JP2016133249A - Heat exchanging tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a failure in brazing a fin due to a projection in a heat exchanging tube having the projection.SOLUTION: In a tube inner wall surface 14 of the heat exchanging tube 10, a recess 16 recessed inside of the projection 15 is provided so as to face the fin 40 and a solder filling groove 17 recessed so as to introduce a brazing material that is melt in brazing the fin 40 is provided lateral of the recess 16.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a heat exchange tube through which a fluid for heat exchange flows.

  Patent Document 1 discloses an EGR cooler in which heat is exchanged between engine exhaust gas (fluid) and cooling water (medium).

  The EGR cooler includes a square cylindrical shell, and a flat cylindrical tube (heat exchange tube) is stacked and accommodated inside the shell. An inner fin for guiding exhaust gas is accommodated in the tube.

  The inner fin is joined into the tube by brazing. A bead that is recessed in a narrow groove shape is formed on the inner wall surface of the tube. When the tube is brazed, the molten brazing material spreads along the bead, and the inner fin is joined by the brazing material in the bead.

JP 2013-113243 A

  The tube used in the EGR cooler has a protrusion that protrudes from the outer wall surface of the tube, and the protrusion abuts on an adjacent tube or shell, thereby forming a gap (flow path) through which cooling water flows around the tube. There is something. On the inner wall surface of the tube having the protrusions, a recess that is recessed inside the protrusion opens to the inner wall surface of the tube.

  However, in the tube having the above-mentioned protrusion, the brazing material melted during brazing of the inner fin is blocked by the recess from spreading to the inner wall surface of the tube along the bead. There is a problem that a defective part occurs.

  The present invention has been made in view of the above problems, and an object of the present invention is to prevent fin brazing defects caused by protrusions in a heat exchange tube having protrusions.

  According to an aspect of the present invention, there is provided a heat exchange tube through which a fluid that exchanges heat flows, and includes a tube inner wall surface to which a fin that guides the fluid is joined by brazing, and a tube outer wall surface from which a protrusion protrudes. On the inner wall surface of the tube, a recess recessed inside the projection is provided opposite to the fin, and a wax filling groove recessed so as to guide the molten brazing material when the fin is brazed is provided on the side of the recess. A heat exchange tube is provided.

  According to the above aspect, the brazing material melted during brazing of the fin is guided to the side of the recess by the brazing filler groove, and is filled between the inner wall surface of the tube and the fin from the brazing filler groove. Thereby, between the tube inner wall surface and the fin, the brazing material is sufficiently filled also around the concave portion, and welding by brazing the fin is performed well.

It is sectional drawing which shows the EGR cooler which concerns on embodiment of this invention. It is sectional drawing which follows the II-II line of FIG. It is a perspective view which shows the inside of a heat exchange tube. It is a perspective view which shows the inside of the heat exchange tube which concerns on a comparative example.

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

  An EGR cooler 1 shown in FIG. 1 is a heat exchanger used in an EGR (Exhaust Gas Recirculation) system of an automobile. The EGR system (not shown) includes an EGR passage that recirculates part of the exhaust gas from the exhaust passage of the internal combustion engine to the intake passage as EGR gas, and the EGR cooler 1 is interposed in the EGR passage. In the internal combustion engine, EGR gas (heat exchange fluid) is cooled by the EGR cooler 1, and the cooled EGR gas is recirculated to the intake passage.

  FIG. 1 is a cross-sectional view showing an EGR cooler 1 according to the present embodiment. The EGR cooler 1 includes a square-shaped shell 2 having a substantially rectangular cross section, and a plurality of heat exchange tubes 10 (hereinafter simply referred to as “tubes 10”) accommodated in the shell 2 in a stacked manner. Is provided.

  A medium flow path 3 is formed between the tube 2 and the tube 10. The shell 2 is connected to a cooling passage through an introduction pipe (not shown) and a discharge pipe (not shown). Thereby, in the EGR cooler 1, the coolant (medium) of the internal combustion engine guided through the piping of the cooling passage circulates through the medium flow path 3 in the shell 2.

  The tube 10 is formed in a flat cylindrical shape, and a heat exchange channel 11 is formed therein. Both open ends (not shown) of the tubes 10 are opened side by side inside the open ends (not shown) of the shell 2. Headers (not shown) are coupled to both open ends of the shell 2, and ducts (not shown) of EGR passages are connected to the headers. As a result, in the EGR cooler 1, the EGR gas guided through the duct flows through the heat exchange flow path 11 in each tube 10.

  The tube 10 is formed into a flat cylindrical shape by connecting the pair of plates 12 to each other. The plate 12 is formed in a semi-cylindrical shape by pressing a metal plate.

  A plurality of protrusions 15 protruding from the tube outer wall surface 13 are formed on the plate 12 by pressing. A gap 30 of the medium flow path 3 is formed between each adjacent tube 10 and each tube outer wall surface 13 when the protrusions 15 abut each other.

  A plurality of protrusions 25 protruding from the inner wall surface 24 of the tube are formed on the shell 2 by pressing. The protrusion 25 of the shell 2 and the protrusion 15 of the tube 10 abut each other, whereby a gap 31 of the medium flow path 3 is formed between the tube inner wall surface 24 of the shell 2 and the tube outer wall surface 13 of the tube 10.

  Thus, each protrusion 15 of the tube 10 contacts the tube 10 or the shell 2 as a counterpart member to position the tube 10.

  Inside the tube 10, fins 40 that guide EGR gas are interposed. In the EGR cooler 1, the heat transfer area of the EGR gas flowing through the heat exchange flow path 11 is secured by the fins 40.

  The fin 40 is formed in a corrugated plate shape by pressing a metal plate. The fin 40 has a fin top portion 41 bent in a mountain shape, and the fin top portion 41 is joined to the tube inner wall surface 14 of the shell 2 by brazing. The fin top portion 41 extends linearly along the flow direction of the EGR gas.

  As shown in FIG. 2, a concave portion 16 that is recessed in a concave shape opens in the tube inner wall surface 14 of the plate 12. The circular recess 16 is recessed in a concave shape with respect to the inner wall surface 14 of the tube and is disposed so as to face the fins 40.

  On the tube inner wall surface 14 of the plate 12, four row filling grooves 17 that are recessed in a shallow groove shape are opened. The wax filling groove 17 is recessed so as to have a step 18 (side wall surface) on the tube inner wall surface 14 of the plate 12, and is disposed so as to face the fins 40. The wax filling groove 17 has a triangular cross-sectional shape. The cross-sectional shape of the wax filling groove 17 is not limited to a triangle, and may be a trapezoid.

  The depth G17 of the wax filling groove 17 is set to a predetermined value smaller than the depth G16 of the recess 16 (see FIG. 2). Thereby, at the time of brazing, the melted brazing material spreads along the brazing filling groove 17 and the brazing material is guided to the side of the recess 16.

  FIG. 3 is a perspective view showing the inside of the tube 10. The four wax filling grooves 17 are formed so as to extend to the side of the concave portion 16 and to extend in a direction intersecting the fin top portion 41 at a position close to the concave portion 16 while avoiding the concave portion 16.

  The four wax filling grooves 17 are arranged so as to surround a portion 14D where one concave portion 16 opens. The pair of wax filling grooves 17 disposed on the sides of the recess 16 are formed so as to intersect with each other at positions close to the recess 16 and extend along two straight lines that intersect with the recess 16 as a center. . As a result, a diamond-shaped portion 14 </ b> D surrounded by the four wax filling grooves 17 is formed on the tube inner wall surface 14 of the plate 12. The recess 16 is open to the trapezoidal portion 14D.

  When the EGR cooler 1 is manufactured, an assembly process for assembling the members and a brazing process for joining the members by brazing are sequentially performed.

  In the assembly process, the tubes 10 are assembled with the fins 40 interposed between the plates 12, and the assembled tubes 10 are assembled in the shell 2. At this time, the brazing material is applied to a predetermined portion of the tube inner wall surface 14 of the plate 12, and the brazing material is applied to a joint portion of the mating plate 12 and the shell 2.

  In the brazing process, the assembly assembled as described above is conveyed to a furnace (not shown) and subjected to heat treatment. Thereby, the junction part of the plate 12, the fin 40, and the shell 2 is joined via a brazing material.

  FIG. 3 shows how the brazing material is guided by the brazing groove 17 in the brazing process. In the brazing process, when the brazing material applied to the region 14C away from the recess 16 in the tube inner wall surface 14 of the plate 12 is melted, the molten brazing material is brazed filling grooves as indicated by arrows A, B, C, and D. 17 is guided along the bottom wall surface 18 of the recess 17 and extends to the side regions 14A and 14B of the recess 16. In addition, the brazing material that has spread in the side region 14A of the recess 16 on the tube inner wall surface 14 of the plate 12 is along the two wax filling grooves 17 as shown by arrows E and F, and the side region 14B on the opposite side of the recess 16. To spread. Thus, the brazing material applied to the region 14C is guided to the side region 14B by the brazing groove 17 and is filled between the plate 12 and the fin top portion 41, so that the side regions 14A and 14B sandwiching the recess 16 are sandwiched. In both cases, the fin 40 is brazed well. Since the melted brazing material is also filled between the solder filling groove 17 and the fin top 41 by surface tension, the fin 40 is brazed well even at the portion where the solder filling groove 17 is opened.

  In the present embodiment, the plate 12 is configured such that the brazing material is applied to the predetermined region 14C. However, the present invention is not limited to this, and a clad material in which the brazing material is laminated in advance may be used.

  FIG. 4 shows a comparative example in which the wax filling groove 17 is not formed on the tube inner wall surface 14 of the plate 12. In this case, in the brazing process, since the flow of the molten brazing material is blocked by the concave portion 16, the brazing material is not guided from the side region 14A of the concave portion 16 to the side region 14B opposite to the concave portion 16, and the region 14B. The part where the brazing of the fin 40 is poor occurs.

  Next, the effect of this embodiment will be described.

  According to this embodiment, the heat exchange tube 10 has the tube inner wall surface 14 to which the fin 40 is joined by brazing, and the tube outer wall surface 13 from which the protrusion 15 protrudes. The tube inner wall surface 14 is provided with a recess 16 that is recessed inside the protrusion 15 so as to face the fin 40, and a wax filling groove 17 that is recessed so as to guide the brazing material melted when the fin 40 is brazed. It is provided on the side of

  Based on the above configuration, the brazing material melted at the time of brazing the fin 40 is guided along the side of the recess 16 to the brazing filler groove 17 and filled between the tube inner wall surface 14 and the fin 40 from the brazing filler groove 17. The As a result, the brazing material is sufficiently filled around the recess 16 between the tube inner wall surface 14 and the fin 40, and welding by brazing the fin 40 is performed well.

  Furthermore, according to the present embodiment, a small amount of brazing material is applied to the inner wall surface 14 of the tube, so that welding by brazing the inner wall surface 14 of the tube and the fins 40 is favorably performed. Thereby, the usage-amount of the brazing material in the heat exchange tube 10 is reduced, and the cost reduction of the EGR cooler 1 is achieved.

  According to the present embodiment, the wax filling groove 17 extends so as to intersect with the fin 40 facing the recess 16.

  Based on the above configuration, the brazing material melted during brazing is guided around the recess 16 along the solder filling groove 17 from the recess 14 and the region 14B away from the fin 40, and the fin 40 is brazed well. .

  According to this embodiment, the four row filling grooves 17 are configured to extend so as to surround the portion 14D where the recess 16 opens.

  Based on the above configuration, the brazing material melted at the time of brazing spreads from the wax filling groove 17 to the portion 14D where the concave portion 16 is opened, and the fin 40 is brazed well in the vicinity of the concave portion 16.

  In addition to the above-described configuration, according to the present embodiment, five or more wax filling grooves 17 may be configured to extend radially around the vicinity of the recess 16. In this case, the brazing material melted at the time of brazing is guided around the recess 16 from a wider range, and welding by brazing the fins 40 is performed well.

  The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

  The present invention is suitable as a heat exchange tube for an EGR cooler mounted on a vehicle, but a heat exchanger such as a radiator, an oil cooler, an intercooler, or a condenser mounted on the vehicle, or a heat exchanger used other than the vehicle. It can also be applied to.

DESCRIPTION OF SYMBOLS 10 Heat exchange tube 13 Tube outer wall surface 14 Tube inner wall surface 14D The part which a recessed part opens 15 Protrusion 16 Recessed part 17 Row filling groove 18 Bottom wall surface 40 Fin

Claims (3)

A heat exchange tube through which a fluid for heat exchange flows,
A tube inner wall surface where fins for guiding fluid are joined by brazing;
A tube outer wall surface from which the protrusion protrudes,
The tube inner wall is provided with a recess recessed inside the projection so as to face the fin, and a wax filling groove recessed so as to guide the molten brazing material when the fin is brazed is provided on the side of the recess. The heat exchange tube characterized by being provided in the direction. The heat exchange tube according to claim 1,
The heat exchange tube, wherein the wax filling groove extends across the fin facing the concave portion. The heat exchange tube according to claim 1 or 2,
The heat exchange tube, wherein the plurality of wax filling grooves extend so as to surround a portion where the concave portion is opened.

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