JP2007285264A - Heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat exchanger inhibiting increase of flow resistance of low temperature fluid due to heat exchange with high temperature fluid. <P>SOLUTION: In a heat exchanger 10 for exhaust heat recovery, an exhaust gas heat exchanger path 38 for circulating exhaust gas which is high temperature fluid and a cooling water heat exchange path 44 for circulating engine cooling water which is low temperature fluid exchanging heat with exhaust gas are adjacently provided. Channel cross-sectional area of the cooling water heat exchange path 44 is continuously expanded from an upstream side toward a downstream side in a flow direction of engine cooling water. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a heat exchanger applied to an exhaust heat recovery device or the like for recovering exhaust heat by performing heat exchange between an exhaust gas of an automobile or the like and a coolant.

A technique in which a heat exchanger for exhaust gas and cooling water is disposed in an exhaust gas passage of exhaust gas is known (for example, see Patent Document 1). In this technique, exhaust heat is recovered while cooling water flows in the same direction as the exhaust gas in a cooling water channel formed in a straight tubular shell covering a plurality of straight tubular bodies through which exhaust gas flows. It is like that.
JP 2004-293395 A

  However, the conventional technology as described above has a problem that the cooling water received from the exhaust gas expands and the water flow resistance increases.

  In view of the above fact, an object of the present invention is to obtain a heat exchanger that can suppress an increase in flow resistance of a low temperature fluid due to heat exchange with a high temperature fluid.

  The heat exchanger according to claim 1 is capable of exchanging heat between a high-temperature side channel for circulating a high-temperature fluid, a low-temperature fluid flowing through the inside, and a high-temperature fluid flowing through the high-temperature side channel. A low-temperature side channel provided adjacent to the high-temperature side channel and having a channel cross-sectional area continuously or stepwise expanded from the upstream side to the downstream side in the flow direction of the low-temperature fluid. ing.

  In the heat exchanger according to claim 1, the high temperature fluid is cooled (dissipates heat) and the low temperature fluid is heated (receives heat) by heat exchange between the high temperature fluid and the low temperature fluid. This heating causes the cryogenic fluid to expand in volume. Here, since the cold-side flow path through which the low-temperature fluid flows has a shape (tapered shape, etc.) in which the cross-sectional area of the flow path expands continuously or stepwise from the upstream to the downstream of the low-temperature fluid, the volume of the low-temperature fluid An increase in flow resistance due to expansion is suppressed.

  Thus, in the heat exchanger according to claim 1, it is possible to suppress an increase in the flow resistance of the low temperature fluid due to heat exchange with the high temperature fluid (a reduction in the flow resistance). On the other hand, since the volume of the high-temperature fluid is reduced by heat radiation, an increase in flow resistance does not become a problem. In addition, the requirement that the flow path cross-sectional area is continuously or stepwise expanded from the upstream side to the downstream side in the flow direction of the low-temperature fluid is that the downstream side of the upstream side in the flow direction of the low-temperature fluid. This indicates that the channel cross-sectional area is enlarged from the upstream side to the downstream side in the flow direction of the low-temperature fluid so that the portion where the channel cross-sectional area becomes small is not formed. May be indefinite. Therefore, for example, the flow path wall of the low temperature side flow path may be a straight line inclined with respect to the flow direction in a cross-sectional view, may be a polygonal line having a change point of the inclination angle, or may be a curved line. It may be a stepped shape.

  The heat exchanger according to a second aspect of the present invention is the heat exchanger according to the first aspect, wherein the high temperature side flow path has a flow path cross-sectional area from the upstream side to the downstream side in the flow direction of the low temperature fluid. Reduced continuously or stepwise.

  In the heat exchanger according to claim 2, the low-temperature flow path is expanded to the downstream side so as to protrude toward the adjacent high-temperature flow path via a partition wall (tube wall or the like). Therefore, it does not increase in size as a whole. Therefore, for example, the channel cross-sectional area of the low temperature side channel can be expanded toward the downstream side while keeping the outer diameter of the outer shell (shell, etc.) constant.

  The heat exchanger according to a third aspect of the present invention is the heat exchanger according to the second aspect, wherein the flow direction of the low-temperature fluid and the flow direction of the high-temperature fluid are the same direction.

  In the heat exchanger according to claim 3, since the low-temperature fluid and the high-temperature fluid flow in the same direction (the high-temperature fluid and the low-temperature fluid coincide with each other on the upstream and downstream sides), The cross-sectional area of the channel increases continuously or stepwise from the upstream side to the downstream side, while the cross-sectional area of the high-temperature side channel decreases continuously or stepwise from the upstream side to the downstream side. Yes. As a result, the high-temperature flow path has a large flow-path cross section on the upstream side where the high-temperature fluid is hot (relatively large in volume), and the flow-path cross section gradually decreases toward the downstream where the volume decreases with heat exchange. Since it shrinks, an increase in the high-temperature side flow resistance due to the low-temperature side channel extending from the high-temperature side channel is prevented. That is, it is possible to reduce the flow resistance of the low-temperature fluid while maintaining the size of the entire heat exchanger and preventing an increase in the flow resistance of the high-temperature fluid.

  As described above, the heat exchanger according to the present invention has an excellent effect that an increase in flow resistance of a low temperature fluid due to heat exchange with a high temperature fluid can be suppressed.

  An exhaust heat recovery heat exchanger 10 as a heat exchanger according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. In the following description, when the terms upstream and downstream are simply used, they indicate upstream and downstream in the flow direction of the exhaust gas.

  FIG. 2 shows a schematic overall flow diagram of the exhaust heat recovery system 18 to which the exhaust heat recovery heat exchanger 10 is applied. As shown in this figure, an exhaust heat recovery system 18 recovers heat of exhaust gas as a high-temperature fluid of an internal combustion engine 12 of an automobile by heat exchange with engine cooling water as a low-temperature fluid (cooling medium). It is a device used for heating and promoting warm-up of the engine 12.

  The engine 12 is connected to an exhaust pipe 14 that constitutes an exhaust path for leading exhaust gas. A catalytic converter 16, an exhaust heat recovery heat exchanger 10, and a main muffler 20 are arranged in this order from the upstream side on the exhaust gas discharge path by the exhaust pipe 14. The catalytic converter 16 is configured to purify exhaust gas passing therethrough by a built-in catalyst 16A. The main muffler 20 as a silencer is configured to reduce the exhaust noise generated when exhaust gas is discharged into the atmosphere.

  The exhaust heat recovery heat exchanger 10 is configured to recover the heat of the exhaust gas to the engine coolant by heat exchange between the exhaust gas and the engine coolant. The exhaust heat recovery heat exchanger 10 is provided with a bypass flow path 22 for exhaust gas and a flow path switching valve 24 as a flow path switching device for opening and closing the bypass flow path 22. The exhaust heat recovery mode in which the exhaust gas exchanges heat with the engine coolant and the normal mode in which the exhaust gas passes through the bypass flow path 22 can be switched. This will be specifically described below.

  As shown in FIGS. 1 (A) and 1 (B), the exhaust heat recovery heat exchanger 10 is formed in a cylindrical shape and is arranged concentrically and an outer tube 28 as a shell. A heat exchanging unit 30 for exchanging heat between the exhaust gas and the engine coolant is formed between the inner cylinder 26 and the outer cylinder 28.

  The inner cylinder 26 is disposed so that the axial direction coincides with the horizontal direction (for example, the longitudinal direction of the vehicle body), passes through the axial center portion of the outer cylinder 28, and both ends in the axial direction are connected to the exhaust pipe 14. Are continuous. The inner cylinder 26 may be configured as a part of the exhaust pipe 14. The exhaust heat recovery heat exchanger 10 has an upstream end fixed to the outer periphery of the inner cylinder 26 in an airtight state and a downstream end connected to the upstream end 28A of the outer cylinder 28, and a downstream end A conical cylinder 34 is fixed to the outer periphery of the inner cylinder 26 in an airtight state and has an upstream end connected to a downstream end 28 </ b> B of the outer cylinder 28.

  The heat exchanger 30 in the exhaust heat recovery heat exchanger 10 is formed between an exhaust gas inlet header 36, which is a space between the inner cylinder 26 and the conical cylinder 32, and the inner cylinder 26 and the outer cylinder 28. Exhaust gas heat exchange path 38 as a high-temperature side flow path that is a substantially cylindrical space (a space excluding the portion occupied by a cooling water pipe 42 to be described later), and an exhaust gas that is a space between the inner cylinder 26 and the conical cylinder 34. A gas outlet header 40 is formed. On the other hand, the inside of the inner cylinder 26 is the bypass channel 22 described above. The inner cylinder 26 is provided in an inner portion of the conical cylinder 32 and communicates with an exhaust gas inlet header 36, and is provided in an inner portion of the conical cylinder 34 and communicates with an exhaust gas outlet header 40. The heat exchanger outlet hole 26B is formed.

  A cooling water pipe 42 is disposed in the exhaust gas heat exchange path 38, and a cooling water heat exchange path 44 as a low-temperature side flow path that is a flow path of engine cooling water in the exhaust heat recovery heat exchanger 10 is provided. It is composed. In this embodiment, the cooling water pipe 42 forms a cylindrical cooling water heat exchange path 44 that covers the inner cylinder 26 inside the double cylinder. More specifically, the cooling water pipe 42 includes a substantially cylindrical inner water pipe 42A, an outer water pipe 42B formed in a conical (conical cylinder) shape, and axial end portions of the inner water pipe 42A and the outer water pipe 42B. And a pair of lid plates 42C for closing. Thus, the cooling water heat exchange path 44 surrounded by the inner water pipes 42A, 42B, and 42C of the cooling water pipe 42 has a channel cross-sectional area that continuously (gradually) expands from one side in the axial direction toward the lower side. ing.

  In the exhaust heat recovery heat exchanger 10, the side with the smaller flow path cross-sectional area in the cooling water heat exchange path 44 is the upstream side in the flow direction of the engine cooling water, and the flow path cross-sectional area in the cooling water heat exchange path 44 is larger. Macroscopically, the engine cooling water flows along the axial direction in the cylindrical cooling water heat exchange path 44 so that the side is the downstream side in the flow direction of the engine cooling water. In this embodiment, the flow direction of the engine cooling water coincides with the flow direction of the exhaust gas, and the exhaust heat recovery heat exchanger 10 is a parallel flow heat exchanger.

  Therefore, the exhaust gas heat exchange path excluding the portion occupied by the cooling water pipe 42 (cooling water heat exchange path 44) in the cylindrical space formed between the outer cylinder 28 and the inner cylinder 26 formed in a cylindrical shape as described above. No. 38 has a channel cross-sectional area that gradually decreases from upstream to downstream in the exhaust gas flow direction. The cooling water pipe 42 described above is connected to the inlet port 46 provided in the upstream portion in the cooling water flow direction through the outer cylinder 28, and the downstream portion in the cooling water flow direction passes through the outer cylinder 28. The outlet port 48 is connected to the outlet port 48.

  In the exhaust heat recovery heat exchanger 10 described above, when the flow path switching valve 24 closes the inner cylinder 26 (bypass flow path 22), the exhaust gas flows into the exhaust gas heat exchange path 38. When the heat exchange function is performed and the flow path switching valve 24 opens the inner cylinder 26, the exhaust gas mainly flows through the bypass flow path 22 to perform the exhaust gas bypass function. Note that the flow resistance (pressure loss) of the exhaust gas heat exchange path 38 provided with the cooling water pipe 42 is larger than the flow resistance of the opened bypass flow path 22, and the flow path switching valve 24 connects the inner cylinder 26. When it is open, almost no exhaust gas flows through the exhaust gas heat exchange path 38.

  The flow path switching valve 24 is controlled by an ECU as a control device (not shown). For example, when a warm-up promotion request is made for the engine 12, a heating request is made when the engine coolant temperature is low, etc. 22 is closed (exhaust heat recovery mode is selected). Further, for example, when the engine coolant temperature rises and exceeds the threshold, the ECU opens the flow path switching valve 24 to open 22 (switch from the exhaust heat recovery mode to the normal mode). .

  On the other hand, the exhaust heat recovery system 18 includes a front heater core 50 and a rear heater core 52 that recover the heat of the engine coolant for heating, and a heater hot water passage 54 that circulates the engine coolant to the front heater core 50 and the rear heater core 52. Yes. The front heater core 50 and the rear heater core 52 are arranged in parallel. The exhaust heat recovery heat exchanger 10 is disposed downstream of the rear heater core 52 in the heater hot water passage 54. That is, the inlet port 46 is disposed on the heater warm water passage 54 on the rear heater core 52 side, and the outlet port 48 is disposed on the heater warm water passage 54 on the upstream side of the engine 12. In this embodiment, the exhaust heat recovery heat exchanger 10 is arranged in parallel to the front heater core 50 and in series to the rear heater core 52 in the engine cooling water system.

  Therefore, in the exhaust heat recovery system 18, the engine cooling water flows as shown by the arrows on the heater hot water passage 54 in FIG. As a result, when hot hot water that has passed through the engine 12 passes through the front heater core 50 and the rear heater core 52, heat is exchanged and used for heating, and engine cooling water that has been cooled at the rear heater core 52 is used for heat recovery for exhaust heat recovery. It is the structure which is introduce | transduced into the container 10 and heat-exchanges with said exhaust gas. The engine coolant that has passed through the exhaust heat recovery heat exchanger 10 is returned to the engine 12 together with the engine coolant that has passed through the front heater core 50. Thus, the exhaust heat recovery heat exchanger 10 is configured to function as a preheater that preheats the engine coolant before being heated by the engine 12 from the viewpoint of the heating function, for example.

  Next, the operation of the first embodiment will be described.

  In the exhaust heat recovery system 18 configured as described above, when the engine coolant temperature is low, such as immediately after the engine 12 is started, the ECU closes the flow path switching valve 24 based on, for example, a heating request or a warm-up promotion request for the engine 12. Driven to close the bypass passage 22. That is, the exhaust heat recovery mode is selected. Then, the exhaust gas of the engine 12 does not flow through the bypass flow path 22 but is introduced into the exhaust gas heat exchange path 38 of the exhaust heat recovery heat exchanger 10. The exhaust gas introduced into the exhaust gas heat exchange path 38 exchanges heat with the engine coolant in the exhaust heat recovery heat exchanger 10 to heat the engine coolant. Thereby, heating is accelerated | stimulated or the warming-up of the engine 12 is accelerated | stimulated.

  By this heat exchange, the exhaust gas radiates heat to the engine cooling water, for example, the temperature is lowered (cooled) from about 400 ° C. to about 100 ° C. and the volume is reduced. On the other hand, the engine cooling water is The temperature is increased from about 80 ° C. to 82 ° C. to 83 ° C., and the volume expands.

  Here, in the heat exchanger 10 for exhaust heat recovery, the flow passage cross-sectional area of the cooling water heat exchange passage 44 is continuously enlarged from upstream to downstream, so that heat exchange with the exhaust gas of the engine cooling water is performed. An increase in flow resistance (water flow resistance) of the engine cooling water due to volume expansion accompanying (heat reception) is prevented or significantly suppressed. That is, the volume expansion accompanying the flow of the engine coolant downstream is absorbed by the capacity expansion toward the downstream of the coolant heat exchange path 44.

  Thereby, the load of the water pump that drives the engine coolant is reduced. In particular, an automobile using an electric pump having a small capacity as a water pump compared with a mechanical pump mechanically driven by the engine 12 (for example, an electric motor in addition to the engine 12 as a driving source for wheels, and running) In the case of a hybrid vehicle or the like that may stop the engine 12 in the middle), the load reduction effect of the electric pump by reducing the flow resistance of the engine cooling water is large, and thus the contribution to the improvement of the fuel consumption of the applied vehicle is large. .

  Thus, in the heat exchanger 10 for exhaust heat recovery according to the first embodiment of the present invention, it is possible to suppress an increase in the flow resistance of engine cooling water due to heat exchange with the exhaust gas.

  On the other hand, in the heat exchanger 10 for exhaust heat recovery, the flow passage cross-sectional area of the exhaust gas heat exchange path 38 is continuously reduced from upstream to downstream. In other words, the cooling water heat exchange path 44 is Although the exhaust gas heats out to the exhaust gas heat exchange path 38 more downstream, the exhaust gas is reduced in volume by heat exchange with the engine coolant as described above, so that the exhaust resistance does not increase. As a result, fuel consumption deterioration due to an increase in exhaust resistance is also prevented.

  The exhaust heat recovery heat exchanger 10 is a parallel flow type heat exchanger in which the flow directions of the exhaust gas heat exchange path 38 and the cooling water heat exchange path 44 coincide with each other. A configuration has been realized in which the cross-sectional area of the cooling water heat exchange path 44 is gradually increased toward the downstream while the path cross-sectional area is gradually reduced toward the downstream side. As a result, the heat exchanger 10 for exhaust heat recovery is a heat exchanger in which the cross-sectional areas of the exhaust gas heat exchange path 38 and the cooling water heat exchange path 44 are constant in each part in the flow direction and the heat exchange performance is equivalent. In comparison, the above-described effects (functions) can be achieved without increasing the outer diameter of the outer cylinder 28, in other words, without increasing the mounting space of the automobile.

  Next, another embodiment of the present invention will be described. In addition, the same reference numerals as those in the first embodiment or the above-described configuration are used for the parts / parts basically the same as those in the first embodiment or the above-mentioned configuration, and the description and illustration are omitted. There is.

(Second Embodiment)
FIG. 3 is a side sectional view showing an exhaust heat recovery heat exchanger 60 according to a second embodiment of the present invention. As shown in this figure, the exhaust heat recovery heat exchanger 60 is a counter flow type heat exchanger in which the flow direction of the exhaust gas and the flow direction of the engine cooling water are opposite to each other. It differs from the heat exchanger 10 for exhaust heat recovery which is an exchanger.

  Specifically, in the heat exchanger 60 for exhaust heat recovery, the cooling water pipe 42 is disposed in the exhaust gas heat exchange path 38 in the direction opposite to the direction in the heat exchanger 10 for exhaust heat recovery, and the inlet port 46 Is disposed downstream of the outlet port 48 in the exhaust gas flow. Thus, the exhaust heat recovery heat exchanger 60 is configured such that the flow passage cross-sectional area of the exhaust gas heat exchange passage 38 is gradually enlarged toward the downstream side (upstream side of the engine cooling water). Other configurations of the exhaust heat recovery heat exchanger 60 are the same as the corresponding configurations of the exhaust heat recovery heat exchanger 10.

  Therefore, the exhaust heat recovery heat exchanger 60 according to the second embodiment also reduces the flow resistance of the engine cooling water by the same action as the exhaust heat recovery heat exchanger 10 according to the first embodiment. Similar effects can be obtained. Further, since the exhaust heat recovery heat exchanger 60 is a counterflow type heat exchanger, the heat exchange efficiency is better than that of the exhaust heat recovery heat exchanger 10. Furthermore, in the heat exchanger 10 for exhaust heat recovery, since the cooling water heat exchange path 44 is configured (arranged) inside the cylindrical outer cylinder 28, the mounting space of the automobile is not increased. Furthermore, the exhaust heat recovery heat exchanger 60 also increases the exhaust gas exhaust resistance with the flow of the exhaust gas heat exchange path 38 (due to the shape of the exhaust gas heat exchange path 38 itself). There is no.

(Third embodiment)
FIG. 4 is a side sectional view showing an exhaust heat recovery heat exchanger 70 according to a third embodiment of the present invention. As shown in this figure, an exhaust heat recovery heat exchanger 70 is a conical shape whose inner diameter is continuously increased from the downstream side to the upstream side in the exhaust gas flow direction instead of the cylindrical outer cylinder 28. This is different from the exhaust heat recovery heat exchanger 60 according to the second embodiment in that an outer cylinder 72 is provided.

  The outer cylinder 72 has an average inner diameter substantially equal to the inner diameter of the outer cylinder 28, and the taper angle thereof is equal to or slightly smaller than the taper angle of the outer water pipe 42B (the outer peripheral side of the cooling water heat exchange path 44). It is said that. As a result, the exhaust gas heat exchange passage 38 of the exhaust heat recovery heat exchanger 70 has a substantially constant cross-sectional area in each part of the exhaust gas flow direction. Other configurations of the exhaust heat recovery heat exchanger 70 are the same as the corresponding configurations of the exhaust heat recovery heat exchanger 60.

  Therefore, the exhaust heat recovery heat exchanger 70 according to the third embodiment also reduces the flow resistance of the engine cooling water by the same action as the exhaust heat recovery heat exchanger 10 according to the first embodiment. Similar effects can be obtained. Further, in the exhaust heat recovery heat exchanger 70 provided with the outer cylinder 72, compared to the exhaust heat recovery heat exchanger 60, the flow path cross-sectional area at the upstream end (exhaust gas inlet) of the exhaust gas heat exchange path 38. Therefore, the throttle part of the exhaust gas flow is not formed (the throttle effect is suppressed). For this reason, in the counterflow type heat exchanger having better heat exchange efficiency than the parallel flow type heat exchanger, it is possible to prevent the back pressure from increasing due to the throttling effect at the inlet of the exhaust gas heat exchange path 38.

(Fourth embodiment)
FIG. 5 is a side sectional view showing an exhaust heat recovery heat exchanger 80 according to a fourth embodiment of the present invention. As shown in this figure, an exhaust heat recovery heat exchanger 80 is a conical shape whose inner diameter is continuously enlarged from the upstream side to the downstream side in the exhaust gas flow direction instead of the cylindrical outer cylinder 28. This is different from the heat exchanger 10 for exhaust heat recovery according to the first embodiment in that an outer cylinder 82 is provided.

  The outer cylinder 82 has an average inner diameter substantially equal to the inner diameter of the outer cylinder 28, and the taper angle thereof is equal to or slightly smaller than the taper angle of the outer water pipe 42B (the outer peripheral side of the cooling water heat exchange path 44). It is said that. As a result, the exhaust gas heat exchange path 38 of the heat exchanger 80 for exhaust heat recovery has a substantially constant cross-sectional area in each part of the exhaust gas flow direction. Other configurations of the exhaust heat recovery heat exchanger 80 are the same as the corresponding configurations of the exhaust heat recovery heat exchanger 10.

  Therefore, the exhaust heat recovery heat exchanger 80 according to the fourth embodiment also has an effect (preventing enlargement) by gradually reducing the cross-sectional area of the exhaust gas heat exchange path 38 toward the downstream side. Except for this, the same effect can be obtained by the same operation as the exhaust heat recovery heat exchanger 10 according to the first embodiment.

  In the first to fourth embodiments described above, the cooling water pipe 42 has an example of the cylindrical inner water pipe 42A. However, the present invention is not limited to this, for example, a substantially cylindrical shape. Instead of the inner water pipe 42A, a tapered inner water pipe may be provided. In this case, a configuration in which a cylindrical outer water pipe is provided instead of the outer water pipe 42B is also possible.

(Fifth embodiment)
FIG. 6 (A) shows a side sectional view of an exhaust heat recovery heat exchanger 90 according to the fifth embodiment of the present invention, and FIG. 6 (B) shows FIG. 6 (A). A sectional view taken along line 6A-6A is shown. As shown in this figure, the exhaust heat recovery heat exchanger 90 is an exhaust heat recovery heat exchanger which is a parallel flow heat exchanger in that the inner cylinder 26, that is, the bypass passage 22 is not provided therein. Different from 10.

  The heat exchanger 90 for exhaust heat recovery is formed in a disc shape and is held in an airtight state inside the outer cylinder 28, and a pair of upstream and downstream tube plates 92, and an upstream and downstream end of each pair of tube plates 92. And a plurality of gas pipes 94 penetrating therethrough. Thus, in the exhaust heat recovery heat exchanger 90, the space inside the plurality of gas pipes 94 is defined as the exhaust gas heat exchange path 38 and surrounded by the outer cylinder 28 and the pair of upstream and downstream tube plates 92. A portion excluding the occupied portion of each gas pipe 94 (exhaust gas heat exchange path 38) from the space is a cooling water heat exchange path 44.

  In this embodiment, each gas pipe 94 is a tapered pipe whose flow path cross-sectional area continuously decreases from the upstream side to the downstream side in the exhaust gas flow direction. The inlet port 46 is disposed upstream of the outlet port 48 in the exhaust gas flow direction. As a result, the exhaust heat recovery heat exchanger 90 is configured such that the flow passage cross-sectional area of the cooling water heat exchange passage 44 continuously increases from upstream to downstream in the engine coolant flow direction, and in parallel. It is a flow type heat exchanger.

  Although not shown, the bypass flow path 22 is provided outside the exhaust heat recovery heat exchanger 90 as an internal space of a bypass pipe arranged in parallel with the exhaust heat recovery heat exchanger 90. Yes. Other configurations of the exhaust heat recovery heat exchanger 90 are the same as the corresponding configurations of the exhaust heat recovery heat exchanger 10.

  Therefore, the exhaust heat recovery heat exchanger 90 according to the fifth embodiment can achieve the same effect by the same operation as the exhaust heat recovery heat exchanger 10 according to the first embodiment.

  In the fifth embodiment, an example in which the bypass flow path 22 is provided outside the outer cylinder 28 has been shown. For example, a gas pipe positioned at the axial center of the outer cylinder 28 shown in FIG. Instead of 94, an inner cylinder 26 (bypass channel 22) may be provided. In this configuration, the counter flow type heat exchanger corresponding to the second embodiment can be configured by exchanging the inlet port 46 and the outlet port 48 and exchanging the directions of the plurality of gas pipes 94. .

  In the fifth embodiment, an example in which all of the plurality of gas pipes 94 are tapered pipes has been described. However, the present invention is not limited to this, and for example, some of the gas pipes 94 may be straight pipes. .

(Sixth embodiment)
FIG. 7 is a side sectional view showing an exhaust heat recovery heat exchanger 100 according to a sixth embodiment of the present invention. As shown in this figure, the exhaust heat recovery heat exchanger 100 is replaced with a cooling water pipe 42 that increases the cross-sectional area of the cooling water heat exchange path 44 at the same rate toward the downstream side in the cooling water flow direction. The heat exchanger 10 for exhaust heat recovery according to the first embodiment is different from the heat exchanger 10 for exhaust heat recovery according to the first embodiment in that it includes a cooling water pipe 102 in which the rate of increase in the cross-sectional area of the flow path changes in the flow direction of the engine cooling water.

  Specifically, the cooling water pipe 102 is configured to include an outer water pipe 102A in place of the outer water pipe 42B formed in a conical shape. The outer water pipe 102A has an inner diameter that gradually increases from the upstream side to the downstream side in the flow direction of the engine cooling water, and a taper angle changing point 102B is set at an intermediate portion in the flow direction. In this embodiment, the outer water pipe 102A has a larger taper angle on the downstream side with respect to the taper angle change point 102B than on the upstream taper angle with respect to the taper angle change point 102B. It is set.

  The other configuration of the cooling water pipe 102 is the same as the corresponding configuration of the cooling water pipe 42. That is, the other configuration of the exhaust heat recovery heat exchanger 100 is the same as the corresponding configuration of the exhaust heat recovery heat exchanger 10 according to the first embodiment.

  Therefore, the exhaust heat recovery heat exchanger 100 according to the sixth embodiment can achieve the same effect by the same action as the exhaust heat recovery heat exchanger 10 according to the first embodiment.

(Seventh embodiment)
FIG. 8 is a side sectional view showing an exhaust heat recovery heat exchanger 110 according to a seventh embodiment of the present invention. As shown in this figure, the heat exchanger 110 for exhaust heat recovery is a cooling water pipe cooling water heat exchange that gradually increases the cross-sectional area of the cooling water heat exchange path 44 toward the downstream side in the cooling water flow direction. It differs from the exhaust heat recovery heat exchanger 10 according to the first embodiment in that a path 112 is provided.

  Specifically, the cooling water pipe 112 is configured to have an outer water pipe 112A in place of the outer water pipe 42B formed in a conical shape. The outer water pipe 112 </ b> A has an inner diameter that increases stepwise (in this embodiment, in one step) at a stepped portion 112 </ b> B formed in the middle of the flow direction of the engine cooling water.

  Other configurations of the cooling water pipe 122 are the same as the corresponding configurations of the cooling water pipe 42. That is, the other configuration of the exhaust heat recovery heat exchanger 110 is the same as the corresponding configuration of the exhaust heat recovery heat exchanger 10 according to the first embodiment.

  Therefore, the exhaust heat recovery heat exchanger 110 according to the seventh embodiment can achieve the same effect by the same action as the exhaust heat recovery heat exchanger 10 according to the first embodiment.

(Eighth embodiment)
FIG. 9 is a side sectional view showing an exhaust heat recovery heat exchanger 120 according to an eighth embodiment of the present invention. As shown in this figure, the heat exchanger 120 for exhaust heat recovery is a cooling water pipe cooling water heat exchange that gradually increases the cross-sectional area of the cooling water heat exchange path 44 toward the downstream side in the cooling water flow direction. It differs from the exhaust heat recovery heat exchanger 10 according to the first embodiment in that a path 122 is provided.

  Specifically, the cooling water pipe 122 is configured to include an outer water pipe 122A in place of the outer water pipe 42B formed in a conical shape. The outer water pipe 122A has a plurality of (in this embodiment, three) step portions 122B, 122C, 122D formed in the middle in the flow direction of the engine cooling water, and the inner diameters thereof increase stepwise.

  Other configurations of the cooling water pipe 122 are the same as the corresponding configurations of the cooling water pipe 42. In other words, the other configuration of the exhaust heat recovery heat exchanger 120 is the same as the corresponding configuration of the exhaust heat recovery heat exchanger 10 according to the first embodiment.

  Therefore, the exhaust heat recovery heat exchanger 120 according to the eighth embodiment can achieve the same effect by the same action as the exhaust heat recovery heat exchanger 10 according to the first embodiment.

  Note that a configuration in which the flow passage cross-sectional area of the cooling water heat exchange channel 44 according to the sixth to eighth embodiments is increased at different increasing rates or a configuration in which the flow rate is increased in stages is a plurality of configurations according to the fifth embodiment. The gas pipe 94 may be applied.

  Further, in each of the above embodiments, the heat exchanger of the present invention is applied as the exhaust heat recovery heat exchanger 10, 60, 70, 80, 90, 100, 110, 120 constituting the exhaust heat recovery system 18. However, the present invention is not limited to this, and can be applied to various types of heat exchangers.

It is a sectional side view which shows the heat exchanger which concerns on the 1st Embodiment of this invention. 1 is a system flow diagram of an exhaust heat recovery system to which a heat exchanger according to a first embodiment of the present invention is applied. It is a sectional side view which shows the heat exchanger which concerns on the 2nd Embodiment of this invention. It is a sectional side view which shows the heat exchanger which concerns on the 3rd Embodiment of this invention. It is a sectional side view which shows the heat exchanger which concerns on the 4th Embodiment of this invention. It is a figure which shows the heat exchanger which concerns on the 5th Embodiment of this invention, Comprising: (A) is a sectional side view, (B) is front sectional drawing along the 6A-6A line | wire of FIG. 6 (A). . It is a sectional side view which shows the heat exchanger which concerns on the 6th Embodiment of this invention. It is a sectional side view which shows the heat exchanger which concerns on the 7th Embodiment of this invention. It is a sectional side view which shows the heat exchanger which concerns on the 8th Embodiment of this invention.

Explanation of symbols

10 Heat exchanger for exhaust heat recovery (heat exchanger)
38 Exhaust gas heat exchange path (high temperature side flow path)
44 Cooling water heat exchange path (low temperature side flow path)
60/70/80/90/100/110/120 Exhaust heat recovery heat exchanger (heat exchanger)

Claims (3)

A high-temperature channel for circulating a high-temperature fluid;
Provided adjacent to the high temperature side flow path so that heat exchange between the low temperature fluid flowing through the inside and the high temperature fluid flowing through the high temperature side flow path is possible, and from the upstream side toward the downstream side in the flow direction of the low temperature fluid A low-temperature channel whose cross-sectional area is expanded continuously or stepwise,
With heat exchanger.   2. The heat exchanger according to claim 1, wherein the high-temperature channel has a channel cross-sectional area that is continuously or stepwise reduced from an upstream side to a downstream side in the flow direction of the low-temperature fluid.   The heat exchanger according to claim 2, wherein a flow direction of the low-temperature fluid and a flow direction of the high-temperature fluid are the same direction.

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