JP2014112013A - Exhaust gas heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas heat exchanger capable of reducing a risk of corrosion by sulfuric acid included in condensate water of an exhaust gas while suppressing increase in cost, improving brazing property, and reducing concentration of stress on a joining portion.SOLUTION: In an exhaust gas heat exchanger 1, an outer case 2 accommodating a heat transfer pipe aggregate 7, is formed by joining a cooling medium circulating portion formation part 3, an exhaust gas lead-in portion 4, and an exhaust gas lead-out portion 5, a first joining portion 61 as a joining portion of the heat transfer pipe aggregate 7 and the exhaust gas lead-in portion 4 is shifted to a downstream side in the exhaust gas flowing direction, with respect to a third joining portion 63 as a joining portion of the cooling medium circulating portion formation part 3 and the exhaust gas lead-in portion 4, and a second joining portion 62 as a joining portion of the heat transfer pipe aggregate 7 and the exhaust gas lead-out portion 5, is shifted to an upstream side in the exhaust gas flowing direction, with respect to a fourth joining portion 64 as a joining portion of the cooling medium circulating portion formation part 3 and the exhaust gas lead-out portion 5.

Description

  The present invention relates to an exhaust gas heat exchanger that cools exhaust gas using a cooling medium such as water, and more particularly to an exhaust gas recirculation (EGR) having a so-called header plateless structure that does not use a header plate. The present invention relates to an exhaust gas heat exchanger suitable for a heat exchanger.

  Conventionally, in order to improve assembly workability and improve productivity, a plurality of heat transfer tubes whose both ends are expanded are stacked, and the heat transfer tubes are joined to each other at both ends to form a stack of heat transfer tubes. And forming the header plate (tube) by partitioning the outer peripheral surface of both end portions of the laminate to the inner peripheral surface of the outer case, thereby partitioning the exhaust gas flow path and the cooling medium flow path at the joint portion. A heat exchanger for EGR having a so-called header plateless structure in which no sheet is used is known (see, for example, Patent Documents 1 and 2).

JP 2007-225190 A JP 2011-2133 A

  The heat exchanger for EGR described in Patent Document 1 has an exhaust gas inlet and an exhaust gas outlet integrally formed in an outer case. However, sulfur such as exhaust gas of an internal combustion engine using gasoline with a low degree of purification is used. In the case of exhaust gas containing a large amount of oxide, the exhaust gas introduction part and the exhaust gas lead-out part, which are parts that come into contact with the condensed water in the outer case, are corroded by sulfuric acid contained in the condensed water generated by cooling the exhaust gas. There was a fear. In order to prevent such corrosion, the outer case is formed of a material having high corrosion resistance against sulfuric acid, such as high nickel high chromium high molybdenum steel called super SUS (super stainless steel). There was a problem.

  Further, as shown in FIG. 11, the problem is that the exhaust gas introduction part 104 and the exhaust gas lead-out part (not shown) are connected to a cooling medium circulation part forming part 102 that forms a part through which the cooling medium of the outer case circulates. May occur even in a separate EGR heat exchanger. In the EGR heat exchanger shown in FIG. 11, the outer peripheral surface of the exhaust gas introducing portion 104 is joined to the inner peripheral surface of the inlet side end portion 102 a of the cooling medium flow portion forming portion 102 and more than the exhaust gas introducing portion 104. The outer peripheral surface of the inlet side end portion 107a of the heat transfer tube laminated body 107 was joined at an interval on the downstream side. Although not shown, the outlet side end portion of the cooling medium circulation portion forming portion 102 has the same structure. Therefore, since there is a portion 103 that contacts the exhaust gas and the condensed water on the inner surface of the cooling medium circulation portion forming portion 102, there is a risk of corrosion due to sulfuric acid. To avoid this, the cooling medium circulation portion forming portion 102 is provided. If the material is made of a material having high corrosion resistance to sulfuric acid, there is a problem that the cost increases.

  Further, the EGR heat exchanger described in Patent Document 2 includes a cooling medium tank portion corresponding to the cooling medium circulation portion forming portion and a gas tank portion corresponding to the exhaust gas introducing portion and the exhaust gas outlet portion as separate bodies. However, the cooling medium tank part, the gas tank part, and the tube expansion part are overlapped and joined in triplicate, and the partition part that is the boundary between the gas tank part and the cooling medium tank part is connected to the gas tank part or the cooling medium over the entire circumference. The heat distortion generated in the partition portion was reduced by forming the portion at least twice as thick as the thickness of the tank portion (see summary).

  However, when brazing the coolant tank part, the gas tank part, and the tube extension part in triplicate, by molding both sides of the same part of the gas tank part with high dimensional accuracy, it is suitable for brazing on each side However, it is difficult to obtain high dimensional accuracy on both sides of the same portion of the gas tank portion that is usually formed by press working. For this reason, the clearance management is not easy, and there is a possibility of causing a brazing defect. In addition, since the cross-sectional shape suddenly changes from a thin single part to a thick triple part in the partition part (joint part) (see FIG. 5 of the same document), stress due to vehicle vibration or the like concentrates on the joint part and joins. There was a risk that the part would break.

  In addition, patent document 2 does not mention at all about the problem of the corrosion by the sulfuric acid contained in the condensed water of exhaust gas.

  The present invention solves the above-mentioned problems, can reduce the risk of corrosion due to sulfuric acid contained in the condensed water of the exhaust gas while suppressing an increase in cost, and can improve brazing properties, It is an object of the present invention to provide an exhaust gas heat exchanger that can relieve stress concentration on a joint.

  The exhaust gas heat exchanger of the present invention is formed by assembling a plurality of heat transfer tubes through which exhaust gas flows, the exhaust gas inlet of each heat transfer tube is opened at one end, and the exhaust of each heat transfer tube at the other end A heat transfer tube assembly in which a gas outlet is opened; and an outer case that accommodates the heat transfer tube assembly; and an outer peripheral surface of the one end portion and the other end portion of the heat transfer tube assembly is defined as an inner periphery of the outer case. Exhaust gas heat exchange in which the inside of the outer case is divided into an exhaust gas circulation part through which exhaust gas circulates and a cooling medium circulation part through which a cooling medium for cooling the exhaust gas circulates by joining to a surface In the apparatus, the outer case is formed with an inlet for the cooling medium and an outlet for the cooling medium so as to surround the cooling medium circulation part, and an exhaust gas inlet is formed to form the exhaust gas circulation. Heat transfer of the part An exhaust gas introduction part that surrounds the upstream side of the assembly, and an exhaust gas lead-out part that is formed with an exhaust gas outlet and surrounds the downstream side of the heat transfer tube assembly of the exhaust gas circulation part. The exhaust gas introduction part is joined to one end part of the medium circulation part forming part, and the exhaust gas outlet part is joined to the other end part of the cooling medium circulation part formation part, and the heat transfer tube assembly The outer peripheral surface of the one end is joined to the inner peripheral surface of the exhaust gas introducing portion to form a first joint portion, and the outer peripheral surface of the other end portion of the heat transfer tube assembly is the exhaust gas. By joining to the inner peripheral surface of the lead-out portion, a second joint portion is formed, and the inner peripheral surface of the one end portion of the cooling medium circulation portion forming portion is joined to the outer peripheral surface of the exhaust gas introducing portion. A third joint portion is formed, and the cooling medium circulation portion The inner peripheral surface of the other end portion of the forming portion is joined to the outer peripheral surface of the exhaust gas lead-out portion, whereby a fourth joint portion is formed, and the first joint portion is the third joint. And the second joint portion is disposed to be shifted to the upstream side or the downstream side with respect to the fourth joint portion. It is characterized by.

  According to this, the cooling medium circulation portion forming portion has an inner peripheral surface at one end joined to the outer peripheral surface of the exhaust gas introduction portion, and an inner peripheral surface at the other end joined to the outer peripheral surface of the exhaust gas outlet portion. Yes. In the heat transfer tube assembly, the outer peripheral surface of one end is joined to the inner peripheral surface of the exhaust gas introducing portion, and the outer peripheral surface of the other end is joined to the inner peripheral surface of the exhaust gas outlet portion. Therefore, the exhaust gas introduced into the exhaust gas introduction part enters each heat transfer tube of the heat transfer tube assembly from the exhaust gas introduction part without touching the cooling medium circulation part forming part, and passes through each heat transfer pipe to exhaust gas. It flows out into the lead-out part and flows out from the exhaust gas lead-out part. For this reason, the exhaust gas introduction part, the exhaust gas lead-out part, and each heat transfer tube are formed of a material having high corrosion resistance to sulfuric acid, while the cooling medium flow part forming part may be formed of a material having low corrosion resistance to sulfuric acid. It is possible to reduce the risk of corrosion due to sulfuric acid contained in the condensed water of the exhaust gas while suppressing an increase in cost.

  And the 1st junction part which is a junction part of a heat exchanger tube aggregate and an exhaust gas introduction part, and the 3rd junction part which is a junction part of an exhaust gas introduction part and a cooling-medium circulation part formation part have shifted. And a second joint that is a joint between the heat transfer tube assembly and the exhaust gas lead-out part, and a fourth joint that is a joint between the exhaust gas lead-out part and the cooling medium flow part forming part. Therefore, the exhaust gas introduction portion may have a high dimensional accuracy on the inner peripheral surface at the first joint portion and the outer peripheral surface at the third joint portion. It is only necessary to increase the dimensional accuracy of the inner peripheral surface at the joint portion 2 and the outer peripheral surface at the fourth joint portion. As described above, since it is easy to increase the dimensional accuracy of only one surface, clearance management becomes easy and brazing can be improved.

  Furthermore, since each joint is doubled, a rapid change in cross section near each joint can be suppressed, so stress concentration at each joint can be alleviated.

  Here, in the exhaust gas heat exchanger according to the present invention, the first joint portion is disposed so as to be shifted to the downstream side with respect to the third joint portion, and the second joint portion is disposed on the first joint. It is preferable that the four joints are arranged shifted to the upstream side.

  According to this, since the amount of insertion of the heat transfer tube assembly into the exhaust gas introduction part and the exhaust gas lead-out part can be small, assembly is easy.

  In addition, the exhaust gas introduction part includes an introduction part main body part in which the exhaust gas introduction port is formed, and a cylindrical shape that is joined to the introduction part main body part and extends to the downstream side of the introduction part main body part. The exhaust gas lead-out part is connected to the lead-out part main body part on the upstream side of the lead-out part main body part. An extended cylindrical lead-out portion extending portion, and an inner peripheral surface of the one end portion of the cooling medium circulation portion forming portion is joined to an outer peripheral surface of the introduction portion extending portion, thereby A third joint portion is formed, and the inner peripheral surface of the other end portion of the cooling medium flow portion forming portion is joined to the outer peripheral surface of the lead-out portion extending portion, whereby the fourth joint portion is It can also be formed.

  According to this, the conventional exhaust gas introduction part and the exhaust gas lead-out part having a short length in the exhaust gas flow direction are used as the lead-in part main part and the lead-out part main part, respectively. By joining the extension portion and the lead-out portion extension portion, the length in the flow direction of the exhaust gas can be increased, and the first joint portion and the third joint portion can be shifted and disposed. It is possible to dispose the second joint and the fourth joint in a shifted manner.

1 is a perspective view of an exhaust gas heat exchanger according to a first embodiment of the present invention. It is a disassembled perspective view of the exhaust gas heat exchanger. It is a right view of the same exhaust gas heat exchanger. It is a front view of the exhaust gas heat exchanger. It is a top view of the exhaust gas heat exchanger. FIG. 5 is a cross-sectional view taken along the line VI-VI in FIG. It is the VII-VII sectional view taken on the line of FIG. It is principal part sectional drawing of the modification of the exhaust gas heat exchanger of 1st Embodiment of this invention. It is a disassembled perspective view of the exhaust gas heat exchanger which concerns on 2nd Embodiment of this invention. It is principal part sectional drawing of the exhaust gas heat exchanger which concerns on 2nd Embodiment. It is principal part sectional drawing of the conventional heat exchanger for EGR.

  Hereinafter, each embodiment of the present invention will be described with reference to the drawings.

  An exhaust gas heat exchanger (hereinafter abbreviated as “heat exchanger”) 1 according to the first embodiment is used as an EGR heat exchanger of an automobile, and as shown in FIGS. A heat tube assembly 7 and an outer case 2 that accommodates the heat transfer tube assembly 7 are provided. In the following description, as shown in FIGS. 1 to 4, the side on which the cooling medium inlet 33 and the cooling medium outlet 34 to be described later are provided, and the side on which the inlet side flange 8 to be described later is provided. Left, the left side of FIG. 3 is the front.

  The outer case 2 is composed of a cooling medium flow part forming part 3, an exhaust gas introducing part 4, and an exhaust gas deriving part 5, which are separate members, and the cooling medium flow part forming part 3 is a separate member. The first forming member 31 and the second forming member 32 are configured.

  The cooling medium circulation part forming part 3 is a member surrounding a cooling medium circulation part 22 to be described later, and both the first forming member 31 and the second forming member 32 are made of general stainless steel (SUS304 in this embodiment). Is formed.

  The first forming member 31 is formed in a U-shaped cross section having an upper wall portion 31a, a front wall portion 31b, and a lower wall portion 31c, and has a circular shape serving as an inlet for a cooling medium on the left side of the upper wall portion 31a. A cooling medium inlet 33 is formed, and a circular cooling medium outlet 34 serving as a cooling medium outlet is formed on the right side of the upper wall portion 31a. In the present embodiment, the cooling medium is water. A cylindrical inlet pipe 35 and an outlet pipe 36 are connected to the cooling medium inlet 33 and the cooling medium outlet 34, respectively. Further, a step portion 31d is formed at the rear end portion of the upper wall portion 31a, and a step portion 31e is formed at the rear end portion of the lower wall portion 31c, so that the first forming member 31 is arranged in the vertical direction of the rear end portion. The width is widened.

  The second forming member 32 is formed in a U-shaped cross section having an upper wall portion 32a, a rear wall portion 32b, and a lower wall portion 32c. The length of the upper wall part 32a and the lower wall part 32c is shorter than the upper wall part 31a and the lower wall part 31c of the first forming member 31 in the front-rear direction.

  The first forming member 31 and the second forming member 32 have the same length in the left-right direction, the left and right ends are aligned, and the front end of the second forming member 32 is fitted to the rear end of the first forming member 31. In this case, the front end portion outer surface of the upper wall portion 32a and the front end portion outer surface of the lower wall portion 32c are configured to fit in contact with the inner surfaces of the step portions 31d and 31e, respectively. Then, by fitting and joining the first forming member 31 and the second forming member 32 as described above, the cooling medium flow portion forming portion 3 having a substantially rectangular tube shape is formed.

  The central part 39 of the cooling medium circulation part forming part 3 is reduced in diameter, and the upper wall part 39a and the lower wall part 39b of the central part 39 are longitudinally central parts of the wall parts 71b and 71b of the first case 71 described later. And the bulging portions 71c and 71c formed in the second case 72 and the bulging portions 72c and 72c formed in the center portion in the longitudinal direction of the wall portions 72b and 72b of the second case 72. Further, the left end portion 37 that is one end portion of the cooling medium circulation portion forming portion 3 and the right end portion 38 that is the other end portion are reduced in diameter to form a substantially short rectangular tube shape. In addition, a short angle cylinder shape means the short cylinder shape where the cross section when cut | disconnecting in the surface orthogonal to an axial direction makes a polygon (this embodiment square).

  The exhaust gas introduction part 4 is a member surrounding the upstream part 21a upstream of the heat transfer tube assembly 7 in the exhaust gas circulation part 21 described later, and is formed of super SUS. As described above, the super SUS is a stainless steel in which the contents of nickel, chromium, and molybdenum are higher than those of general stainless steel (for example, SUS304, SUS316). SUS is used. Further, the upstream and downstream in this specification refer to the upstream and downstream in the flow direction of the exhaust gas. In this embodiment, the exhaust gas flows from the left to the right in the heat exchanger 1, and therefore the left side is the upstream side. The right side is the downstream side.

  As shown in FIGS. 2, 6, and 7, the exhaust gas introduction portion 4 has a left side portion formed as a funnel-like portion 41 having a substantially square funnel shape with a left end portion narrowed, and a right side portion substantially a stepped shape. It is set as the rectangular tube-shaped part 42 which makes a rectangular tube shape. Then, the rectangular tubular part 42 passes through the right short side of the first short rectangular cylindrical part 42a and the first short rectangular cylindrical part 42a which is substantially short rectangular cylindrical continuous with the right end of the funnel-like part 41, and the inclined part 42b. The second short-angle cylindrical portion 42c is a first short-angle cylindrical shape. The second short-angle cylindrical portion 42c has a continuous substantially short-angle cylindrical shape (see an enlarged view of the main part in the circle in FIG. 6). The diameter is larger than that of the portion 42a, that is, the width in the front-rear direction and the up-down direction is larger than that of the first short tubular portion 42a. The right end of the second short-angle cylindrical portion 42c, that is, the right end of the exhaust gas introduction portion 4 is a right end opening 43 that opens in a substantially rectangular shape. A circular exhaust gas inlet 45 serving as an exhaust gas inlet is formed at the left end of the funnel-shaped portion 41, that is, the left end of the exhaust gas inlet 4. An inlet flange 8 is attached to the exhaust gas inlet 45.

  The exhaust gas deriving unit 5 is formed of the same super SUS as the exhaust gas introducing unit 4 and in the same shape as the exhaust gas introducing unit 4. That is, the exhaust gas deriving unit 5 is the same member as the exhaust gas introducing unit 4. Are arranged symmetrically and surround a downstream portion 21b on the downstream side of the heat transfer tube assembly 7 in the exhaust gas circulation portion 21 described later.

  The exhaust gas lead-out part 5 has a right-side portion formed as a funnel-shaped portion 51 having a substantially square funnel shape with a right end portion narrowed, and a left-side portion formed as a step-shaped substantially rectangular tube-shaped portion 52 Has been. Then, the rectangular tubular portion 52 is connected to the left end of the funnel-shaped portion 51 through a first short rectangular tubular portion 52a having a substantially short rectangular tubular shape, and an inclined portion 52b on the left side of the first short rectangular tubular portion 52a. The second short-angle cylindrical portion 52c has a continuous substantially short-angle cylindrical shape, and the second short-angle cylindrical portion 52c is larger in diameter than the first short-angle cylindrical portion 52a. The left end of the second short-angle cylindrical portion 52c, that is, the left end of the exhaust gas deriving portion 5 is a left end opening 53 that opens in a substantially rectangular shape. A circular exhaust gas outlet 55 serving as an exhaust gas outlet is formed at the right end of the exhaust gas outlet 5. An outlet side flange 9 is attached to the exhaust gas outlet 55.

  The inner peripheral surfaces of the left end portion 37 and the right end portion 38 of the cooling medium flow portion forming portion 3 have a first short cross section (hereinafter referred to as a “longitudinal cross section”) when cut along a plane orthogonal to the left-right direction. The rectangular cylindrical portions 42a and 52a have a substantially rectangular shape substantially the same as the longitudinal section of the outer peripheral surface of the square cylindrical portions 42a, 52a, the inner peripheral surface of the left end portion 37 is the outer peripheral surface of the first short rectangular cylindrical portion 42a, and the inner periphery of the right end portion 38. When the surface is joined to the outer peripheral surface of the first short cylindrical portion 52 a, the exhaust gas introduction part 4 is connected to the left end part 37 of the cooling medium circulation part forming part 3, and the right end part 38 of the cooling medium circulation part forming part 3. The exhaust gas outlet 5 is joined to the outer case 2 to form the outer case 2.

  The heat transfer tube assembly 7 is formed by assembling a plurality (six in the embodiment) of heat transfer tubes 70, and as shown in FIG. 6, each heat transfer tube 70 is provided at one end 7 a of the heat transfer tube assembly 7. The exhaust gas inlet 70a of each heat transfer tube 70 is opened at the other end 7b of the heat transfer tube assembly 7.

  Specifically, as shown in FIGS. 2 and 6, each heat transfer tube 70 includes a first case 71, a second case 72, and heat transfer fins 73 (see FIG. 3) each formed from a thin plate made of Super SUS. The heat transfer fins 73 are arranged in a pipe formed by the first case 71 and the second case 72. The first case 71, the second case 72, and the heat transfer fins 73 are made of Super SUS having high corrosion resistance against sulfuric acid, like the exhaust gas introduction part 4, but are thinner than the exhaust gas introduction part 4. The heat transfer fin 73 is formed of a thin plate and is thinner than the first case 71 and the second case 72. More specifically, the plate thickness of the coolant circulation part forming unit 3 is about 0.8 to 1.2 mm, and the plate thicknesses of the exhaust gas introducing unit 4 and the exhaust gas deriving unit 5 are about 0.8 to 1.2 mm. The plate thickness of the first case 71 and the second case 72 is about 0.3 to 0.4 mm, and the plate thickness of the heat transfer fins 73 is a predetermined thickness in the range of about 0.1 to 0.2 mm.

  As shown in FIGS. 5 to 7, the first case 71 and the second case 72 are formed in a substantially U-shaped cross section in which wall portions 71 b and 72 b are respectively erected on both sides of the substantially flat plate portions 71 a and 72 a. The heat transfer fin 73 is formed in a corrugated plate shape in which a concave portion and a convex portion having a substantially U-shaped cross section are continuous. The width between the wall portions 71 b and 71 b of the first case 71 is slightly narrower than that between the wall portions 72 b and 72 b of the second case 72. The first case 71 and the second case 72 are arranged such that the heat transfer fins 73 are sandwiched between the first case 71 and the second case 72 so that the walls 71b and 71b are in contact with the insides of the walls 72b and 72b. The first case 71 and the second case 72 form a substantially rectangular tube with a flat vertical cross section, and the heat transfer fins 73 are arranged in the tube, so that the heat transfer tube 70 is formed, and each heat transfer tube 70 has an exhaust gas inlet 70a at one end in the longitudinal direction (tube axis direction) and an exhaust gas outlet 70b at the other end.

  Further, as shown in FIG. 6, the flat plate portions 71 a and 72 a in each heat transfer tube 70 have inclined portions 71 d and 72 d that are inclined so as to be separated from each other at the left end portion and the right end portion, respectively. Both end portions in the longitudinal direction are expanded in width in the front-rear direction to form expanded portions 74. In addition, the up-down direction on the paper surface of FIG. 6 is equivalent to the front-back direction of the heat exchanger 1, and also about each heat exchanger tube 70, the direction equivalent to the front-back direction of the heat exchanger 1 is demonstrated as the front-back direction. Then, these six heat transfer tubes 70 are overlapped in the front-rear direction so that both ends in the longitudinal direction (corresponding to the left-right direction) are aligned, and the expanded portions 74 of the adjacent heat transfer tubes 70 are joined together. The heat pipe assembly 7 is formed, and a gap 22 a is formed between the non-expanded portions 75 of the adjacent heat transfer tubes 70. The non-expanded portion 75 is a portion where the width in the front-rear direction between the left and right expanded portions 74 and 74 in each heat transfer tube 70 is narrower than that of the expanded portion 74. The gap 22a forms a part of a cooling medium circulation part 22 to be described later.

  The extended portion 74 has a substantially rectangular shape with a flat vertical cross section, and the one end portion 7a and the other end portion 7b of the heat transfer tube assembly 7 are joined by overlapping a plurality of extended portions 74 with long side portions in the vertical cross section. Therefore, the outer peripheral surfaces of the one end portion 7a and the other end portion 7b are substantially rectangular in longitudinal section.

  In addition, the vertical cross section of the inner peripheral surface of the second short-angle cylindrical portions 42c and 52c described above has a substantially rectangular shape that is substantially the same shape as the vertical cross sections of the outer peripheral surfaces of the one end portion 7a and the other end portion 7b described above. . And as mentioned above, while joining the cooling-medium distribution | circulation part formation part 3, the exhaust gas introducing | transducing part 4, and the exhaust gas derivation | leading-out part 5, the outer peripheral surface of the one end part 7a is used as the inner peripheral surface of the 2nd short angle cylindrical part 42c. The outer case 2 is formed by joining the outer peripheral surface of the other end portion 7b to the inner peripheral surface of the second short rectangular tubular portion 52c, and the one end portion 7a and the second short rectangular cylindrical portion are formed. The first joint 61 described later, which is a joint with 42c, and the second joint 62 described later, which is a joint between the other end 7b and the second short cylindrical portion 52c, serve as boundaries. The inside of the outer case 2 is divided into an exhaust gas circulation part 21 through which exhaust gas circulates and a cooling medium circulation part 22 through which a cooling medium circulates, and the exhaust gas circulation part 21 is upstream of the heat transfer tube assembly 7. Upstream portion 21a, downstream portion 21b downstream of heat transfer tube assembly 7, and heat transfer Composed of a pipe flow path 21c is inside of each heat transfer tube 70 constituting the aggregate 7. Further, the cooling medium circulation part 22 includes a gap 22 a between the heat transfer tubes 70 and a peripheral part 22 b surrounding the heat transfer tube assembly 7.

  Here, the second short-angle cylindrical portion 42c of the exhaust gas introducing portion 4 is located downstream of the first short-angle cylindrical portion 42a, and the second short-angle cylindrical portion 52c of the exhaust gas outlet portion 5 is the first It is located on the upstream side of the 1 short rectangular tubular portion 52a. Therefore, the joint portion between the outer peripheral surface of the one end portion 7a of the heat transfer tube assembly 7 and the inner peripheral surface of the second short-angle cylindrical portion 42c is the first joint portion 61 and the other end portion 7b of the heat transfer tube assembly 7. The joint portion between the outer peripheral surface and the inner peripheral surface of the second short-angle cylindrical portion 52c is the second joint portion 62, the inner peripheral surface of the left end portion 37 of the cooling medium flow portion forming portion 3 and the first short-angle cylindrical portion. The joint portion between the outer peripheral surface of 42a is the third joint portion 63, and the joint portion between the inner peripheral surface of the right end portion 38 of the cooling medium flow portion forming portion 3 and the outer peripheral surface of the first short tubular portion 52a is the fourth. In this case, the first joining portion 61 is arranged to be shifted to the downstream side with respect to the third joining portion 63 (see an enlarged view of the main part in the circle in FIG. 6), and the second joining portion. 62 is displaced from the fourth joint 64 on the upstream side.

  Next, the assembly and brazing process of the heat exchanger 1 will be described. The assembly and brazing are performed with the front-rear direction shown in FIGS. The first forming member 31, the second forming member 32, the exhaust gas introducing unit 4, the exhaust gas deriving unit 5, each first case 71, each second case 72, and each heat transfer fin 73 are formed by multistage pressing. , Pre-molded.

  First, each heat transfer tube 70 is assembled. Specifically, a brazing material is applied to the inner surfaces of the first case 71 and the second case 272, and the heat transfer fins 73 are accommodated in the second case 72. Then, the heat transfer tube 70 is assembled by fitting the first case 71 to the second case 72 so that the wall portions 71b and 71b are in contact with the inside of the wall portions 72b and 72b. A brazing material is applied between the wall portion 71b and the wall portion 72b that are in contact with each other.

  Next, a brazing material is applied to the entire outer peripheral surfaces of the expansion portions 74 and 74 of the heat transfer tubes 70 assembled as described above, so that both ends in the tube axis direction are aligned as shown in FIGS. The heat transfer tube assembly 7 is formed by stacking the heat transfer tubes 70. In this lamination, the front and rear directions shown in FIGS. The adjacent heat transfer tubes 70 are in contact with the expanded portions 74, and a gap 22 a is formed between the non-expanded portions 75.

  Since the outer peripheral surface of the one end portion 7 a of the heat transfer tube assembly 7 is formed by the outer peripheral surface of the extended portion 74 of each heat transfer tube 70, the brazing material is applied. In this state, the one end portion 7 a is fitted into the exhaust gas introduction portion 4 from the right end opening 43 of the exhaust gas introduction portion 4. Then, the longitudinal section of the outer peripheral surface of the one end portion 7a has a substantially rectangular shape substantially the same shape as the longitudinal section of the inner peripheral surface of the second short-angle cylindrical portion 42c, and is located on the left side of the second short-angle cylindrical portion 42c. Since the inclined portion 42b and the first short-angle cylindrical portion 42a are smaller in diameter than the second short-angle cylindrical portion 42c, the outer peripheral surface of the one end portion 7a is the inner periphery of the second short-angle cylindrical portion 42c. In the state of being in contact with the surface, it is fitted into the exhaust gas introduction part 4 without entering further to the left.

  Similarly, the outer peripheral surface of the other end portion 7 b of the heat transfer tube assembly 7 is also in a state where a brazing material is applied. In this state, the other end portion 7 b is exhausted from the left end opening 53 of the exhaust gas outlet portion 5. When fitted inside the gas lead-out part 5, the other end part 7b is in the state where the outer peripheral surface is in contact with the inner peripheral surface of the second short-angled cylindrical part 52c, and does not enter the right side any more and exhausts the exhaust gas. It is fitted to the part 5.

  Further, a brazing material is applied to the base end portion 35a of the inflow pipe 35 and the base end portion 36a (see FIG. 7) of the outflow pipe 36, the base end portion 35a serves as the cooling medium inlet 33, and the base end portion 36a serves as the cooling medium outlet. 34, the inflow pipe 35 and the outflow pipe 36 are assembled to the first forming member 31.

  Next, on the inner surfaces of the left end portion 31f, the right end portion 31g, and the step portions 31d and 31e of the first forming member 31, and the inner surfaces of the left end portion 32d and the right end portion 32e of the second forming member 32, Apply brazing material. Then, the left and right ends of the first forming member 31 and the second forming member 32 are aligned, and the front end portion of the second forming member 32 (the front-rear direction in FIG. 2 is defined between the step portions 31d and 31e of the first forming member 31). And the heat transfer tube assembly 7 is accommodated inside the cooling medium flow part forming part 3 formed by the first forming member 31 and the second forming member 32. The left end portion 37 of the cooling medium circulation portion forming portion 3 formed by the left end portion 31f and the left end portion 32d is fitted to the first short-angle cylindrical portion 42a, and is formed by the right end portion 31g and the right end portion 32e. The right end portion 38 of the cooling medium flow portion forming portion 3 is fitted into the first short-angle cylindrical portion 52a.

  In addition, a brazing material is applied around the exhaust gas inlet 45 of the exhaust gas inlet 4, the inlet flange 8 is fitted, and a brazing material is applied around the exhaust gas outlet 55 of the exhaust gas outlet 5. Then, the outlet side flange 9 is fitted.

  As described above, in the heat exchanger 1 assembled to the product shape, the parts to which the brazing material is applied are joined by brazing in the furnace. That is, the outer peripheral surface of the one end portion 7 a of the heat transfer tube assembly 7 is bonded to the inner peripheral surface of the second short-angle cylindrical portion 42 c of the exhaust gas introducing portion 4, thereby forming the first joint portion 61. Then, the outer peripheral surface of the other end portion 7b of the heat transfer tube assembly 7 is bonded to the inner peripheral surface of the second short-angle cylindrical portion 52c of the exhaust gas deriving portion 5, whereby the second joint portion 62 is formed. The inner peripheral surface of the left end portion 37 of the cooling medium circulation portion forming portion 3 is joined to the outer peripheral surface of the first short-angle cylindrical portion 42a of the exhaust gas introducing portion 4, thereby forming the third joint portion 63. Then, the inner peripheral surface of the right end portion 38 of the cooling medium circulation portion forming portion 3 is joined to the outer peripheral surface of the first short-angle tubular portion 52a of the exhaust gas deriving portion 5, whereby the fourth joint portion 64 is formed. It is formed. Note that the first joint 61 is disposed on the downstream side with respect to the third joint 63, and the second joint 62 is disposed on the upstream side with respect to the fourth joint 64. The

  And the junction part of the 1st case 71 and the 2nd case 72 of each heat exchanger tube 70, the 1st junction part 61, the 2nd junction part 62, the 3rd junction part 63, and the 4th junction part 64, The exhaust gas circulation part 21 through which the exhaust gas circulates is formed inside the outer case 2, and the cooling medium circulation part 22 through which the cooling medium circulates so as to surround each heat transfer tube 70. Is formed.

  Next, the operation of the heat exchanger 1 configured as described above will be described. Exhaust gas is introduced into the heat exchanger 1 from the exhaust gas inlet 45. The exhaust gas passes through the upstream portion 21 a surrounded by the exhaust gas introduction portion 4 and enters the in-tube flow path 21 c of each heat transfer tube 70. On the other hand, water, which is a cooling medium, is supplied from the inflow pipe 35 into the cooling medium circulation part forming part 3 through the cooling medium inlet 33. This water flows through the cooling medium flow part 22 in the cooling medium flow part forming part 3, and performs heat exchange with the exhaust gas in the pipe flow path 21c to cool the exhaust gas. Then, it flows out of the cooling medium circulation part forming part 3 from the outflow pipe 36 via the cooling medium outlet 34. The exhaust gas cooled in the pipe flow path 21 c enters the downstream portion 21 b surrounded by the exhaust gas outlet portion 5 and flows out of the heat exchanger 1 from the exhaust gas outlet port 55.

  As described above, according to the heat exchanger 1, the coolant circulation part forming unit 3 has the inner peripheral surface of the left end 37 joined to the outer peripheral surface of the exhaust gas introduction unit 4 and the inner peripheral surface of the right end 38. It is joined to the outer peripheral surface of the exhaust gas outlet 5. The outer peripheral surface of one end portion 7 a of the heat transfer tube assembly 7 is joined to the inner peripheral surface of the exhaust gas introducing portion 4, and the outer peripheral surface of the other end portion 7 b of the heat transfer tube assembly 7 is connected to the exhaust gas deriving portion 5. It is joined to the inner peripheral surface. Accordingly, the exhaust gas introduced into the exhaust gas introduction part 4 from the exhaust gas introduction port 45 enters each heat transfer pipe 70 from the exhaust gas introduction part 4 without touching the cooling medium circulation part forming part 3, and each heat transfer pipe 70. And flows out into the exhaust gas outlet 5 and out of the heat exchanger 1 through the exhaust gas outlet 55 of the exhaust gas outlet 5. Therefore, the exhaust gas introduction unit 4, the exhaust gas lead-out unit 5, and each heat transfer tube 70 are formed of a material having high corrosion resistance to sulfuric acid (for example, super SUS), while the cooling medium circulation unit formation unit 3 It can be formed of a material (for example, general SUS) having a lower corrosion resistance to sulfuric acid than the material forming the introduction unit 4, the exhaust gas deriving unit 5, and the heat transfer pipes 70. The possibility of corrosion due to sulfuric acid contained in the condensed water of the gas can be reduced.

  And the 1st junction part 61 which is a junction part of the heat exchanger tube aggregate 7 and the exhaust gas introduction part 4, and the 3rd junction which is a junction part of the exhaust gas introduction part 4 and the cooling-medium circulation part formation part 3 Since the portion 63 is displaced from the portion 63, the exhaust gas introduction portion 4 only needs to increase the dimensional accuracy of the inner peripheral surface of the first joint portion 61 and the outer peripheral surface of the third joint portion 63. Similarly, since the second joint portion 62 and the fourth joint portion 64 in the exhaust gas lead-out portion 5 are also shifted from each other, the exhaust gas lead-out portion 5 is disposed on the inner peripheral surface of the second joint portion 62. In the fourth joint portion 64, the dimensional accuracy of the outer peripheral surface may be increased. As described above, since it is easy to increase the dimensional accuracy of only one surface, the heat exchanger 1 can easily manage the clearance and improve the brazing property.

  Furthermore, the first joint 61, the second joint 62, the third joint 63, and the fourth joint 64 are all double, and a sudden change in cross section near each joint. Therefore, it is possible to reduce stress concentration at each joint.

  Further, in the heat exchanger 1, the first joint 61 is arranged to be shifted downstream with respect to the third joint 63, and the second joint 62 is shifted upstream with respect to the fourth joint 64. Are arranged. That is, the first joining portion 61 is closer to the right end opening 43 of the exhaust gas introducing portion 4 than the third joining portion 63, and the second joining portion 62 is more exhausted than the fourth joining portion 64. Since it is close to the left end opening 53 of the portion 5, the amount of insertion of the heat transfer tube assembly 7 into the exhaust gas introduction portion 4 and the amount of insertion into the exhaust gas lead-out portion 5 can be reduced, and assembly is easy.

  If this point is not taken into consideration, as shown in FIG. 8, the first joint 61 is shifted from the third joint 63 on the upstream side, and the second joint 62 is replaced with the fourth joint 62. You may shift | deviate and arrange | position downstream with respect to the junction part 64. FIG. In FIG. 8, reference numerals in parentheses are shown in the case where FIG. 8 is a cross-sectional view of the main part on the exhaust gas deriving unit 5 side.

  FIG. 8 is a cross-sectional view of a main part of a modification of the heat exchanger 1. In this modification, the rectangular tubular portion 42 of the exhaust gas introducing portion 4 is formed into a substantially rectangular tubular shape without a step, and the longitudinal section of the inner peripheral surface of the rectangular tubular portion 42 is one end portion 7 a of the heat transfer tube assembly 7. The vertical cross section of the outer peripheral surface of the rectangular tube-shaped portion 42 is substantially the same shape as the vertical cross section of the inner peripheral surface of the left end portion 37 of the cooling medium flow portion forming portion 3. It is made into the substantially rectangular shape. Moreover, the cooling medium distribution | circulation part formation part 3 is made shorter in the left-right direction than what was shown in FIGS. Then, the outer peripheral surface of the one end portion 7 a of the heat transfer tube assembly 7 is joined to the inner peripheral surface of the rectangular tube-shaped portion 42 to form the first bonded portion 61, and the cooling medium is formed on the outer peripheral surface of the rectangular tube-shaped portion 42. The inner peripheral surface of the left end part 37 of the flow part forming part 3 is joined to form a third joined part 63, and the first joined part 61 is arranged so as to be shifted upstream from the third joined part 63. ing. The exhaust gas lead-out portion 5 side is also configured in the same manner, and the second joint portion 62 is shifted from the fourth joint portion 64 to the downstream side.

  In the modification shown in FIG. 8, the movement of the one end portion 7a of the heat transfer tube assembly 7 to the left (toward the exhaust gas introduction port 45) when inserted into the exhaust gas introduction portion 4 is a rectangular tube shape. It is regulated by a funnel-like portion 41 having a diameter smaller than that of the portion 42, and similarly, when inserted into the exhaust gas deriving portion 5, the exhaust gas guide 7 (to the right side of the other end portion 7b of the heat transfer tube assembly 7). The movement (to the outlet 55 side) is restricted by the funnel-shaped portion 51 having a diameter smaller than that of the rectangular tube-shaped portion 52, so that the rectangular tube-shaped portion 42 of the exhaust gas introducing portion 4 and the exhaust gas deriving portion 5 The rectangular tubular portion 52 may not be stepped.

  Next, the heat exchanger 1B of 2nd Embodiment is demonstrated based on FIG. In addition, about the part similar to the heat exchanger 1 of 1st Embodiment, the same code | symbol is used and the description and illustration are abbreviate | omitted suitably. In FIG. 10, reference numerals in parentheses are shown in FIG. 10, where FIG. 10 is a cross-sectional view of the main part of the heat exchanger 1 </ b> B on the exhaust gas outlet 5 side.

  In the heat exchanger 1B, the exhaust gas introduction part 4 is composed of a separate introduction part main part 46 and an introduction part extension part 47, and the exhaust gas lead-out part 5 is a separate lead-out part main part 56, respectively. And the lead-out portion extending portion 57 are significantly different from the heat exchanger 1. The introduction part main body part 46, the introduction part extension part 47, the lead part main part 56, and the lead part extension part 57 are all formed by pressing a thin plate made of Super SUS having high corrosion resistance against sulfuric acid. Has been. In addition, the introducing | transducing part main-body part 46 and the derivation | leading-out part main-body part 56 are the same shape (same member), the derivation | leading-out part main-body part 56 and the derivation | leading-out extension part 57 are the same shape (same member), They are only arranged symmetrically.

  Specifically, the introduction main body 46 has a left side portion that is a substantially square funnel-shaped funnel-like portion 41 having an exhaust gas introduction port 45 formed at the left end portion, and a right-side portion that is at the right end of the funnel-like portion 41. It is a short-angle cylindrical portion 48 having a substantially short-angle cylindrical shape having no steps.

  The introduction portion extending portion 47 is formed in a stepped square tube shape, and has a first short angle tubular portion 47a having a substantially short angle tube shape, and an inclined portion 47b on the right side of the first short angle tubular portion 47a. The second short-angle cylindrical portion 47c, which is substantially short-angle cylindrical and has a diameter smaller than that of the first short-angle cylindrical portion 47a, and the second short-angle cylindrical portion 47c on the right side through the inclined portion 47d. A third short-angle cylindrical portion 47e having a substantially short-angle cylindrical shape that is continuous with a smaller diameter than the short-angle cylindrical portion 47c. The right end of the third short tubular portion 47 e is a right end opening 43.

  Then, the inner peripheral surface of the first short cylindrical portion 47a is joined to the outer peripheral surface of the short rectangular tubular portion 48, and the introduction portion extending portion 47 is extended to the downstream side of the introduction portion main body portion 46. A gas introduction part 4 is formed.

  The lead-out portion main body portion 56 has a right side portion that is a substantially square funnel-shaped funnel-like portion 51 in which an exhaust gas lead-out port 55 is formed at the right end portion, and a left-side portion that is continuous with the left end of the funnel-like portion 51. The short-angle cylindrical portion 58 has a substantially short-angle cylindrical shape without a step.

  The lead-out portion extending portion 57 is formed in a stepped substantially rectangular tube shape, and includes a first short-angle cylindrical portion 57a having a substantially short-angle cylindrical shape, and an inclined portion 57b on the left side of the first short-angle cylindrical portion 57a. After that, the second short-angle cylindrical portion 57c having a substantially short-angle cylindrical shape that is continuous with a diameter smaller than that of the first short-angle cylindrical portion 57a and the inclined portion 57d on the left side of the second short-angle cylindrical portion 57c. The second short-angle cylindrical portion 57c has a third short-angle cylindrical portion 57e having a substantially short-angle cylindrical shape and a continuous diameter. The left end of the third short-angle cylindrical portion 57 e is a left end opening 53.

  Then, the inner peripheral surface of the first short-angle cylindrical portion 57a is joined to the outer peripheral surface of the short-angle cylindrical portion 58, and the lead-out portion extending portion 57 extends to the upstream side of the lead-out portion main body portion 56. A gas outlet 5 is formed.

  Further, as shown in FIG. 10, the outer peripheral surface of the one end portion 7a of the heat transfer tube assembly 7 is bonded to the inner peripheral surface of the third short-angle cylindrical portion 47e to form the first bonding portion 61, The inner peripheral surface of the left end portion 37 of the cooling medium circulation portion forming portion 3 is joined to the outer peripheral surface of the second short-angle cylindrical portion 47c, so that a third joint portion 63 is formed. Similarly, the outer peripheral surface of the other end portion 7b of the heat transfer tube assembly 7 is bonded to the inner peripheral surface of the third short tube portion 57e to form the second bonding portion 62, thereby forming a cooling medium circulation portion. The inner peripheral surface of the right end portion 38 of the portion 3 is joined to the outer peripheral surface of the second short-angle cylindrical portion 57c, so that a fourth joint portion 64 is formed.

  Note that, as in the first embodiment, each part is joined at one time by brazing.

  Also in the heat exchanger 1B, like the heat exchanger 1, the 1st junction part 61 is shifted | deviated and arrange | positioned downstream from the 3rd junction part 63, and the 2nd junction part 62 is a 4th junction part. Since it is arranged to be shifted to the upstream side of 64, the same effect as the heat exchanger 1 is achieved. However, the heat exchanger 1 is more advantageous than the heat exchanger 1B in that the number of parts is smaller and the manufacturing cost is lower.

  Further, according to the heat exchanger 1B, the conventional exhaust gas introduction part 104 and the exhaust gas lead-out part having a short length in the exhaust gas flow direction as shown in FIG. As the main body 56, the length in the flow direction of the exhaust gas can be increased by joining the introduction portion extension portion 47 and the lead-out portion extension portion 57, respectively. It is possible to displace the second joint portion 62 and the fourth joint portion 64 while shifting the second joint portion 63 and the fourth joint portion 64.

  In the heat exchanger 1B, the joint portion between the introduction portion main body portion 46 and the introduction portion extension portion 47 is arranged so as to be shifted upstream from the first joint portion 61 and the third joint portion 63. The first joint 61 and the third joint 63 do not overlap with each other, and the joint between the lead-out body 56 and the lead-out extension 57 is the second joint 62 and the fourth joint. The second joint part 62 and the fourth joint part 64 do not overlap with each other because the second joint part 62 and the fourth joint part 64 are arranged so as to be shifted to the downstream side of 64. That is, since these joint portions are all double, clearance management is easy and stress concentration can be reduced.

1, 1B Exhaust gas heat exchanger 2 Outer case 3 Cooling medium circulation part formation part 4 Exhaust gas introduction part 5 Exhaust gas outlet part 7 Heat transfer tube assembly 7a One end part 7b Other end part 21 Exhaust gas circulation part 22 Cooling medium circulation part 33 Cooling medium inlet 34 Cooling medium outlet 37 Left end portion 38 Right end portion 45 Exhaust gas introduction port 46 Introduction portion main body portion 47 Introduction portion extension portion 55 Exhaust gas outlet portion 56 Lead portion main portion 57 Lead portion extension portion 61 First Joint part 62 Second joint part 63 Third joint part 64 Fourth joint part 70 Heat transfer tube 70a Exhaust gas inlet 70b Exhaust gas outlet

Claims (3)

A heat transfer tube assembly formed by assembling a plurality of heat transfer tubes through which exhaust gas circulates, wherein an exhaust gas inlet of each heat transfer tube opens at one end and an exhaust gas outlet of each heat transfer tube opens at the other end; And an outer case for housing the heat transfer tube assembly,
By joining the outer peripheral surfaces of the one end portion and the other end portion of the heat transfer tube assembly to the inner peripheral surface of the outer case, an exhaust gas circulation portion in which the exhaust gas flows inside the outer case, and In an exhaust gas heat exchanger divided into a cooling medium circulation part through which a cooling medium for cooling the exhaust gas flows,
The outer case is formed with a cooling medium inlet and a cooling medium outlet to surround the cooling medium circulation part, and an exhaust gas inlet is formed to form the exhaust gas circulation part. An exhaust gas introduction portion that surrounds the upstream side of the heat transfer tube assembly, and an exhaust gas discharge portion that forms an exhaust gas outlet and surrounds the downstream side of the heat transfer tube assembly of the exhaust gas circulation portion, Formed by joining the exhaust gas introduction part to one end of the cooling medium circulation part forming part and joining the exhaust gas outlet part to the other end of the cooling medium circulation part formation part,
By joining the outer peripheral surface of the one end portion of the heat transfer tube assembly to the inner peripheral surface of the exhaust gas introduction portion, a first joint portion is formed,
By joining the outer peripheral surface of the other end portion of the heat transfer tube assembly to the inner peripheral surface of the exhaust gas outlet portion, a second joint portion is formed,
A third joint portion is formed by joining the inner peripheral surface of the one end portion of the cooling medium circulation portion forming portion to the outer peripheral surface of the exhaust gas introducing portion,
By joining the inner peripheral surface of the other end portion of the cooling medium circulation portion forming portion to the outer peripheral surface of the exhaust gas outlet portion, a fourth joint portion is formed,
The first joint portion is arranged to be shifted to the upstream side or the downstream side in the exhaust gas flow direction with respect to the third joint portion,
The exhaust gas heat exchanger is characterized in that the second joint portion is arranged to be shifted to the upstream side or the downstream side with respect to the fourth joint portion. The first joint portion is arranged to be shifted to the downstream side with respect to the third joint portion;
2. The exhaust gas heat exchanger according to claim 1, wherein the second joint portion is arranged to be shifted to the upstream side with respect to the fourth joint portion. The exhaust gas introduction part includes an introduction part main body part in which the exhaust gas introduction port is formed, and a cylindrical introduction part joined to the introduction part main body part and extending to the downstream side of the introduction part main body part An extension part,
The exhaust gas lead-out portion is a lead-out portion main body portion in which the exhaust gas lead-out port is formed, and a tubular lead-out portion that is joined to the lead-out portion main body portion and extends to the upstream side of the lead-out portion main body portion. An extension part,
The inner peripheral surface of the one end portion of the cooling medium circulation portion forming portion is bonded to the outer peripheral surface of the introduction portion extending portion, thereby forming the third bonding portion,
The fourth joint portion is formed by joining an inner peripheral surface of the other end portion of the cooling medium circulation portion forming portion to an outer peripheral surface of the extended portion extending portion. The exhaust gas heat exchanger according to claim 1 or 2.

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