High-reliability exhaust gas recirculation cooler

Abstract

This invention relates to the field of exhaust gas cooling technology and discloses a high-reliability exhaust gas recirculation cooler, comprising a shell and inlet and outlet main plates installed on both sides of the shell. A heat dissipation tube assembly is provided inside the shell, comprising several evenly spaced, dotted heat dissipation tubes. The inlet and outlet main plates have square holes equal in number to the dotted heat dissipation tubes. The top and bottom ends of the heat dissipation tube assembly do not have dotted heat dissipation tubes. A tube bundle fixing member is provided on the shell near the outer outlet to constrain the dotted heat dissipation tubes. The cross-section of the tube bundle fixing member is the same as the outer contour of the heat dissipation tube assembly, and the long and short sides of the outermost ring of dotted heat dissipation tubes are in close contact with the inner edge of the tube bundle fixing member. This invention provides a high-reliability exhaust gas recirculation cooler with high thermal shock resistance life, improved vibration resistance while ensuring heat exchange capacity and boiling resistance, resulting in high reliability.

Description

Technical Field

[0001] This invention relates to the field of exhaust gas cooling technology, and more specifically to a highly reliable exhaust gas recirculation cooler. Background Technology

[0002] The main function of the Exhaust Gas Recirculation (EGR) system is to suppress NOx formation by reducing the high temperature and oxygen-rich environment inside the engine cylinders. Together with Selective Catalytic Reduction (SCR) technology, it forms the main technical route for reducing harmful emissions from automobiles. Its principle is to cool a portion of the combusted exhaust gas and return it to the intake manifold, where it re-enters the cylinders with the fresh air-fuel mixture. The exhaust gas contains a large amount of inert gases that do not participate in combustion within the combustion chamber, but they can absorb a significant amount of heat and dilute the air-fuel mixture, thereby reducing the oxygen concentration and the maximum combustion temperature, and suppressing NOx formation.

[0003] An exhaust gas recirculation (EGR) cooler is a device that lowers the temperature of recirculated exhaust gas. Before it mixes with fresh air, it reduces the temperature to a target value (110–140°C), thereby lowering the temperature of the mixture in the combustion chamber. This reduces the pressure rise rate and peak pressure during the initial combustion phase, minimizes fresh air throttling losses, increases the intake air volume, prolongs the combustion delay period, increases the proportion of premixed combustion, shortens the combustion duration, lowers the maximum combustion temperature, and reduces NOx emissions. For ease of explanation, the exhaust gas recirculation (EGR) cooler will be referred to simply as an EGR cooler below.

[0004] EGR coolers, due to their high-temperature exhaust gas pulse and strong vibration working environment, are prone to failure in engines, with thermal shock and vibration failures being the most common. As OEMs significantly extend the design life, optimizing the reliability of EGR coolers, improving their resistance to thermal shock and vibration, and meeting higher design life requirements have become essential goals.

[0005] Currently, most EGR coolers on the market use smooth, flat-tube heat dissipation pipes, evenly distributed within the housing at the same spacing. The heat dissipation pipe bundles are arranged with a regular rectangular cross-section, meaning that heat dissipation pipes are also arranged near the four corners of the housing. This design has the following disadvantages: When the EGR cooler is running, under the action of high-temperature exhaust gas pulses, the heat dissipation pipes and the main intake plate will undergo thermal expansion and bending deformation. The weld seams between the square holes at the four corners of the main intake plate and the heat dissipation pipes are areas of concentrated thermal stress, especially at the R-corners of the weld seams. The regular rectangular cross-section arrangement of the heat dissipation pipe bundles can easily lead to thermal fatigue cracking in the areas of concentrated thermal stress at the four corners of the main intake plate, making it difficult to meet the requirements for improving the thermal shock resistance life of the entire vehicle.

[0006] Regarding the heat pipe fixing device, there are currently two structures. One is without additional fixing method, that is, the heat pipe is fixed only by welding to the main plates on both sides. This structure has the following disadvantages: the vibration frequency response caused by the poor connection rigidity between the heat pipe and the shell is not synchronized, which can easily lead to excessive stress at the connection and failure. The failure is manifested as cracking at the root of the connection between the heat pipe and the main exhaust plate.

[0007] Another method involves clamps located in the middle and on both sides of the casing. These clamps surround and tightly adhere to the flat tube assembly, securing themselves with clips. The clamps have flanged structures on all four sides, ensuring close contact with the inner wall of the casing and providing support. While this conventional method of securing the heat exchange tube bundle with clamps enhances the overall rigidity of the EGR cooler, it has the following drawbacks: the annular clamps installed on the inlet side and in the middle of the heat exchange tubes obstruct the flow of coolant between the heat exchange tube assembly and the casing, resulting in increased liquid-side pressure resistance, poorer uniformity of the coolant flow field distribution, and a higher risk of boiling.

[0008] Therefore, it is necessary to provide a highly reliable EGR cooler to solve the problem of cracking in the stress concentration area of ​​the intake main plate caused by the expansion and bending deformation of the existing heat pipe assembly and intake main plate under high-temperature exhaust gas pulses, thereby improving its thermal shock resistance life; and to solve the problem of cracking at the weld root of the heat pipe and the exhaust main plate due to poor connection rigidity under high-frequency engine vibration environment, and reduce the deterioration of the cooling pressure drop and flow field distribution caused by the tube bundle fixing components, thereby improving the vibration resistance of the EGR cooler, while ensuring the heat exchange capacity and boiling resistance of the EGR cooler. The above improvements enhance the reliability of the EGR cooler and meet the requirements of extending the design life of the whole vehicle. Summary of the Invention

[0009] The purpose of this invention is to address the shortcomings of the aforementioned technologies by providing a highly reliable exhaust gas recirculation cooler with long thermal shock resistance and improved vibration resistance while ensuring the heat exchange capacity and boiling resistance of the exhaust gas recirculation cooler, resulting in high reliability.

[0010] To achieve the above objectives, the high-reliability exhaust gas recirculation cooler designed in this invention includes a shell and an inlet main plate and an outlet main plate installed on both sides of the shell. A heat dissipation tube assembly is provided inside the shell, comprising several evenly spaced, dotted heat dissipation tubes. The inlet and outlet main plates have square holes equal in number to the dotted heat dissipation tubes. The dotted heat dissipation tubes are assembled with the inlet and outlet main plates by laser welding. The top and bottom ends of the heat dissipation tube assembly do not have dotted heat dissipation tubes. A tube bundle fixing member is also provided on the shell near the outer outlet to constrain the dotted heat dissipation tubes. The cross-section of the tube bundle fixing member is the same as the outer contour of the heat dissipation tube assembly, and the long and short sides of the outermost ring of dotted heat dissipation tubes arranged in close contact with the inner edge of the tube bundle fixing member.

[0011] Preferably, the upper surface of the tube bundle fixing member near the outer water outlet and parallel to the short side of the cross-section of the pitted heat dissipation tube extends along the draft angle direction of the inner wall of the housing to form a first flange. When the tube bundle fixing member is installed in the housing, the first flange abuts against the inner wall of the housing.

[0012] Preferably, the end of the first flange has a semi-circular outline, and a circular boss is provided on the outer surface of the end, the circular boss engaging with the edge of the water outlet of the housing located on the housing.

[0013] Preferably, the lower surface of the tube bundle fixing member on the side away from the outer outlet and parallel to the short side of the cross-section of the pitted heat dissipation tube extends along the draft angle direction of the inner wall of the housing to form a second flange. When the tube bundle fixing member is installed in the housing, the second flange abuts against the inner wall of the housing.

[0014] Preferably, the side of the tube bundle fixing member near the outer outlet and parallel to the long side of the cross-section of the pitted heat dissipation tube extends along the draft angle direction of the inner wall of the housing to form a third flange. When the tube bundle fixing member is installed in the housing, the third flange abuts against the inner wall of the housing. The side of the tube bundle fixing member away from the outer outlet and parallel to the long side of the cross-section of the pitted heat dissipation tube extends along the draft angle direction of the inner wall of the housing to form a fourth flange. When the tube bundle fixing member is installed in the housing, the fourth flange abuts against the inner wall of the housing.

[0015] Preferably, the tube bundle fixing member has raised ribs arranged on the side parallel to the long side of the cross-section of the pitted heat dissipation tube.

[0016] Preferably, the main air intake plate and the dotted heat dissipation pipe are connected by laser welding, with the weld seam covering the mating gap between the dotted heat dissipation pipe and the main air intake plate, and the welding is performed at a uniform speed from the inside to both sides; the main air exhaust plate and the dotted heat dissipation pipe are connected by laser welding, with the weld seam covering the mating gap between the dotted heat dissipation pipe and the main air exhaust plate, and the welding is performed at a uniform speed from the inside to both sides.

[0017] Preferably, the surface of the pitted heat dissipation tube is uniformly distributed with "eight"-shaped grooves and conical protrusions along the tube length direction, and the grooves and protrusions are uniformly distributed along the tube length direction in the form of alternating combination units.

[0018] Preferably, the number of the dotted heat dissipation tubes is 50 to 80.

[0019] Preferably, the tube bundle fixing member has a water outlet notch near the water outlet of the shell.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. The four pinhole-shaped heat pipes located at the four corners of the housing were removed, which eliminated the thermal stress concentration points on the main intake plate, reduced the overall thermal stress amplitude, and improved the thermal fatigue life of the EGR cooler. The results of thermal shock simulation and bench verification showed that removing the pinhole-shaped heat pipes at the four corners improved the thermal shock life of the EGR cooler by 70%.

[0022] 2. Removing the four corner heat pipes increases the flow area on the liquid side of the EGR cooler, reduces the pressure resistance of the coolant, and allows the EGR cooler to obtain more coolant in the engine cooling circuit, improving the heat exchange efficiency for high-temperature circulating exhaust gas. At the same time, it ensures the coolant flow field distribution and velocity in the hot side of the shell near the inlet area, reduces the blind zone of coolant distribution on the high-temperature side, and reduces the risk of local boiling in the EGR cooler. Performance-pressure drop bench verification shows that after removing the four corner heat pipes, the coolant pressure drop can be reduced by about 9%, and the outlet air temperature only increases by 1°C, meeting the heat exchange performance requirements. CFD simulation results show that after removing the four corner heat pipes, the boiling volume can be reduced by 58%.

[0023] 3. The arrangement of the tube bundle fixing component at the water outlet of the shell, away from the high-temperature air intake side, can significantly reduce the impact on the flow field distribution of the hot side coolant and ensure the uniformity of the flow field of the air intake side coolant, thereby avoiding the increase of boiling risk in the EGR cooler.

[0024] 4. The coolant flow rate on the outlet side is relatively low, the tube bundle fixing component has little impact on the coolant pressure loss along the flow path, and the tube bundle fixing component has a notch near the outlet to ensure that the coolant flows out without obstruction, thereby reducing the increase in hydraulic resistance to the coolant and ensuring the flow rate of the EGR cooler in the vehicle's water circuit.

[0025] 5. The flange on which the tube bundle fixing part contacts the shell is provided with a boss. The positioning and installation are carried out by using the edge of the outlet and the draft angle of the inner cavity of the shell, which eliminates welding, simplifies assembly, and saves manpower.

[0026] 6. Through performance-pressure drop verification, the increase in liquid-side pressure drop using the tube bundle fixing component of this invention is less than 1%; through vibration frequency sweep verification, the first-order natural frequency of the entire EGR cooler can be increased by 30Hz. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the high-reliability exhaust gas recirculation cooler of the present invention;

[0028] Figure 2 for Figure 1 Installation diagram of the dotted heat dissipation pipe and the pipe bundle fixing component;

[0029] Figure 3 for Figure 1 Schematic diagram of the structure of the central tube bundle fixing component;

[0030] Figure 4 for Figure 3 Top view;

[0031] Figure 5 This is an assembly diagram of the tube bundle fixing component;

[0032] Figure 6 This is an assembly diagram of the tube bundle fastener from another perspective;

[0033] Figure 7 This is a schematic diagram of the assembly of the tube bundle fixing component from a third perspective.

[0034] Figure 8 A sectional view of the assembly of the tube bundle fastener;

[0035] Figure 9 Another view of the assembly section of the tube bundle fastener;

[0036] Figure 10 for Figure 9 A magnified view of part A shown below;

[0037] Figure 11 for Figure 9 A magnified view of section B shown below;

[0038] Figure 12 This is a stress distribution diagram of the intake main plate of the EGR cooler of the present invention under thermal shock.

[0039] Figure 13 A comparison diagram of the maximum thermal stress of the main intake plate before and after removing the four pitted heat pipes in this invention.

[0040] Figure 14 Comparison of the liquid-side flow field before and after removing the four pitted heat dissipation tubes and installing the tube bundle fixing component in this invention;

[0041] Figure 15 A comparison of boiling volume before and after removing the four pitted heat dissipation tubes and installing the tube bundle fixing component in this invention.

[0042] Figure 16 This is a comparison diagram of the liquid-side pressure drop before and after removing the four pitted heat dissipation tubes and installing the tube bundle fixing component, which is the present invention.

[0043] The components in the diagram are labeled as follows:

[0044] 1. Housing, 2. Main air inlet plate, 3. Main air outlet plate, 4. Drilled heat dissipation tube, 5. Outer water outlet, 6. Tube bundle fixing piece, 7. First flange, 8. Circular boss, 9. Housing water outlet, 10. Second flange, 11. Third flange, 12. Fourth flange, 13. Raised rib, 14. Heat dissipation tube assembly, 15. Water outlet notch. Detailed Implementation

[0045] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0046] like Figures 1-11 As shown, a high-reliability exhaust gas recirculation cooler includes a shell 1 and an inlet main plate 2 and an outlet main plate 3 installed on both sides of the shell 1. A heat dissipation tube assembly 14 is provided inside the shell 1. The heat dissipation tube assembly 14 includes a number of evenly spaced dotted heat dissipation tubes 4. The inlet main plate 2 and the outlet main plate 3 are provided with square holes of the same number as the dotted heat dissipation tubes 4. The dotted heat dissipation tubes 4 are assembled with the inlet main plate 2 and the outlet main plate 3 by laser welding. The top and bottom ends of the heat dissipation tube assembly 14 are not provided with dotted heat dissipation tubes 4. A tube bundle fixing member 6 for constraining the dotted heat dissipation tubes 4 is also provided at one end of the shell 1 near the outer outlet 5. The cross-section of the tube bundle fixing member 6 is the same as the outer contour of the heat dissipation tube assembly 14, and the long side and short side of the outermost ring of dotted heat dissipation tubes 4 arranged in the heat dissipation tube assembly 14 are in close contact with the inner edge of the tube bundle fixing member 6.

[0047] Among them, the upper surface of the tube bundle fixing member 6, which is close to the outer outlet 5 and parallel to the short side of the cross section of the pitted heat dissipation tube 4, extends along the draft angle direction of the inner wall of the housing 1 to form a first flange 7. When the tube bundle fixing member 6 is installed in the housing 1, the first flange 7 abuts against the inner wall of the housing 1.

[0048] In addition, the end of the first flange 7 has a semi-circular outline, and a circular boss 8 is provided on the outer surface of the end. The circular boss 8 is engaged with the edge of the water outlet 9 on the housing 1. In this embodiment, the height of the circular boss 8 is 1.5mm.

[0049] In this embodiment, the lower surface of the tube bundle fixing member 6, which is away from the outer water outlet 5 and parallel to the short side of the cross section of the pitted heat dissipation tube 4, extends along the draft angle direction of the inner wall of the housing 1 to form a second flange 10. When the tube bundle fixing member 6 is installed in the housing 1, the second flange 10 abuts against the inner wall of the housing 1.

[0050] In this embodiment, the side of the tube bundle fixing member 6 that is close to the outer outlet 5 and parallel to the long side of the cross-section of the dotted heat dissipation tube 4 extends along the draft angle direction of the inner wall of the housing 1 to form a third flange 11. When the tube bundle fixing member 6 is installed in the housing 1, the third flange 11 abuts against the inner wall of the housing 1. The side of the tube bundle fixing member 6 that is away from the outer outlet 5 and parallel to the long side of the cross-section of the dotted heat dissipation tube 4 extends along the draft angle direction of the inner wall of the housing 1 to form a fourth flange 12. When the tube bundle fixing member 6 is installed in the housing 1, the fourth flange 12 abuts against the inner wall of the housing 1.

[0051] In this embodiment, ribs 13 are arranged on the side of the tube bundle fixing member 6 that are parallel to the long side of the cross-section of the pitted heat dissipation tube 4.

[0052] In this embodiment, the main air intake plate 2 and the dotted heat dissipation pipe 4 are connected by laser welding. The weld seam covers the mating gap between the dotted heat dissipation pipe 4 and the main air intake plate 2, and the welding is performed at a uniform speed from the inside to both sides. The main air exhaust plate 3 and the dotted heat dissipation pipe 4 are connected by laser welding. The weld seam covers the mating gap between the dotted heat dissipation pipe 4 and the main air exhaust plate 3, and the welding is performed at a uniform speed from the inside to both sides.

[0053] In this embodiment, the surface of the pitted heat dissipation tube 4 is uniformly distributed with "eight"-shaped grooves and conical protrusions along the tube length direction. The grooves and protrusions are uniformly distributed along the tube length direction in the form of alternating combination units.

[0054] In this embodiment, the number of dotted heat dissipation tubes 4 is approximately 68. In other embodiments, the number may be 80 or more.

[0055] In this embodiment, the tube bundle fixing member 6 is provided with a water outlet notch 15 near the water outlet 9 of the shell.

[0056] In this embodiment, a relatively low-temperature coolant (85-95°C) is used to reduce the temperature of the circulating exhaust gas (600-750°C) to a specified limit. The exhaust gas passage is a dotted heat dissipation pipe 4. The coolant surrounds the dotted heat dissipation pipe 4 and flows in the same direction as the exhaust gas for heat exchange. The exhaust gas enters the dotted heat dissipation pipe 4 through the dual-flow channel of the intake chamber, and after cooling, it flows through the exhaust chamber, mixes with fresh air, and flows back to the combustion chamber.

[0057] The current EGR cooler uses smooth, flat-tube heat exchangers, numbering approximately 16 to 22, with the flat-tube assembly distributed within the housing 1 in a regular rectangular cross-section. The highest temperature of the circulating exhaust gas can reach 750℃ and fluctuates with changes in vehicle operating conditions. Irregular thermal expansion and contraction occur in the intake main plate 2 and the heat exchangers, causing the intake main plate 1 to bend and deform, generating thermal stress. Furthermore, because the intake main plate 1 is in direct contact with the exhaust gas, heat transfer to it can reach temperatures of 260–280℃, while the heat exchangers, cooled by coolant, maintain a temperature of 140–150℃. Therefore, there is a significant temperature difference between the intake main plate 1 and the heat exchanger assembly, resulting in a difference in the amount of thermal deformation between the intake main plate 2 and the heat exchangers. This difference in thermal deformation exacerbates the bending of the intake main plate 2. Deformation and increased thermal stress: Thermal shock FEA simulation and bench verification results of the EGR cooler show that the failure mode is local cracking of the intake main plate 2. The thermal fatigue cracks are all located in the welding area between the heat sink and the intake main plate near the four corners of the shell. When the intake main plate 2 undergoes bending deformation under the combined effect of high-temperature exhaust gas pulse and the difference in thermal deformation between the intake main plate 2 and the heat sink, the connection between the square hole at the four corners of the intake main plate 2 and the heat sink is the thermal stress concentration area, especially located at the R corner of the weld. This area will first show thermal fatigue cracking under high stress amplitude, thereby reducing the thermal shock resistance life of the EGR cooler.

[0058] There are two current methods for fixing heat pipes. The first method involves no additional fixing, where the heat pipes are fixed solely by welding to the main plates on both sides. The second method uses clamps at both ends and the middle of the casing. These clamps surround and tightly adhere to the flat tube assembly, securing themselves with clips. The clamps have flanged structures on all four sides, ensuring close contact with the inner wall of the casing for support. In the first method, the heat pipes rely entirely on welding to the main plates. Under strong vibration, the difference in vibration frequency response between the heat pipes and the casing due to poor connection rigidity can easily lead to failure, manifesting as cracking at the root of the connection between the heat pipes and the exhaust plate. The second method can enhance the installation strength of the heat pipes, increase the overall rigidity of the EGR cooler, and improve its vibration resistance. However, the annular clamps installed on the inlet side and middle of the heat pipes obstruct the flow of coolant between the heat pipe assembly and the casing, resulting in increased liquid-side pressure resistance, poorer uniformity of coolant flow field distribution, and increased risk of boiling. Furthermore, this method involves complex assembly processes and high labor costs.

[0059] In this embodiment, the tube bundle fixing member 6 is positioned by the snap-fit ​​engagement of two circular bosses 8 with the edge of the water outlet 9 of the housing to limit the displacement of the tube bundle fixing member 6 in the direction of the air outlet of the housing 1, and the displacement in the direction of the air inlet of the housing 1 is limited by the draft angle of 1.6° in the inner cavity of the housing 1, thereby positioning the tube bundle fixing member 6.

[0060] In addition, in this embodiment, the friction between the tube bundle fixing member 6 and the inner wall of the shell 1 is enhanced by the first flange 7, the shell outlet 9, the second flange 10, the third flange 11, the fourth flange 12 and the rib 13, so as to prevent the tube bundle fixing member 6 from being displaced.

[0061] In this embodiment, unlike the existing EGR coolers which use smooth flat tube heat dissipation pipes distributed in a complete rectangular cross section, the EGR cooler of this invention uses small cross section multi-tube dotted heat dissipation pipes 4, numbering about 50 to 80, and removes the four dotted heat dissipation pipes 4 near the four corners of the housing 1 of the heat dissipation pipe group 14. This design can eliminate the thermal stress concentration points on the main intake plate 2, reduce the overall thermal stress amplitude, and improve the thermal shock resistance life of the EGR cooler.

[0062] Figure 12 This is a thermal stress distribution diagram of the intake main plate 2 in the thermal shock test of the EGR cooler of the present invention. It can be seen that the stress is greatest at the weld seams of the heat dissipation pipes at the four corners. Figure 13 The image shows a comparison of the maximum thermal stress on the main intake plate 2 before and after the removal of the four corner heat pipes in the EGR cooler of this invention. It can be seen that the maximum thermal stress on the main intake plate 2 is reduced after the four corner heat pipes are removed. The results of the thermal shock test show that removing the four corner heat pipes can increase the thermal shock resistance life of the EGR cooler by 70%.

[0063] In this invention, the tube bundle fixing component 6 is installed at the water outlet, with a thickness of 2mm and made of stainless steel. It can significantly enhance the connection rigidity between the heat dissipation tube assembly 14 and the shell 1, ensure the fixing strength of the heat dissipation tube bundle 14, improve vibration resistance, and reduce the risk of fatigue failure at the connection between the heat dissipation tube and the main air outlet plate 2. Vibration test results show that by using the tube bundle fixing component 6 of this invention, the first natural frequency of the entire EGR cooler can be increased by 30Hz.

[0064] The arrangement of the tube bundle fixing member 6 away from the high-temperature intake side can significantly reduce the impact on the flow field distribution of the hot side coolant and ensure the uniformity of the coolant flow field on the intake side, thereby avoiding an increase in the risk of boiling of the EGR cooler. The coolant flow velocity on the outlet side is relatively low, and the tube bundle fixing member 6 has little impact on the pressure loss of the coolant along the flow path. In addition, the tube bundle fixing member 6 is provided with an outlet notch 15 near the outlet 9 of the housing to ensure that the coolant flows out without obstruction, thereby reducing the increase in hydraulic resistance to the coolant and ensuring the flow rate of the EGR cooler in the vehicle's water circuit.

[0065] Figure 14The diagram shows a comparison of the liquid-side flow field before and after removing four heat dissipation pipes and installing the tube bundle fixing component 6 in the EGR cooler of the present invention. It can be seen that after removing the heat dissipation pipes and installing the tube bundle fixing component 6, the coolant flow field distribution in the area of ​​the hot side of the shell 1 away from the water inlet is more uniform, reducing the liquid-side distribution blind zone and improving the boiling resistance of the EGR cooler.

[0066] Figure 15 The image shows a comparison of the boiling volume of the EGR cooler of this invention before and after removing four heat dissipation tubes and installing the tube bundle fixing component 6. It can be seen that the boiling volume is significantly reduced after removing the heat dissipation tubes and adding the tube bundle fixing component 6. CFD flow field simulation results show that the boiling volume can be reduced by 58% after optimization.

[0067] Figure 16 The image shows a comparison of the liquid-side pressure drop before and after removing four heat pipes and installing the tube bundle fixing component 6 in the EGR cooler of the present invention. It can be seen that the liquid-side pressure drop can be reduced by about 9% after removing the heat pipes and installing the tube bundle fixing component 6.

Claims

1. A high-reliability exhaust gas recirculation cooler, comprising a shell (1) and an intake main sheet (2) and an exhaust main sheet (3) installed on both sides of the shell (1), a heat dissipation pipe group (14) is arranged in the shell (1), characterized in that: The heat dissipation tube assembly (14) includes several equally spaced and evenly distributed dotted heat dissipation tubes (4). The main air intake plate (2) and the main air outlet plate (3) are provided with square holes of the same number as the dotted heat dissipation tubes (4). The dotted heat dissipation tubes (4) are assembled with the main air intake plate (2) and the main air outlet plate (3) by laser welding. The dotted heat dissipation tubes (4) are not arranged at both ends of the uppermost and lowermost rows in the heat dissipation tube assembly (14). The end of the housing (1) near the outer water outlet (5) is also provided with a tube bundle fixing member (6) to constrain the dotted heat dissipation tubes (4). The cross-section of the tube bundle fixing member (6) is the same as the outer contour of the heat dissipation tube assembly (14), and the long side and short side of the outermost ring of dotted heat dissipation tubes (4) arranged in the heat dissipation tube assembly (14) are in close contact with the inner edge of the tube bundle fixing member (6).

2. The high-reliability exhaust gas recirculation cooler according to claim 1, characterized in that: The upper surface of the tube bundle fixing member (6) near the outer outlet (5) and parallel to the short side of the cross section of the pitted heat dissipation tube (4) extends along the draft angle direction of the inner wall of the housing (1) to form a first flange (7). When the tube bundle fixing member (6) is installed in the housing (1), the first flange (7) abuts against the inner wall of the housing (1).

3. The high-reliability exhaust gas recirculation cooler according to claim 2, characterized in that: The end of the first flange (7) is a semi-circular outline, and a circular boss (8) is provided on the outer surface of the end. The circular boss (8) is engaged with the edge of the shell outlet (9) located on the shell (1).

4. The high-reliability exhaust gas recirculation cooler according to claim 2, characterized in that: The lower surface of the tube bundle fixing member (6) on the side away from the outer outlet (5) and parallel to the short side of the cross section of the pitted heat dissipation tube (4) extends along the draft angle direction of the inner wall of the housing (1) to form a second flange (10). When the tube bundle fixing member (6) is installed in the housing (1), the second flange (10) abuts against the inner wall of the housing (1).

5. The high-reliability exhaust gas recirculation cooler according to claim 3, characterized in that: The side of the tube bundle fixing member (6) that is close to the outer outlet (5) and parallel to the long side of the cross section of the prickled heat dissipation tube (4) extends along the draft angle direction of the inner wall of the housing (1) to form a third flange (11). When the tube bundle fixing member (6) is installed in the housing (1), the third flange (11) abuts against the inner wall of the housing (1). The side of the tube bundle fixing member (6) that is away from the outer outlet (5) and parallel to the long side of the cross section of the prickled heat dissipation tube (4) extends along the draft angle direction of the inner wall of the housing (1) to form a fourth flange (12). When the tube bundle fixing member (6) is installed in the housing (1), the fourth flange (12) abuts against the inner wall of the housing (1).

6. The high-reliability exhaust gas recirculation cooler according to claim 3, characterized in that: The tube bundle fixing member (6) has ribs (13) arranged on the side parallel to the long side of the cross section of the pitted heat dissipation tube (4).

7. The high-reliability exhaust gas recirculation cooler according to claim 1, characterized in that: The main air intake plate (2) and the dotted heat dissipation pipe (4) are connected by laser welding. The weld seam covers the mating gap between the dotted heat dissipation pipe (4) and the main air intake plate (2), and the welding is performed at a uniform speed from the inside to both sides. The main air exhaust plate (3) and the dotted heat dissipation pipe (4) are connected by laser welding. The weld seam covers the mating gap between the dotted heat dissipation pipe (4) and the main air exhaust plate (3), and the welding is performed at a uniform speed from the inside to both sides.

8. The high-reliability exhaust gas recirculation cooler according to claim 1, characterized in that: The surface of the pitted heat dissipation tube (4) is uniformly distributed with "eight"-shaped grooves and conical protrusions along the tube length direction. The grooves and protrusions are uniformly distributed along the tube length direction in the form of alternating combination units.

9. The high-reliability exhaust gas recirculation cooler according to claim 1, characterized in that: The number of the puncture-type heat dissipation tubes (4) is 50 to 80.

10. The high-reliability exhaust gas recirculation cooler according to claim 3, characterized in that: The tube bundle fixing member (6) has a water outlet notch (15) near the water outlet (9) of the shell.

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