JP6505976B2 - EGR cooler - Google Patents

Description

  The present invention relates to an EGR cooler that cools EGR gas recirculated from the exhaust side to the intake side of an engine.

  Conventionally, in an automobile engine or the like, part of exhaust gas is extracted from the exhaust side and returned to the intake side, and the exhaust gas returned to the intake side suppresses combustion of fuel in the engine to lower the combustion temperature. That is, so-called exhaust gas recirculation (EGR: Exhaust Gas Recirculation) is performed to reduce the generation of NOx.

  Generally, when this kind of exhaust gas recirculation is performed, an EGR pipe is used between an appropriate position of the exhaust passage extending from the exhaust manifold to the exhaust pipe and an appropriate position of the intake passage extending from the intake pipe to the intake manifold. It is connected and recirculates the exhaust gas through the EGR pipe.

  At this time, if the exhaust gas to be recirculated to the engine is cooled in the middle of the EGR pipe, the temperature of the exhaust gas is lowered and the volume thereof is reduced, so that the combustion temperature is lowered without lowering the output of the engine too much. In order to reduce the generation of nitrogen oxides, a water-cooled EGR cooler is installed in the middle of the EGR pipe that recirculates the exhaust gas to the engine.

  FIG. 3 is a plan view showing an example of the EGR cooler. In the figure, 1 shows a shell formed to form a tubular shape such as a rectangular cross section, and shells 1 at both ends in the axial direction of the shell 1 The plates 2 and 3 are fixed so as to close the end faces of the plates, and the bonnets 4 and 5 are fixed so as to enclose the end faces of the plates 2 and 3 on the side opposite the shell 1 of the plates 2 and 3 A plurality of tubes 6 extending in the axial center direction (left and right direction in FIG. 3) of the shell 1 and having both ends fixedly penetrated to the respective plates 2 and 3 are accommodated in the shell 1 ing.

  The cooling water 7 is supplied and discharged to the inside of the shell 1 via a water cooling system (not shown), and the EGR pipe 8 on the upstream side and the downstream side are provided on both ends of the shell 1. The EGR pipe 9 is connected via the bonnets 4 and 5, and the exhaust gas 10 introduced from the upstream EGR pipe 8 exchanges heat with the surrounding cooling water 7 while flowing through the tubes 6. The exhaust gas 10 whose temperature has been reduced is extracted to the downstream EGR pipe 9.

  In addition, there exists following patent document 1 grade | etc., As a prior art literature information relevant to this kind of EGR cooler.

JP 2001-74380 A

  However, the EGR cooler in recent years has been increased in size as exhaust gas regulations become stricter, and the EGR pipes 8, 9 are gently bent relative to the bonnets 4, 5 at both ends of the shell 1 until now. As shown in FIG. 4, the EGR pipe 8 is rapidly cut from the direction substantially orthogonal to the axial center direction of the shell 1 with respect to the bonnet 4 on the gas introduction side as shown in FIG. Since cases where it is necessary to bend and connect are increasing, the rapid bending of the EGR pipe 8 separates the flow of the exhaust gas 10 inside the bending direction of the flow of the exhaust gas 10 and turbulence is likely to occur. As a result, the main flow of the exhaust gas 10 flows unevenly along the wall surface of the bonnet 4 on the outside in the bending direction, so that the main flow of the exhaust gas 10 is only biased to a part of the tubes 6 Been introduced Te, the cooling performance of the EGR cooler to be exerted originally has arisen a problem that no longer pulled out enough.

  The present invention has been made in view of the above-described circumstances, and the exhaust gas flow distribution for each tube, even when it is necessary to rapidly bend and connect the EGR pipe from the direction substantially orthogonal to the axial direction of the shell. The purpose is to make it possible to introduce it uniformly.

In the present invention, a cylindrical shell, a plate fixed to both ends in the axial direction of the shell so as to close the shell end face, and a plate end face fixed to the opposite shell side of each plate A bonnet, and a plurality of tubes axially extending in the interior of the shell and having both ends penetrated and fixed to the respective plates, and supplying and discharging cooling water to the interior of the shells and In the EGR cooler, heat exchange between the exhaust gas and the cooling water is conducted through the exhaust gas from one bonnet to the other bonnet, and substantially orthogonal to the axial center direction of the shell with respect to the one bonnet Guiding and connecting the EGR pipe from the opposite direction and making it possible to bend the exhaust gas from the EGR pipe in the one bonnet and introduce it into each tube To, a portion facing the plate of the gas inlet side of the one of the bonnet, in proximity to the plate of the gas inlet side as it goes from the warp and the EGR pipe side to side away from the plate to the flow direction of the exhaust gas the It is characterized in that one of the bonnets is formed as a depression to flatten , and the formation of the depression is started from the upstream side of a portion of the one bonnet facing the plate on the gas introduction side. .

  In this way, when the exhaust gas introduced to one of the bonnets through the EGR pipe from the direction substantially orthogonal to the axial direction of the shell flows in the direction of the axial direction of the shell and flows, Since the flow of exhaust gas directed outward in the bending direction is suppressed by the depression and the flow of exhaust gas directed inward in the bending direction is induced, a relatively large amount of exhaust gas flows unevenly outward in the bending direction. The tendency is corrected, and the flow distribution of the exhaust gas introduced into each tube is equalized.

In this case, formation of the recess portion, Runode begins from the upstream side of the portion facing the plate of the gas inlet side of the one of the bonnet, the faster correction of flow distribution of the exhaust gas introduced into each tube It will be started from the stage.

  Further, in the present invention, it is preferable that the one bonnet is widened so as not to decrease the cross-sectional area of the flow path even when flattened by the formation of the depressed portion. In this way, the depressed portion is formed However, it is not necessary to cause an increase in pressure loss.

  According to the above-described EGR cooler of the present invention, the following various excellent effects can be obtained.

  (I) According to the invention of claim 1 of the present invention, even when it is necessary to sharply bend and connect the EGR pipe from the direction substantially orthogonal to the axial center direction of the shell, the exhaust gas for each tube Since all the tubes can be efficiently introduced for heat exchange of the exhaust gas, the cooling performance of the EGR cooler to be originally exhibited can be sufficiently extracted.

According to the invention described in claim 1, (II) the present invention, since the beginning of the recess formed from the upstream side of the portion facing the plate of the gas inlet side in one of the bonnet, is introduced into each tube The correction of the exhaust gas flow distribution can be started from an earlier stage, and a more effective flow distribution equalization can be realized.

(III) According to the invention described in claim 2 of the present invention, since the flow passage cross-sectional area is widened so as not to decrease even if one bonnet is flattened by the formation of the depressions, the formation of the depressions An increase in pressure loss as a factor can be avoided in advance.

It is a top view which shows an example of the form which implements this invention. It is the perspective view which looked at the hollow part of FIG. 1 from diagonally upward. It is a top view which shows an example of the conventional EGR cooler. It is a top view which shows another example of the conventional EGR cooler.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIGS. 1 and 2 show an example of the embodiment of the present invention. In this embodiment, the EGR cooler constructed substantially similar to that of FIG. The EGR pipe 8 is led and connected from a direction substantially orthogonal to the axial direction (left and right direction in FIG. 1) of 1 (including not only the 90 ° crossing but also the 70 ° to 110 ° crossing); The exhaust gas 10 from the EGR pipe 8 is configured to be bent in the bonnet 4 and introduced into each tube 6, and in the part of the bonnet 4 facing the plate 2 on the gas introduction side, It warps to the side (right side in FIG. 1) separated from the plate 2 and flattens the bonnet 4 close to the plate 2 on the gas introduction side as it goes from the EGR pipe 8 side to the flow direction of the exhaust gas 10 Forming a crimped recess 11.

  In the case of the example illustrated here, the formation of the recess 11 starts from the upstream side of the portion of the one bonnet 4 facing the plate 2 on the gas introduction side, and the one bonnet In order to prevent the decrease in the cross-sectional area of the flow path even if the flat portion 4 is flattened due to the formation of the hollow portion 11, the width 4 is widened along with the formation of the hollow portion 11.

  Thus, in this way, the exhaust gas 10 introduced into one of the bonnets 4 via the EGR pipe 8 from the direction substantially orthogonal to the axial center direction of the shell 1 changes its direction in the axial center direction of the shell 1 Since the flow of the exhaust gas 10 directed outward in the bending direction is suppressed by the depression portion 11 and the flow of the exhaust gas 10 directed inward in the bending direction is induced when the air flows, relatively The tendency of the exhaust gas 10 to flow unevenly is corrected, and the flow distribution of the exhaust gas 10 introduced into each tube 6 is made uniform.

  In the case of the present embodiment, in particular, the formation of the recess 11 starts from the upstream side of the portion of the bonnet 4 facing the plate 2 on the gas introduction side, so the exhaust introduced into each tube 6 The correction of the flow distribution of the gas 10 will be started earlier.

  Therefore, according to the above embodiment, even when the EGR pipe 8 has to be sharply bent and connected from the direction substantially orthogonal to the axial center direction of the shell 1, the flow distribution of the exhaust gas 10 to each tube 6 is Since uniform introduction can be performed, all the tubes 6 are efficiently used for heat exchange of the exhaust gas 10, and the cooling performance of the EGR cooler that should be originally exhibited can be sufficiently extracted.

  Here, particularly in the present embodiment, since the formation of the recess 11 is started from the upstream side of the part facing the plate 2 in the bonnet 4 on the gas introduction side, the flow of the exhaust gas 10 introduced into each tube 6 The correction of the distribution can be started from an earlier stage, and a more even flow distribution can be realized, and even if the bonnet 4 is flattened by the formation of the hollow portion 11, the flow path is cut off. Since the width is increased so as not to reduce the area, an increase in pressure loss due to the formation of the recess 11 can be avoided in advance.

  In addition, the EGR cooler of the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the scope of the present invention.

Reference Signs List 1 shell 2 plate 3 plate 4 bonnet 5 bonnet 6 tube 7 cooling water 8 EGR pipe 9 EGR pipe 10 exhaust gas 11 hollow portion

Claims (2)

A cylindrical shell, a plate fixed to both ends in the axial direction of the shell so as to close the end face of the shell, and a bonnet fixed so as to enclose the end face of the plate on the opposite shell side of each plate; A plurality of tubes extending axially inside the shell and having both ends fixedly penetrated to the respective plates, and supplying and discharging cooling water to the inside of the shells and one of the tubes in the respective tubes An EGR cooler directed from the bonnet to the other bonnet through heat exchange between the exhaust gas and the cooling water, the EGR cooler from the direction substantially orthogonal to the axial center direction of the shell with respect to the one bonnet A pipe is led and connected, and exhaust gas from the EGR pipe can be bent in the one bonnet and introduced into each tube, Square of a portion facing the plate of the gas inlet side of the hood, the one bonnet close to the plates of the gas introduction side as it goes from the warp and the EGR pipe side to side away from the plate to the flow direction of the exhaust gas An EGR cooler characterized in that the hollow portion is formed as a hollow portion for flattening the hollow portion , and the formation of the hollow portion is started from the upstream side of a portion of the one bonnet facing the plate on the gas introduction side . The EGR cooler according to claim 1 , wherein the one bonnet is widened so as not to reduce the cross-sectional area of the flow path even if it is flattened by the formation of the recess.

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