JP4683111B2 - Exhaust heat exchanger - Google Patents

Description

  The present invention relates to an exhaust heat exchange device that exchanges heat between exhaust gas discharged from an internal combustion engine and a cooling fluid, and an EGR gas heat exchange device (EGR) that cools exhaust gas for an EGR (exhaust gas recirculation device). It is effective when applied to a gas cooler.

  As a conventional exhaust heat exchange device, for example, a device disclosed in Patent Document 1 is known. That is, in the exhaust heat exchange device of Patent Document 1, an offset type inner fin is disposed in the exhaust passage in the tube through which the exhaust flows, and a protrusion projecting inward is provided on the top surface portion of the inner fin. The exhaust gas flowing through the exhaust passage forms a meandering flow in a direction connecting the opposing top surface portions.

  More specifically, in the inner fin, each segment formed by the offset is arranged in a staggered manner along the flow direction of the exhaust gas, and the protruding portion is a triangular wing cut and raised inward from the top surface of each segment. It is formed as. Further, two wings are provided so that one segment is aligned in the exhaust flow direction.

In the exhaust heat exchanger, the exhaust gas meandering flow formed by the projections (wings) allows the exhaust to collide with the projections substantially evenly when viewed in the entire exhaust passage. It is possible to improve the heat transfer coefficient. In addition, by disturbing the flow of exhaust gas, the flow rate of exhaust gas is increased, and unburned substances (PM, etc.) in the exhaust gas adhering to the wall surface of the inner fin are blown away to prevent the unburned substance from accumulating on the wall surface. Like to do.
JP 2003-106785 A

  However, in the exhaust heat exchange device described in Patent Document 1, since a plurality of (two) protrusions are provided in one segment, the dimension of one segment in the exhaust flow direction increases, so-called segment The tip effect at the upstream end is not fully exhibited. That is, as the size of one segment in the exhaust flow direction increases, the boundary layer formed on the side surface of the segment from the upstream end toward the downstream side becomes thicker, and the exhaust flow velocity is lower on the downstream side than on the upstream side. The area where the decrease is increased. Therefore, the heat transfer coefficient in heat exchange between the exhaust and the cooling fluid is reduced. Furthermore, when the region where the flow rate of the exhaust gas decreases increases, the wall shear force for blowing off the unburned material decreases, and the accumulation of unburned material on the side surface portion is promoted.

  Further, as shown in FIG. 7, an exhaust flow stagnation region A is easily formed between a plurality of (two) protrusions 124 in one segment 123, leading to a decrease in the exhaust flow velocity. A decrease in the flow rate of the exhaust gas causes a decrease in heat transfer rate, and a wall surface shearing force for blowing off the unburned material decreases, which promotes the accumulation of unburned material on the wall surface.

  In view of the above problems, an object of the present invention is to improve the tip effect in the offset fin, eliminate the occurrence of a stagnant region of the exhaust flow, and further improve heat transfer performance and prevent accumulation of unburned substances. It is to provide a heat exchange device.

  In order to achieve the above object, the present invention employs the following technical means.

In the first aspect of the present invention, an exhaust passage (111) through which the exhaust discharged from the internal combustion engine (10) flows,
In addition to being disposed in the exhaust passage (111), the cross-sectional shape viewed from the exhaust flow direction is formed in a rectangular wave shape, and the wavy side surface portion (121) is offset in the wave continuous direction. And an offset type fin (120) formed with a plurality of segments (123).
In the exhaust heat exchange device for exchanging heat between the exhaust and the cooling fluid flowing outside the exhaust passage (111) (131),
On the wavy top surface portion (122) of the fin (120), a protruding portion (124) protruding inside the wavy shape is formed,
The protrusion (124) is a cut-and-raised portion (124) formed by cutting and raising from the top surface portion (122).
One cut and raised portion (124) is formed for one segment (123),
The segments (123) are arranged in a staggered pattern along the flow direction of the exhaust,
The cut-and-raised part (124) has a triangular shape, and the cut-and-raised side (124a) is arranged so as to be inclined with respect to the flow direction of the exhaust gas, and further toward the downstream side in the flow direction of the exhaust gas. It is formed so that the protruding amount is large,
The inclination direction of the side (124a) to be cut and raised is alternately different for each segment (123) arranged in the exhaust flow direction,
Of the segments (123) adjacent in the exhaust flow direction, the cut-and-raised portion (124) of the upstream segment (123) is located at the upstream end (121a) position of the side surface portion (121) of the downstream segment (123). It is characterized by being arranged so as to face each other.

In this way, since one cut-and-raised portion (124) is formed for one segment (123), the dimension in the flow direction of the exhaust gas of one segment (123) is made smaller than that of the prior art. Therefore, the tip effect at the upstream end (121a) of the so-called segment (123) can be sufficiently exerted. That is, since the dimension of one segment (123) in the exhaust flow direction can be reduced, the boundary formed on the side surface (121) of the segment (123) from the upstream end (121a) of the segment (123) toward the downstream side. It is possible to make the layer thinner, prevent a decrease in the flow rate of the exhaust gas on the downstream side, and improve the heat transfer coefficient in the heat exchange between the exhaust gas and the cooling fluid. Furthermore, since the flow rate of the exhaust gas can be prevented from being lowered, the wall surface shearing force for blowing off the unburned material can be maintained, and accumulation of unburned material on the side surface portion (121) can be prevented.

Further, since the vortex (turbulent flow) can be formed in the exhaust flow by the cut-and-raised portion (124), in addition to the above-mentioned tip effect, a turbulent flow forming effect is given to the exhaust, and the heat transfer coefficient is further increased. Can be improved. Further, due to the turbulent flow formation effect by the cut-and-raised part (124), the flow rate of the exhaust gas is increased, and the wall shear force for blowing off the unburned substance is increased, so that the accumulation of unburned substance on the side part (121) is further increased. Can be prevented.

Since one cut-and-raised portion (124) is formed for one segment (123), a plurality of cut-and-raised portions (124) in one segment (123) as described in the prior art are used. This does not cause a decrease in the flow rate of the exhaust gas. Therefore, the heat transfer coefficient is not reduced due to the decrease in the exhaust flow rate. Furthermore, since the flow rate of the exhaust gas is not reduced, the wall surface shear force for blowing off the unburned material can be maintained and the accumulation of unburned material can be prevented.

  In general, the tip effect of the offset type fin (120) can be enhanced, and the generation of the stagnant region of the exhaust flow can be eliminated, thereby further improving the heat transfer performance and preventing the accumulation of unburned substances.

Further, since the protrusion (124) is a cut-and-raised part (124) formed by cutting and raising from the top surface part (122), the fin (120) and the protrusion (124) can be integrally formed. Therefore, it is possible to respond at a low cost.

Further, the segments (123) are arranged in a staggered manner along the exhaust flow direction, the cut-and-raised portion (124) forms a triangle shape, and the cut-and-raised side (124a) flows through the exhaust. It is arranged so as to be inclined with respect to the direction, and is formed so that the protruding amount becomes larger toward the downstream side of the exhaust flow direction. The inclined direction of the side (124a) to be raised is Since each segment (123) arranged alternately in the flow direction is different , an effective vortex flow can be formed on the downstream side of the cut-and-raised part (124). Furthermore, since a meandering flow of exhaust gas can be formed in the offset direction in the exhaust passage (111), the heat transfer rate can be further improved.

As in the invention described in claim 2 , the exhaust gas is recirculation exhaust gas supplied to the intake side of the internal combustion engine (10).
The cooling fluid is suitable for use in an exhaust heat exchanger that uses cooling water to cool the internal combustion engine (10).

In the third aspect of the invention, the dimension (L1) of the segment (123) in the exhaust flow direction is not less than 1 and not more than 7 times the dimension (L2) of the cut-and-raised part (124) in the exhaust flow direction. It is characterized by being.

This enables effective vortex (turbulent flow) formation by the cut-and-raised part (124) and increase in the flow velocity of exhaust gas (increase in wall shearing force), and ensures accumulation of unburned material on the side surface part (121). Can be prevented.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows a corresponding relationship with the specific means of embodiment description mentioned later.

(First embodiment)
In the present embodiment, the exhaust heat exchanger according to the present invention is applied to an EGR gas cooling device (hereinafter referred to as an EGR gas cooler) 100 for a diesel engine 10. FIG. 1 is a schematic diagram showing an EGR (exhaust gas recirculation device) using an EGR gas cooling device 100 in the present embodiment.

  The EGR is an apparatus for reducing nitrogen oxides in exhaust gas provided in a vehicle engine (internal combustion engine) 10, and includes an exhaust gas recirculation pipe 11, an EGR valve 12, and an EGR gas cooler 100. The exhaust gas recirculation pipe 11 is a pipe that recirculates a part of the exhaust gas discharged from the engine 10 to the intake side of the engine 10.

  The EGR valve 12 is disposed in the middle of the exhaust gas flow in the exhaust gas recirculation pipe 11 and adjusts the amount of exhaust gas (hereinafter referred to as EGR gas) flowing through the exhaust gas recirculation pipe 11 according to the operating state of the engine 10. Is. The EGR gas cooler 100 is a heat exchanger that performs heat exchange between the EGR gas and the cooling water of the engine 10 to cool the EGR gas, and is disposed between the exhaust side of the engine 10 and the EGR valve 12. Yes.

  Next, the structure of the gas cooler 100 will be described with reference to FIGS. 2 is a front view showing the EGR gas cooler 100, FIG. 3 is a perspective view showing the appearance of the tube 110, and FIG. 4 is a perspective view showing the appearance of the inner fin 120. As shown in FIG.

  As shown in FIG. 2, the EGR gas cooler 100 includes a tube 110, an inner fin 120, a casing 130, a core plate 140, tank units 150 and 160, an inlet 170, an outlet 180, and the like. Each member is made of, for example, a stainless material having excellent heat resistance and corrosion resistance, and the contact portions of the members are joined to each other by brazing.

  As shown in FIG. 3, the tube 110 is a tube member that forms an exhaust passage 111 through which EGR gas flows, and a cross section that intersects the flow direction of the EGR gas is formed in a rectangular flat shape. The tube 110 is formed, for example, by joining the U-shaped opening side end portions of two tube plates 110A and 110B press-molded in a U-shape having a shallow cross section. A plurality of tubes 110 are stacked such that the long side surfaces (hereinafter referred to as facing surfaces) of the flat cross section face each other.

  Convex portions 112 and 113 projecting outward are formed on the opposing surface of the tube 110. The convex portions 112 and 113 are formed simultaneously with the press forming of the tube plates 110A and 110B.

  The convex portion 112 is provided on the EGR gas inflow side in the longitudinal direction of the tube 110 and close to the downstream side position of the cooling water inlet 170. The convex portion 112 is formed so as to extend in a direction intersecting the flow direction of the EGR gas on the opposite surface of the tube 110, and the position of the end portion in the longitudinal direction of the convex portion 112 is the short side of the flat cross section of the tube 110. Is set at a position having a predetermined interval with respect to the surface. The convex portion 112 partitions the vicinity of the inlet 170 when the cooling water flows into a relatively small space, so that the flow rate of the cooling water near the EGR gas inlet is increased.

  In addition, a plurality of convex portions 113 (a plurality of sets of two convex portions 113) are arranged at a predetermined interval toward the downstream side in the flow direction of the EGR gas with respect to the convex portion 112 (FIG. 2). The convex portion 113 is formed, for example, in an oval shape so as to partially protrude from the facing surface of the tube 110. In the tubes 110 that are stacked in a plurality, the convex portions 112 and the convex portions 113 are joined so that the top sides are in contact with each other (FIG. 2), so that the gap dimensions of the plurality of tubes 110 are appropriately maintained. It has become.

  The inner fin (fin) 120 is a heat transfer member that promotes heat exchange between the EGR gas and the cooling water, and is disposed in the tube 110, that is, in the exhaust passage 111. As shown in FIG. 4, the inner fin 120 is formed such that the cross-sectional shape viewed from the EGR gas flow direction is a rectangular wave shape by the side surface portion 121 and the top surface portion 122. The side surface portion 121 is a portion corresponding to the wavy vertical wall portion of the inner fin 120, and is a wall surface connecting the inner side surfaces of the opposing surfaces in the tube 110. The top surface portion 122 is a portion corresponding to the wavy peaks and valleys of the inner fin 120, and is a wall surface that is in contact with and joined to the inner surface of the opposing surface of the tube 110.

  The inner fin 120 is an offset type inner fin in which a plurality of segments 123 are formed in the wave peak direction by offsetting the side surface portion 121 in the wave continuous direction. The amount of offset is about half of the width of one wave. The plurality of offset segments 123 are arranged in a staggered manner (alternately) along the flow direction of the EGR gas. In addition, the wave width dimension of the segment 123 and the dimension in the flow direction of the EGR gas are set to the minimum dimensions that allow the protrusion 124 to be described later to be formed on the top surface part 122.

  The top surface portion 122 is formed with a protruding portion 124 that protrudes inwardly in a wavy shape. One protrusion 124 is formed for one segment 123. Of the segments 123 adjacent to each other in the EGR gas flow direction, the protruding portion 124 of the upstream segment 123 is disposed so as to face the position of the front end portion (upstream end) 121a of the side surface portion 121 of the downstream segment 123. (FIGS. 5 and 6).

  Furthermore, the protrusion part 124 is formed here as the cut-and-raised part 124 formed by cutting and raising from the top surface part 122. The cut-and-raised portion 124 is formed in a triangular shape, and hereinafter, this cut-and-raised portion 124 is referred to as a wing 124. In the triangular wing 124, one side to be raised (hereinafter, the raised side) 124a is disposed so as to be inclined with respect to the flow direction of the EGR gas, and the wing that has been raised and raised. The protruding amount of 124 is set so as to increase toward the downstream side in the flow direction of the EGR gas. In addition, the inclination direction of the cut and raised side 124a is set to be alternately different with respect to the segments 123 arranged in the EGR gas flow direction.

  Further, as shown in FIG. 6, the dimension of the EGR gas in the direction of flow of the segment 123 is L1 (hereinafter referred to as segment dimension L1), and the dimension of the wing 124 in the direction of flow of EGR gas is L2 (exhaust flow direction dimension of the protrusion). In the following description, the segment dimension L1 is set to be not less than 1 and not more than 7 times the wing dimension L2 when the wing dimension L2) is adopted. Further, it is desirable that the segment dimension L1 is 1 to 4 times the wing dimension L2. Note that the above dimension setting of 1 or more means that the wing 124 in the segment 123 can be substantially formed, and the segment dimension L1 and the wing dimension L2 are made equal.

  As shown in FIG. 2, the casing 130 stores therein a stacked body of the tubes 110 that are stacked and joined together by the convex portions 112 and the convex portions 113, and is cooled around the stacked body of the tubes 110. It is a rectangular pipe-shaped container body that forms a cooling water passage 131 through which water flows. The cooling water passage 131 is a passage formed between the tube 110 and the tube 110 and between the tube 110 and the casing 120.

  The core plate 140 is a pair of plate members formed in a shallow arm shape and having a plurality of tube holes drilled on the bottom surface side of the arm shape. The plurality of tubes 110 are held by the pair of core plates 140 by having both end portions in the longitudinal direction of the plurality of stacked tubes 110 penetrate through the tube holes of the pair of core plates 140. The pair of core plates 140 are joined to the inner peripheral surfaces of both opening end portions in the longitudinal direction of the casing 130. A pair of core plates 140 partitions a cooling water passage 131 in the casing 130 and internal spaces of tank units 150 and 160 described later.

  The inflow side tank unit 150 is a funnel-shaped member that distributes and supplies EGR gas to each tube 110, and the end of the funnel-shaped large opening area is one end side in the longitudinal direction of the casing 130 (the left side in FIG. 2). ) (Specifically, the opening side inner peripheral surface of the core plate 140). A joint portion 151 for connecting to an intermediate portion of the exhaust gas recirculation pipe 11 is joined to an end portion of the inflow side tank portion 150 on the side having a small funnel-shaped opening area.

  The outflow side tank section 160 is a funnel-shaped member that collects EGR gas flowing out from each tube 110, and the end of the funnel-shaped large opening area is the other end side in the longitudinal direction of the casing 130 (FIG. 2). To the right side) (specifically, the opening side inner peripheral surface of the core plate 140). A joint portion 161 for connecting to an intermediate portion of the exhaust gas recirculation pipe 11 is joined to the end portion of the outflow side tank portion 160 on the side having a small funnel-like opening area.

  The inflow port 170 is a pipe member that introduces cooling water into the cooling water passage 131, and the EGR gas of the casing 130 is communicated with the inside of the inflow port 170 and the inside of the casing 130 (cooling water passage 131). It is joined to the inflow side. The inflow port 170 is set in a direction along the opposing surface of the tubes 110 in which the axial direction is laminated.

  Outflow port 180 is a pipe member that causes the cooling water flowing through cooling water passage 131 to flow out to the outside. Casing 130 is arranged so that the inside of outflow port 180 communicates with the inside of casing 130 (cooling water passage 131). It is joined to the outflow side of the EGR gas. The outflow port 180 is set in a direction orthogonal to the facing surface of the tube 110 in which the axial direction is laminated.

  Next, the operation and effects of the EGR gas cooler 100 based on the above configuration will be described with reference to FIGS. 5 and 6 are model diagrams schematically showing the flow of EGR gas in the inner fin 120.

  In the EGR gas cooler 100 of the present embodiment, when the EGR valve 12 is opened, EGR gas that is a part of the exhaust flows from the inflow side tank unit 150, and the EGR gas is distributed to each tube 110. The exhaust passage 111 is circulated. Then, the EGR gas that has passed through the exhaust passage 111 is collected in the outflow side tank unit 160, passes through the EGR valve 12, and is supplied to the intake side of the engine 10.

  On the other hand, the cooling water of the engine 10 flows into the casing 130 from the inlet 170, and the cooling water that has flowed in passes through the cooling water passage 131, flows out of the outlet 180, and returns to the engine 10.

  At this time, heat exchange is performed between the EGR gas flowing through the exhaust passage 111 and the cooling water flowing through the cooling water passage 131, thereby cooling the EGR gas. By supplying the EGR gas cooled as described above to the intake side of the engine 10, the maximum temperature during combustion of the engine 10 is reduced, and the amount of nitrogen oxides generated is reduced.

  As shown in FIGS. 5 and 6, the EGR gas flowing through the exhaust passage 111 forms a vortex when passing (overcoming) the wing 124 (protrusion) of the inner fin 120. In the main wing 124, the vortex is formed so as to wrap around the inclined side of the wing 124 toward the downstream side. At this time, the flow of the EGR gas when passing through one wing 124 becomes an inclined flow along the inclination direction of the wing 124 due to the vortex.

  The EGR gas that has passed through one wing 124 in one segment 123 hits the tip 121a of the adjacent downstream segment 123, forms a turbulent flow, and passes through the downstream wing 124.

  Here, in this embodiment, the segments 123 of the inner fins 120 are arranged in a staggered manner along the EGR gas flow direction, and the inclination directions of the cut-and-raised sides 124a of the wings 124 of each segment 123 are alternated. Therefore, the inclination direction of the flow is alternately changed for each wing 124, and the flow of the EGR gas becomes a meandering flow in the offset direction when viewed in the entire exhaust passage 111. Since the wings 124 in the inner fin 120 are formed on the upper and lower top surface portions 122 in FIG. 4, the flow of EGR gas becomes a meandering flow in the direction connecting the opposing top surface portions 122.

  In the inner fin 120 of the present embodiment that forms the flow of EGR gas as described above, one protrusion (wing 124) is formed for one segment 123. Therefore, EGR of one segment 123 is formed. The dimension (segment dimension L1) in the gas flow direction can be made smaller than that of the conventional technique. Therefore, the tip effect at the tip 121a of the so-called segment 123 can be sufficiently exhibited. That is, since the dimension of one segment 123 in the EGR gas flow direction can be reduced, the boundary layer formed on the side surface portion 121 of the segment 123 from the front end portion 121a of the segment 123 toward the downstream side can be made thinner. The flow rate of the EGR gas on the side can be prevented from decreasing, and the heat transfer coefficient in heat exchange between the EGR gas and the cooling water can be improved. Furthermore, since the decrease in the flow rate of the EGR gas can be prevented, the wall surface shearing force for blowing off the unburned material can be maintained, and the accumulation of unburned material on the side surface portion 121 can be prevented.

  Moreover, since the vortex (turbulent flow) can be formed in the exhaust flow by the protrusion (wing 124), in addition to the above-mentioned tip effect, a turbulent flow forming effect is given to the exhaust, and the heat transfer rate is further increased. Can be improved. Furthermore, the turbulent flow formation effect by the protrusion (wing 124) increases the flow rate of EGR gas, increases the wall shear force for blowing off the unburned material, and further prevents the accumulation of unburned material on the side surface 121. can do.

  Since one projection 123 (wing 124) is formed for one segment 123, the EGR gas between the plurality of projections (wing 124) in one segment 123 as described in the prior art. This does not cause a decrease in the flow rate. Therefore, the heat transfer rate is not reduced due to the decrease in the flow rate of the EGR gas. Furthermore, since the flow rate of the EGR gas is not reduced, the wall surface shear force for blowing off the unburned material can be maintained, and accumulation of unburned material on the wall portion of the inner fin 120 can be prevented.

  In general, the tip effect of the offset type inner fin 120 can be enhanced, and the occurrence of the stagnant region of the EGR gas flow can be eliminated, thereby further improving the heat transfer performance and preventing the accumulation of unburned substances.

  Further, in the present embodiment, since the protruding portion of the inner fin 120 is formed as the wing 124 by cutting and raising, the inner fin 120 and the wing 124 can be integrally formed, and an inexpensive response is possible. Become.

  In the present embodiment, the segments 123 are arranged in a zigzag pattern along the flow direction of the EGR gas. Further, the wing 124 has a triangular shape, and the cut-and-raised side 124a is disposed so as to be inclined with respect to the flow direction of the EGR gas, and the amount of protrusion increases as it becomes downstream in the flow direction of the EGR gas. Furthermore, the inclination direction of the cut and raised side 124a is alternately different from the flow direction of the EGR gas.

  Therefore, an effective vortex flow can be formed on the downstream side of the wing 124. Furthermore, in the exhaust passage 111, the meandering flow of the exhaust gas can be formed in the offset direction in addition to the direction connecting the opposing top surface portions 122, so that the heat transfer rate can be further improved.

  In setting the dimensions of the segment 123 and the protrusion (wing) 124, the segment dimension L1 is set to be 1 to 7 times (preferably 1 to 4 times) of the wing dimension L2. The formation of effective vortices (turbulent flow) by 124 and the increase in the flow rate of EGR gas (increase in the wall shearing force) are enabled, and the accumulation of unburned substances on the side surface portion 121 can be reliably prevented.

(Other embodiments)
In the first embodiment, the protrusions of the inner fin 120 are formed as the wings 124 formed by cutting and raising, but the present invention is not limited to this, and the protrusions may be formed from the top surface portion 122 by, for example, pressing. Further, the protruding portion may be formed as a separate part and joined to the top surface portion 122.

  Further, the protrusion is not limited to a triangular shape like the wing 124, but may be a quadrangular shape, a semicircular shape, or the like. Furthermore, although the wings 124 are disposed so as to be inclined with respect to the flow direction of the EGR gas, they may be disposed so as to be orthogonal to the flow direction of the EGR gas.

  In the inner fin 120, the plurality of segments 123 are arranged in a staggered manner along the flow direction of the EGR gas, but may be offset in one direction.

  In addition, as the EGR gas cooling device 100, both ends of a plurality of tubes 110 are penetrated and joined to the core plate 140, and a cooling water passage 131 is formed between the tubes 110 by the casing 130 and the core plate 140. However, the present invention is not limited to this. For example, a weir-like bulging portion that bulges outward is formed at the outer peripheral portion of the facing surface of each tube 110, and the bulging portions that face each other when the tubes 110 are stacked are joined together, It is also possible to apply to an EGR gas cooling apparatus in which the core plate 140 is eliminated by forming a space in the space and using the space as the cooling water passage 131.

  Moreover, although the target engine in EGR (exhaust gas recirculation apparatus) was demonstrated as a diesel engine, it is good also as a gasoline engine.

  Moreover, although demonstrated as what utilizes the cooling water of the engine 10 as a cooling fluid of the EGR gas cooling device 100, it is not restricted to this, The cooling water of the exclusive cooling water circuit formed independently of the engine 10 is utilized. It is good as a thing. Examples of the dedicated cooling water circuit include a circuit including a sub radiator and a dedicated pump.

  In addition, the exhaust gas heat exchanger is applied to the EGR gas cooling device 100 that cools the EGR gas with cooling water. However, heat is exchanged between the exhaust gas and a predetermined heating object, and the heating object is positively driven by the exhaust heat. The present invention may be applied to an exhaust heat recovery apparatus that heats the heat. Examples of the heating target include engine coolant immediately after the vehicle is started, engine oil, A / T fluid, and the like.

It is a schematic diagram which shows EGR (exhaust gas recirculation apparatus) using the EGR gas cooling device in 1st Embodiment. It is a front view which shows an EGR gas cooler. It is a perspective view which shows the external appearance of a tube. 2 is a perspective view showing an outer appearance of an inner fin 120. FIG. It is a model figure which shows typically the mode of the flow of EGR gas in an inner fin (three-dimensional figure). It is a model figure which shows typically the mode of the flow of EGR gas in an inner fin (plan view). It is a model figure which shows typically the mode of the flow of EGR gas in a prior art.

Explanation of symbols

10 Engine (Internal combustion engine)
100 EGR gas cooling device (exhaust heat exchange device)
111 Exhaust passage 120 Inner fin (fin)
121 Side part 121a Tip part (upstream end)
122 Top surface part 123 Segment 124 Wing (protrusion part, cut and raised part)
L1 segment dimensions (dimensions in the flow direction of the segment exhaust)
L2 Wing dimensions (dimension in the flow direction of the exhaust of the protrusion)

Claims (3)

An exhaust passage (111) through which the exhaust discharged from the internal combustion engine (10) flows;
In addition to being disposed in the exhaust passage (111), the cross-sectional shape as viewed from the flow direction of the exhaust gas is formed in a rectangular wave shape, and the wavy side surface portion (121) is offset in the direction in which the waves continue. An offset type fin (120) formed with a plurality of segments (123),
In the exhaust heat exchange device for exchanging heat between the exhaust and the cooling fluid flowing through the outside (131) of the exhaust passage (111),
A projection (124) projecting inwardly into the wavy shape is formed on the wavy top surface portion (122) of the fin (120), and
The protrusion (124) is a cut and raised portion (124) formed by cutting and raising from the top surface portion (122).
One cut and raised portion (124) is formed for one segment (123),
The segments (123) are arranged in a staggered manner along the flow direction of the exhaust,
The cut-and-raised portion (124) has a triangular shape and is arranged such that a side to be raised (124a) is inclined with respect to the flow direction of the exhaust gas, and is downstream of the flow direction of the exhaust gas. It is formed so that the protruding amount becomes larger as
The inclination direction of the side to be raised (124a) is alternately different with respect to the segments (123) arranged in the exhaust flow direction,
Of the segments (123) adjacent in the exhaust flow direction, the cut-and-raised portion (124) of the upstream segment (123) is the upstream end (121a) of the side surface portion (121) of the downstream segment (123). ) An exhaust heat exchanger characterized by being arranged to face the position. The exhaust is recirculation exhaust supplied to the intake side of the internal combustion engine (10),
The exhaust heat exchanger according to claim 1, wherein the cooling fluid is cooling water for cooling the internal combustion engine (10). The dimension (L1) of the segment (123) in the flow direction of the exhaust gas is 1 to 7 times the dimension (L2) of the cut-and-raised part (124) in the flow direction of the exhaust gas. The exhaust heat exchanger according to claim 1 or 2 .

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