Figure 11 shows the results obtained by analysis.

[0036] It can be seen that the larger the chamfered area S, the more the standard deviation SD decreases. Meanwhile, as shown in Fig. 11, when the chamfered area S increases, and the value obtained by dividing the chamfered area S by the 1.8th power of the inner diameter φ of the cross-over cylinder is 0.001 or less, the standard deviation SD decreases more rapidly than when the value obtained by dividing the chamfered area S by the 1.8th power of the inner diameter φ of the cross-over cylinder exceeds 0.001. In other words, when the value obtained by dividing the chamfered area S by the 1.8th power of the inner diameter φ of the cross-over cylinder is gradually decreased, the standard deviation SD increases rapidly when the value obtained by dividing the chamfered area S by the 1.8th power of the inner diameter φ of the cross-over cylinder falls below 0.001. Therefore, it was confirmed that the value obtained by dividing the chamfered area S by the 1.8th power of the inner diameter φ of the connecting portion cylinder is preferably greater than 0.001.

[0037] The present invention has been described above based on the embodiment and examples. The present embodiment is an example of the present invention, and is not limited to the above-mentioned embodiment, and can be modified, improved, etc. as appropriate. In addition, the material, shape, size, numerical value, form, number, arrangement location, etc. of each component in the above-mentioned embodiment are arbitrary and not limited as long as the present invention can be achieved.

[0038] For example, in this embodiment, a counterflow type EGR cooler in which the water inlet is located behind the water outlet is used as an example, but the EGR cooler may be a parallel flow type EGR cooler in which the water inlet is located ahead of the water outlet and the cooling water flows in the same direction as the exhaust gas flows.

[0039] In the above embodiment, the present invention is applied to an EGR cooler, but the present invention may be applied to a vehicle waste heat recovery device. A vehicle waste heat recovery device is a component mounted on a vehicle, also called a heat collector. A vehicle waste heat recovery device is used to exchange heat between exhaust gas and coolant, and to warm the engine with the warmed 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 the same manner as the above-mentioned configuration. [Explanation of symbols]

[0040] 1 EGR cooler 2. Pipe 3 O-ring 10 Heat exchange section 11 Tube 12 Casing 13 Dimples 14 Front end plate 14a aperture 15 Rear end plate 16 Mounting hole 17 Finn 20 Gas inlet 30 Gas outlet 40 Water inlet 50 Water outlet 51 Adapter 52 Introduction 53 Ferry 54 Squeezing section 55 Connection 520 Tapered section AX center axis R1, R2 R chamfered part

Claims

1. A rectangular tubular casing through which cooling water flows to cool the exhaust gas; An adapter connected to the casing on a downstream side of a cooling water flow path, The adapter comprises: an inlet for introducing cooling water from within the casing into the adapter; A cylindrical transfer portion having an inner diameter φ and connected to the inlet; a throttle portion provided downstream of the cooling water flow path with respect to the transfer portion and configured to be machined to an arbitrary inner diameter smaller than φ for adjusting the water flow resistance of the EGR cooler, a distance a from the opening of the introduction port to the throttle portion is 0.15 times or more an inner diameter φ of the transfer portion, The inlet is provided with a tapered portion, An EGR cooler that satisfies the following formula, in a cross section taken along the center line of the inlet, when a length of a chamfered portion of the tapered portion is c and an angle between the chamfered portion and the center line is θ. [0050]

2. The EGR cooler according to claim 1 , wherein both ends of the tapered portion are rounded.

3. A rectangular tubular casing through which cooling water flows to cool the exhaust gas; An adapter connected to the casing on a downstream side of a cooling water flow path, The adapter comprises: an inlet for introducing cooling water from within the casing into the adapter; A cylindrical transfer portion having an inner diameter φ and connected to the inlet; a throttle portion provided downstream of the flow path of the cooling water with respect to the transfer portion and configured to be machined to an arbitrary inner diameter smaller than φ for adjusting the water flow resistance of the vehicle waste heat recovery device; a distance a from the opening of the introduction port to the throttle portion is 0.15 times or more an inner diameter φ of the transfer portion, The inlet is provided with a tapered portion, A waste heat recovery device for a vehicle that satisfies the following formula, in a cross section taken along the center line of the inlet, where c is the length of the chamfered portion of the tapered portion and θ is the angle between the chamfered portion and the center line. [006]

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