JP2016145524A - EGR cooler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EGR cooler that can suppress boiling of cooling water flowing in a main portion even when mounted to a gasoline vehicle.SOLUTION: An EGR cooler includes: a main portion (20) having a plurality of divided gas flow passages (24) in which exhaust gas flows and exchanging heat between cooling water flowing around the gas flow passages and exhaust gas; and a cylindrical introduction portion (10) provided at a gas flow upstream side end of the main portion to introduce the exhaust gas to the main portion. The introduction portion includes: a straightening vane (15) thermally coupled to an inner wall of the introduction portion and partitioning inside of the introduction portion along a flow of exhaust gas; and a water passage (14) in which cooling water flows to cool a joining portion between the straightening vane and the inner wall of the introduction portion.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an EGR cooler that cools recirculated exhaust gas.

  A technique called EGR (Exhaust Gas Recirculation) is known, in which exhaust gas discharged from an automobile engine is returned to the intake side and reused. An EGR cooler that lowers the temperature of the exhaust gas so that EGR can be performed efficiently. Has been developed.

  In a vehicle equipped with this EGR cooler, when a part of the exhaust gas is returned to the intake system, the exhaust gas is cooled by the EGR cooler, and there is an effect that the maximum temperature during combustion is lowered and the amount of NOx produced is suppressed. For this reason, EGR coolers are mounted on diesel vehicles that emit more NOx than gasoline vehicles. The technique described in Patent Document 1 is also an EGR cooler developed for a diesel vehicle.

  In this patent document 1, a technique is disclosed in which a flow straightening plate is provided inside an introduction portion into which exhaust gas flows and the flow rate difference between exhaust gases flowing into plate tubes stacked inside the core is reduced.

JP 2010-209878 A

  However, with the tightening of global fuel economy and emission regulations, the introduction of EGR coolers in gasoline vehicles has been attempted. In this case, for example, when the EGR cooler described in Patent Document 1 is applied to a gasoline vehicle, the temperature of the exhaust gas flowing into the EGR cooler is higher than the temperature of the exhaust gas of the diesel vehicle. There is a possibility that the cooling water will boil due to the high-temperature exhaust gas flowing into the gas.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an EGR cooler that can suppress boiling of the cooling water flowing in the main part even when mounted on a gasoline vehicle. .

  The present invention is an EGR cooler having a plurality of divided gas passages through which exhaust gas is circulated, and a main part that performs heat exchange between the cooling water flowing around the gas passages and the exhaust gas; An EGR cooler provided at a gas flow upstream end of the main part and including a cylindrical introduction part for introducing the exhaust gas into the main part, wherein the introduction part is provided on an inner wall of the introduction part A rectifying plate that is thermally joined and partitions the inside of the introduction portion along the flow of the exhaust gas; and a water channel that circulates cooling water so as to cool the joining portion between the rectification plate and the inner wall of the introduction portion; It is characterized by providing.

  According to the above configuration, the EGR cooler includes the main part and the introduction part. The main part has a plurality of gas flow paths through which the exhaust gas flows. Cooling water flows around the gas flow path, and heat exchange between the cooling water and the exhaust gas is performed. The introduction part is provided at the upstream end of the gas flow of the main part, and exhaust gas is supplied to the main part.

  Further, at least one end of the inner wall and the inner wall is thermally bonded to the introducing portion, and the rectifying plate that partitions the inside of the introducing portion along the flow of exhaust gas and the bonding portion between the rectifying plate and the inner wall of the introducing portion are cooled. And a water channel through which the cooling water flows. For this reason, since the exhaust gas flowing into the introduction part is branched by the rectifying plate that partitions the inside of the introduction part, the flow rate of the exhaust gas is leveled. As a result, compared with the case where there is no flow straightening plate and the exhaust gas is not branched, it is possible to suppress a large amount of exhaust gas flowing into only some gas flow paths. Therefore, when the exhaust gas flows into the main part, it is suppressed that only a part of the gas passages is heated excessively.

  Furthermore, since at least one end of the current plate is thermally joined to the inner wall of the introduction portion, the current plate is also cooled by the cooling water flowing through the water channel. Accordingly, the rectifying plate that suppresses the flow rate difference of the exhaust gas can also play a role of cooling the exhaust gas, and it is possible to expect an increase in the cooling efficiency of the exhaust gas in the introduction portion. Therefore, the high-temperature exhaust gas flowing into the introduction part flows into the main part with the temperature lowered. As described above, it is possible to suppress boiling of the cooling water flowing in the main portion.

It is a schematic longitudinal cross-sectional view which shows the whole EGR cooler concerning this embodiment. It is an II-II cross-sectional arrow view of FIG. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 1. It is the example of a change of the II-II cross-sectional arrow view of FIG. It is the example of a change of the II-II cross-sectional arrow view of FIG. It is the example of a change of the III-III cross-sectional arrow view of FIG. It is a schematic longitudinal cross-sectional view which shows the whole EGR cooler concerning other embodiment. It is a schematic longitudinal cross-sectional view which shows the whole inlet header concerning other embodiment.

  Hereinafter, the present embodiment will be described with reference to the drawings.

  1 to 3 show an EGR cooler according to the present embodiment.

  The EGR cooler 100 of this embodiment is mounted on an EGR system of a water-cooled internal combustion engine (hereinafter referred to as an engine) mounted on a vehicle. The EGR system uses a part of engine exhaust gas. The exhaust gas is recirculated from the exhaust device side to the intake device side to be recirculated. The EGR system also passes through an EGR valve for adjusting the exhaust gas recirculation amount and an EGR gas passage in the middle of an exhaust gas recirculation EGR gas passage that bypasses each combustion chamber of the engine and connects the exhaust passage and the intake passage. And an EGR cooler 100 that cools the exhaust gas recirculated (hereinafter referred to as EGR gas) by heat exchange with engine cooling water.

  First, the configuration of the present embodiment will be described.

  As shown in FIG. 1, the EGR cooler 100 includes an inlet header that allows EGR gas to flow into both ends of a core portion 20 (corresponding to a main portion) that performs heat exchange between EGR gas and cooling water from the exhaust device side of the engine. 10 (corresponding to the introduction portion) and an outlet header 30 for discharging EGR gas to the intake device side of the engine are attached.

  The inlet header 10 includes a cylindrical first case 11 that is an outer shell, and a first coolant introduction pipe portion 12 a is provided at a predetermined position on the outer periphery of the first case 11. A first cooling water discharge pipe portion 12b is provided on the opposite side. At this time, the first water channel 14 (corresponding to the water channel) shown in FIG. 2 showing a cross section of the II-II portion of the first case 11 in FIG. 1 is installed in an annular shape along the circumferential direction of the first case 11. The Thereby, the cooling water introduced from the first cooling water introduction pipe part 12 a flows through the first water channel 14 to the entire inner wall of the first case 11.

  A gas inlet 13 for introducing EGR gas from the exhaust device side of the engine is formed at the gas flow upstream end of the first case 11. The EGR gas flowing in from the gas inlet 13 is branched by a partition plate 15 (corresponding to a rectifying plate) shown in FIG. 2 installed along the flow of the EGR gas, and flows into the core portion 20. ing. The partition plate 15 is integrally formed with the inner wall of the first case 11 by casting. In the present embodiment, the two partition plates 15 cross in a cross so as to pass through the center of the cross section of the first case 11 as shown in FIG.

  The core part 20 is provided with the 2nd case 21 which is an outer shell, and the 2nd case 21 has comprised "I" shape as a whole. A second coolant introduction pipe 22a is provided at the gas flow downstream end of the outer periphery of the second case 21, and a second coolant discharge pipe portion 22b is provided at the gas flow upstream end of the outer periphery of the second case 21. Yes. For this reason, the flow of the cooling water is opposed to the flow of the EGR gas.

  FIG. 3 shows a cross section taken along the line III-III of the second case 21 in FIG. In the second case 21, a plurality of gas flow paths 25 are provided in a horizontal row. The EGR gas branched by the partition plate 15 provided in the inlet header 10 flows into these gas flow paths 25. The plurality of gas flow paths 25 are formed independently from each other, and the EGR gas that has flowed into one gas flow path 25 flows to the outlet header 30 without flowing into another gas flow path 25.

  Around each gas flow path 25, a second water path 24 is provided for the cooling water flowing from the second cooling water introduction pipe portion 22a to flow therethrough. In addition, a large number of fins 26 in which both ends in the arrangement direction of the gas flow paths 25 are thermally bonded to the inner wall of the gas flow path 25 are provided in the gas flow path 25.

  The outlet header 30 includes a cylindrical third case 31 that is an outer shell, and a gas discharge port 32 that discharges EGR gas to the intake device side of the engine is formed at the downstream end of the gas flow of the third case 31. ing.

  Next, the operation of the EGR cooler 100 of this embodiment will be described.

  A first water channel 14 is annularly installed along the circumferential direction of the inner wall of the first case 11 provided in the inlet header 10. For this reason, the entire circumference of the inner wall of the first case 11 is cooled by the cooling water flowing into the first water channel 14 from the first cooling water introduction pipe portion 12a installed at a predetermined position on the outer periphery of the first case 11. . The partition plate 15 formed integrally with the inner wall of the first case 11 is also cooled by the cooling water flowing through the first water channel 14. As a result, the EGR gas flowing in from the gas inlet 13 provided at the upstream end of the gas flow of the first case 11 is cooled by the cooled inner wall of the first case 11 and the partition plate 15 and further branched by the partition plate 15. It is made to flow into the core part 20.

  The EGR gas that has flowed into the core portion 20 flows into the gas flow path 25 that exists in the second case 21 that constitutes the core portion 20. A large number of fins 26 exist in the gas flow path 25, and both ends of the fins 26 in the arrangement direction of the gas flow paths 25 and the inner walls of the gas flow path 25 are thermally joined. The heat transferred from the EGR gas to the fins 26 is transferred to the cooling water through the fins 26. Thereby, heat exchange is performed between the cooling water and the EGR gas in the core portion 20.

  Moreover, about the core part 20, the 2nd cooling water introduction pipe | tube part 22a is provided in the gas flow downstream end of the 2nd case 21, a cooling water flows in from there, and the 2nd case 21 of 2nd case 21 so that it may oppose the flow of EGR gas. The coolant flows toward the upstream end of the gas flow, and the coolant is discharged from the second coolant discharge pipe portion 22b installed at the upstream end of the gas flow of the second case 21. With this configuration, the temperature difference between the cooling water and the EGR gas is increased, and the heat exchange rate between the cooling water and the EGR gas through the fins 26 can be improved.

  The EGR gas cooled in the above steps is discharged from the gas discharge port 32 formed at the gas flow downstream end of the outlet header 30 to the intake device.

  With the above configuration, the EGR cooler according to the present embodiment has the following effects.

  The inlet header 10 includes a cylindrical first case 11. The inner wall and both ends of the first case 11 are thermally joined together, and a partition plate 15 that partitions the inside of the first case 11 along the flow of EGR gas, and a joint portion between the partition plate 15 and the inner wall of the first case 11 And a first water channel 14 for circulating the cooling water so as to cool the water. For this reason, since the EGR gas flowing in from the gas inlet 13 provided at the upstream end of the gas flow of the first case 11 is branched by the partition plate 15 that partitions the inside of the first case 11, the flow rate of the EGR gas is leveled. Is done. As a result, it is possible to suppress a large amount of EGR gas from flowing into only a part of the gas flow paths 25 as compared with a case where the EGR gas is not branched without the partition plate 15. Therefore, when the EGR gas flows into the core portion 20, it is possible to prevent only a part of the gas flow paths 25 from being heated excessively.

  Furthermore, since both ends of the partition plate 15 are integrally formed with the inner wall of the first case 11 by casting, the partition plate 15 is also cooled by the cooling water flowing in the first water channel 14. Thereby, the partition plate 15 that suppresses the flow rate difference of the EGR gas can also play a role of cooling the EGR gas, and an increase in the cooling efficiency of the EGR gas in the inlet header 10 can be expected. Therefore, the high-temperature EGR gas that has flowed into the inlet header 10 flows into the core portion 20 with the temperature lowered. As described above, it is possible to suppress boiling of the cooling water flowing in the core portion 20.

  -The 1st water channel 14 installed in the 1st case 11 distribute | circulates cooling water circularly along the circumferential direction of the 1st case 11. As shown in FIG. Thereby, it becomes possible to cool the whole circumference of the inner wall of the first case 11, and the cooling effect of the EGR gas by the inner wall of the first case 11 can be improved.

  Cooling water is supplied from a predetermined position on the outer periphery of the first case 11, and cooling water is discharged from the opposite side of the predetermined position on the outer periphery of the first case 11. Thereby, since cooling water can be flowed separately from the core part 20, the cooling effect of the EGR gas by the inner wall of the first case 11 can be enhanced.

  -The flow of the cooling water flowing in the core part 20 is opposed to the flow of the EGR gas. In such a configuration, as the cooling water moves to the upstream side of the gas flow, the water temperature rises, and the cooling water may boil at the upstream end of the gas flow in the core portion where the temperature of the EGR gas is highest. However, since the temperature of the EGR gas has already been lowered at the inlet header 10, there is little possibility that the cooling water will boil in the core portion 20. Therefore, it is safe and the flow of the cooling water flowing in the core part 20 is opposed to the flow of the EGR gas, so that the temperature difference between the EGR gas and the cooling water in the core part 20 becomes large. The heat exchange rate can be increased.

  The partition plate 15 is installed so as to pass through the center of the cross section of the core portion 20. By installing the partition plate 15 so as to pass through the center of the cross section of the inlet header 10 along the flow of the EGR gas, it is possible to disperse the main flow portion of the EGR gas that is the highest temperature.

  In the first case 11, the partition plate 15 and the inner wall forming the first water channel 14 are integrally formed by casting. As a result, the partition plate 15 and the first water channel 14 are surely thermally bonded, and the EGR gas cooling effect by the partition plate 15 can be achieved.

  -Since the EGR gas starts cooling with the cooling water from the time when it flows into the inlet header 10, the heat exchange rate of the entire EGR cooler 100 is increased. Therefore, since the length of the core part 20 required for cooling the EGR gas can be shortened as compared with the conventional one, the EGR cooler 100 can be downsized.

  In addition, the said embodiment can also be changed and implemented as follows.

  In the above embodiment, the second cooling water introduction pipe portion 22a is provided at the downstream end of the gas flow of the second case 21, and the cooling water flows in from there and flows so as to face the flow of EGR gas. The cooling water is discharged from the water discharge pipe portion 22b. About this, you may replace the 2nd cooling water introduction pipe part 22a and the 2nd cooling water discharge pipe part 22b. Specifically, the second cooling water introduction pipe portion 22 a may be provided at the gas flow upstream end of the second case 21, and the second cooling water discharge pipe portion 22 b may be provided at the gas flow downstream end of the second case 21.

  The inlet header 10 was attached to one end of the core part 20. In this regard, the core 20 and the inlet header 10 may be integrally formed. In this case, the cooling water may be supplied from the gas flow downstream side of the core portion 20 and the cooling water may be discharged from the inlet header 10. By taking such a structure, the number of piping which supplies cooling water can be suppressed.

  About this example, the cooling water was supplied from the gas flow downstream side of the core part 20, and the cooling water was discharged from the inlet header 10. About this, you may comprise so that cooling water may be supplied from the inlet header 10 and it may discharge | emit from the gas flow downstream of the core part 20. FIG.

  -The 1st cooling water introduction pipe part 12a was provided in the predetermined position of the 1st case 11 outer periphery, and the 1st cooling water discharge pipe part 12b was provided in the other side of the predetermined position. About this, even if the 1st cooling water discharge pipe part 12b is not provided in the other side of the 1st case 11 outer periphery, the 1st cooling water discharge pipe part 12b is not provided in the other side of the predetermined position of the 1st case 11 outer periphery. Good.

  The partition plate 15 was integrally formed with the inner wall of the first case 11 by casting. In this regard, the partition plate 15 may be fixed to the inner wall of the first case 11 by screwing, for example.

  In the above embodiment, both ends of the partition plate 15 are thermally joined to the inner wall of the first case 11. In this regard, if one end of the partition plate 15 is thermally joined to the inner wall of the first case 11, the other end may not be joined to the inner wall of the first case 11.

  As shown in FIG. 2, the two partition plates 15 were installed so as to cross the cross so as to pass through the center of the cross section of the first case 11. In this regard, for example, as shown in FIG. 4, the first case 11 may be installed diagonally so as to pass through the center of the cross section.

  The two partition plates 15 were installed crossing the cross so as to pass through the center of the cross section of the first case 11. In this regard, one partition plate 15 may be installed so as to pass through the center of the cross section of the first case 11. Even when a plurality of partition plates 15 are installed, for example, as shown in FIG. 5, if at least one partition plate 15 is installed so as to pass through the center of the cross section of the first case 11, the other partition plates 15 It is not always necessary to install the first case 11 so as to pass through the center of the cross section.

  In the above embodiment, the plurality of gas flow paths 25 existing inside the second case 21 are provided in a horizontal row. In this regard, the plurality of gas flow paths 25 may be provided in, for example, a vertical row.

  -The several gas flow path 25 which exists in a core part had many fins 26 in each. In this regard, the gas flow path 25 may be formed of a plurality of tubes 125 that do not have the fins 26 as shown in FIG. 6, for example. Even in this case, the EGR gas can be cooled by the cooling water flowing in the second water channel 124 arranged so as to surround the tube 125.

  In the above-described embodiment, the second case 21 constituting the core portion 20 has an “I” shape as a whole. In this regard, as shown in FIG. 7, the core portion 20 may be configured in a “U” shape as a whole. In this case, a cooling water introduction pipe part is installed on the outer periphery of the inlet header 10, and a cooling water discharge pipe part is installed on the outer periphery of the inlet header 10 as far as possible from the position of the cooling water introduction pipe part.

  In this another example, when the core part 20 and the inlet header 10 are integrally formed, the cooling water is supplied from the gas flow downstream side of the core part 20 and the cooling water is discharged from the inlet header 10. You can also By taking such a structure, the number of piping which supplies cooling water can be suppressed.

  The partition plate 15 does not necessarily have to be installed so as to pass through the center of the cross section of the inlet header 10. Specifically, as shown in FIG. 8, when the main flow portion of the EGR gas that is the highest temperature does not pass through the center of the cross section of the inlet header 10, the position and inclination of the partition plate 15 corresponding to the flow of the EGR gas are changed. Adjustments may be made. As a result, even when the main flow portion of the EGR gas does not pass through the center of the cross section of the inlet header 10, the EGR gas main flow portion can be dispersed by adjusting the partition plate 15.

DESCRIPTION OF SYMBOLS 10 ... Inlet header, 14 ... 1st waterway, 15 ... Partition plate, 20 ... Core part, 25 ... Gas flow path, 100 ... EGR cooler.

Claims (7)

A main part (20) having a plurality of divided gas passages (25) for circulating the exhaust gas, and performing heat exchange between the cooling water flowing around the gas passages and the exhaust gas;
A cylindrical introduction part (10) provided at the gas flow upstream end of the main part for introducing the exhaust gas into the main part;
An EGR cooler (100) comprising:
The introduction part is
A rectifying plate (15) that is thermally joined to the inner wall of the introduction portion and partitions the introduction portion along the flow of the exhaust gas;
A water channel (14) for circulating cooling water so as to cool a junction between the current plate and the inner wall of the introduction portion;
An EGR cooler comprising:   2. The EGR cooler according to claim 1, wherein the water channel causes the cooling water to circulate in an annular shape along a circumferential direction of an inner wall of the introduction portion.   3. The EGR cooler according to claim 1, wherein the cooling water is supplied from a predetermined position on an outer periphery of the introduction portion, and the cooling water is discharged from a side opposite to the predetermined position on the outer periphery.   4. The EGR cooler according to claim 1, wherein a flow of the cooling water flowing in the main portion is opposed to a flow of the exhaust gas. 5. The main part and the introduction part are integrated,
The EGR cooler according to claim 4, wherein the cooling water is supplied from a gas flow downstream end of the main part, and the cooling water is discharged from the introduction part.   The EGR cooler according to any one of claims 1 to 5, wherein the rectifying plate is installed so as to pass through a center of a cross section of the introduction portion.   The EGR cooler according to any one of claims 1 to 6, wherein the current plate and the inner wall forming the water channel are integrally formed by casting.

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