JP2005351567A - Heat transfer tube internally provided with fin member and heat exchanger provided therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive heat transfer tube having improved heat conductivity to improve the efficiency and performance of heat exchanging inside/outside fluid via the heat transfer tube by internally mounting fin members in a flat tube while using simple manufacturing technique without requiring strict dimensional accuracy. <P>SOLUTION: The heat transfer tube having a U-recessed wall face comprises fin parts 7 each consisting of a partition wall portion 5 and a base wall portion 6 and formed in at least axial one line in an internal space 4 to form an internal tube 3. The internal tube 3 is inserted and arranged in the flat tube 2. The inner peripheral face of the flat tube 2 has close contact with the outer peripheral face of a non-recessed portion of the internal tube 3 to form fluid distribution passages in an internal space 8 between each of the internal space 4 of the internal tube 3 and the outer periphery of a recessed portion of the internal tube 3 and the inner peripheral face of the flat tube 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a multi-pipe heat exchanger such as an EGR gas cooling apparatus, and a combustion exhaust gas containing a cooling medium such as cooling water, cooling air, refrigerant for car air conditioner, other refrigerant liquid, EGR gas, and soot. The present invention relates to a heat transfer tube in which a fin member for various uses is installed, such as a heat exchanger used for performing heat exchange with a cooled high-temperature heat medium fluid, and a heat exchanger in which the heat transfer tube is assembled.

  Conventionally, in an automobile engine or the like, an EGR system in which a part of exhaust gas is extracted from the exhaust gas system, returned to the engine intake system, and added to the mixture or intake air has been used for gasoline engines and diesel engines. . EGR systems, especially cooled EGR systems with a high EGR rate for diesel engines, reduce NOx in exhaust gas, prevent fuel consumption deterioration and prevent deterioration of EGR valve function and durability due to excessive temperature rise. Therefore, an EGR gas cooling device that cools the heated EGR gas with a cooling medium such as cooling water, cooling air, a car air conditioner refrigerant, or other refrigerant liquid is provided.

  As the EGR gas cooling device, as shown in the conventional inventions of Patent Documents 1 and 2 above, a plurality of heat transfer tubes through which EGR gas can flow are arranged, and cooling water and cooling air are provided outside the heat transfer tubes. In some cases, the EGR gas is cooled by circulating a cooling medium such as a refrigerant liquid through a heat transfer tube to exchange heat between the EGR gas and the cooling medium.

  And the manufacturing process of the heat exchanger tube of patent document 1 inserts and arrange | positions the fin member which provided the several cut-and-raised part in the thin plate material, and formed the several unevenness | corrugation in the flat tube made from a metal material. A nickel-based brazing material is applied between the flat tube and the fin member. After the insertion of the fin member into the flat tube, heating is performed while applying a load or the like from the outer surface of the flat tube, whereby the flat tube is crushed and brought into contact with the fin member, and the brazing material is melted and solidified. Thus, the fin member and the flat tube are connected and fixed. In such a heat transfer tube, the internal fluid flows while meandering between the concavo-convex portions, whereby heat exchange between the internal fluid and the external fluid is promoted via the fin member and the flat tube.

Further, in Patent Document 2, an inner tube formed by projecting long plate-like fins inside a fluid flow path is formed by folding the wall surface of a circular inner tube at least one place in close contact with each other. The heat transfer tube is formed by inserting into the outer tube and brazing and fixing the inner peripheral surface of the outer tube and the outer peripheral surface of the inner tube. Thus, only the inner pipe provided with the fins has a problem such that the cooling medium flowing outside from the joint of the fins flows into the inner pipe. However, as in Patent Document 2, the heat transfer pipe with the outer pipe sheathed is used. It was possible to eliminate such problems. Further, by providing the fins, it is possible to improve the heat conductivity of the heat transfer tube and improve the heat exchange performance between the internal fluid and the external fluid.
JP 2002-137054 A JP 2003-254690 A

  However, in Patent Document 1, the flat tube and the fin member are separately formed, and then the flat member is interposed with an appropriate gap so that the fin member can be easily inserted into the flat tube. It is necessary to form a tube, and in order to enable reliable adhesion between the fin member and the flat tube, it is necessary to form the tube with high-precision dimensions, which requires a high level of technology and labor. In addition, since the flat tube is deformed by applying a load from the outer surface of the flat tube after insertion and joined to the fin member, both sides of the flat tube may be pressed and deformed unevenly, and the R shape on both sides is formed with high accuracy. It was difficult to do. In addition, if there are variations in the size of the unevenness provided on the fin member, brazing failure occurs and the fin member and the flat tube are not joined well, and the fin member blurs due to fluid flow or vibration. There was a thing. In addition, in order to improve the brazing accuracy, it is necessary to have advanced manufacturing techniques and precise dimensional alignment to accurately form all the irregularities. Although there is a method of closing the gap by filling the brazing material even if some gap is generated, since a lot of expensive brazing material having corrosion resistance against EGR gas or condensate is used, Manufacturing cost is expensive.

  Further, in Patent Document 2, since the inner tube having no irregularities on the outer peripheral surface is inserted into the outer tube, the insertion work is easy, and the contact area between the outer peripheral surface of the inner tube and the inner peripheral surface of the outer tube is large. High adhesion to each other. Also, by forming the outer tube slightly larger in diameter than the inner tube, the insertion work becomes easier, and by extending the outer tube, the inner tube and the outer tube can be securely adhered. High precision brazing is possible. However, since it is a circular heat transfer tube, the amount of fluid flow is limited, and when manufacturing large heat exchangers, etc., it was necessary to install many heat transfer tubes, increasing the number of manufacturing steps and costs .

  The present invention is intended to solve the above-described problems, and is intended to improve heat exchange performance by incorporating a fin member in a flat tube having a large cross-sectional area of the flow path of the internal fluid and a large flow rate of the internal fluid. In the heat tube, the adhesiveness between the flat tube and the fin member housed in the flat tube is enhanced without requiring highly accurate dimensional alignment and manufacturing technology. The heat conductivity of the fin member and the flat tube is increased to improve the heat exchange performance of the heat transfer tube and the heat exchanger assembled with the heat transfer tube, and the durability of the heat transfer tube against the flow and vibration of the internal and external fluids. Is also improved.

  In this specification, the flat tube has a cross-sectional shape perpendicular to the tube axis direction that is oval, elliptical, rectangular, or the like, and the other forming width is longer than one forming width orthogonal to each other. It is a collective term for scales.

  In order to solve the above-described problems, the first invention is to form a fin portion composed of a partition wall portion and a base wall portion in the inner space at least in a row in the inner space by recessing the wall surface in a U-shape. The inner tube made of the metal material is inserted and disposed in the flat tube made of metal material, and the inner peripheral surface of the flat tube and the outer peripheral surface of the non-recessed portion of the inner tube are in close contact with each other. It is a heat transfer tube in which the inner space between the outer periphery of the recessed portion of the inner tube and the inner peripheral surface of the flat tube serves as a fluid flow path.

  According to a second aspect of the present invention, there is provided an inner tube made of a metal material, in which a wall surface is recessed in a U-shape and fin portions each including a partition wall portion and a base wall portion are formed in the inner space in at least one line in the axial direction. Inserted into a flat tube made of material, the inner peripheral surface of the flat tube and the outer peripheral surface of the non-recessed portion of the inner tube are brought into close contact, and the inner space of the inner tube and the outer periphery of the recessed portion of the inner tube and the flat tube It is a heat exchanger formed by assembling a heat transfer tube having an internal space between the inner peripheral surface of the heat transfer pipe and a fluid flow path.

  Further, the internal pipe may be divided into a plurality of internal spaces by bringing the base wall portion of the fin portion protruding from the internal space into contact with the inner peripheral surface of the opposing internal tube.

  The inner tube may be formed without bringing the base wall portion of the fin portion projecting into the inner space into contact with the inner peripheral surface of the opposing inner tube.

  In addition, the inner tube may be cut and raised in the direction of the inner space by the wall surface of the non-recessed portion in close contact with the flat tube, and the fin may be protruded in the inner space.

  The inner tube and the flat tube may be metallurgically joined to each other.

  Since the present invention is configured as described above, the heat transfer area of the heat transfer tube can be increased by disposing the inner tube as a fin member in the flat tube. Further, the flat tube and the inner tube can be brought into surface contact with a wide contact area, and the thermal conductivity between the inner tube and the flat tube can be improved. Therefore, it is possible to perform heat exchange through the heat transfer tubes between the fluids flowing inside and outside the heat transfer tubes with high performance. In addition, the fin portion projects from the inner space of the inner tube, and there is no protrusion on the outer surface of the inner tube, so that the inner tube can be easily inserted and arranged in the flat tube. In addition, by improving the adhesion between the inner tube and the flat tube, it is possible to suppress blurring and deformation of the fin due to fluid flow and vibration of the heat transfer tube, and to prevent fretting of the wall surface of the inner tube and flat tube. Heat exchange can be performed smoothly and the durability of the heat transfer tube can be improved. Moreover, a product with high heat transfer characteristics and durability can be obtained by using a heat transfer tube excellent in heat exchange performance for a multi-tube heat exchanger or the like.

  Compared to the conventional heat transfer tube with a plate-like fin member with multiple uneven parts, the fin tube has better adhesion between the inner tube and the flat tube. In addition, it is possible to connect to each other such as brazing with a simple manufacturing technique, and it is difficult to cause brazing defects, and less brazing material is used. Product can be obtained. Moreover, since it is a flat heat transfer tube, it is possible to introduce more fluid into the internal space than in a conventional circular heat transfer tube, and efficient heat exchange is possible. In addition, when a heat exchanger is manufactured by arranging heat transfer tubes, a heat exchanger can be obtained by using a small number of heat transfer tubes, and productivity can be improved by reducing the number of steps. .

  The first invention of the present invention is an inner tube made of a metal material in which a wall surface is recessed in a U-shape, and fin portions composed of a partition wall portion and a base wall portion are formed in the inner space in at least one line in the axial direction. It is inserted into a flat tube made of metal. The inner peripheral surface of the flat tube and the outer peripheral surface of the non-recessed portion of the inner tube are preferably brought into close contact with each other by drawing or the like, and the inner space of the inner tube and the outer periphery of the recessed portion of the inner tube and the inner periphery of the flat tube The heat transfer tube is formed with the internal space between the surfaces as a fluid flow path.

  According to a second aspect of the present invention, there is provided an inner tube made of a metal material, in which a wall surface is recessed in a U-shape and fin portions each including a partition wall portion and a base wall portion are formed in the inner space in at least one line in the axial direction. Inserted into a flat tube made of material. The inner peripheral surface of the flat tube and the outer peripheral surface of the non-recessed portion of the inner tube are preferably brought into close contact with each other by drawing or the like, and the inner space of the inner tube and the outer periphery of the recessed portion of the inner tube and the inner periphery of the flat tube A heat exchanger is formed by assembling a heat transfer tube having an internal space between the surface and a fluid flow path.

  Example 1 of the heat transfer tube of the present invention will be described in detail with reference to FIG. 1. (1) is a heat transfer tube, and a fin member is provided inside a flat tube (2) having an oval end surface shape. An internal tube (3) is inserted and arranged. As shown in FIG. 1, the inner pipe (3) has a flat shape corresponding to the flat pipe (2), and the wall surface is recessed in a U-shaped cross section so that the inner space (4) has a pipe axis direction. Three rows of fin portions (7) each having a long partition wall portion (5) and a base wall portion (6) are formed. Further, the partition wall portion (5) and the base wall portion (6) are formed in a linear shape parallel to the tube axis in the first embodiment.

  The manufacturing process of the heat transfer tube (1) as described above will be described below. First, the inner pipe (3) provided with the fin part (7) composed of the partition wall part (5) and the base wall part (6) is a thin-walled pipe made of austenitic stainless steel such as SUS304, SUS304L, SUS316, SUS316L. Although it shape | molds by press work etc., since the partition part (5) and base wall part (6) which comprise a fin part (7) are long in an axial direction, easy manufacture becomes possible. In addition, it is preferable that the plate | board thickness of an internal pipe | tube (3) shall be 0.03-0.2 mm, and a fin part (7) will become weak if it is thinner than 0.03 mm. On the other hand, if the plate thickness is greater than 0.2 mm, the weight of the heat transfer tube (1) increases, and the weight of the product assembled with the heat transfer tube (1) cannot be achieved.

  Moreover, in Example 1, the inner pipe (3) has the base wall part (6) of the fin part (7) projecting in the inner space (4) on the inner peripheral surface of the opposing inner pipe (3). The inner space (4) of the inner pipe (3) can be divided into a plurality of parts in the axial direction. The base wall portions (6) that are in contact with each other may be fixedly connected to the inner peripheral surface of the inner tube (3) by brazing, diffusion bonding, or the like, or any connection can be made by simply contacting them. You may not fix. Also, brazing and diffusion bonding may be performed before or after the inner tube (3) in the next process is inserted into the flat tube (2).

  Next, the inner pipe (3) in which the fin portion (7) is formed is inserted and arranged in a flat tube (2) made of a metal material that is formed slightly larger than the inner pipe (3). The inner tube (3) has a fin portion (7) projecting inward, but there is no protrusion on the outer side, so that it can be easily inserted into the flat tube (2). In this inserted state, the flat tube (2) is formed by drawing so as to have a desired size and shape, and at the same time as the flat tube (2) is formed, the inner peripheral surface and the inner tube (3 ) Can be brought into close contact with the outer peripheral surface of the non-recessed portion with a wide contact area. In this pultrusion molding, the flat tube (2) is expanded while the inner tube (3) is being molded, even if the dimensional accuracy of the outer tube (3) and the fins (7) are somewhat bad. The degree of adhesion between the tube (3) and the flat tube (2) can be increased.

  The heat transfer tube (1) shown in FIG. 1 can be obtained by drawing the flat tube (2). In this heat transfer tube (1), the base wall portion (6) of the fin portion (7) is brought into contact with the inner peripheral surface of the inner tube (3) to thereby divide the inner space (4) into a plurality of parts and the inner tube. A plurality of internal spaces (8) are formed between the outer periphery of the partition wall portion (5) and the base wall portion (6) of (3) and the inner peripheral surface of the flat tube (2), such as EGR gas. It is a flow path for internal fluid.

  In the heat transfer tube (1) formed as described above, the heat transfer area of the heat transfer tube (1) can be increased by disposing the inner tube (3) provided with the fins (7) protruding therefrom. In addition, due to the excellent thermal conductivity due to the close contact between the inner tube (3) and the flat tube (2), an internal fluid such as EGR gas flowing in the heat transfer tube (1) and an external fluid such as outside air and a cooling medium The heat exchange efficiency can be improved. Further, the EGR gas disperses the inner space (4) of the inner pipe (3) divided into a plurality of parts and the inner space (8) of the flat pipe (2) by the fin portion (7), thereby forming a flat shape. Even in the heat transfer tube (1), it is possible to prevent the uneven flow of the EGR gas. Furthermore, the contact pressure between the EGR gas and the wall surface of the fin portion (7), the inner tube (3), and the flat tube (2) increases, and the heat of the inner fluid flowing in the inner spaces (4) and (8) is increased. Since heat can be efficiently transferred to the surface of the heat transfer tube (1), heat exchange efficiency can be promoted, and an excellent cooling effect on the internal fluid can be obtained.

  Further, the inner tube (3) is brought into close contact with the flat tube (2) with a wide contact area, and the base wall portion (6) of the fin portion (7) is brought into surface contact with the inner peripheral surface of the inner tube (3). As a result, the stability of the inner pipe (3), which is a fin member, is improved, and blurring and deformation of the fin part (7) due to the flow of EGR gas, vibration of the heat transfer pipe (1), and the like can be suppressed. Moreover, the fretting of the wall of the inner pipe (3) and the flat pipe (2) can be prevented, heat conduction between them can be performed well, and the durability of the heat transfer pipe (1) can be improved. it can.

  In order to further improve the stability of the adhesion between the flat tube (2) and the inner tube (3), a powdery or paste-like brazing material such as nickel is applied to the outer peripheral surface of the inner tube (3). After the inner tube (3) is inserted and arranged in the flat tube (2), both may be connected and fixed by brazing. In addition, the inner tube (3) coated with a binder for adhering brazing material to the outer peripheral surface is inserted into the flat tube (2), and then a brazing material in the form of powder or paste is supplied into the flat tube (2). May be. Further, the brazing material as described above may be applied to the inner peripheral surface of the flat tube (2) instead of the inner tube (3). Further, the flat tube (2) and the inner tube (3) may be formed of a raw tube clad with a brazing material. By this brazing, not only the adhesion between the flat tube (2) and the inner tube (3) is increased, but also the mutual adhesion area is increased by the fillet of the brazing material, and the thermal conductivity can be further increased. .

  In addition to brazing, the contact surface of the flat tube (2) and the inner tube (3) may be connected and fixed by diffusion bonding, or connected and fixed using any other metallurgical technique. Also good.

  In addition, the surface of the flat tube (2) and the inner tube (3) is plated with a brazing material layer made of copper, nickel, these base alloys, etc., so that the flat tube (2) and the inner tube (3) are brazed. You may attach it. In addition, the flat tube (2) and the inner tube (3) may be formed of the same metal material, and depending on the purpose of use and cost, etc. if brazing or diffusion bonding can be performed. Both may be formed of different metal materials.

  As another method, after supplying brazing paste to both side edges of the inner tube (3) and the flat tube (2), the inner tube (3) can be inserted into the flat tube (2). Alternatively, the brazing material paste may be supplied into the flat tube (2) after the inner tube (3) is inserted into the flat tube (2).

  In the first embodiment, the flat tube (2) has an oval end surface shape. However, if the flat tube is flat, the end surface shape may be an ellipse or a rectangle. Also, in Examples 2 to 5 described below, the end surface may be an oblong flat tube (2), or an elliptical or rectangular flat tube (2).

  In the first embodiment, the fin portion (7) protruding from the inner pipe (3) forms the partition wall portion (5) and the base wall portion (6) in a straight line parallel to the axial direction. In the second embodiment shown in FIG. 2, the partition wall portion (5) of the fin portion (7) is formed to be curved in a waveform with respect to the axial direction. By using such a corrugated partition wall portion (5), both side edges of the base wall portion (6) continuous with the partition wall portion (5) are also corrugated, but the wall surface of the base wall portion (6) is an inner tube ( 3), the inner space (4) is divided into a plurality of parts by being formed in parallel with the inner peripheral surface, with the base wall (6) abutting against the inner peripheral surface. In the corrugated fin portion (7), the turbulent flow and stirring effect of the fluid such as EGR gas flowing inside is obtained, the boundary layer is separated, and the heat exchange between the inner and outer fluids via the heat transfer tube (1) is achieved. The performance can be improved. Further, since the corrugated fin portion (7) is long in the tube axis direction, it can be easily provided simultaneously with the forming of the inner tube (3) by press working or roll forming.

  Moreover, in the said Example 1 and 2, the base wall part (6) of a fin part (7) is contact | abutted with the internal peripheral surface of the opposing internal pipe | tube (3), and internal space (4 of an internal pipe | tube (3)) ) Is divided into multiple parts. On the other hand, as shown in FIG. 3, the base wall portion (6) of the fin portion (7) is disposed in the internal space (4) without being brought into contact with the inner peripheral surface of the internal tube (3). The inner space (4) of the inner tube (3) may be formed as one. Even in this case, since the outer peripheral surface of the inner tube (3) is brought into close contact with the inner peripheral surface of the flat tube (2), a plurality of gaps are provided between the outer peripheral surface of the fin portion (7) and the inner peripheral surface of the flat tube (2). An internal space (8) is formed and these are not in communication with each other.

  In the heat transfer tube (1) as in the third embodiment, the EGR gas that flows in the internal space (4) is formed by projecting the fin portion (7) without dividing the single internal space (4). The turbulent flow and the stirring action are promoted, and the heat exchange efficiency can be improved by the separation of the boundary layer. Even if the base wall portion (6) of the fin portion (7) is not connected and fixed, the inner tube (3) and the flat tube (2) are in close contact with each other in a wide area. Stable use is possible by reducing the vibration of the fin portion (7) due to vibration of the heat transfer tube (1).

  In the third embodiment, as shown in FIG. 3, the fin portion (7) is formed in a straight line parallel to the tube axis direction. However, as in the second embodiment, the fin portion (7) is formed in a waveform. You may do it. In addition, the inner tube (3) and the flat tube (2) may be connected and fixed by brazing, diffusion bonding, or other metallurgical bonding, improving both adhesion and obtaining good thermal conductivity. Thus, a heat transfer tube (1) having excellent heat exchange performance and durability can be obtained.

  In the fourth embodiment shown in FIG. 4, the wall surface of the inner tube (3) that is in close contact with the flat tube (2) is cut into a U-shape in the direction of the inner space (4), thereby forming a square in the inner space (4). A cut-and-raised fin (10) having a shape is protruded.

  Further, in the fifth embodiment shown in FIG. 5, the wall of the inner pipe (3) is cut into a V shape in the direction of the inner space (4), so that a triangular cut and raised fin (10 ) And project.

  In the heat transfer tube (1) formed by inserting and arranging the inner tube (3) provided with the cut and raised fins (10) as in Examples 4 and 5 into the flat tube (2), the cut and raised fins (10) By this edge portion, the turbulent flow and stirring action of fluid such as EGR gas flowing in the internal space (4) is further promoted, and the heat exchange performance of the heat transfer tube (1) can be improved. In the fourth embodiment, a quadrangular cut-and-raised fin (10) is provided in the fifth embodiment. However, a polygon more than a pentagon may be used, and other shapes such as a cross, a star, and a semicircle may be used. The fins (10) may be formed by combining any one of them. Moreover, although the cut-and-raised fins (10) of the fourth and fifth embodiments are formed by cutting and raising the wall surface of the inner pipe (3) at right angles to the flow of the fluid, The raised fins (10) may be formed by inclining the wall surface of the inner pipe (3) by inclining the fluid flow.

  A sixth embodiment in which the heat transfer tube (1) as shown in the first to fifth embodiments is used in an EGR gas cooling device (20) incorporated in a cooled EGR system of an automobile will be described with reference to FIG. In this EGR gas cooling device (20), a pair of tube sheets (22) are connected to both ends of the trunk tube (21) so that the inside can be sealed. And between the pair of tube sheets (22), a plurality of the flat heat transfer tubes (1) of this embodiment are connected through the tube sheet (22). The heat transfer tube (1) may be one in which the inner tube (3) and the flat tube (2) are connected and fixed in advance by brazing or the like, after being assembled in the trunk tube (21). You may braze. A bonnet (26) provided with an EGR gas inlet (24) and an outlet (25) is connected to both ends of the trunk pipe (21).

  Further, the outer periphery of the trunk tube (21) is partitioned by a pair of tube sheets (22) by providing an introduction passage (27) and an outlet passage (28) for a cooling medium such as engine cooling water and cooling air. A heat exchange section (23) through which a cooling medium can flow is used in the airtight space. In addition, a plurality of support plates (30) are joined and arranged in the heat exchanging portion (23), and the heat transfer tube (1) is inserted into an elongated insertion hole (29) provided in the support plate (30). As a result, the heat transfer tube (1) is stably supported as a baffle plate, and the flow of the cooling medium flowing in the heat exchange section (23) is made meandering.

  In the EGR gas cooling device (20), when high-temperature EGR gas is introduced into the trunk tube (21) from the inlet (24), a plurality of EGR gases are arranged in the trunk tube (21). It flows into the heat transfer tube (1). In the heat exchange section (23) in which the heat transfer tube (1) is arranged, a cooling medium such as engine cooling water is circulated outside the heat transfer tube (1) in advance, so that the heat transfer tube (1) is interposed via the outer surface of the heat transfer tube (1). Thus, heat exchange is performed between the EGR gas and the cooling medium.

  As described above, the heat transfer tube (1) increases the heat transfer area by arranging the inner tube (3) as a fin member in the flat tube (2), thereby increasing the contact frequency with the EGR gas. At the same time, the inner tube (3) and the flat tube (2) are brought into surface contact with each other over a wide area to enhance thermal conductivity. Then, the EGR gas is dispersed and flows in the internal space (4) (8) where the fin portion (7) is projected, and not only the heat of the EGR gas near the wall surface of the flat tube (2) but also the center vicinity. The heat of the flowing EGR gas is also efficiently transferred to the inner peripheral surface of the flat tube (2) through the fin portion (7), and then dissipated to the cooling medium through the outer peripheral surface of the flat tube (2). The As a result, the entire EGR gas is uniformly cooled without unevenness, and an excellent cooling effect on the EGR gas is obtained.

  The EGR gas thus well cooled flows out of the EGR gas cooling device (20) through the outlet (25) and is returned to the intake manifold side. Accordingly, it is possible to prevent the EGR valve from being heated to high temperature and obtain the excellent functionality and durability of the EGR valve, and to reduce the temperature of the intake air, so that NOx can be reduced and good fuel consumption can be achieved.

  In addition, the heat transfer tube (1) of each of the above embodiments can be used in any device that performs heat exchange, such as an automobile engine, other internal combustion engines, and air conditioning. If these heat transfer tubes (1) are assembled not only in the engine EGR gas cooling device (20) but also in other multi-tube heat exchangers, the EGR gas can be efficiently cooled. Therefore, in an EGR system, particularly a cooled EGR system with a high EGR rate of a diesel engine, NOx in the exhaust gas can be reduced and fuel consumption can also be prevented from deteriorating. In addition, it is possible to prevent an excessive increase in temperature and to surely prevent the EGR valve from deteriorating and functioning.

The perspective view which shows the heat exchanger tube of Example 1 of this invention. The perspective view which shows the heat exchanger tube of Example 2 of this invention. The perspective view which shows the heat exchanger tube of Example 3 of this invention. The partial expansion perspective view of the internal pipe | tube used in Example 4 of this invention. The partially expanded perspective view of the internal pipe | tube used in Example 5 of this invention. The conceptual diagram which shows the EGR gas cooling device of Example 6 of this invention.

Explanation of symbols

2 Flat tube 3 Internal tube 4 Internal space 5 Bulkhead 6 Base wall 7 Fin 8 Internal space 10 Cut and raised fin

Claims (10)

  A metal-made inner tube with a wall surface recessed in a U-shape and fin portions consisting of partition walls and base wall portions formed in the inner space in the axial direction is inserted into the metal-made flat tube. The inner peripheral surface of the flat tube and the outer peripheral surface of the non-recessed portion of the inner tube are brought into close contact with each other, and the inner space of the inner tube and the outer periphery of the recessed portion of the inner tube and the inner peripheral surface of the flat tube are A heat transfer tube with a fin member, characterized in that the internal space is used as a fluid flow passage.   A metal-made inner tube with a wall surface recessed in a U-shape and fin portions consisting of partition walls and base wall portions formed in the inner space in the axial direction is inserted into the metal-made flat tube. The inner peripheral surface of the flat tube and the outer peripheral surface of the non-recessed portion of the inner tube are brought into close contact with each other, and the inner space of the inner tube and the outer periphery of the recessed portion of the inner tube and the inner peripheral surface of the flat tube are A heat exchanger assembled with a heat transfer tube with a fin member, which is characterized by mounting a heat transfer tube with an internal space as a fluid flow passage.   The internal pipe is characterized in that a base wall portion of a fin portion projecting from the internal space is brought into contact with an inner peripheral surface of the opposed internal pipe, and the internal space of the internal pipe is divided into a plurality of parts. Heat transfer tube with an internal fin member.   The internal pipe is characterized in that a base wall portion of a fin portion projecting in the internal space is brought into contact with an inner peripheral surface of the opposing internal pipe, and the internal space of the internal pipe is divided into a plurality of parts. Heat exchanger with built-in heat transfer tube with internal fin member.   The inner pipe is formed with a fin member according to claim 1, wherein a base wall portion of the fin portion projecting in the inner space is formed without contacting an inner peripheral surface of the opposing inner pipe. Heat pipe.   The inner pipe is formed with the fin member according to claim 2, wherein the base wall part of the fin part projecting in the inner space is formed without contacting the inner peripheral surface of the opposing inner pipe. A heat exchanger with a built-in heat tube.   6. The fin according to claim 1, 3 or 5, wherein the inner tube is formed by cutting and raising the wall surface of the non-recessed portion in close contact with the flat tube in the direction of the inner space and projecting the fin into the inner space. Heat transfer tube with internal components.   The fin member according to claim 2, 4 or 6, wherein the inner tube is formed by cutting and raising the wall surface of the non-recessed portion in close contact with the flat tube in the direction of the inner space and projecting the fin into the inner space. Heat exchanger with built-in heat transfer tube.   8. The heat transfer tube with the fin member according to claim 1, wherein the inner tube and the flat tube are metallurgically joined to each other.   The heat exchanger assembling the heat transfer tube in which the fin member according to claim 2, 4, 6, or 8 is assembled, wherein the inner tube and the flat tube are metallurgically joined to each other.

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