JP2008014566A - Flat heat transfer tube for heat exchanger, and multitubular heat exchanger and egr gas cooling apparatus incorporating the heat transfer tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively provide a flat heat transfer tube for a heat exchanger including a corrugated fin by forming the inexpensive corrugated fin having rectangular cross sections by a simple machining means with respect to raw material, and also to provide a multitubular heat exchanger and a heat exchange type EGR gas cooling apparatus provided with at least two of the heat transfer tubes while providing superior performance. <P>SOLUTION: The corrugated fin 2 included in an inner circumference face of the flat heat transfer tube is comprised of hoop material 3 using a metallic sheet, plural slit like cutout parts 4 are formed in multiple rows and columns by applying drilling to the hoop material at predetermined intervals, and the cross-sectionally rectangular channel shaped corrugated fin is formed by bending the hoop material in predetermined dimensions. The flat heat transfer tube for a heat exchanger is used wherein at least one of the corrugated fins is included in contact with an inner circumference wall surface to form small passages for fluid capable of communicating with each other. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heat exchanger tube for a heat exchanger in a so-called shell-and-tube type exhaust gas cooling device, and more specifically, a heat exchanger tube having a flat cross-sectional shape that is disposed in the heat exchanger and forms an exhaust gas passage. A corrugated fin having a cross-sectional channel shape that is incorporated in the inner peripheral surface of the flat heat transfer tube and that divides the flow path of the exhaust gas flowing through the pipe into small flow paths to improve heat exchange performance. It is possible to provide a relatively low cost by performing predetermined processing on the thin plate material, and for the heat exchanger in which the obtained corrugated fin is installed in contact with the inner peripheral wall surface. The present invention relates to a flat heat transfer tube, a multi-tube heat exchanger in which a plurality of the flat heat transfer tubes are incorporated, and an EGR gas cooling device in which the multi-tube heat exchange is incorporated in a gas flow path in an EGR recirculation system.

  A method of taking a part of the exhaust gas from the exhaust system of the diesel engine, returning it to the intake system of the engine again, and adding it to the air-fuel mixture is called EGR (Exhaust Gas Recirculation), which is the NOx (nitrogen oxide) Many effects such as suppression of generation, reduction of pump loss, reduction of heat dissipation loss to coolant due to lowering of combustion gas temperature, increase of specific heat ratio due to change of working gas amount and composition, and improvement of cycle efficiency associated with it Therefore, it is widely adopted as an effective method for purifying exhaust gas from diesel engines and improving thermal efficiency.

  However, if the temperature of the EGR gas rises and the amount of EGR gas increases, the durability of the EGR valve deteriorates due to its thermal action, and there is a risk of early breakage. There is a need for a structure, and as the intake air temperature rises, the charging efficiency is lowered and the fuel consumption is lowered. In order to avoid such a situation, a device for cooling EGR gas with engine coolant, car air-conditioner refrigerant or cooling air is used, and in particular, gas-liquid that cools EGR gas, which is a gas, with engine coolant. Many heat exchange type EGR gas cooling devices have been proposed and used. Among these gas-liquid heat exchange type EGR gas cooling devices, there is still a strong demand for double-tube heat exchange type EGR gas cooling devices that have a simple structure and can be easily installed even in narrow installation spaces. For example, in an exchanger that arranges an outer tube through which liquid passes outside the inner tube through which high-temperature EGR gas passes and performs heat exchange between the gas and the liquid, a metal corrugated plate is inserted as a fin in the inner tube 2 A double-pipe heat exchanger (see, for example, Patent Document 1), an inner pipe through which a medium to be cooled is circulated, an outer pipe provided so as to surround and surround the outer circumference of the inner pipe, and the inner pipe Numerous improvements have been made to the fin structure, including a double-pipe heat exchanger (see, for example, Patent Document 2) that includes a heat dissipating fin having a thermal stress relaxation function disposed inside. Double pipe heat exchange In spite of its simple and compact structure, it can be expected to have excellent cooling efficiency. As a heat exchanger for EGR gas cooling, which has limited installation space, such as small cars, there are already many Although it is put into practical use, because of its compact structure, the absolute amount of fluid that flows is naturally limited, resulting in an unsolved problem that the total heat exchange efficiency cannot be satisfied. It was.

In order to solve such problems, even if the structure is somewhat complicated and the size must be increased, so-called shell-and-tube type multi-tubular heat exchangers must be adopted, and various types of these heat exchangers can be used. Improvements have been made. For example, according to the shell-and-tube type multi-tube heat exchanger shown in FIG. 10, cooling that becomes the cooling water inlet 70-1 and the cooling water outlet 70-2 is provided on the outer peripheral portion of the shell main body 40 constituting the cooling jacket. Water nozzles are respectively provided, and the inner peripheral portion of the shell body 40 is provided with a multi-entry corrugated fin 10 on the inner peripheral surface thereof via header plates 30 attached to the left and right ends. A heat transfer tube composed of a plurality of flat tubes 20 is mounted at intervals, and further, gas pipes serving as exhaust gas inlets 80-1 and exhaust ports 80-2 are provided outside the header plates 30 at both ends thereof. Proposed is a multi-tube heat exchanger 100 for an exhaust gas cooling device in which bonnets 50 are integrally attached to each other (see, for example, Patent Document 3), and a heat transfer tube formed of a flat tube. By the action of the multi-entry corrugated fins that are furnished on the inner peripheral surface, it has been reported that the obtained excellent heat transfer performance. Further, in the invention of Japanese Patent Application No. 2005-203906 previously filed by the applicant of the present application, a fluid comprising a cooled medium or a cooling medium that is embedded in a flat heat transfer tube for a heat exchanger and flows through the heat transfer tube. The flow path of the plate fin is composed of plate fins having a rectangular cross section and having a free shape in the longitudinal direction. At least one notch portion and a through hole are formed on the side surface or upper and lower wall surfaces of the plate fin. By developing cut-and-raised parts, uneven parts, etc., we have developed a flat heat transfer tube with a structure that allows fluids flowing between adjacent small channels to communicate with each other and easily maintain a uniform flow rate. It is disclosed that it has been confirmed that heat exchange performance at a level can be obtained.
Japanese Patent Laid-Open No. 11-23181 JP 2000-1111277 A JP 2002-137054 A

  In each of the above prior arts, in the case of the EGR gas cooling device of the double pipe type disclosed in Patent Documents 1 and 2, the structure is simple and compact as described above, but it is excellent as such. Since cooling efficiency can be expected, many heat exchangers for EGR gas cooling that have limited installation space, such as small automobiles, have already been put to practical use. The absolute amount is naturally limited, and as a result, unsolved problems remain in the total heat exchange efficiency. In the shell-and-tube type multi-tube heat exchange type EGR gas cooling device in Patent Document 3 for solving such a problem, a plurality of media are arranged at intervals in the heat exchanger body, The heat transfer tube forming the exhaust gas flow path is a flat tube having a larger heat transfer area, and in addition, a multi-entry type corrugated fin is provided on the inner surface of the flat tube to form a heat transfer tube. By promoting the stirring action on the high-temperature EGR gas flowing through the heat pipe, heat exchange through the heat transfer pipe wall surface is promoted. Here, the corrugated fin and the inner surface of the heat transfer tube, which are installed on the inner surface of the heat transfer tube, are usually joined together by brazing, but the brazed surface has a partial defect and a non-brazed portion is generated. In this case, since there is a concern about a decrease in the amount of heat exchanged, the internal means for fins in the flat tube according to Patent Document 3 maintains the gap between the flat tube inner surface and the fin, which becomes the joining surface, at 100 μm or less, It has been reported that a uniform brazed surface is obtained by brazing with a material interposed, and that heat exchange performance is improved while ensuring the reliability of brazing. However, the inner peripheral surface of the flat tube and the top of the corrugated fin in contact therewith are not necessarily flush with each other, and it is easy to make it difficult to maintain a uniform gap between the wide contact surfaces at 100 μm or less. However, in order to finish the gap so as to keep it uniform while ensuring the accuracy of 100 μm or less, an extremely advanced processing technique is required, resulting in a significant increase in cost. On the other hand, in the plate fin according to the invention of Japanese Patent Application No. 2005-203906 which is the prior application of the present applicant, at least one notch, a through hole, a cut and raised formed on the side surface and upper and lower wall surfaces of the plate fin. It has been confirmed that heat exchange performance at a high level can be obtained by the action of the portion, the concavo-convex portion, etc. In addition, there is a difficulty in processing means for making this a free-form shape in the longitudinal direction with a rectangular cross section, and the resulting fin structure itself has to be expensive, and as a result, a heat transfer tube that incorporates this, and This was a major issue that led to an increase in the cost of a heat exchanger or the like incorporating the heat transfer tube, and which required immediate improvement.

  The present invention is intended to solve the above problems, and as a forming material of a corrugated fin installed in a heat transfer tube, it preferably focuses on a hoop material made of a thin metal plate, and a simple punching of the hoop material or the like. Depending on the processing method, a slit-shaped notch is provided in advance, and then a predetermined bending process is performed, whereby a channel-shaped corrugated fin having a rectangular cross section is formed at an extremely low processing cost. In addition, by installing at least one of the corrugated fins on the inner peripheral surface of the flat heat transfer tube, it has succeeded in obtaining a flat heat transfer tube for a heat exchanger at a relatively low cost while having high heat transfer performance. The present invention has been completed. That is, the present invention forms a corrugated fin having a rectangular cross section at a low cost by applying a simple processing method to a hoop material made of a thin metal plate, and the obtained flat heat transfer tube for a heat exchanger having the corrugated fin provided therein. And a multi-tube heat exchanger in which at least two heat transfer tubes are arranged, and further a heat exchange type gas cooling device.

  The heat transfer tube according to the present invention for solving the above problems is a flat heat transfer tube for a heat exchanger having a substantially elliptical cross section with a corrugated fin on the inner peripheral surface, or a rectangular cross section including a substantially rectangular shape, The corrugated fins provided on the inner peripheral surface of the flat heat transfer tube are made of a metallic thin plate, and a plurality of slits are formed in multiple rows and multiple rows by drilling the metallic thin plate material at predetermined intervals. A corrugated fin having a substantially rectangular channel shape and a linear or free wave shape in the longitudinal direction was obtained by bending the metal thin plate material with a predetermined dimension. A flat shape for a heat exchanger characterized in that at least one of the corrugated fins is provided in contact with the inner peripheral wall surface thereof and forms a small flow path of fluid that can flow mutually. It is an gist heat pipe.

  Further, in the above-described flat heat exchanger tube for heat exchanger according to the present invention, the corrugated fins in the shape of corrugated fins are made of a thin metal plate, and multi-row, multi-row slit-shaped notches formed by the thin metal plate are provided. Further, it is formed in a rectangular shape, an oval shape, or an arbitrary shape equivalent thereto, and the arrangement of the notch portions between rows or columns is formed in any desired shape.

  Further, in the flat heat transfer tube for a heat exchanger according to the present invention, the corrugated fin having a corrugated shape is formed by a punching or other mechanical processing method using a press as a means for forming a slit-shaped notch portion on the metal thin plate. It is one of chemical processing methods including etching, and the preferred embodiment is that the corrugated bending means having a rectangular cross section and a free shape in the longitudinal direction with respect to the metallic thin plate material is press forming. is there.

  In the flat heat transfer tube for a heat exchanger according to the present invention, the metal thin plate forming the corrugated fin to be installed is made of austenitic stainless steel such as SUS304, SUS304L, SUS316, SUS316L, and the thickness thereof is 0.05. The preferred embodiment is that it is -0.3 mm.

  The flat heat transfer tube for a heat exchanger according to the present invention further comprises a flat tube obtained by rolling a cylindrical tube made of the metal material, the flat heat transfer tube being made of the same metal material as the corrugated fins incorporated therein. A preferred embodiment is a flat tube formed by roll forming a material in advance and electro-welded and a flat tube formed by joining a press-formed upper plate and a lower plate together in the middle.

  In the heat exchanger tube according to the present invention, the inner means of the corrugated fin on the inner peripheral surface of the flat heat exchanger tube is appropriately selected from brazing, welding, diffusion bonding, bonding using an adhesive, and other bonding means. It is preferable that the selected flat plate is in close contact with the inner peripheral wall surface of the flat heat transfer tube and fixed as a unit.

  In the shell-and-tube type multi-tube heat exchanger according to the present invention, at least two or more of the above-described flat heat transfer tubes for heat exchanger are incorporated in the shell body, and are separated by corrugated fins built in the flat heat transfer tubes. The gist of the present invention is a multi-tubular heat exchanger characterized in that a gas body as a cooling medium flows between the small flow paths so as to be able to flow through each other.

  In the EGR gas cooling device according to the present invention, the gas body flowing through the heat exchanger flat heat transfer tube is EGR gas, and a shell-and-tube type multi-tube heat exchanger incorporating the flat heat transfer tube is provided. The gist of the EGR cooling apparatus is characterized by being incorporated into a gas flow path in an EGR recirculation system.

  In the flat heat transfer tube for a heat exchanger according to the present invention, the exhaust gas flow path in the flat heat transfer pipe is divided into a plurality of small flow paths by a corrugated fin having a channel shape with a substantially rectangular cross section. The plurality of slit-shaped notches formed in the corrugated fin allow exhaust gas flowing through the flow path to flow between adjacent flow paths, so that the fluid pressure is made uniform. As a result, the heat transfer performance is improved in an almost uniform state between all the flow paths divided into the small flow paths in the heat transfer tube. Furthermore, the fluid streamlines are complicatedly disturbed by the notches, and turbulence and vortex are generated, and effective stirring is repeated. At the same time, the edge effect acts and the laminar flow is separated everywhere. The fluid flowing inside and outside the flat heat transfer tube repeatedly contacts the wall surface of the heat transfer tube, and heat exchange with the cooling medium or the cooled medium on the outer surface of the heat transfer tube is efficiently promoted, and excellent cooling efficiency is ensured. The Also, the multi-tube heat exchanger according to the present invention in which at least two flat heat transfer tubes according to the present invention having the corrugated fins installed therein are provided, or the multi-tube heat exchanger is used as a gas flow in the EGR recirculation system. The EGR gas cooling device incorporated in the passage is such that the high-temperature exhaust gas flowing through the flat heat transfer tube is repeatedly brought into contact with the wall surface of the heat transfer tube, whereby heat to the cooling medium flowing on the outer peripheral surface of the heat transfer tube is obtained. The exchange is efficiently promoted and excellent cooling efficiency is ensured. Furthermore, the excellent heat exchange performance contributes to the reduction of the size and weight of the devices, making the devices compact and enabling easy installation in a limited space. On the other hand, in the flat heat transfer tube for a heat exchanger according to the present invention, the corrugated fins provided therein are preferably punched into a predetermined shape in advance for a hoop material made of a thin metal plate, and a plurality of multi-row multi-rows are provided. After the slit-shaped notch is formed, the hoop material is bent into a predetermined size and shape, which is obtained by an extremely simple processing means by an omitted process, so that the processing cost is greatly reduced. As a result, the cost of the flat heat transfer tube that embeds it can be kept at a low price, and it can be provided to the market as a flat heat transfer tube for a heat exchanger with excellent heat transfer performance but relatively low cost. it can. Therefore, a great effect is obtained that the cost of a multi-tube heat exchanger in which a plurality of the heat transfer tubes are arranged, and also the cost of the EGR gas cooling device can be greatly reduced. Further, the use of corrugated corrugated fins further improves the heat transfer performance.

  Hereinafter, the embodiments of the present invention will be described in more detail and specifically with reference to the accompanying drawings and examples. However, the present invention is not limited thereto, and the obtained flat heat transfer tube and the heat transfer tube will be described. The design can be freely changed within the scope of the present invention, including the structure and shape of the corrugated fins installed in the heat pipe.

  FIG. 1 is an enlarged perspective view of a main part schematically showing a flat heat transfer tube for a heat exchanger according to a first embodiment of the present invention, and FIG. 2 shows a predetermined interval with respect to a hoop material made of a thin metal plate in the same embodiment. 3 is an enlarged plan view of a main part showing a state in which a slit-like cutout is formed, and FIG. 3 is a diagram illustrating a bending process by press molding of the hoop material in which the cutout is formed in the same embodiment. 4 is an enlarged perspective view of a main part schematically showing a state in which a corrugated fin having a channel shape in cross section is formed, and FIG. 4 is a second embodiment according to the present invention, in which a hoop material is alternately drilled into different shapes. FIG. 5 is an enlarged plan view of a main part showing a state in which a slit-like cutout is formed. FIG. 5 is a cross-sectional view of the hoop material in which the cutout is formed according to the same embodiment. FIG. 6 is an enlarged perspective view of a main portion schematically showing a state in which a tunnel-shaped corrugated fin is formed. FIG. 6 is a third embodiment according to the present invention. FIG. 7 is an enlarged plan view of a main part showing a state in which a notch is formed. FIG. 7 is a corrugated corrugation having a cross-sectional channel shape by press-forming the hoop material in which the notch is formed in a staggered manner FIG. 8 is an enlarged perspective view of a main part schematically showing a state in which fins are formed, and FIG. 8 is a slit-like cutout in the fourth embodiment according to the present invention, in which hole processing is performed at different positions and shapes on the hoop material. FIG. 9 is an enlarged perspective view of an essential part schematically showing a flat heat transfer tube for a heat exchanger equipped with a corrugated fin according to a fifth embodiment of the present invention.

  A flat heat transfer tube for a heat exchanger according to a first embodiment of the present invention is a SUS304L austenite having a racetrack shape with a substantially oval cross-section and a plate thickness of 0.5 mm as shown in FIG. Corrugated fin 2 having a channel shape with a rectangular cross section on the inner peripheral surface and formed with notches 4 at predetermined intervals in the longitudinal direction. The flow path of the fluid flowing through the flat heat transfer tube is divided into a plurality of small flow paths. Here, the corrugated fin 2 for fluid agitation installed in the flat heat transfer tube for heat exchanger according to the present embodiment is a hoop material made of the same kind of SUS304L austenitic stainless steel having a thickness of 0.05 mm as shown in FIG. 3 to form a rectangular slit-shaped cutout portion 4 in advance by punching by punching with a press at predetermined intervals and in multiple rows and multiple rows with respect to the hoop material 3. The hoop material 3 is subjected to bending processing by repeatedly bending the bent portion 5 by press molding, and as shown in FIG. 3, the channel section has a rectangular cross section and multi-row, multi-row cutout portions 4 are formed in the longitudinal direction. The formed corrugated fin 2 is formed. The formed corrugated fin 2 according to the present embodiment is internally mounted in the flat heat transfer tube 1 and is integrally fixed to the inner peripheral surface thereof by brazing, and the fluid flow path in the flat heat transfer tube 1 is divided into a plurality of small flow streams. At the same time as dividing into the passages, the fluids flowing through the partitioned small flow paths can freely move back and forth with each other by the plurality of cutout portions 4 provided in multi-rows and multi-columns in the longitudinal direction. Thus, the uneven flow velocity between the channels is effectively eliminated. Further, the laminar flow is separated by the edge action of the formed notches 4 and heat exchange with the cooling medium flowing outside the flat heat transfer tube 1 is promoted, so that the heat transfer performance is remarkably increased. Will be improved. A plurality of flat heat transfer tubes 1 according to the present embodiment formed in this way are prepared and incorporated as gas flow paths in a multi-tube heat exchanger for an exhaust gas cooling device (not shown) for exhaust gas cooling performance tests. As a result, it was proved that the built-in corrugated fins 2 functioned as designed, and the heat transfer efficiency as a heat exchanger reached an extremely high level, and the heat exchanger was further recirculated by EGR. It was confirmed that the hot EGR gas was efficiently cooled to the initial set temperature by incorporating it into the gas flow path in the system. Note that the corrugated fins 2 may be manufactured by bending from a flat plate material that is cut in conformity with the length of the heat transfer tube instead of the hoop material.

  When punching the hoop material 3a by a press and performing multi-row and multi-row drilling, as shown in FIG. 4, an oval cut-out portion 4a and a rectangular cut-out portion are provided at predetermined intervals in each row. 4b is formed in the shape of a channel having a rectangular cross section as shown in FIG. 5 in the longitudinal direction in the same manner as in Example 1 except that each column is alternately formed in each column and each column is shifted in phase between adjacent rows. A corrugated fin 2a having a large number of multi-row, multi-row cutouts 4a and 4b is formed, and then the corrugated fin 2a is mounted in a flat tube in the same manner as in the first embodiment, and is used for the heat exchanger according to the present embodiment. A flat heat transfer tube (not shown) was obtained. A plurality of the flat heat transfer tubes for the heat exchanger according to the present example obtained were prepared and incorporated as a gas flow path in a multi-tube heat exchanger for an exhaust gas cooling device in the same manner as in Example 1 above, under the same conditions. As a result of the exhaust gas cooling performance test, it was demonstrated that the corrugated fins 2a incorporated therein showed an excellent function, and the heat transfer efficiency of the heat exchanger reached an extremely high level as in Example 1, Furthermore, it was confirmed that a cooling efficiency substantially equivalent to that of Example 1 can be obtained by incorporating the heat exchanger into the gas flow path in the EGR recirculation system.

  When punching the hoop material 3b by a press and performing multi-row multi-row drilling, as shown in FIG. 6, between the rectangular notches 4c formed at intervals in each row, adjacent rows 7 except that the rectangular cutouts 4d are formed by staggering the rows in a zigzag manner and having a rectangular channel shape as shown in FIG. A corrugated fin 2b in which a large number of row notches 4c and 4d are formed is formed, and then the corrugated fin 2b is mounted in a flat tube in the same manner as in the first embodiment. A heat transfer tube (not shown) was obtained. A plurality of the flat heat transfer tubes for the heat exchanger according to the present embodiment obtained are prepared and incorporated as a gas flow path in a multi-tube heat exchanger (not shown) for an exhaust gas cooling device in the same manner as in the first embodiment. As a result of the exhaust gas cooling performance test under the same conditions, the cutout portions 4c and 4d formed in a zigzag shape in the corrugated fin 2b provided in the interior exhibit a unique and excellent function, and the heat transfer tube It has been proved that heat is exchanged almost evenly with the cooling medium flowing through the upper surface and the lower surface side, and the heat transfer efficiency as a heat exchanger has reached a very high level equivalent to or higher than that of the first embodiment. It was confirmed that a cooling efficiency higher than that of Example 1 can be obtained by incorporating the exchanger into the gas flow path in the EGR recirculation system.

  When punching the hoop material 3c with a press to perform multi-row multi-row drilling, rectangular notches 4e formed at intervals in each row as shown in FIG. Except that the notch portion 4f, the notch portion 4g having a convex portion on the front, and the like are formed by appropriately shifting the phase between adjacent rows, the channel shape has a rectangular cross section in the longitudinal direction as in the first embodiment. A corrugated fin (not shown) in which multi-row, multi-column cutouts 4e, 4f and 4g are formed is formed, and then the corrugated fin is mounted in a flat tube in the same manner as in the first embodiment. A flat heat transfer tube for heat exchanger (not shown) was obtained. A plurality of flat heat transfer tubes for the heat exchanger according to the present embodiment obtained are prepared and incorporated as a gas flow path in a multi-tube heat exchanger (not shown) for an exhaust gas cooling device in the same manner as in the first embodiment. As a result of being subjected to the exhaust gas cooling performance test under the same conditions, the notches 4e, 4f and 4g formed in the corrugated fins that are built in each show unique actions, and the flowing gas is complicated The agitation and laminar flow further proceed and heat exchange is effectively performed with the cooling medium flowing outside the heat transfer tube, and the heat transfer efficiency as a heat exchanger reaches a very high level equal to or higher than that of the first embodiment. Further, it was confirmed that the cooling efficiency higher than that of Example 1 can be obtained by incorporating the heat exchanger into the gas flow path in the EGR recirculation system.

  The corrugated fin 2c formed with corrugated undulations at predetermined pitch intervals in the longitudinal direction as shown in FIG. 9 by further drawing the corrugated fin 2 formed in the first embodiment. After that, the corrugated fin was installed in a flat tube in the same manner as in Example 1 to obtain a heat exchanger flat heat transfer tube 1a according to this example as shown in FIG. A plurality of the flat heat transfer tubes 1a for the heat exchanger according to the present example obtained are prepared, and as a gas flow path in a multi-tube heat exchanger (not shown) for an exhaust gas cooling device in the same manner as in Example 1 above. As a result of the built-in and exhaust gas cooling performance test under the same conditions, the notch 4 formed in the corrugated corrugated fin 2c provided in the interior and the undulation formed at a predetermined pitch interval in the longitudinal direction are synergistic. It is demonstrated that the heat transfer efficiency as a heat exchanger has reached an extremely high level as compared with Example 1, and the heat exchanger is incorporated into the gas flow path in the EGR recirculation system. It was confirmed that a cooling efficiency higher than Example 1 could be obtained.

  In each of the above embodiments based on the present invention, SUS304L austenitic stainless steel having a thickness of 0.05 mm is used as a material as a hoop material made of a thin metal plate forming a corrugated fin installed in a flat heat transfer tube. However, the hoop material is not limited to this, and other stainless steel having a thickness of 0.05 to 0.5 mm, for example, austenitic stainless steel such as SUS304, SUS304L, SUS316, SUS316L, etc. It is also possible to select and use appropriately, and the flat tube forming the flat heat transfer tube is preferably formed of the same kind of material whose plate thickness is basically higher than that, and the cylindrical tube is rolled to obtain a cross-sectional shape. In addition to those formed in the shape of a substantially oval race track, the metallic material is previously flattened. Flattened tube with electric resistance welding by roll forming, it is possible to preferably adopt a flattened tube or the like bonded in the combined during the press-molded upper and lower plate. Further, the slit-like drilling process for the hoop material can be formed by appropriately selecting other mechanical processing means, chemical processing means by etching, etc. in addition to punching by press in each of the above embodiments. The shape of the slit-like cutouts, the form of the arrangement, and the like are not prevented from being arbitrarily changed within a range in which the object of the present invention can be achieved. Furthermore, the interior means of the corrugated fin on the inner peripheral surface of the flat heat transfer tube may be arbitrarily selected from welding, diffusion bonding, bonding with an adhesive, etc. in addition to brazing in the above embodiment.

  As is clear from the above embodiments, the flat heat transfer tube for a heat exchanger according to the present invention has a channel shape in which the exhaust gas flow path in the flat heat transfer tube has a substantially rectangular cross section and is linear in the longitudinal direction. Alternatively, the exhaust gas flowing through the channel is separated by a plurality of slit-shaped notches formed in the corrugated fin by the corrugated fin having a free shape. In order to allow mutual flow between the channels, the fluid pressure is made uniform so that the heat transfer performance is almost uniform among all the channels divided into the small channels in the heat transfer tube. Improve in condition. In addition, the streamline of the fluid is complexly disturbed by the edge effect of the notch, and turbulent flow and vortex flow are generated, and effective stirring is repeated. At the same time, the edge effect acts to reach laminar flow. The fluid that has been peeled off and flows through the inside and outside of the flat heat transfer tube repeatedly contacts the heat transfer tube wall surface, and heat exchange with the cooling medium or the medium to be cooled on the outer peripheral surface of the heat transfer tube is efficiently promoted, resulting in excellent cooling efficiency. Is secured. Also, the multi-tube heat exchanger according to the present invention in which at least two flat heat transfer tubes according to the present invention having the corrugated fins installed therein are provided, or the multi-tube heat exchanger is used as a gas flow in the EGR recirculation system. The EGR gas cooling device incorporated in the passage is such that the high-temperature exhaust gas flowing through the flat heat transfer tube is repeatedly brought into contact with the wall surface of the heat transfer tube, whereby heat to the cooling medium flowing on the outer peripheral surface of the heat transfer tube is obtained. The exchange is efficiently promoted and excellent cooling efficiency is ensured. Furthermore, the excellent heat exchange performance contributes to the reduction of the size and weight of the devices, making the devices compact and enabling easy installation in a limited space. On the other hand, the flat heat transfer tube for a heat exchanger according to the present invention includes a corrugated fin that is punched into a predetermined shape in advance for a hoop material made of a thin metal plate, and has a plurality of slits in multiple rows and multiple rows. After the formation of the cut-out portion in the shape, the hoop material is bent into a predetermined dimensional shape, which is obtained by an extremely simple processing means by an omitted process, the processing cost is greatly reduced, As a result, the cost of the flat heat transfer tube that houses it can be kept low, and it can be offered to the market as a relatively low cost flat heat transfer tube for heat exchangers while having excellent heat transfer performance. The price of a multi-tube heat exchanger in which a plurality of the heat transfer tubes are arranged, and also an EGR gas cooling apparatus equipped with the multi-tube heat exchanger can be greatly reduced. Furthermore, although the structure of the heat exchange type cooling device is simplified by mounting the flat heat transfer tube with the corrugated fin according to the present invention, the cooling efficiency of these devices is improved. In order to enable light weight and downsizing, not only the EGR gas cooling device for automobiles but also the target condition of the medium to be cooled and the cooling medium is converted into gas-gas, gas-liquid, liquid-liquid, etc. It is possible to flexibly cope with changes in viscosity and temperature, and it can be used as a cooling device for other gas cooling devices and liquids such as oil and fuel. Expectations for a wide range of applications.

It is a principal part expansion perspective view which shows typically the flat heat exchanger tube for heat exchangers by 1st Example which concerns on this invention. In the Example, it is a principal part enlarged plan view which shows the state which gave the drilling process with the predetermined space | interval with respect to the hoop material which consists of metal thin plates, and formed the slit-shaped notch part. In the Example, it is a principal part expansion perspective view which shows typically the state which gave the press molding process with respect to the said hoop material in which the notch part was formed, and formed the corrugated fin of the cross-sectional channel shape. In 2nd Example which concerns on this invention, it is a principal part enlarged plan view which shows the state which bored in a different shape alternately with respect to a hoop material, and formed the slit-shaped notch part. In the Example, it is a principal part expansion perspective view which shows typically the state which gave the press molding process with respect to the said hoop material in which the notch part was formed, and formed the corrugated fin of the cross-sectional channel shape. In 3rd Example which concerns on this invention, it punches with respect to a hoop material in zigzag form, It is a principal part enlarged plan view which shows the state which formed the slit-shaped notch part. In the same Example, it is a principal part expansion perspective view which shows typically the state which performed the press molding process with respect to the said hoop material in which the notch part was formed in the zigzag form, and formed the corrugated fin of the cross-sectional channel shape. In 4th Example which concerns on this invention, it is a principal part enlarged plan view which shows the state which gave the drilling process from which a position and a shape differ, respectively, and formed the slit-shaped notch part with respect to the hoop material. It is a principal part expansion perspective view which shows typically the flat heat exchanger tube for heat exchangers by 5th Example which concerns on this invention. 1 shows a conventional multi-tube heat exchange type EGR gas cooling device, in which (a) is a partially broken perspective view, (b) is an exploded perspective view of a flat heat transfer tube alone, and (c) is the flat heat transfer tube. FIG.

Explanation of symbols

1, 1a Flat heat transfer tube 2, 2a, 2b Corrugated fin 2c Corrugated corrugated fin 3, 3a, 3b, 3c Hoop material 4, 4a, 4b, 4c, 4d, 4e, 4f, 4g Notch 5, 5a, 5c, 5d bent part

Claims (9)

  A flat heat transfer tube for a heat exchanger having a substantially elliptical racetrack shape having a corrugated fin on the inner peripheral surface or a rectangular cross section including a substantially rectangular shape, wherein the corrug is provided on the inner peripheral surface of the flat heat transfer tube. The fin is made of a metallic thin plate, and a plurality of slit-shaped notches are formed in multiple rows and multiple columns by drilling the metallic thin plate material at a predetermined interval, and then the metallic thin plate material Is bent to a predetermined dimension to form a corrugated fin having a substantially rectangular cross section in the longitudinal direction and having a linear or free wave shape in the longitudinal direction. At least one of the obtained corrugated fins is formed on the inner peripheral wall surface. A flat heat transfer tube for a heat exchanger, characterized in that it forms a small flow path of fluids that are installed in contact with each other and can flow with each other.   The multi-row multi-column slit-shaped notches formed of the metallic thin plate are formed in a rectangular shape or an oval shape or any shape equivalent thereto, and the arrangement of the notch portions between rows or columns is as follows: The flat heat transfer tube for a heat exchanger according to claim 1, wherein the flat heat transfer tube is formed in any desired form.   3. The method according to claim 1, wherein the means for forming the slit-shaped notch on the metal thin plate is any one of a punching or other mechanical processing method using a press or a chemical processing method including etching. Flat heat transfer tube for heat exchanger.   The flat heat transfer tube for a heat exchanger according to any one of claims 1 to 3, wherein the corrugated bending means having a rectangular cross section with respect to the metal thin plate and having a linear shape or a free wave shape in the longitudinal direction is press forming. .   The metal thin plate is made of austenitic stainless steel such as SUS304, SUS304L, SUS316, SUS316L or the like, and the plate thickness is 0.05 to 0.3 mm. A flat heat transfer tube for a heat exchanger as described in 1.   The flat heat transfer tube is a flat tube obtained by rolling a cylindrical tube made of the same metallic material as the corrugated fins installed therein, a flat tube formed by roll forming the metallic material in advance and electro-welded, and press forming The flat heat transfer tube for a heat exchanger according to any one of claims 1 to 5, wherein the flat heat transfer tube is a flat tube or the like in which a plate and a lower plate are joined together.   The means for fixing the corrugated fin in the flat heat transfer tube to the inner peripheral surface is appropriately selected from brazing, welding, diffusion bonding, adhesion using an adhesive, and other bonding means, and the inside of the flat heat transfer tube The flat heat transfer tube for a heat exchanger according to any one of claims 1 to 6, wherein the flat heat transfer tube for a heat exchanger according to any one of claims 1 to 6, wherein the heat exchanger is in close contact with and fixed to the peripheral wall surface.   Between at least 2 or more of the flat heat exchanger tubes for heat exchangers of any one of Claims 1 thru | or 7 built in the shell main body, and was separated by the corrugated fin built in this flat heat exchanger tube A shell-and-tube multi-tubular heat exchanger characterized in that a gas body, which is a medium to be cooled, flows so as to be able to pass through each other.   The gas body flowing through the flat heat transfer tube for heat exchanger is EGR gas, and a shell and tube type multi-tube heat exchanger incorporating the flat heat transfer tube is provided as a gas flow path in the EGR recirculation system. A built-in EGR cooling device.