JP2015098947A - Exhaust heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust heat exchanger in which retention of condensed water on a fin surface can be suppressed.SOLUTION: The exhaust heat exchanger is provided which exchanges heat between a cooling medium and exhaust generated by combustion to cool the exhaust. The exhaust heat exchanger comprises exhaust tubes 21 inside which exhaust flow passages 21a for flowing exhaust is provided, and fins 22 arranged in the exhaust flow passages 21a and accelerating heat exchange between the exhaust and the cooling medium. The fin 22 has a wall part 42 which divides the exhaust flow passage 21a into a plurality of passages in a vertical direction of the gravity direction as viewed from an exhaust flow direction. The wall part 42 is divided into a plurality of the wall parts 42 along the exhaust flow direction, and a gap of a predetermined length A is formed between adjacent wall parts 42 along the exhaust flow direction.

Description

  The present invention relates to an exhaust heat exchanger that cools exhaust gas by exchanging heat between exhaust gas generated by combustion and a cooling medium.

  2. Description of the Related Art Conventionally, an exhaust heat exchanger that cools exhaust gas by exchanging heat between exhaust gas generated by combustion and a cooling medium is known (see, for example, Patent Document 1). This exhaust heat exchanger includes a tube through which exhaust flows and an inner fin joined to the inside of the tube, and exchanges heat between the exhaust flowing inside the tube and the cooling medium flowing outside the tube. Configured to do.

JP 2008-39380 A

  By the way, in the exhaust heat exchanger of the said structure, condensed water generate | occur | produces on the surface of a tube and an inner fin by exhaust_gas | exhaustion being cooled. This condensed water contains sulfate ions, nitrate ions, and the like, and if the water evaporates and the condensed water is concentrated, the tubes and the inner fins may be corroded.

  Also, if the condensed water stays on the surface of the inner fin and the exhaust flow in the heat exchanger is obstructed, the time for the condensed water to stay on the surface of the inner fin becomes longer, and the tube or inner fin is prematurely corroded. May be incurred.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an exhaust heat exchanger capable of suppressing condensate retention on the inner fin surface.

In order to achieve the above object, the invention according to claim 1 is an exhaust heat exchanger that cools exhaust gas by performing heat exchange between a cooling medium and exhaust gas generated by combustion,
An exhaust tube (21) provided with an exhaust passage (21a) through which exhaust flows is provided, and a fin (22) that is disposed in the exhaust passage (21a) and promotes heat exchange between the exhaust and the cooling medium. The fin (22) includes a wall portion (42) that divides the exhaust flow path (21a) into a plurality of vertical directions in the direction of gravity when viewed from the exhaust flow direction, and the wall portion (42) A gap having a predetermined length (A) is formed between the wall portions (42) which are divided into a plurality along the exhaust flow direction and are adjacent along the exhaust flow direction.

  Due to the presence of such a gap between the adjacent wall portions (42), the condensed water droplets are easily divided. As a result, the gravity acting on the droplets is superior to the surface tension, the condensed water can easily move downward, and the drainage of the condensed water can be improved. Thereby, the residence of the condensed water in the surface of a fin (22) can be suppressed.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is a perspective view of the EGR cooler concerning a 1st embodiment of the present invention. It is a disassembled perspective view of the EGR cooler which concerns on 1st Embodiment of this invention. It is a front view of the exhaust tube which concerns on 1st Embodiment of this invention. It is IV-IV sectional drawing of FIG. It is a perspective view of the fin concerning a 1st embodiment of the present invention. It is a top view of the fin concerning a 1st embodiment of the present invention. It is sectional drawing of the exhaust tube and fin which concern on 2nd Embodiment of this invention. It is sectional drawing of the exhaust tube and fin which concern on 3rd Embodiment of this invention.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. In the present embodiment, an example in which the heat exchanger of the present invention is applied to an exhaust heat exchanger (EGR cooler) will be described.

  The EGR cooler 1 is an exhaust heat exchanger that cools exhaust gas generated by combustion in an internal combustion engine (engine) (not shown) to the engine using engine coolant (cooling medium). As shown in FIGS. 1 and 2, the EGR cooler 1 includes a plurality of exhaust tubes 21, in which fins 22 are disposed, a water tank 130, an inlet gas tank 140, an outlet gas tank 160, an inlet water pipe 170, and outlet water. It consists of a pipe 180 and the like. Each member is made of stainless steel, lightweight, excellent thermal conductivity, and inexpensive aluminum material or aluminum alloy material, and the contact portions of the members are joined by brazing or welding.

  An exhaust tube 21 shown in FIG. 2 is a tube constituting an exhaust passage 21a through which exhaust flows, and the exhaust flows through the inside. Cooling water flows outside the exhaust tube 21, and heat is exchanged between the exhaust gas and the cooling water via the exhaust tube 21.

  The exhaust tube 21 has a flat cross-sectional shape when viewed from the exhaust flow direction, and a plurality of exhaust tubes 21 are stacked in a direction perpendicular to the flat surface (the left-right direction in FIG. 2). As shown in FIG. 3, a cooling water flow path 115 through which cooling water flows between the adjacent exhaust tubes 21 is formed by the outer wall of the adjacent exhaust tubes 21.

  Further, fins 22 are provided in the exhaust passage 21 a in the exhaust tube 21. The fins 22 are brazed to the inner surface of the exhaust tube 21. The fin 22 is arrange | positioned in each exhaust tube 21, and accelerates | stimulates the heat exchange between exhaust_gas | exhaustion and cooling water. Details of the fins 22 will be described later.

  The basic surface 111 of the exhaust tube 21 is provided with a convex portion 112 and a concave portion 113. The convex portion 112 is a stamped portion that is pressed so as to protrude outward from the surface of the exhaust tube basic surface 111, and is formed like a weir on the outer peripheral portion of the exhaust tube basic surface 111. And the recessed part 113 is formed so that it may dent from the protrusion vertex of the said convex part 112 to the exhaust-tube basic surface 111 side.

  Here, the positions where the recesses 113 are formed are two locations which are one diagonal position on the exhaust tube basic surface 111. As shown in FIG. 2, a plurality of the exhaust tubes 21 are stacked such that the convex portions 112 formed on the exhaust tube basic surface 111 are in contact with each other, and the convex portions 112 are joined to each other.

  And the convex part 112 formed in the longitudinal direction edge part of each exhaust tube 21 among the convex parts 112 is joined, and the longitudinal direction edge part of the laminated | stacked exhaust tube 21 has water to mention later. A partition 112A that partitions the inside of the tank 130 (cooling water flow path 115) and the inside of each gas tank 140, 160 is formed.

  Here, a space is formed in the inner region of the convex portion 112 between the plurality of stacked exhaust tubes 21, and this space serves as the cooling water flow path 115. Of the recesses 113 formed at two locations on the exhaust tube basic surface 111, the opening formed by the recesses 113 on one side (lower left side in FIG. 2) in the longitudinal direction of the exhaust tube 21 is formed between the outside and the cooling water flow. The passage 115 communicates with the inflow side opening 113a through which cooling water flows.

  Of the recesses 113 formed at two locations on the exhaust tube basic surface 111, the opening formed by the other recesses 113 in the longitudinal direction of the exhaust tube 21 (upper right side in FIG. 2) is formed between the outside and the cooling water flow. An outflow side opening 113b through which the cooling water flows out through the passage 115 is formed. Here, in the exhaust passage 21a (in the exhaust tube 21), the side into which the exhaust gas flows is referred to as an inflow side opening 113a, and the opposite side is referred to as an outflow side opening 113b.

  And the convex part as a temperature reduction means which reduces the temperature of the temperature boundary layer of the cooling water in the outer surface of the exhaust tube 21 is formed in the exhaust tube basic surface 111 which becomes the inflow side opening part 113a side of the exhaust tube 21. Has been. Here, the convex portion is formed as a plurality of dimples 116. The dimples 116 can be set as cylindrical convex portions, for example, and a plurality of dimples 116 are arranged in a grid pattern. The projecting dimension of the dimple 116 is the same as the projecting dimension of the convex part 112 on the outer peripheral part of the exhaust tube 21.

  Further, in the vicinity of the inflow side opening 113a of the exhaust tube basic surface 111, the flow of the cooling water is spread over the entire exhaust tube basic surface 111 as much as possible and directed to the outflow side opening 113b. Is provided. The rectifying portion 117 is also formed so as to protrude from the exhaust tube basic surface 111 in the same manner as the dimple 116.

  The water tank 130 is a cylindrical container body that houses a plurality of stacked exhaust tubes 21 therein, and is formed of a first water tank 130A and a second water tank 130B.

  The first water tank 130 </ b> A includes a main body portion 131 that faces the exhaust tube basic surface 111, an upper surface portion 132 that is bent from the upper end portion of the main body portion 131 to the exhaust tube 21 side by approximately 90 degrees, And a lower surface portion 133 bent at approximately 90 degrees from the lower end portion toward the exhaust tube 21 side, and the cross-sectional shape is a U-shape.

  A bulging portion 132a bulging outward (upward) is formed at an end portion of the upper surface portion 132 corresponding to the outflow side opening portion 113b in the longitudinal direction, and further, in the region of the bulging portion 132a. Is provided with a burring portion (border portion), and is provided with a pipe hole 132b for connecting the outlet water pipe 180. Further, bulging portions 133a and 133b bulging outward (downward) are formed at both ends of the lower surface portion 133 in the longitudinal direction.

  The second water tank 130B includes a main body portion 134 that faces the exhaust tube basic surface 111, an upper surface portion 135 that is bent from the upper end of the main body portion 134 to the exhaust tube 21 side by approximately 90 degrees, and the main body portion 131. And a lower surface portion 136 bent at approximately 90 degrees from the lower end portion toward the exhaust tube 21 side, and has a U-shaped cross-sectional shape shallower than the first water tank 130A.

  A bulging portion 135a that bulges outward (upward) is formed at the end of the upper surface portion 135 corresponding to the outflow side opening 113b in the longitudinal direction, similar to the first water tank 130A. In addition, bulging portions 136a and 136b bulging outward (downward) are formed at both ends in the longitudinal direction of the lower surface portion 136, similarly to the first water tank 130A.

  The first water tank 130 </ b> A and the second water tank 130 </ b> B are joined to each other at the opening side of the U-shaped cross section to form a cylindrical water tank 130 having a quadrangular cross section. Both ends in the longitudinal direction of the water tank 130 are opening-side end portions 130C and 130D that open to the outside. Of the opening side end portions 130C and 130D, an opening side end portion 130C on the inlet gas tank 140 side described later is formed with a bulging portion 133c as a water tank bulging portion.

  The bulging portion 133c is a central portion of the lower side of the opening-side end portion 130C having a quadrangular shape and bulges outward (lower side) from the lower side, and the bulging described above. It is formed so as to be connected to the portion 133a.

  The inlet gas tank 140 circulates the exhaust from the exhaust pipe and forms an exhaust passage 140C for distributing and supplying the exhaust to the plurality of exhaust tubes 21, and includes an outer gas tank 140A and an inner gas tank 140B. Formed into a double structure.

  The outer gas tank 140A is formed as a semi-container body whose outer shape is a rectangular parallelepiped shape and one surface on the exhaust tube 21 side is open. The opened part is an opening 141. The opening 141 has a quadrangular shape. A circular flange hole 142 that is provided with a burring portion and that is used for connecting the flange 148 is formed below the other surface on the side facing the opening 141. A pipe hole 143 for connecting the inlet water pipe 170 is formed on the upper surface of the outer gas tank 140A.

  Furthermore, a bulging portion (not shown) as a gas tank bulging portion is formed on the outer wall portion 144 which is the lower side of the outer gas tank 140A. The bulging portion is a central portion of the lower side of the rectangular opening 141, and bulges outward (lower side) from the lower side and sequentially bulges toward the flange hole 142 side. The amount is formed to be small. The bulging portion 145 is provided on a surface facing (opposed to) the surface where the pipe hole 143 is formed in the outer gas tank 140A.

  The inner gas tank 140B has a funnel-like shape and forms an exhaust passage 140C therein. An opening 146 having a rectangular shape is formed on one side which is the exhaust tube 21 side, and a burring portion is formed on the other side. A circular flange hole 147 for connecting the flange 148 is formed. The opening 146 corresponds to one opening in the present invention, and the flange hole 147 corresponds to the other opening in the present invention. The other opening is open in a direction along the axis passing through the one opening.

  The inner gas tank 140B is inserted into the outer gas tank 140A, the outer peripheral surface of the opening 146 is joined to the inner peripheral surface of the opening 141 excluding the bulging portion 145, and the outer periphery of the burring portion of the flange hole 147. The surface and the inner peripheral surface of the burring portion of the flange hole 142 are joined together to form the inlet gas tank 140.

  The inlet gas tank 140 formed in this way has an outer space between the inner gas tank 140B and the outer gas tank 140A, that is, between the inner gas tank 140B and the outer gas tank 140A by the double structure of the inner gas tank 140B and the outer gas tank 140A. It is a tank with 140D. The outer space 140D communicates with the outside of the inlet gas tank 140 through the bulging portion 145.

  The inlet gas tank 140 is joined with a flange 148 for connection with a counterpart exhaust pipe in the exhaust gas recirculation device. The flange 148 is a plate member whose outer shape has a rhombus shape, a communication hole 148a is formed at the center, and bolt holes (internal threads) 148b for fastening with bolts are formed at both ends.

  The flange 148 is joined to the inlet gas tank 140 so that the communication hole 148 a communicates with the flange holes 142 and 146 of the inlet gas tank 140. And the inner peripheral surface of the opening part 146 of the inlet gas tank 140 is joined to the outer peripheral surface of the partition part 112A of the exhaust tube 21 laminated in multiple numbers. Therefore, the exhaust flow path 140C of the inner gas tank 140B communicates with the exhaust flow path 21a in each exhaust tube 21.

  The outlet gas tank 160 has a funnel-like shape and forms an exhaust passage inside. The outlet gas tank 160 has a square-shaped opening 161 on one side which is the exhaust tube 21 side, and a burring portion on the other side. A circular flange hole 162 for connecting the flange 163 is formed. The outlet gas tank 160 is joined with a flange 163 for connection with a counterpart exhaust pipe in the exhaust gas recirculation device.

  Like the flange 148, the flange 163 is a plate member having an outer shape of rhombus, a communication hole is formed in the center, and bolt holes (internal threads) for fastening with bolts are formed on both ends. Yes. The flange 163 is joined to the outlet gas tank 160 so that the communication hole communicates with the flange hole 162 of the outlet gas tank 160. And the inner peripheral surface of the opening part 161 of the exit gas tank 160 is joined to the outer peripheral surface of the division part 112A of the exhaust tube 21 laminated in multiple numbers. Therefore, the exhaust flow path that is the inside of the outlet gas tank 160 communicates with the exhaust flow path 21 a in each exhaust tube 21.

  The first water tank 130 </ b> A and the second water tank 130 </ b> B are assembled so as to cover the outside of the plurality of exhaust tubes 21 stacked from the exhaust tube stacking direction, and the exhaust tubes 21 are accommodated in the water tank 130. It is in shape. The inner peripheral surfaces of the opening side end portions 130 </ b> C and 130 </ b> D of the water tank 130 are joined to the outer peripheral surfaces of the opening portions 141 and 161 of each gas tank 140.

  Therefore, the space formed by the bulging portions 133 a and 136 a of the water tank 130 and the opening 113 a in the side surface portion of the plurality of stacked exhaust tubes 21 communicate with each other. Further, the space formed by the bulging portions 132 a and 135 a of the water tank 130 and the opening 113 b in the side surface portion of the plurality of stacked exhaust tubes 21 communicate with each other. Further, a space is formed between the side surface portion of the exhaust tube 21 and the bulging portions 133b and 136b.

  Further, a cooling water passage 115 similar to the cooling water passage 115 formed between the exhaust tubes 21 is formed between the outermost exhaust tube 21 (exhaust tube basic surface 111) and the main body portions 131 and 134. Has been. Further, gaps are formed between the upper side surface portion of the exhaust tube 21 and the upper surface portions 132 and 135 and between the lower side surface portion of the exhaust tube and the lower surface portions 133 and 136. A space formed outside the exhaust tube 21 inside the water tank 130 is a water tank internal space.

  Furthermore, the inner peripheral surface of the bulging portion 133c of the water tank 130 is joined to the outer peripheral surface of the bulging portion 145 of the inlet gas tank 140, and the bulging portion 133c and the bulging portion 145 are connected. A flow path is formed inside the bulges 133c and 145 by the bulges 133c and 145, and the flow path serves as the communication part 150. The communication part 150 communicates the space formed by the bulging parts 133 a and 136 a of the water tank 130 and the outer space of the inlet gas tank 140.

  The inlet water pipe 170 forms a cooling fluid inlet into which cooling water flowing out from the engine flows, and is formed from a pipe member. The leading end of the inlet water pipe 170 is inserted into and joined to the pipe hole 143 of the outer gas tank 140A. The inlet water pipe 170 communicates with the outer space 140D of the inlet gas tank 140.

  The outlet water pipe 180 forms a cooling fluid outlet through which the cooling water flowing through the cooling water passage 115 of the exhaust tube 21 flows out, and is formed from a pipe member. The distal end portion of the outlet water pipe 180 is inserted into and joined to the pipe hole 132 b in the bulging portion 132 a of the water tank 130. The outlet water pipe 180 communicates with the space formed by the bulging portions 132 a and 135 a of the water tank 130.

  Next, the structure of the fin 22 of this embodiment is demonstrated based on FIGS. 3, 4, and 6, the vertical direction in the figure corresponds to the vertical direction of the gravitational direction, and in FIG. 5, the left side in the figure corresponds to the upward direction of the gravitational direction. The right side corresponds to the downward direction of gravity.

  As shown in FIG. 5, when viewed from the exhaust flow direction, the fins 22 are wavy portions 22 a and 22 b in which the top portions 41 are alternately positioned on one side and the other side, and the adjacent wall portions 42 are connected by the top portions 41. Is formed. Further, the fins 22 of the present embodiment have cut-and-raised portions 43 formed at predetermined intervals along the exhaust flow direction, and corrugated portions 22b formed by the cut-and-raised portions 43 are adjacent in the exhaust flow direction. It is comprised as an offset fin offset with respect to the part 22a.

  As shown in FIG. 3, when viewed from the exhaust flow direction, the exhaust passage 21 a is divided into a plurality of passages by the wall portions 42 of the fins 22. Further, as shown in FIG. 5, since the wall portions 42 are arranged in a staggered manner along the exhaust flow direction, the flow path divided into a plurality in the exhaust tube 21 by the wall portion 42 is in the exhaust flow direction. Partially offset.

  As shown in FIGS. 4-6, the wall part 42 of the fin 22 is divided | segmented along the exhaust flow direction, and the clearance gap of predetermined length A is between the adjacent wall parts 42 along an exhaust flow direction. Is provided. In the present embodiment, a plurality of wall portions 42 formed in one wave shape portion 22a, 22b are formed at the same position as viewed from a direction (vertical direction in FIG. 4) orthogonal to the exhaust flow direction. For this reason, the clearance gap of the predetermined length A provided between the wall parts 42 which respectively comprise the adjacent waveform part 22a, 22b is located on a straight line.

  Further, as shown in FIGS. 4 to 6, when the EGR cooler 1 is in use, the end portion of the fin 22 positioned in the downward direction of the gravity is located between the wall portion 42 and the inner wall surface of the exhaust tube 21. A stopper portion 44 for forming a gap having a predetermined length B is provided. The stopper portion 44 is formed in a flat plate shape when the EGR cooler 1 is used, and has a plate surface having a predetermined length B along the vertical direction of gravity (the horizontal direction in FIG. 4).

  In the EGR cooler 1, condensed water may be generated when the exhaust gas that passes through the exhaust passage 21 a of the exhaust tube 21 is cooled by the cooling water that passes through the cooling water passage 115. When condensed water is generated, it becomes droplets on the surface of the wall portion 42 of the fin 22 due to surface tension.

  As described above, the fin 22 of the present embodiment is provided with the gap of the predetermined length A between the adjacent wall portions 42 along the exhaust flow direction. Also, the downward movement of the condensed water can be promoted. In other words, the presence of a gap between the adjacent wall portions 42 makes it easy for the condensed water droplets to be broken. As a result, the gravity acting on the droplets surpasses the surface tension, and the condensed water easily moves downward. It is possible to improve the drainage of condensed water. Thereby, stagnation of condensed water on the surface of the fin 22 can be suppressed, and corrosion of the exhaust tube 21 and the fin 22 can be suppressed.

  If the predetermined length A of the gap provided between the wall portions 42 adjacent to each other in the exhaust flow direction is too small, the effect of dividing the droplets is low, and if it is too large, the heat exchange efficiency is lowered. For this reason, the predetermined length A of the gap provided between the adjacent wall portions 42 along the exhaust flow direction can divide the droplet, and the gravity acting on the droplet can overcome the surface tension. Any length is acceptable.

  Further, since a gap having a predetermined length A is provided between the wall portions 42 adjacent to each other in the exhaust flow direction, a space in which the exhaust gas flows between the wall portions 42 can be secured. For this reason, it becomes easy for exhaust to flow between the wall parts 42, the condensed water on the surface of the fin 22 can be dried efficiently, and corrosion of the exhaust tube 21 and the fin 22 can be suppressed.

  Condensed water that has moved downward through a gap provided between adjacent wall portions 42 along the exhaust flow direction gathers at the lower end of the exhaust passage 21 a in the exhaust tube 21. As described above, the stopper portion 44 is provided at the lower end of the fin 22, and a gap having a predetermined length B is formed between the wall portion 42 of the fin 22 and the inner wall surface of the exhaust tube 21. For this reason, even if condensed water collects at the lower end in the exhaust tube 21, the space between the lower end of the exhaust tube 21 and the wall portion 42 of the fin 22 is not filled with condensed water, and a space through which exhaust flows is secured. The Rukoto. For this reason, by ensuring the exhaust flow, the condensed water accumulated at the lower end of the exhaust passage 21a can be efficiently dried.

  Further, the fins 22 of the present embodiment are configured as offset fins in which the wall portions 42 are arranged in a staggered manner along the exhaust flow direction, and the wall portions 42 are not continuous in a straight line along the exhaust flow direction. ing. In such an offset fin, the condensate can be effectively improved in drainage by providing a gap having a predetermined length A between the wall portions 42 adjacent in the exhaust flow direction.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. In FIG. 7, the vertical direction in the figure corresponds to the vertical direction of the gravity direction. Only the parts different from the first embodiment will be described below.

  As shown in FIG. 7, the fins 22 of the second embodiment are configured as straight fins in which the wall portions 42 are arranged in a straight line when viewed from the exhaust flow direction. Also in the second embodiment, the wall portions 42 of the fins 22 are divided along the exhaust flow direction, and a gap having a predetermined length A is provided between the adjacent wall portions 42 along the exhaust flow direction. It has been. And the clearance gap of the predetermined length A provided between the wall parts 42 adjacent along the exhaust flow direction is located on a straight line.

  In addition, as shown in FIG. 7, when the EGR cooler 1 is in use, a predetermined length is provided between the wall 42 and the inner wall surface of the exhaust tube 21 at the end of the fin 22 positioned in the downward direction of the gravity. A stopper portion 44 for forming a gap B is provided. The stopper portion 44 is formed in a flat plate shape.

  Even with the configuration of the second embodiment described above, the same effects as those of the first embodiment can be obtained.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. In FIG. 8, the vertical direction in the figure corresponds to the vertical direction of the gravity direction. Only the parts different from the first embodiment will be described below.

  As shown in FIG. 8, the fin 22 of the third embodiment is configured as a wave fin in which a wall portion 42 is arranged on a curve as viewed from the exhaust flow direction. Also in the third embodiment, the wall portion 42 of the fin 22 is divided along the exhaust flow direction, and a gap having a predetermined length A is provided between the adjacent wall portions 42 along the exhaust flow direction. It has been. And the clearance gap of the predetermined length A provided between the wall parts 42 adjacent along the exhaust flow direction is located on a straight line. In the third embodiment, a gap having a predetermined length A is formed at the apex located below the gravitational direction in the curve formed by the plurality of wall portions 42 provided along the exhaust flow direction. .

  Further, as shown in FIG. 8, when the EGR cooler 1 is in use, a predetermined length is provided between the wall 42 and the inner wall surface of the exhaust tube 21 at the end of the fin 22 positioned in the downward direction of the gravitational direction. A stopper portion 44 for forming a gap B is provided. The stopper portion 44 is formed in a flat plate shape.

  Even with the configuration of the third embodiment described above, the same effects as those of the first embodiment can be obtained. Further, in the third embodiment, in the configuration in which the wall portion 42 is arranged on the curve along the exhaust flow direction, a gap of a predetermined length A is formed at the apex located below the gravity direction. For this reason, even if it is a case where condensed water adheres on the surface of the wall part 42, condensed water can move below easily.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and can be variously modified as follows without departing from the spirit of the present invention.

  (1) In the configuration of each of the above embodiments, the surface of the fin 22 may be subjected to a hydrophilic treatment. Thereby, the contact angle of the condensed water becomes small, and even when the gap of the predetermined length A provided between the wall portions 42 adjacent to each other along the exhaust flow direction is relatively small, the condensed water Can be easily drained. Further, by performing the hydrophilic treatment of the fins 22, the condensed water does not easily become large droplets, so that it is easy to secure a space in which the exhaust gas flows in the exhaust passage 21 a.

  (2) In the configuration of each of the above embodiments, the surface of the fin 22 may be subjected to water repellent treatment. Thereby, the condensed water can be easily drained from the gap of the predetermined length A provided between the wall portions 42 adjacent to each other in the exhaust flow direction, and the condensed water stays on the surface of the fin 22. Can be suppressed. Such a water repellent treatment is effective when the gap of the predetermined length A provided between the wall portions 42 adjacent to each other in the direction of flow of the condensed water is relatively large.

  Further, the water repellent treatment of the fins 22 makes it easy for the condensed water to move due to the exhaust flow, so that it is easy to secure a space for the exhaust to flow in the exhaust flow path 21a. In particular, the water repellent treatment is performed on the stopper portion 44 positioned at the lower end of the exhaust flow path 21a where condensed water collects, so that a space in which exhaust gas can flow effectively can be secured.

21 Exhaust tube 21a Exhaust flow path 22 Fin 41 Top part 42 Wall part 44 Stopper part

Claims (4)

An exhaust heat exchanger that cools the exhaust by performing heat exchange between the cooling medium and the exhaust generated by combustion,
An exhaust tube (21) provided with an exhaust passage (21a) through which the exhaust flows,
A fin (22) disposed in the exhaust flow path (21a) for promoting heat exchange between the exhaust and the cooling medium;
The fin (22) includes a wall portion (42) that divides the exhaust passage (21a) into a plurality of vertical directions in the direction of gravity when viewed from the exhaust flow direction.
The wall (42) is divided into a plurality along the exhaust flow direction, and a gap of a predetermined length (A) is formed between the wall (42) adjacent in the exhaust flow direction. Exhaust heat exchanger characterized by being.   In order to form a gap of a predetermined length (B) between the wall (42) and the inner wall surface of the exhaust tube (21) at the end of the fin (22) positioned below the gravitational direction. The exhaust heat exchanger according to claim 1, wherein a stopper portion (44) is provided.   The exhaust heat exchanger according to claim 1 or 2, wherein a surface of the fin (22) is subjected to a hydrophilic treatment.   The exhaust heat exchanger according to claim 1 or 2, wherein a water repellent treatment is applied to a surface of the fin (22).

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