JP4248095B2 - EGR cooler - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an EGR cooler attached to an EGR device that recirculates engine exhaust gas to reduce generation of nitrogen oxides and cools the recirculation exhaust gas.
[0002]
[Prior art]
Conventionally, an EGR device that reduces the generation of nitrogen oxides by recirculating a part of exhaust gas of an engine such as an automobile to the engine is known. In such an EGR device, the exhaust gas recirculated to the engine is known. When the engine is cooled, the temperature of the exhaust gas is reduced and the volume of the exhaust gas is reduced, so that the combustion temperature can be lowered and the generation of nitrogen oxides can be effectively reduced without significantly reducing the output of the engine. Some engines are equipped with an EGR cooler for cooling the exhaust gas in the middle of the line for recirculating the exhaust gas to the engine.
[0003]
2 and 3 are cross-sectional views showing an example of the EGR cooler described above, in which 1 denotes a shell formed in a cylindrical shape, and end faces of the shell 1 are provided at both axial ends of the shell 1. Plates 2 and 2 are fixed so as to be closed, and both ends of a large number of tubes 3 are fixed to each of the plates 2 and 2 in a penetrating state. Extending in the direction.
[0004]
A cooling water inlet 4 is attached in the vicinity of one end of the shell 1, a cooling water outlet 5 is attached in the vicinity of the other end of the shell 1, and the cooling water 9 passes from the cooling water inlet 4 to the shell. 1 is supplied to the inside of the pipe 1 and flows outside the tube 3, and is discharged from the cooling water outlet 5 to the outside of the shell 1.
[0005]
Further, bonnets 6, 6 formed in a bowl shape are fixed to the opposite shell 1 side of each plate 2, 2 so as to enclose the end faces of the respective plates 2, 2, and in the center of one bonnet 6. The gas inlet 7 is provided in the center of the other bonnet 6, and the gas outlet 8 is provided in the center of the other bonnet 6. The engine exhaust gas 10 enters the inside of one bonnet 6 from the gas inlet 7 and passes through a number of tubes 3. After being cooled by heat exchange with the cooling water 9 flowing outside the tube 3, it is discharged into the other bonnet 6 and recirculated from the gas outlet 8 to the engine.
[0006]
[Problems to be solved by the invention]
However, in the conventional EGR cooler shown in FIGS. 2 and 3, the cooling water 9 supplied from the cooling water inlet 4 to the inside of the shell 1 is evenly supplied to the cooling water outlet 5 with respect to the internal cross section of the shell 1. As shown by the path 12, after flowing into the shell 1 from the cooling water inlet 4, the flow toward the cooling water outlet 5 is bent toward the cooling water outlet 5 and slanted toward the cooling water outlet 5. Since the cooling water 9 stagnates in the vicinity of the corner of the shell 1 facing the cooling water inlet 4 and the cooling water outlet 5 and the cooling water stagnation part 13 is generated in the shell 1, a particularly high temperature exhaust gas 10 is introduced. At a position facing the cooling water inlet 4 in the diametrical direction, the tube 3 may locally become high temperature near the cooling water stagnation portion 13 and may be thermally deformed. The heat exchange efficiency of There was also a problem.
[0007]
The present invention has been made in view of the above circumstances, and it is an object of the present invention to prevent heat deformation by avoiding local high temperature of the tube and to improve heat exchange efficiency between exhaust gas and cooling water. It is said.
[0008]
[Means for Solving the Problems]
In the present invention, the shell formed in a cylindrical shape, the plate fixed so as to close the shell end surface at both axial ends of the shell, and the plate end surface fixed to enclose the plate end surface on the opposite shell side of the plate A bonnet and a tube extending in the axial direction inside the shell and having both ends penetrated and fixed to the plates; cooling water is supplied to and discharged from the shell; An EGR cooler configured to exchange heat between the exhaust gas and the cooling water through the exhaust gas toward the other bonnet side, and cooling for introducing the cooling water into the shell on one end side in the axial direction of the shell A water inlet is provided, and a cooling water outlet for discharging cooling water from the inside of the shell is provided on the other end side in the axial direction of the shell, and a diameter of the cooling water inlet on one end side in the axial direction of the shell is provided. At a position facing the direction is characterized in that a bypass outlet for withdrawing a portion of the cooling water introduced from the cooling water inlet.
[0009]
Thus, when the cooling water is introduced into the shell from the cooling water inlet and a part of the introduced cooling water is extracted from the bypass outlet, the diameter of the cooling water inlet on one end side in the axial direction of the shell is reduced. The cooling water does not stagnate at the position facing the direction, and the cooling water stagnation part is not generated here, so that the local high temperature of the tube is avoided at one end in the axial direction of the shell. In addition, the heat exchange efficiency between the exhaust gas and the cooling water is greatly improved.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0011]
FIG. 1 shows an example of an embodiment of the present invention. The same parts as those in FIGS. 2 and 3 are denoted by the same reference numerals.
[0012]
In the EGR cooler of the present embodiment, the EGR cooler configured in substantially the same manner as the EGR cooler described above with reference to FIGS. 2 and 3 is opposed to the cooling water inlet 4 on one end side in the axial direction of the shell 1 in the diametrical direction. A bypass outlet 14 for extracting a part of the cooling water 9 introduced from the cooling water inlet 4 is provided at a position where the cooling water is introduced.
[0013]
Thus, in this way, the exhaust gas 10 of the engine is dispersed from the gas inlet 7 through the inside of one bonnet 6, passes through many tubes 3, enters the inside of the other bonnet 6, and enters the gas outlet 8. The cooling water 9 is supplied from the cooling water inlet 4 to the inside of the shell 1 and flows toward the cooling water outlet 5. At this time, the cooling water 9 is supplied from the cooling water inlet 4. When a part of the introduced cooling water 9 is extracted from the bypass outlet 14 while being introduced into the inside of the shell 1, the shell 1 is opposed to the cooling water inlet 4 on one end side in the axial direction in the diametrical direction. Since the cooling water 9 does not stagnate and a cooling water stagnation portion does not occur here, local high temperature of the tube 3 at one end side in the axial direction of the shell 1 is avoided, and the exhaust gas 10 Heat exchange efficiency between the cooling water 9 also will be greatly improved.
[0014]
Therefore, according to the above embodiment, the cooling water stagnation portion is located at a position facing the cooling water inlet 4 in the diametrical direction by extracting a part of the cooling water 9 just introduced from the cooling water inlet 4 from the bypass outlet 14. Therefore, it is possible to avoid the local high temperature of the tube 3 and to reliably prevent thermal deformation, and to greatly improve the heat exchange efficiency between the exhaust gas 10 and the cooling water 9. Can be improved.
[0015]
Note that the EGR cooler of the present invention is not limited to the above-described embodiments, and various changes can be made without departing from the scope of the present invention.
[0016]
【The invention's effect】
According to the above-described EGR cooler of the present invention, it is possible to avoid the local high temperature of the tube and to reliably prevent thermal deformation, and to greatly improve the heat exchange efficiency between the exhaust gas and the cooling water. An excellent effect that it can be performed can be achieved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing an example of a conventional EGR cooler.
3 is a cross-sectional view taken along the line III-III in FIG. 2;
[Explanation of symbols]
1 Shell 2 Plate 3 Tube 4 Cooling Water Inlet 5 Cooling Water Outlet 6 Bonnet 7 Gas Inlet 9 Cooling Water 10 Exhaust Gas 14 Bypass Outlet

Claims (1)

  A shell formed in a cylindrical shape, a plate fixed so as to close the shell end surface at both axial ends of the shell, a bonnet fixed so as to encapsulate the plate end surface on the opposite shell side of the plate, and A tube extending in the axial direction inside the shell and penetrating and fixing both ends of the shell to each of the plates. Cooling water is supplied to and discharged from the inside of the shell. The EGR cooler is configured to exchange heat between the exhaust gas and the coolant through the exhaust gas toward the end of the shell, and is provided with a coolant inlet for introducing the coolant into the shell at one end side in the axial direction of the shell. In addition, a cooling water outlet for discharging cooling water from the inside of the shell is provided at the other axial end side of the shell, and is opposed to the cooling water inlet at one axial end side of the shell in the diametrical direction. That the position, EGR cooler, characterized in that a bypass outlet for withdrawing a portion of the cooling water introduced from the cooling water inlet.

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