JP4208632B2 - Heat transfer tube with fins - Google Patents

Description

[0001]
[Industrial application fields]
The present invention provides a multi-tube heat exchanger such as an EGR gas cooling device, a radiator built-in oil cooler, a cooling medium such as cooling water, cooling air, a refrigerant for a car air conditioner, other refrigerant liquid, EGR gas, The present invention relates to heat transfer tubes for various uses such as those used for heat exchange with a cooled high-temperature heat medium fluid such as combustion exhaust gas containing soot.
[0002]
[Prior art]
[Patent Document 1]
JP-A-11-108578
[Patent Document 2]
JP 2000-179410 A
[Patent Document 3]
JP 2001-227413 A
[0003]
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.
[0004]
And as this EGR gas cooling device, as shown in the conventional invention of the said patent document 1-patent document 3, etc., the several small diameter heat exchanger tube which can distribute | circulate an EGR gas is arrange | positioned inside this heat exchanger tube. There exist some which perform heat exchange with EGR gas and a cooling medium via a heat exchanger tube by circulating cooling media, such as cooling water, cooling air, and a refrigerant liquid.
[0005]
The heat transfer tube used in the EGR gas cooling apparatus as described above is often a metal tube with a smooth inner peripheral surface, but in such a heat transfer tube, most of the EGR gas flows in the vicinity of the center of the heat transfer tube at high speed. However, heat is only conducted from the EGR gas passing through the inner peripheral surface of the heat transfer tube, and heat exchange with the cooling medium is difficult to be performed. In order to improve this heat exchange performance, in the conventional inventions of Patent Documents 1 and 2, a fin member formed by spirally twisting a flat plate is inserted and arranged in a metal element tube having a protrusion protruding on the inner peripheral surface. To form a heat transfer tube. Moreover, in patent document 3, the flat fin member is integrally protruded in the raw tube, and the heat exchanger tube is formed.
[0006]
In this way, by arranging a helically twisted fin member in the raw tube or by projecting a flat fin member integrally, the heat transfer area of the heat transfer tube is increased and the heat near the center of the heat transfer tube is increased. The heat conductivity between the EGR gas and the heat transfer tube was increased by transmitting the gas to the fin member. Furthermore, the flow of the EGR gas in the heat transfer tube is turbulent by the fin member, the flow distance of the EGR gas in the heat transfer tube is lengthened, and the contact time between the heat transfer tube and the EGR gas is lengthened. The heat exchange efficiency between the EGR gas and the cooling medium is increased.
[0007]
[Problems to be solved by the invention]
However, in the prior arts of Patent Documents 1 and 2, the contact between the fin member and the raw tube is an intermittent point contact between both side edges of the fin member and the protruding portion of the inner peripheral surface of the raw tube. Moreover, in the prior art of patent document 3, it is line contact with the outer peripheral edge of a fin member, and the internal peripheral surface of a raw material pipe | tube. Therefore, in any case, the contact area between the fin member and the raw tube is small, and even if the fin member receives the heat of the EGR gas, the heat transfer from the fin member to the raw tube is not sufficiently performed, and the EGR gas and the heat transfer tube There was a limit to increasing the efficiency of heat exchange with the cooling medium flowing on the outer periphery. Also, in the point contact where the contact with the raw tube is a line contact or intermittent contact, the fin member is poorly fixed, and due to the vibration of the heat transfer tube or the fluid flow force, each fin or fin wall surface is in contact. Fretting is likely to occur, and the heat exchange function and durability of the heat transfer tube may be impaired.
[0008]
The present invention is intended to solve the above-described problems, and by increasing the contact area between the fin member and the element tube inserted into the element tube of the heat transfer tube, the heat of the fin member and the element tube is increased. As a result, it is intended to improve the heat exchange performance between the fluid flowing inside the heat transfer tube and the fluid flowing outside the heat transfer tube. In addition, it is possible to form a fin member with a structure that generates a swirling flow in the fluid flowing inside the heat transfer tube or creates a turbulent flow of the fluid, and a boundary layer that is likely to occur near the inner peripheral surface of the elementary tube To increase the heat exchange efficiency. Furthermore, the use of heat transfer tubes is improved by improving the fixing of the fin members in the tube and suppressing the fretting of each fin and the wall surface of the tube in contact with the fins due to fluid flow and vibration of the heat transfer tube. It is possible to improve the property and durability.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a metal plate-like fin member to be inserted and disposed in a metal base tube, which is long in the tube axis direction and at least 2 from the shaft center portion. A fin is formed by projecting a fin in the direction, and a plurality of slits intersecting the tube axis direction are provided on the outer end side of the plate-like fin member, and a twisted piece is obtained by twisting between the slits in the direction intersecting the surface of the fin. By forming the twisted piece into a shape corresponding to a part of the inner peripheral surface of the blank tube, the close contact surface provided on the tip side of the twisted piece is brought into surface contact with the inner peripheral surface of the blank tube. It is fixed.
[0010]
According to a second aspect of the present invention, a metal plate-like fin member inserted and disposed in a metal base tube is formed so as to be long in the tube axis direction and projecting the fin in at least two directions from the shaft center portion. A plurality of slits intersecting the tube axis direction are provided on the front end side of the plate-shaped fin member in the outer direction, and a twist piece is formed by twisting between the slits in the direction intersecting the surface of the fin. Before insertion and placement into the pipe, a plate-like fin member is formed with a diameter such that the tip side of the twisted piece is arranged outward from the inner peripheral surface of the pipe, and the plate-like fin member is attached to the pipe. At the time of insertion, the twisted piece deforms in the axial center direction corresponding to a part of the inner peripheral surface of the raw tube, so that the contact surface formed on the tip side of the twisted piece becomes the inner peripheral surface of the raw tube. It is made to adhere and fix to.
[0011]
Further, the plate-like fin member may be provided with at least one window portion through which a fluid flowing in the raw tube can pass.
[0012]
Moreover, the window part may protrude a protrusion piece inside at regular intervals.
[0013]
[Action]
The present invention is configured as described above. In the first invention, the plate-like fin member inserted and disposed in the metal base tube is long in the tube axis direction and is finned in at least two directions from the shaft center portion. Is formed protruding. A plurality of slits intersecting the tube axis direction are provided on the distal end side in the outer direction of the plate-like fin member, and twisted pieces are formed by twisting between the slits in the intersecting direction with the surface of the fin. By forming the tip side of the twisted piece into a shape corresponding to a part of the inner peripheral surface of the raw tube, a close contact surface that can be brought into surface contact with the inner peripheral surface of the raw tube is formed on the tip side of the twisted piece. . By inserting and disposing the plate-like fin member formed in this manner in the raw tube, a heat transfer tube in which the tight contact surface of the twisted piece is tightly fixed to the inner peripheral surface of the raw tube is obtained.
[0014]
In this way, the plate-like fin member is in surface contact with the inner peripheral surface of the raw tube through the contact surface, so that the heat of the plate-like fin member and the raw tube is higher than that of the conventional point contact or line contact fin member. The conductivity can be increased. Further, a part of the fluid flowing in the heat transfer tube flows while swirling or causing turbulence along the surface where the twist pieces intersect with each other. Due to the swirling flow and the turbulent flow of the fluid, the boundary layer that is likely to be generated in the vicinity of the inner peripheral surface of the raw pipe can be peeled off to improve the heat exchange efficiency. In addition, the surface contact between the element tube and the close contact surface improves the fixability of the plate-like fin member to the element tube, and can prevent fretting of the wall surface of the element tube in contact with each fin or fin. .
[0015]
Next, in the second invention, as in the first invention, a plurality of slits are provided on the front end side of the plate-like fin member projecting a plurality of fins in at least two directions, and the slits are twisted in the crossing direction. , Forming twisted pieces. And in the 1st invention, the adhesion side is formed by making a twist piece into the shape corresponding to the inner peripheral surface of a blank before inserting and arranging to a blank. However, in the second invention, the twisted piece does not have a shape corresponding to the inner peripheral surface of the raw tube, and the tip side of the twisted piece is more than the inner peripheral surface of the raw tube before being inserted into the raw tube. The plate-like fin member is formed with such a diameter as to be arranged outward.
[0016]
When the plate-like fin member of the second invention as described above is inserted into the element pipe having an inner diameter smaller than the diameter, the twisted piece is pressed against the inner peripheral surface of the element pipe and deformed into a shape corresponding to the inner peripheral surface. Thus, a close contact surface that can be brought into surface contact with the inner peripheral surface of the raw tube is formed. Accordingly, after the insertion into the raw tube is completed, the tight contact surface of the twisted piece is elastically brought into surface contact with the inner peripheral surface of the raw tube, and the fixability of the plate-like fin member to the raw tube can be further improved. .
[0017]
In the heat transfer tubes as in the first and second aspects of the present invention, a metal plate-like fin member formed by projecting fins in at least two directions from the axial center portion is inserted and arranged in a metal base tube excellent in thermal conductivity. By installing, the heat transfer area can be increased, and the heat absorption characteristics and heat dissipation characteristics of the heat transfer tube can be improved. And in the heat transfer pipe | tube which does not arrange | position the conventional fin member, only the heat | fever of the one part fluid which flows the inner peripheral surface vicinity of an elementary pipe is transmitted to a heat exchanger tube, and most fluids transmit heat to a heat exchanger tube. Although the center of the heat transfer tube was passed at high speed without any problems, in the heat transfer tube of the present invention, the internal space of the heat transfer tube is divided by projecting fins in at least two directions from the axial center, The flow of fluid is prevented, and the fluid flows in a dispersed manner while contacting the surface of the plate-like fin member not only in the inner peripheral surface of the elementary tube but also in the vicinity of the center in the heat transfer tube, and between the fluid and the heat transfer tube. Can be efficiently conducted.
[0018]
Further, since the close contact surface provided on the front end side in the outward direction of the plate-like fin member is brought into surface contact with the inner peripheral surface of the raw tube, the metal tube and the plate-like fin as in the conventional inventions of Patent Documents 1 to 3, etc. Compared to a heat transfer tube in which the member is in point contact or line contact, the contact area between the plate fin member and the raw tube can be increased, and the thermal conductivity between the plate fin member and the raw tube can be increased. Can do. In addition, the surface contact improves the fixing of the plate-like fin member to the raw tube, and even if there is fluid flow or heat transfer tube vibration, the fretting of the wall surface of the raw tube where the fin or fin is in contact. The heat exchange can be performed smoothly and the durability of the heat transfer tube is improved.
[0019]
Further, since the plate-like fin member has the tip of the twisted piece in surface contact with the raw tube, a flow gap through which fluid can pass is intermittent between the proximal end of the twisted piece and the inner peripheral surface of the raw tube. Will occur. Accordingly, the fluid repeatedly enters and exits through the plurality of internal spaces divided by the plate-like fin members while passing through the intersecting surfaces of the twist pieces and the flow gap, and flows to the flow destination. For this reason, the fluid flows while swirling or generating turbulence near the inner peripheral surface of the raw tube, and heat exchange between the inner and outer fluids via the heat transfer tube can be promoted by separation of the boundary layer.
[0020]
Therefore, for example, when high-temperature EGR gas is flowed into the heat transfer tube of the present invention and cooled by the refrigerant liquid, in the heat transfer tube of the present invention, not only the wall surface of the raw tube but also plate fins It can be efficiently transmitted to the member. In addition, the heat of the EGR gas flowing not only in the vicinity of the inner peripheral surface of the element pipe but also in the center is efficiently transmitted to the plate-like fin member. The close contact surface of the plate-like fin member that is in surface contact with the elemental tube promotes the transfer of heat from the plate-like fin member to the elemental tube, and this heat flows outside through the inner and outer surfaces of the elemental tube. Heat is dissipated. As a result, heat exchange between the refrigerant liquid and the EGR gas can be performed efficiently, and the EGR gas can be uniformly cooled without unevenness.
[0021]
Further, since the plate-like fin member is closely fixed to the inner peripheral surface of the raw tube by surface contact as described above, the fixing property in the raw tube is good. However, if both are connected and fixed by welding, brazing, etc., the fixability of the plate-like fin member in the raw pipe can be further enhanced, and the plate-like fin member may be shaken by fluid flow or heat transfer tube vibration. Since deformation is prevented, the usability and durability of the heat transfer tube can be improved. Furthermore, when brazing the close contact surface of the plate-like fin member to the inner peripheral surface of the raw tube, the heat transfer between the plate-like fin member and the inner peripheral surface of the raw tube is not limited to the close contact surface but the braze filler fillet. Since it is carried out over a wide area including the wall thickness, the thermal conductivity is further improved, and the heat exchange performance of the heat transfer tube can be improved.
[0022]
Further, if the plate-like fin member is provided with at least one window portion through which the fluid flowing in the raw tube can pass, the heat transfer area is reduced by the area provided with the window portion, but a lighter heat transfer tube can be obtained. Can do. In addition, the fluid flowing in the divided internal space of the heat transfer tube not only generates a swirling flow in the flow gap between the proximal end portion of the twisted piece and the raw tube, but also flows through the window portion. By doing so, meandering or turbulent flow of the fluid occurs, and the flow distance of the fluid in the heat transfer tube becomes long. And while the contact time with the inner peripheral surface of a raw pipe and the surface of a plate-like fin member becomes long, the fluid is stirred, and not only a part of the fluid but the whole comes into contact with the raw pipe and the plate-like fin member repeatedly. It will be a thing. Therefore, the heat conductivity of the heat transfer tube is increased, and the heat exchange efficiency between the fluid flowing inside and the fluid flowing outside can be improved even if the window is provided to reduce the heat transfer area.
[0023]
Further, if the plate-like fin member is provided with an opening communicating with the window portion by cutting out the fluid inflow source side, the flow resistance received when fluid such as EGR gas flows into the heat transfer tube is reduced. Therefore, the fluid can smoothly flow into the heat transfer tube from the fluid supply source.
[0024]
Moreover, even when a window portion is provided on the plate-like fin member, it is possible to increase the heat transfer area by projecting the projecting pieces at regular intervals inside the window portion. The unevenness formed in the part further promotes the turbulent flow and stirring action of the fluid, and can increase the thermal conductivity of the heat transfer tube.
[0025]
The heat transfer tubes of the first and second inventions can be used for any device that exchanges heat, such as an automobile engine, an internal combustion engine, and an air conditioner. And if the heat exchanger tube of this invention is assembled | attached to the EGR gas cooling device of an engine, and another multi-tube heat exchanger, cooling of EGR gas can be performed efficiently. 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.
[0026]
Also, the heat transfer tube of the present invention may be installed in an oil cooler built in a radiator that circulates high-temperature oil inside and cools with engine cooling water, and performs excellent heat exchange and heat transfer characteristics. High oil cooler can be obtained.
[0027]
【Example】
Hereinafter, an embodiment in which the heat transfer tube of the present invention is used in an EGR gas cooling apparatus in a cooled EGR system of an automobile will be described in detail with reference to the drawings. FIG. 1 is an end view of a heat transfer tube according to the first embodiment, and fins projecting in four directions at intervals of 90 ° are disposed in a metal base tube, and a cross-shaped plate-like fin member is disposed. And the twist piece provided in the front end side of the plate-like fin member is deformed to form a close contact surface in advance, and this close contact surface is brought into surface contact with the inner peripheral surface of the raw tube. FIG. 2 shows a manufacturing process of the plate-like fin member according to the first embodiment, in which a plurality of slits are formed on the tip side of each fin of the plate-like fin member, and a twisted piece is formed by twisting between the slits. In addition, the fin shown in the lower end has shown the state before twisting. FIG. 3 is a partially cutaway plan view of FIG.
[0028]
FIG. 4 is a plan sectional view of the heat transfer tube of the second embodiment, in which a grooved slit is provided to form a twisted piece. Further, the plate-like fin member of the second embodiment is formed with a diameter so that the tip end side of the twisted piece is disposed outward from the inner peripheral surface of the raw tube before being inserted into the raw tube. When the tube is inserted and arranged, the twisted piece is deformed by the inner peripheral surface of the tube to form a close contact surface with the tube. FIG. 5 is a perspective view of the plate-like fin member showing the state before the twisted piece is formed by providing a groove-like slit and showing the manufacturing process of the plate-like fin member of the second embodiment. FIG. 6 is a perspective view of the plate-like fin member in a state where twisted pieces are formed by twisting between the slits formed in FIG. 5.
[0029]
FIG. 7 is a perspective view of the plate-like fin member before twisted piece formation in the third embodiment, and a plurality of relatively small window portions are provided on each fin. FIG. 8 is a perspective view of the plate-like fin member before the twisted piece is formed in the fourth embodiment. Each fin is provided with a plurality of windows larger than those in the third embodiment, and the projecting pieces are provided inward in each window. Projected to FIG. 9 shows a plate-like fin member before the twisted piece is formed in the fifth embodiment. Each of the fins is provided with a plurality of windows larger than those in the third embodiment, and the inflow source side of each fin is cut away. An opening that communicates with the window is provided. FIG. 10 is a schematic view of an EGR gas cooling device using the heat transfer tube of the present invention.
[0030]
The first embodiment of the present invention will be described in detail with reference to FIGS. 1 to 3, and FIG. 10. (1) is a heat transfer tube, and a thin metal element through which EGR gas can flow. Inside the pipe (2), a metal plate-like fin member (4) which is long in the axial direction of the pipe and radially protrudes the fins (3) in four directions at intervals of 90 ° from the axial center is inserted and disposed. Is formed.
[0031]
The raw tube (2) and the plate-like fin member (4) are formed using copper, aluminum, brass, stainless steel, or the like, so that the heat transfer tube has excellent thermal conductivity and corrosion resistance against EGR gas and the like. (1) can be obtained. In addition, in order to further improve the reliability of corrosion resistance, the metal material as described above is subjected to a single-layer plating treatment of zinc, copper, tin, tin-zinc alloy, nickel, zinc-nickel alloy, etc., and chromate as necessary. A coating or the like may be applied, or two or more layers of plating may be performed, such as plating the outer surface of the metal material with nickel and further plating a zinc-nickel alloy on the outer peripheral surface of the nickel. The blank tube (2) and the plate-like fin member (4) may be formed of the same metal material, and if it can be brazed or welded as described later, the purpose of use, cost, etc. Depending on the case, both may be formed of different metal materials.
[0032]
As shown in FIG. 2, the plate-like fin member (4) is long in the tube axis direction and perpendicular to both surfaces of the central portion of the wide plate member (5) elongated in the tube axis direction. A pair of narrow plate members (6) having a narrower width than (5) is connected, and fins (3) are projected in four directions at intervals of 90 °. The narrow plate member (6) is connected to the wide plate member (5) by bending one side of the narrow plate member (6) in parallel with the wide plate member (5). 5) and a flat connecting portion (8) in surface contact with each other, and as shown in FIG. 3, the connecting portion (8) of each narrow plate member (6) is brought into surface contact with the wide plate member (5). Brazing.
[0033]
Next, a plurality of slits (7) intersecting the tube axis direction are provided on the distal end side of the plate-like fin member (4) in the outer direction. FIG. 2 shows a state in which the fin (3) on the lower end side of the pair of fins (3) of the wide plate member (5) only forms the slit (7). In this embodiment, the slit (7) is cut at the distal end side of the plate-like fin member (4) so as to cross the tube axis direction, and further, at the base end of the slit (7), parallel to the tube axis direction. A short cut is made to form a T-shape. A plurality of twist pieces (10) are formed by twisting between the T-shaped slits (7) in the direction intersecting the surface of the fin (3). In the first embodiment, the slits (7) of the fins (3) are all twisted in the counterclockwise crossing direction with respect to the central axis, and the twisting directions of the fins (3) are the same direction. It is said.
[0034]
Further, when the twisted piece (10) is formed, the outer diameter of the plate-like fin member (4) is larger than the inner diameter of the raw tube (2) as shown by a two-dot chain line in FIG. In this embodiment, each of the twisted pieces (10) of the plate-like fin member (4) is then bent and deformed in the axial center direction, so that the plate-like fin member (2) inserted into the element tube (2) ( The diameter of 4) is formed to be substantially the same as the inner diameter of the raw tube (2). In addition, due to this bending deformation, the tip end surface of the twisted piece (10) arranged substantially parallel to the inner peripheral surface of the element pipe (2) becomes the contact surface (11) to the element pipe (2). The contact surface (11) is preferably curved and deformed in an arc shape corresponding to the arc-shaped inner peripheral surface of the raw tube (2). After such molding, the plate-like fin member (4) can be smoothly inserted into the blank tube (2), and after the insertion is completed, as shown in FIG. (11) is tightly fixed to the inner peripheral surface of the raw tube (2) by surface contact. By this surface contact, the plate-like fin member (4) is stably fixed in the raw tube (2).
[0035]
Further, in order to further improve the fixing property and thermal conductivity of the plate-like fin member (4) to the raw tube (2), the contact surface (11) and the inner peripheral surface of the raw tube (2) are brazed. . By this brazing, the heat conduction between the plate-like fin member (4) and the raw tube (2) is performed not only through the contact surface (11) but also through the filler fillet (not shown). Thermal conductivity can be increased. Furthermore, even if a slight gap is formed between the close contact surface (11) and the inner peripheral surface of the blank tube (2), the close contact surface is closed by a filler fillet (not shown). The heat conduction between (11) and the inner peripheral surface of the raw tube (2) is performed well. Further, it is not necessary to form the close contact surface (11) in a strictly arcuate shape so as to correspond to the inner peripheral surface of the raw tube (2), and the manufacturing work can be simplified.
[0036]
Furthermore, the close contact surface (11) and the inner peripheral surface of the raw tube (2) are firmly fixed by brazing, and the fixability of the plate-like fin member (4) can be improved. As a result, vibration and deformation of the plate-like fin member (4) due to fluid flow, heat transfer tube vibration, and the like, and flapping of the wall surface of the elementary tube (2) with which the fins (3) and fins (3) are in contact, It is possible to improve the usability and durability of the heat transfer tube (1) by suppressing the ting and the like.
[0037]
Further, at the time of brazing, before inserting the plate-like fin member (4) into the blank tube (2), at least both side edges of the plate-like fin member (4) or the close-contact surface in advance. The brazing material is plated on the entire surface of (11). Further, the plating of the brazing material is preferably performed on the entire surface of the plate-like fin member (4) because it is easy to work, or the brazing material is plated on the inner peripheral surface of the base pipe (2). Also good. Also, a brazing material is clad on the wide plate member (5) and the narrow plate member (6), which are forming materials of the plate fin member (4), and the clad material is processed to form the plate fin member (4). It may be formed.
[0038]
Further, after inserting the plate-like fin member (4) coated with the binder for adhering the brazing material on both side edges of the contact surface (11) into the raw tube (2), the powdery brazing material is put into the raw tube (2). May be supplied. As another method, a plate-like fin member (4) supplied with brazing paste on both side edges of the contact surface (11) may be inserted into the raw tube (2), or a plate-like member may be inserted into the raw tube (2). After inserting the fin member (4), a brazing paste may be supplied into the raw tube (2). And it may braze at the time of manufacture of a heat exchanger tube (1), or may braze after attaching a heat exchanger tube (1) to the below-mentioned EGR gas cooling device (20).
[0039]
In the heat transfer tube (1) formed as described above, the heat transfer area can be increased by disposing the plate-like fin member (4) provided with the fins (3) projecting in four directions from the axial center. Furthermore, the tip side of each fin (3) and the inner peripheral surface of the raw pipe (2) are brought into surface contact via the contact surface (11), not the point contact or the line contact as in the prior art, and are further brought into contact with each other. Since it is brazed, the thermal conductivity between the plate-like fin member (4) and the raw tube (2) is increased, and the heat of the EGR gas received by the plate-like fin member (4) is transferred to the raw tube (2). After efficiently transmitting, heat can be dissipated to the outside.
[0040]
In addition, due to the arrangement of the plate-like fin member (4), the internal space (12) of the heat transfer tube (1) is divided into four, and the fluid is dispersed and flows in the four divided internal spaces (12). Therefore, it is possible to prevent the uneven flow of the fluid. Further, the fluid and the heat transfer tube (1) are dispersed in the internal space (12) while flowing in contact with the surface of the plate-like fin member (4) as well as the inner peripheral surface of the raw tube (2). ) Can be efficiently conducted. Further, as shown in FIG. 3, a flow gap (13) through which fluid can pass is intermittently formed between the inner peripheral surface of the raw tube (2) and the base end of the twisted piece (10). Passes through the intersecting surface of the twisted piece (10) and the flow gap (13) and flows into the flow destination while entering and leaving the interior space (12) divided into four. Therefore, the fluid on the inner peripheral surface of the raw pipe (2) swirls and flows, and the thermal conductivity between the fluid and the raw pipe (2) can be increased by the separation of the boundary layer by the swirling flow. . By these actions, it becomes possible to efficiently exchange heat between fluids flowing inside and outside the heat transfer tube (1).
[0041]
In the first embodiment, as described above, since all the twisted pieces (10) of the fins (3) are twisted in the same direction counterclockwise, the inner peripheral surface of the raw pipe (2) The swirling direction of the fluid flowing by swirling the tip side of the fin (3) is the same, and the fluid can smoothly flow to the flow destination. In addition, twisting in the same direction facilitates the processing of the twisted piece (10), and it is not necessary to form the pair of narrow-width plate members (6) in different shapes on the left and right, and the same one should be used. Therefore, the productivity of the plate-like fin member (4) can be improved.
[0042]
The EGR gas cooling device (20) assembled with the heat transfer tube (1) as described above has a pair of tube sheets (22) connected to both ends of a cylindrical body tube (21) as shown in FIG. The inside can be sealed. And between the pair of tube sheets (22), a plurality of heat transfer tubes (1) of the present embodiment are connected and arranged through the tube sheet (22). A bonnet (26) having an EGR gas inlet (24) and an outlet (25) is connected to both ends of the trunk pipe (21).
[0043]
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. Further, a plurality of support plates (30) are joined and arranged in the heat exchange section (23), and the heat transfer tube (1) is inserted into the insertion hole (29) provided in the support plate (30). The heat transfer tube (1) is stably supported as a baffle plate, and the flow of the cooling medium flowing in the heat exchanging portion (23) is meandered.
[0044]
In the EGR gas cooling device (20), when high-temperature EGR gas is introduced into the trunk pipe (21) from the inlet (24), a plurality of EGR gases are arranged in the trunk pipe (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. Thus, heat exchange is performed between the EGR gas and the cooling medium.
[0045]
As described above, the heat transfer tube (1) increases the heat transfer area by arranging the plate-like fin member (4), thereby increasing the contact frequency with the EGR gas, and the plate-like fin member (4). The pipe (2) is brought into surface contact to increase thermal conductivity. Therefore, not only the heat of the EGR gas on the inner peripheral surface side of the raw pipe (2) but also the heat of the EGR gas flowing in the vicinity of the center is affected by the inner circumference of the raw pipe (2) via the plate-like fin member (4). After the heat is efficiently transferred to the surface, the heat is radiated to the cooling medium through the outer peripheral surface of the base tube (2). Then, the entire EGR gas is uniformly cooled without unevenness, and an excellent cooling effect on the EGR gas can be obtained.
[0046]
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 generation of a swirling flow of EGR gas in the heat transfer tube (1) and the turbulent flow promote the separation of soot mixed in the EGR gas and prevent it from becoming a large lump. It is also possible to prevent deterioration of cooling performance and engine trouble caused by the engine.
[0047]
Further, in the first embodiment, when the plate-like fin member (4) is inserted into the raw pipe (2), as described above, the twisted piece (10) is inserted in advance before being inserted into the raw pipe (2). ) Is bent and deformed in the axial center direction to form a close contact surface (11) to the inner peripheral surface of the tube (2). In the second embodiment shown in FIGS. The plate-like fin member (4) is formed with such a diameter that the piece (10) is not bent and deformed, and the distal end side of the twisted piece (10) is arranged outward from the inner peripheral surface of the blank tube (2). The twisted piece (10) is deformed to form the contact surface (11) when inserted into the raw tube (2).
[0048]
In the manufacturing process, when the plate-like fin member (4) is first formed, the second embodiment uses only the wide plate member (5) as shown in FIG. It is set as the simple plate-shaped fin member (4) set to (3). Next, a plurality of slits (7) are formed at intervals in each fin (3). In the first embodiment, the slit (7) of the plate-like fin member (4) is T-shaped on the fin (3). In contrast to this, in the second embodiment, as shown in FIG. 5, the tip side of the fin (3) is cut into a concave groove shape to provide a slit (7). In the groove-shaped slit (7) as in the second embodiment, the base end portion of the twist piece (10) is smooth.
[0049]
Then, by twisting the groove-like slits (7) counterclockwise in a direction substantially intersecting the surface of the fin (3), as shown in FIG. 6, the outward direction of the plate-like fin member (4) is obtained. A plurality of twisted pieces (10) are formed on the distal end side. In the second embodiment, the twisted piece (10) is not formed into a shape corresponding to the inner peripheral surface of the raw pipe (2) before being inserted into the raw pipe (2). In the plate-like fin member (4) before insertion of the plate-like fin member (4), the outer diameter of the plate-like fin member (4) is larger than the inner diameter of the raw tube (2), as shown by a two-dot chain line in FIG. When the plate-like fin member (4) is inserted into the raw pipe (2) having a smaller diameter than the outer diameter, the plate-like fin member (4) is pressed against the inner peripheral surface of the raw pipe (2) to have a shape corresponding to the inner peripheral face. By deforming the twisted piece (10), as shown on the right side of FIG. 4, a close contact surface (11) is formed on the distal end side of the twisted piece (10) that can come into surface contact with the inner peripheral surface of the raw tube (2). The After the insertion into the tube (2), the elastic restoring force to the outside of the contact surface (11) acts, and the contact surface (11) corresponds to the inner peripheral surface of the tube (2). In this way, good thermal conductivity between the raw tube (2) and the plate-like fin member (4) is maintained, and the plate-like fin member (4) in the raw tube (2) is maintained. Fixability is improved and further stable.
[0050]
In the heat transfer tube (1) of the second embodiment formed as described above, the heat transfer area of the heat transfer tube (1) can be increased by arranging the plate-like fin member (4). The heat of EGR gas can be efficiently transferred not only to the inner peripheral surface of the raw tube (2) but also to the plate-like fin member (4). Furthermore, since the contact surface (11) of the twisted piece (10) provided in the outward direction of the plate-like fin member (4) is in close contact with the inner peripheral surface of the raw tube (2) and is in close contact. The heat received by the plate-like fin member (4) can be efficiently transferred to the inner peripheral surface of the base tube (2), and the EGR gas flowing inside and outside the heat transfer tube (1) and the cooling medium Heat exchange can be performed efficiently.
[0051]
And, as in the first embodiment, the manufacturing means for forming the twisted piece (10) into a shape corresponding to the inner peripheral surface of the raw pipe (2) before insertion into the raw pipe (2) is made of a hard metal. This is effective when a material is used or a metal material is thick and it is difficult to deform the twisted piece (10) on the inner peripheral surface of the base tube (2). Further, as in the second embodiment, the twisted piece (10) is not formed into a shape corresponding to the inner peripheral surface of the blank (2) before being inserted into the blank (2). The manufacturing means for forming the contact surface (11) by deforming the twisted piece (10) on the inner peripheral surface of the base tube (2) during insertion into the tube uses a relatively soft metal material, It is effective when it is thin and the twisted piece (10) can be easily deformed on the inner peripheral surface of the base tube (2).
[0052]
Moreover, in the said 1st, 2nd Example, although it twists in the same direction which makes the twist direction of the twist piece (10) counterclockwise for every fin (3), as another different Example, it adjoins. The twisted pieces (10) may be formed by twisting one of the fins (3) or the fins (3) that are symmetric with respect to the tube axis by twisting one counterclockwise and the other twisting clockwise. Alternatively, the twist pieces (10) may be formed by alternately twisting clockwise and counterclockwise between the slits (7) of one fin (3). By changing the twist direction of the twist piece (10) in this way, turbulence of the fluid flowing inside can be promoted.
[0053]
In the first and second embodiments, the fins (3) of the plate-like fin member (4) are not provided with any windows, openings, irregularities, or the like. As shown in FIG. 7, by using the wide plate member (5), a plate-like fin member (4) projecting the fin (3) in two directions through a 180 ° interval is formed, and a fluid is applied to each fin (3). A plurality of small windows (14) through which can pass is opened. By providing such a window (14), the EGR gas flowing in the internal space (12) of the heat transfer tube (1) flows to the flow destination while passing through the plurality of windows (14). The meandering and turbulence of the EGR gas are promoted.
[0054]
In addition, the EGR gas flow distance in the heat transfer tube (1) is increased, the contact time with the inner peripheral surface of the base tube (2) and the surface of the plate-like fin member (4) is increased, and the EGR gas is As a result of stirring, not only a part of the EGR gas but the whole is repeatedly brought into contact with the raw tube (2) and the plate-like fin member (4). As a result, the heat of the EGR gas can be efficiently transferred to the heat transfer tube (1), and this heat is dissipated to the cooling medium through the outer surface of the heat transfer tube (1), thereby improving the heat exchange performance. High EGR gas cooling is possible.
[0055]
In another different fourth embodiment, as shown in FIG. 8, a plurality of relatively large windows (14) are opened in each fin (3) as compared to the third embodiment. By providing such a large window (14), a lighter plate-like fin member (4) can be obtained. Accordingly, it is possible to reduce the weight of the heat transfer tube (1) and the EGR gas cooling device (20) using the heat transfer tube (1). Although the heat transfer area may be reduced by providing a large window (14), the area of the inner peripheral surface of the window (14) can be used as the heat transfer surface. Further, in this embodiment, since a plurality of projecting pieces (15) are formed at predetermined intervals in each window portion (14), the heat transfer area of the heat transfer tube (1) is increased as compared with the conventional case. I can do things.
[0056]
Also, in the heat transfer tube (1) of the fourth embodiment, the fluid flows while largely meandering in the internal space (12) due to the formation of the large window (14). Furthermore, in the fourth embodiment, since the projections (15) are provided, the windows (14) are uneven, so that the turbulent flow and the stirring action of the meandering fluid can be promoted. It becomes. Therefore, the contact frequency between the plate-like fin member (4) and the fluid is increased, and the heat transfer tube (1) capable of efficiently performing heat exchange between the EGR gas and the cooling medium can be obtained.
[0057]
Moreover, in the said 3rd, 4th Example, although the plate-shaped fin member (4) does not provide an opening part in the inflow origin side of EGR gas, and makes the front end surface smooth, 5th shown in FIG. In the embodiment, a plurality of relatively large windows (14) are opened in each fin (3) of the plate-like fin member (4), and the EGR gas inflow source side of each fin (3) is cut out. An opening (16) communicating with the window (14) on the inflow source side is provided.
[0058]
Thus, by providing the opening (16) communicating with the window (14) on the EGR gas inflow source side of each fin (3), the flow when the EGR gas flows into the heat transfer tube (1) is provided. The resistance can be reduced, and the EGR gas can flow smoothly from the EGR gas inlet (24) into the heat transfer tube (1).
[0059]
When the heat transfer tube (1) is formed using the plate-like fin members (4) of the third to fifth embodiments, the twisted piece (10) is preliminarily placed in the raw tube (2) as in the first embodiment. ) Is formed into a shape corresponding to the inner peripheral surface of the substrate, and a close contact surface (11) is provided to form a plate-like fin member (4), and this plate-like fin member (4) is inserted into the raw tube (2). It may be formed by production means. Further, as in the second embodiment, the twisted piece (10) is not previously formed into a shape corresponding to the inner peripheral surface of the element tube (2), and is inserted into the element tube (2) before being inserted into the element tube (2). The plate-like fin member (4) is formed with a diameter larger than the inner diameter of the inner tube (2), and the twisted piece (10) is placed on the inner peripheral surface of the elementary tube (2) when inserted into the elementary tube (2). The contact surface (11) may be formed by being deformed, and may be formed by a manufacturing means that is in close contact with the inner peripheral surface of the base tube (2).
[0060]
Moreover, in the said 2nd-5th Example, the plate-shaped fin member (4) is formed only by the wide-width plate member (5), and the both ends of a 180 degree direction are made into the fin (3), Other different Example As in the first embodiment, a wide plate member (5) and a pair of narrow plate members (6) are formed, and the fins (3) are projected in four directions at 90 ° intervals, and the cross-sectional shape is a cross shape. A plate-like fin member (4) may be used.
[0061]
As another different embodiment, the plate-like fin member (4) of the first to fifth embodiments may be formed by projecting the fin (3) in six directions at intervals of 60 °, or at a narrower interval. You may form the plate-shaped fin member (4) which protruded many fins (3). As a further different embodiment, the interval between the adjacent fins (3) may be projected through different intervals.
[0062]
In each of the above embodiments, the EGR gas cooling device (20) is described as being assembled with the heat transfer tube (1) of the present invention. However, the heat transfer tube of the present invention is applied to another different multi-tube heat exchanger. A heat tube (1) may be used, and excellent heat exchange performance can be obtained. In addition, a heat transfer tube (1) of the present invention is used in a built-in oil cooler for a radiator that circulates high-temperature oil such as engine oil, mission oil, ATF, and power steering oil and cools the high-temperature oil with engine cooling water. ) Can also be assembled. And through the heat transfer pipe (1) having a large heat transfer area and high heat conductivity of the present invention, the engine cooling water flowing in the heat transfer pipe (1) and the oil to be cooled flowing in the outside of the heat transfer pipe (1) Heat exchange with the oil is promoted, and the oil to be cooled can be cooled uniformly and efficiently.
[0063]
【The invention's effect】
The present invention is configured as described above, and a metal plate-like fin member having fins protruding in at least two directions from the axial center of the element tube is disposed in the metal element tube having excellent heat conductivity. As a result, the heat transfer area of the heat transfer tube can be increased. Further, a twisted piece is provided in the distal direction of the plate-like fin member, and the contact surface provided at the tip of the twisted piece is brought into surface contact with the inner peripheral surface of the elementary pipe. The conductivity can be increased. In addition, the fluid flowing inside the heat transfer tube flows to the flow destination along the intersecting surfaces of the twisted pieces, thereby causing the fluid to swirl or turbulently flow, peel off the boundary layer, and The thermal conductivity with the tube can be further increased. Therefore, the heat exchange performance of the heat transfer tube is improved, and the heat exchange between the fluids flowing inside and outside the heat transfer tube can be performed efficiently.
[0064]
In addition, the surface contact between the raw pipe and the plate-like fin member improves the fixability of the plate-like fin member in the raw pipe, and prevents the fin from being bent or deformed due to fluid flow or heat transfer pipe vibration. . Further, fretting of the fins and the wall surfaces of the raw pipes that are in contact with the fins can be prevented, heat exchange can be performed smoothly, and the durability of the heat transfer tubes is improved. And by using this heat transfer tube excellent in heat exchange performance for a multi-tube heat exchanger, a radiator built-in oil cooler, etc., a product with high heat transfer characteristics can be obtained.
[Brief description of the drawings]
FIG. 1 is an end view showing a heat transfer tube according to a first embodiment of the present invention.
FIG. 2 is a plan view showing a manufacturing process of the plate-like fin member of the first embodiment.
FIG. 3 is a partially cutaway plan view of FIG. 1;
FIG. 4 is a cross-sectional view showing a manufacturing process of a heat transfer tube of a second embodiment.
FIG. 5 is a perspective view of the manufacturing process of the plate-like fin member according to the second embodiment, showing a state in which a groove-like slit is formed.
FIG. 6 is a perspective view of the manufacturing process of the plate-like fin member according to the second embodiment, showing a state in which twisted pieces are formed by twisting the slits in the crossing direction.
FIG. 7 is a perspective view showing a plate-like fin member according to a third embodiment.
FIG. 8 is a perspective view showing a plate-like fin member according to a fourth embodiment.
FIG. 9 is a perspective view showing a plate-like fin member of a fifth embodiment.
FIG. 10 is a partially cutaway plan view of an EGR gas cooling apparatus in which the heat transfer tube of the present invention is assembled.
[Explanation of symbols]
2 Elementary tube
3 Fin
4 Plate-shaped fin member
7 Slit
10 Twisted pieces
11 Contact surface
14 windows
15 Projection

Claims (4)

A metal plate-like fin member to be inserted and disposed in the metal base tube is formed by extending the fin in the tube axis direction and projecting the fin in at least two directions from the axial center portion. A plurality of slits intersecting the tube axis direction are provided on the distal end side, and a twisted piece is formed by twisting between the slits in the direction intersecting the surface of the fin, and this twisted piece is formed as a part of the inner peripheral surface of the raw tube A heat transfer tube with a fin member, which is characterized by having a close contact surface provided on the tip end side of the twisted piece in surface contact with the inner peripheral surface of the base tube and fixing it closely by adopting a corresponding shape. A metal plate-like fin member to be inserted and disposed in the metal base tube is formed by extending the fin in the tube axis direction and projecting the fin in at least two directions from the axial center portion. A plurality of slits intersecting the tube axis direction are provided on the distal end side, and twisted pieces are formed by twisting between the slits in the intersecting direction with the surface of the fin, and before the plate-like fin member is inserted into the raw tube. The plate-shaped fin member is formed with such a diameter that the distal end side of the twisted piece is arranged outward from the inner peripheral surface of the raw tube, and when the plate-like fin member is inserted into the raw tube, the twisted piece Is characterized by the fact that the contact surface formed on the tip side of the twisted piece is closely fixed to the inner peripheral surface of the raw tube by deforming in the axial center direction corresponding to a part of the inner peripheral surface of the raw tube. Heat transfer tube with an internal fin member. The plate-like fin member is provided with at least one window portion through which a fluid flowing in the raw tube can pass. 4. The heat transfer tube with the fin member according to claim 3, wherein the window part has protruding pieces protruding at regular intervals.

Images