JP2007247555A - Exhaust heat recovery device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust heat recovery device capable of preventing condensation water from staying in a heat exchanger. <P>SOLUTION: The exhaust heat recovery system 10 is provided with the heat exchanger 18 for exhaust heat recovery in which an exhaust gas passage for heat exchanging the exhaust gas with a cooling medium is divided into an upper side heat exchanging portion 30A and a lower side heat exchanging portion 30B, and a passage switching valve 24 capable of adjusting the flow ratio of the exhaust gas introduced into the upper side heat exchanging portion 30A and the lower side heat exchanging portion 30B of the heat exchanger 18 of the exhaust gas recovery. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust heat recovery apparatus for recovering exhaust heat by exchanging heat between exhaust gas of an automobile or the like and engine cooling water, for example.

An inner pipe and an outer pipe with an exhaust control valve arranged on the upstream side form a double pipe structure, and an exhaust cooler that exchanges heat between the cooling water and the exhaust is provided between the inner pipe and the outer pipe. An exhaust cooling device for a mounted engine is known (see, for example, Patent Document 1). The exhaust gas exchanges heat while passing through a plurality of small exhaust pipes in the exhaust cooler, and joins and exhausts at the downstream ends of the outer pipes where the downstream ends of the small exhaust pipes open.
JP 2004-293395 A JP-A-5-77991 Japanese Patent Laying-Open No. 2005-16477

  However, in the conventional technology as described above, when the engine is stopped, when the exhaust gas is cooled by heat exchange with the engine cooling water in the exhaust cooler, condensed water is generated, and this condensed water is There is a concern that the downstream end of the small exhaust pipe may stay in the opening portion. The condensed water staying in this way causes, for example, an uneven exhaust gas flow, that is, a reduction in heat transfer area, which causes a decrease in heat exchange performance.

  In view of the above facts, an object of the present invention is to obtain an exhaust heat recovery device capable of preventing condensate from staying in a heat exchanger.

  In order to achieve the above object, the exhaust heat recovery apparatus according to the first aspect of the present invention provides an exhaust gas flow path for exchanging heat between the exhaust gas and the cooling medium at the first flow path and the second flow path. A heat exchanger that is divided; and a flow rate adjusting means that can adjust a ratio of a flow rate of exhaust gas introduced into the first flow path and the second flow path of the heat exchanger.

  In the exhaust heat recovery apparatus according to claim 1, when the exhaust gas exchanges heat with the cooling medium while flowing through the first flow path or the second flow path of the heat exchanger, the heat of the exhaust gas is recovered into the cooling medium. Is done. In some cases, moisture is condensed from the exhaust gas cooled along with this heat exchange to generate condensed water. Here, since the flow rate adjusting means capable of adjusting the flow rate ratio of the exhaust gas to the first channel and the second channel is provided, convection of the condensed water can be prevented. For example, when condensed water is likely to be generated due to a low cooling medium temperature or the like, the amount of exhaust gas introduced into the flow path in which the condensed water tends to stay is reduced depending on the arrangement and shape of the first and second flow paths. It is possible to prevent stagnation of condensed water by suppressing the amount of condensed water generated on the side where the condensed water tends to stay. In addition, for example, exhaust gas can be intensively introduced into one of the first flow path and the second flow path to forcibly discharge the condensed water that has temporarily accumulated.

  Thus, in the exhaust heat recovery apparatus according to the first aspect, it is possible to prevent the condensed water from staying in the heat exchanger.

  The exhaust heat recovery apparatus according to a second aspect of the present invention is the exhaust heat recovery apparatus according to the first aspect, wherein the flow rate adjusting means connects the first flow path and the second flow path to each exhaust gas inlet of the exhaust gas. A first state in which the opening is made at the same opening, and a second opening in which one of the second flow path and the second flow path has an opening larger than the opening of the other exhaust gas inlet. It is a regulating valve device that can take a state.

  In the exhaust heat recovery apparatus according to claim 2, when the regulating valve device selects the first state, the exhaust gas is distributed substantially evenly to the first flow path and the second flow path, and cools the heat of the exhaust gas. It can be effectively recovered in the medium. On the other hand, in the second state, the exhaust gas flows intensively in one of the first and second flow paths, and the condensed water that has accumulated can be discharged. For this reason, if the condition corresponding to the fact that the condensed water stays in the second flow path or the possibility that the condensed water stays is satisfied, etc., if the regulating valve device is switched to the second state, It can be forcibly discharged downstream.

  An exhaust heat recovery apparatus according to a third aspect of the present invention is the exhaust heat recovery apparatus according to the second aspect, wherein an exhaust gas inlet opening at an opening portion of each exhaust gas inlet of the first flow path and the second flow path is provided. A bypass passage that bypasses the heat exchanger, and the regulating valve device is provided at an exhaust gas inlet of the bypass passage, and is capable of opening and closing the bypass passage. It has a single valve body that can take the first state and the second state while closing the flow path.

  In the exhaust heat recovery apparatus according to the third aspect, in a state where the valve body of the regulating valve device opens the bypass passage (hereinafter referred to as a third state), the exhaust gas mainly flows through the bypass passage. The valve body of the regulating valve device switches between the first state and the second state with the bypass flow path closed. Therefore, in the first state, the exhaust gas is introduced into the first and second channels without escaping to the bypass channel, and the exhaust heat is effectively recovered. On the other hand, in the second state, the exhaust gas flows intensively through the first or second channel without escaping to the bypass channel. Here, the valve body of the regulating valve device can open and close the bypass flow path, and can take the first state and the second state while closing the bypass flow path. The first state, the second state, and the third state can be selectively switched. Thereby, in the structure provided with the bypass flow path of the heat exchanger, stagnation of condensed water can be prevented with a simple structure.

  An exhaust heat recovery apparatus according to a fourth aspect of the present invention is the exhaust heat recovery apparatus according to the third aspect, wherein the heat exchanger has an outer periphery of the bypass passage disposed in an axial center portion along a horizontal direction. The exhaust gas inlet of the first channel and the exhaust gas inlet of the second channel are arranged so as to oppose each other in the direction of gravity on the upstream side of the exhaust gas inlet of the bypass channel. And the valve body of the regulating valve device forms a right angle with respect to both the axial direction and the gravity direction of the bypass flow path, and rotates around an axis passing through the axis of the bypass flow path. The posture of opening the bypass flow path by rotating around the axis, and opening the first flow path and the second flow path at the same opening degree of the exhaust gas while closing the bypass flow path While closing the bypass flow path and the first flow path So that the switching between the attitude for opening the serial second circuit.

  In the exhaust heat recovery apparatus according to the fourth aspect, the posture of the valve body is changed by rotating around an axis passing through the axis of the bypass flow path, and the bypass flow path is opened in a posture along the horizontal direction. 3 state), close the bypass flow path in a posture substantially upright along the direction of gravity, and open the exhaust gas inlets of the first flow path and the second flow path (select the first state), For example, the exhaust gas inlet of the first or second flow path is substantially closed by the upper portion protruding while the bypass flow path is substantially closed in an inclined posture in which the upper part protrudes upstream from the bypass flow path in the exhaust gas flow direction (second Select the state). As a result, the function of selectively switching the first to third states with a single valve body can be realized with a simple structure.

  An exhaust heat recovery apparatus according to a fifth aspect of the present invention is the exhaust heat recovery apparatus according to the third or fourth aspect, wherein the inner pipe is arranged along the horizontal direction and a part of the inner pipe is used as the bypass flow path. The heat exchanger having the first flow path located above the partition wall in the gravitational direction and the second flow path located below the partition wall in the gravitational direction is configured between the outer pipe and the outer pipe covering the inner pipe The inner pipe is provided with a communication port that communicates the lower part in the direction of gravity on the downstream side of the first flow path with the inside of the inner pipe.

  In the exhaust heat recovery apparatus according to claim 5, the condensed water generated in the first flow path located on the upper side flows from the communication port to the inner pipe, that is, the bypass flow path or the exhaust gas discharge path downstream of the bypass flow path. It is discharged and discharged to the outside by the exhaust gas flow in the inner pipe. In the second flow path having a portion where the condensed water is likely to stay in the lower side in the gravity direction than the inner pipe, the condensed water generated in the second flow path may temporarily stay, By temporarily introducing the exhaust gas in the second flow path with the regulating valve device in the second state, the temporarily accumulated condensed water can be discharged.

  Here, as described above, the condensed water generated in the first flow path is discharged from the communication port to the inside of the inner pipe, so that the amount of condensed water temporarily retained in the second flow path is reduced, and the regulating valve device is By switching to the second state, the condensed water discharge time can be shortened.

  The exhaust heat recovery apparatus according to a sixth aspect of the present invention is the exhaust heat recovery apparatus according to the fifth aspect, wherein the partition wall is disposed below the axis of the heat exchanger.

  In the exhaust heat recovery apparatus according to claim 6, the first flow path is made larger and the second flow path is made smaller by offsetting the partition wall downward with respect to the axis of the heat exchanger (inner tube, outer tube). Further, the condensed water that is generated in the second flow path and temporarily stays can be further reduced. Further, in the second state, the flow rate of the exhaust gas passing through the second flow path is increased, so that the condensed water that has temporarily accumulated is effectively discharged.

  The exhaust heat recovery apparatus according to claim 7 is the exhaust heat recovery apparatus according to claim 5 or 6, wherein the communication port is an exhaust gas outlet of the second flow path provided in the inner pipe. It is arrange | positioned rather than the downstream of the exhaust gas flow direction.

  The exhaust heat recovery apparatus according to claim 7, wherein a portion of the inner pipe where the exhaust gas outlet of the second flow path is opened is a joining portion of the second flow path and the bypass flow path. The condensed water in the second flow path is discharged. Since the communication port is disposed downstream of the exhaust gas outlet (that is, the bypass channel) of the second flow path, the condensed water discharged from the communication port to the inner pipe may enter the second flow path. Is prevented.

  An exhaust heat recovery apparatus according to an eighth aspect of the present invention is the exhaust heat recovery apparatus according to the third or fourth aspect, wherein the inner pipe is disposed along the horizontal direction and a part of the inner pipe is used as the bypass flow path. The first flow path located on the upper side in the gravity direction of the partition wall and the second flow path located on the lower side in the gravity direction of the partition wall are formed vertically symmetrically between the outer pipe covering the inner pipe and the inner pipe A heat exchanger is configured, and the partition member is provided with a communication port that communicates the downstream side of the first flow path and the second flow path.

  In the exhaust heat recovery apparatus according to the eighth aspect, the condensed water generated in the first flow path located on the upper side is introduced into the second flow path through the communication port. In the second flow path that is located below the inner pipe in the direction of gravity and has a portion where the condensed water tends to stay, the condensed water generated in the second flow path is temporarily combined with the condensed water from the first flow path. However, the condensate temporarily retained can be discharged by intensively introducing the exhaust gas in the second flow path with the regulating valve device in the second state.

  Here, in the heat exchanger of the present exhaust heat recovery apparatus, the first flow path and the second flow path are formed vertically symmetrically across the partition wall, so that the exhaust gas flow is symmetrical between the upper and lower flow paths. The exhaust heat recovery amount can be made uniform.

  As described above, the exhaust heat recovery apparatus according to the present invention has an excellent effect that it is possible to prevent the condensed water from staying in the heat exchanger.

  An exhaust heat recovery system 10 as an exhaust heat recovery apparatus according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 4. 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. In addition, an arrow UP and an arrow LO shown in each figure indicate an upper side and a lower side in the direction of gravity (the vehicle body vertical direction), respectively.

  FIG. 4 is a schematic flow diagram showing the schematic overall configuration of the exhaust heat recovery system 10. As shown in this figure, the exhaust heat recovery system 10 recovers the heat of the exhaust gas of the internal combustion engine 12 of the automobile by heat exchange with the engine cooling water, and uses it for heating, promoting warm-up of the engine 12 or the like. Device.

  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 18, 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 18 as a heat exchanger is configured to recover the heat of the exhaust gas to the engine cooling water by heat exchange between the exhaust gas and the engine cooling water. The exhaust heat recovery heat exchanger 18 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.

  FIG. 1 is a side sectional view showing an exhaust heat recovery heat exchanger 18. 2A is a cross-sectional view perpendicular to the axis along line 2A-2A in FIG. 1, and FIG. 2B is a cross-sectional view perpendicular to the axis along line 2B-2B in FIG. It is shown. The heat exchanger 18 for exhaust heat recovery is configured to have an inner tube 26 as an inner tube and an outer tube 28 as an outer tube, which are each formed in a cylindrical shape and arranged concentrically. Between the cylinder 26 and the outer cylinder 28, a heat exchanging unit 30 for exchanging heat between the exhaust gas and the engine coolant is configured.

  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 18 has a conical cylinder 32 whose upstream end is fixed to the outer periphery of the inner cylinder 26 in an airtight state and whose downstream end is connected to the upstream end 28A of the outer cylinder 28; 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 18 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. An exhaust gas heat exchange path 38 that is a cylindrical space and an exhaust gas outlet header 40 that is a space between the inner cylinder 26 and the conical cylinder 34 are formed. On the other hand, inside the inner cylinder 26, the bypass flow path 22, an exhaust gas branching portion 42 which is a space between the exhaust pipe 14 (upstream part from the conical cylinder 32) and the bypass flow path 22, and an exhaust pipe 14 (a portion downstream of the conical cylinder 34) and an exhaust gas merging portion 44 that is a space between the bypass passage 22 is formed.

  As shown in FIGS. 1 and 2A, a cooling water pipe 46 is disposed in the exhaust gas heat exchange path 38 in the heat exchanging section 30, and the engine cooling water in the exhaust heat recovery heat exchanger 18 is provided. The cooling water heat exchange path 48 which is the flow path of the is constituted. In this embodiment, the cooling water pipe 46 shows an example in which a cylindrical cooling water heat exchange path 48 is formed inside a double cylinder. As shown in FIG. 4, the cooling water pipe 46 is connected to an inlet port 46A 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 is outside. It is connected to an outlet port 46B provided through the cylinder 28. In this embodiment, the inlet port 46A is disposed downstream of the outlet port 46B in the heat exchange unit 30, and the exhaust heat recovery heat exchanger 18 is a countercurrent heat exchanger.

  Further, the exhaust heat recovery heat exchanger 18 is provided with a partition plate 50 as a partition that divides (divides) the exhaust gas flow path of the heat exchanging unit 30 into upper and lower portions. The partition plate 50 is formed in a flat plate shape along a horizontal plane, and the exhaust gas inlet header 36, the exhaust gas heat exchange path 38, and the exhaust gas outlet header 40 are each divided into two symmetrically in the vertical direction.

  Hereinafter, when distinguishing the upper part and the lower part with respect to the partition plate 50 in the heat exchanging part 30, the upper heat exchanging part 30 as the first flow path is referred to as the upper heat exchanging part 30A and is referred to as the second flow path. The lower heat exchange unit 30 is referred to as a lower heat exchange unit 30B. Further, regarding the exhaust gas inlet header 36, the exhaust gas heat exchange path 38, and the exhaust gas outlet header 40, the parts constituting the upper heat exchange section 30A are the exhaust gas inlet header 36A, the exhaust gas heat exchange path 38A, and the exhaust gas outlet header. The parts constituting the lower heat exchange section 30B are referred to as 40A, and are referred to as an exhaust gas inlet header 36B, an exhaust gas heat exchange path 38B, and an exhaust gas outlet header 40B. The exhaust gas branching portion 42 penetrates the partition plate 50, and constitutes a single cooling water heat exchange path 48 without being divided by the partition plate 50.

  An exhaust gas branch portion 42 in the inner cylinder 26 includes an upper heat exchange portion exhaust gas inlet hole 52 that communicates the exhaust gas branch portion 42 and the upper exhaust gas inlet header 36A, and the exhaust gas. A lower heat exchanging portion exhaust gas inlet hole 54 that communicates the branch portion 42 and the lower exhaust gas inlet header 36B is formed. The upper heat exchange section exhaust gas inlet hole 52 is provided to open upward at the top of the inner cylinder 26, and the lower heat exchange section exhaust gas inlet hole 54 is opened downward to the bottom of the inner cylinder 26. Is provided.

  Further, an upper gas exchange portion exhaust gas outlet hole 56 that communicates the exhaust gas merging portion 44 and the upper exhaust gas outlet header 40A, and a portion of the inner cylinder 26 constituting the exhaust gas merging portion 44, and the exhaust gas. A lower heat exchanging portion exhaust gas outlet hole 58 that communicates the junction portion 44 and the lower exhaust gas outlet header 40B is formed. The upper heat exchange part exhaust gas outlet hole 56 is provided to open upward at the uppermost part of the inner cylinder 26, and the lower heat exchange part exhaust gas outlet hole 58 is opened downward to the lowermost part of the inner cylinder 26. Is provided.

  Further, as shown in FIG. 1 and FIG. 2 (B), the portion constituting the exhaust gas merging portion 44 in the inner cylinder 26 communicates with the exhaust gas merging portion 44 and the upper exhaust gas outlet header 40A. A condensed water discharge hole 60 is formed as a mouth. The lower edge of the condensed water discharge hole 60 substantially coincides with the upper surface of the partition plate 50 so as to open at the lowest position of the exhaust gas outlet header 40A. As shown in FIG. 2B, the condensed water discharge holes 60 are provided on both the left and right sides of the exhaust gas merging portion 44 in a front view.

  In the heat exchanger 18 for exhaust heat recovery described above, that is, the exhaust heat recovery system 10, as described above, the exhaust gas heat recovery mode in which the exhaust gas exchanges heat with the engine coolant is performed by the flow path switching valve 24, and the exhaust gas. Can be switched to the normal mode passing through the bypass passage 22. The flow path switching valve 24 is disposed at the upstream end of the bypass flow path 22 and extends in a direction substantially perpendicular to both the axial direction and the vertical direction of the inner cylinder 26 (bypass flow path 22). A shaft 62 and a valve 64 as a disc-like valve body supported so as to be rotatable around the support shaft 62 with respect to the inner cylinder 26 via the support shaft 62 are provided.

  As shown in FIG. 3A, the flow path switching valve 24 closes the bypass flow path 22 in a posture in which the valve 64 is substantially upright along the vertical plane as described above, whereby the upper and lower heat exchanging portions 30A. , 30B is configured to take an exhaust heat recovery mode as a first state in which the exhaust gas is distributed substantially evenly. Further, as shown in FIG. 3C, the flow path switching valve 24 opens the bypass flow path 22 in a posture in which the valve 64 is substantially along the horizontal plane, so that the exhaust gas mainly flows through the bypass flow path 22. It is configured to take normal mode. Note that the flow resistance (pressure loss) of the exhaust gas heat exchange path 38 provided with the cooling water pipe 46 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. In the open normal mode, the exhaust gas heat exchange path 38 is configured such that almost no exhaust gas flows.

  Then, as shown in FIG. 3B, the flow path switching valve 24 is in a state in which the bypass flow path 22 is substantially closed with the valve 64 inclined so that the upper part protrudes to the upstream side of the bypass flow path 22. The condensate discharge mode as the second state in which the upper heat exchange part exhaust gas inlet hole 52 is substantially closed is maintained. In order to close (decrease) the gap between the peripheral edge of the inclined valve 64 and the inner peripheral surface of the inner cylinder 26 in this condensed water discharge mode, the upper weir 66, A lower weir 68 is erected. The upper weir 66 and the lower weir 68 are each formed in a substantially crescent shape with the highest protrusion height at the top or bottom when viewed in the axial direction (not shown). The upper weir 66 and the lower weir 68 do not interfere with the rotation trajectory around the support shaft 62 of the valve 64 so that the valve 64 can switch between the condensed water discharge mode and the normal mode with the minimum rotation angle. Is formed.

  Further, the flow path switching valve 24 includes an actuator 70 that rotationally drives the valve 64 around the support shaft 62. The actuator 70 controls the actuator 70, that is, the flow path switching valve 24 based on a command from the ECU 72 as a control device, and switches between the normal mode, the exhaust heat recovery mode, and the condensed water discharge mode. The ECU 72 selects the exhaust heat recovery mode when, for example, it is determined that warm-up promotion or rapid heating of the engine 12 is required based on the input vehicle information.

  Further, the ECU 72 selects the condensed water discharge mode when it is determined that the condensed water is required to be discharged from the lower heat exchange unit 30B. For example, when a predetermined time has elapsed since the start of the engine or the end of the previous condensed water discharge mode, the ECU 72 has a predetermined pressure loss in the lower heat exchange unit 30B (and a difference in pressure loss in the upper heat exchange unit 30A). When the value exceeds the value, the condensate discharge mode is selected when it is determined from the number of revolutions of the engine 12 and the elapsed time that the amount of exhaust gas discharged (in the exhaust heat recovery mode) exceeds a predetermined amount. Yes. The ECU 72 selects the normal mode when neither the exhaust heat recovery mode selection condition nor the condensed water discharge mode selection condition is satisfied.

  The flow of engine cooling water in the exhaust heat recovery system 10 that has described the flow of exhaust gas will be briefly described. The exhaust heat recovery system 10 includes a front heater core 74 and a rear heater core 76 that recover the heat of the engine coolant for heating, and a heater hot water passage 78 that circulates the engine coolant to the front heater core 74 and the rear heater core 76. The front heater core 74 and the rear heater core 76 are arranged in parallel. An exhaust heat recovery heat exchanger 18 is disposed downstream of the rear heater core 76 in the heater hot water passage 78. That is, the inlet port 46A is disposed on the heater warm water passage 78 on the rear heater core 76 side, and the outlet port 46B is disposed on the heater warm water passage 78 on the upstream side of the engine 12. In this embodiment, the exhaust heat recovery heat exchanger 18 is arranged in parallel to the front heater core 74 and in series to the rear heater core 76 in the engine cooling water system.

  Therefore, in the exhaust heat recovery system 10, the engine coolant flows as indicated by the arrows on the heater hot water passage 78 in FIG. As a result, high-temperature hot water that has passed through the engine 12 undergoes heat exchange when passing through the front heater core 74 and the rear heater core 76 and is used for heating, and the engine coolant that has been cooled by the rear heater core 76 is used for heat exchange for exhaust heat recovery. It is the structure which is introduce | transduced into the container 18 and heat-exchanges with the said exhaust gas. The engine coolant that has passed through the exhaust heat recovery heat exchanger 18 is returned to the engine 12 together with the engine coolant that has passed through the front heater core 74. The exhaust heat recovery heat exchanger 18 is configured to function as a heater that heats the engine coolant before being introduced into the engine 12 from the viewpoint of engine warm-up.

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

  In the exhaust heat recovery system 10 having the above-described configuration, for example, immediately after the engine 12 is started, when the cooling water temperature is low and there is a request for warming up, the ECU 72 drives the flow path switching valve 24 to close and closes the bypass flow path 22. Let 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, and passes from the upper heat exchange part exhaust gas inlet hole 52 and the lower heat exchange part exhaust gas inlet hole 54 to the upper heat exchange part 30A and the lower heat exchange part 30B. Almost evenly distributed.

  In the exhaust gas heat exchange path 38A of the upper heat exchange section 30A and the exhaust gas heat exchange path 38B of the lower heat exchange section 30B, the introduced exhaust gas exchanges heat with the engine cooling water, and uses the engine cooling water. Let it heat. On the other hand, since the exhaust gas is cooled by heat exchange with the engine coolant, the moisture in the exhaust gas is condensed and liquefied in the exhaust gas heat exchange path 38A and the exhaust gas heat exchange path 38B. That is, condensed water is generated.

  Condensed water generated in the exhaust gas heat exchange path 38 </ b> A moves to the partition plate 50, which is a low part in the direction of gravity, while moving to the exhaust gas outlet header 40 </ b> A and joins the exhaust gas via the condensed water discharge hole 60. It is discharged to the part 44. The condensed water discharged to the exhaust gas merging portion 44 is discharged downstream by the flow of the exhaust gas, and is discharged to the outside via the main muffler 20.

  On the other hand, a part of the condensed water generated in the exhaust gas heat exchange path 38B is discharged to the exhaust gas merging portion 44 via the lower heat exchange portion exhaust gas outlet hole 58 by the flow of the exhaust gas. Is temporarily retained at the lowest position of the exhaust gas heat exchange path 38B or the exhaust gas outlet header 40B. When the ECU 72 determines that the condensed water is stagnant based on information such as the elapsed time and the pressure loss of the lower heat exchange unit 30B, the ECU 72 operates the actuator 70 of the flow path switching valve 24 and turns the valve 64 on. The inclined posture shown in FIG. That is, it switches to condensed water discharge mode.

  As a result, the upper heat exchanging portion exhaust gas inlet hole 52, that is, the upper heat exchanging portion 30A is substantially closed, so that the flow of exhaust gas concentrates on the lower heat exchanging portion 30B. Then, the condensed water temporarily staying at the lowest place of the exhaust gas heat exchange path 38B or the exhaust gas outlet header 40B is exhausted from the lower heat exchange section by the strong flow of the exhaust gas generated in the lower heat exchange section 30B. The gas is forcibly discharged to the exhaust gas merging portion 44 via the gas outlet hole 58.

  For example, the ECU 72 sets the flow path switching valve 24 according to the vehicle information after detecting the decrease in the pressure loss of the lower heat exchange unit 30B in the condensed water discharge mode after elapse of time necessary for discharging the condensed water. Operates to switch to normal mode or exhaust heat recovery mode. When the mode is switched to the normal mode, the exhaust gas is not cooled by the engine cooling water, so that the amount of condensed water generated is small, and the generated condensed water passes through the inner cylinder 26 (exhaust pipe 14) to the outside. Discharged.

  As described above, in the exhaust heat recovery system 10 according to the first embodiment, the heat exchange unit 30 includes the upper heat exchange unit 30A and the lower heat exchange unit 30B divided by the partition plate 50. The condensed water staying in the side heat exchange unit 30B can be effectively discharged by the condensed water discharge mode. Further, in the structure in which the inner cylinder 26 constituting the bypass flow path 22 is disposed in the axial center portion of the exhaust gas heat exchange path 38, the upper heat exchange section located above the gravitational direction is provided because the condensed water discharge hole 60 is provided. The condensed water generated at 30A can be discharged to the inner cylinder 26 using gravity in addition to the flow of exhaust gas. That is, without changing the posture of the valve 64 of the flow path switching valve 24 and setting the mode for discharging the condensed water of the upper heat exchange unit 30A, the condensed water generated in the upper heat exchange unit 30A is recovered as exhaust heat. It can be discharged in the selected mode. Moreover, since the condensed water produced | generated by 30 A of upper side heat exchange parts is not introduce | transduced into the lower heat exchange part 30B, the time or frequency which discharges the condensed water of the lower side heat exchange part 30B can be decreased.

  In the exhaust heat recovery system 10, the upstream end of the bypass flow path 22, the upper heat exchange part exhaust gas inlet hole 52, and the lower heat exchange part exhaust gas inlet hole 54 are all configured by the inner cylinder 26 and exhausted. Since it is arranged so as to face the gas branch portion 42, the normal mode, the exhaust heat recovery mode, and the condensed water discharge mode can be switched by the single valve 64 constituting the flow path switching valve 24. In particular, since the bypass flow path 22 is disposed at the axial center of the exhaust heat recovery heat exchanger 18, the above-described three structures can be achieved with a simple structure using a valve 64 rotating around the support shaft 62, that is, a butterfly valve. A configuration for selectively switching modes was realized.

  Next, another embodiment of the present invention will be described. Note that parts and portions that are basically the same as those in the first embodiment or the previous configuration are denoted by the same reference numerals as those in the first embodiment or the previous configuration, and description thereof is omitted. Moreover, illustration may be omitted.

  (2nd Embodiment) The principal part of the exhaust heat recovery system 80 which concerns on the 2nd Embodiment of this invention is shown by the sectional side view in FIG. As shown in this figure, the exhaust heat recovery system 80 is replaced with a partition plate 50 that divides the upper heat exchanging portion 30A and the lower heat exchanging portion 30B symmetrically in the vertical direction from the central portion in the vertical direction of the heat exchanging portion 30. The exhaust heat recovery system 10 according to the first embodiment is different from the exhaust heat recovery system 10 according to the first embodiment in that a partition plate 82 is provided as a partition wall that is offset and disposed on the lower side.

  As shown in FIG. 6, the partition plate 82 is disposed substantially along the horizontal plane, and moves up and down the heat exchanging portion 30 that is a space between the inner cylinder 26 and the outer cylinder 28 in the vicinity of the lower end of the inner cylinder 26. It is divided into. In this embodiment, the partition plate 82 divides the heat exchange part 30 into an upper heat exchange part 30C as a first flow path and a lower heat exchange part 30D as a second flow path. Further, the upper heat exchanging section 30C includes an exhaust gas inlet header 36C, an exhaust gas heat exchange path 38C, and an exhaust gas outlet header 40C, and the lower heat exchange section 30D includes an exhaust gas inlet header 36D and an exhaust gas heat exchange path. 38D and exhaust gas outlet header 40D. In addition, although illustration is abbreviate | omitted, the exhaust-gas branching part 42 has penetrated the partition plate 82, and comprises the single cooling water heat exchange path 48, without being divided | segmented by the partition plate 82. FIG.

  Further, as shown in FIG. 5 and FIG. 6, the portion constituting the exhaust gas merging portion 44 in the inner cylinder 26 serves as a communication port that communicates the exhaust gas merging portion 44 and the upper exhaust gas outlet header 40 </ b> C. A condensed water discharge hole 84 is formed. The lower edge of the condensed water discharge hole 84 substantially coincides with the upper surface of the partition plate 82 so as to open to the lowest portion of the exhaust gas outlet header 40C. As shown in FIG. 6, the condensed water discharge holes 84 are provided on both the left and right (horizontal directions) sides in a front view.

  Other configurations of the exhaust heat recovery system 80 are the same as the corresponding configurations of the exhaust heat recovery system 10 including portions not shown.

  Therefore, also by the exhaust heat recovery system 80 according to the second embodiment, the same effect can be obtained by the same operation as the exhaust heat recovery system 10 according to the first embodiment. Further, in the exhaust heat recovery system 80, since the partition plate 82 is arranged to be offset downward, in other words, since the volume of the lower heat exchange unit 30D is small, it is generated by the lower heat exchange unit 30D. The amount of condensed water is small. Accordingly, the amount of condensed water temporarily staying in the exhaust gas heat exchange path 38D and the exhaust gas outlet header 40D of the lower heat exchange unit 30D is reduced, and the condensed water is transferred to the lower heat exchange unit 30D in a short condensed water discharge mode. Can be discharged from. In addition, since the flow passage cross-sectional area of the lower heat exchange unit 30D is small, the flow rate of the exhaust gas passing through the lower heat exchange unit 30D in the condensed water discharge mode increases and temporarily stays in the lower heat exchange unit 30D. Condensed water can be discharged in a shorter time.

  On the other hand, in the upper heat exchanger 30C having a large capacity, a relatively large amount of condensed water is generated. This condensed water, while maintaining the exhaust heat recovery mode, as in the first embodiment, In addition to the flow, gravity can be used to discharge from the condensed water discharge hole 84 to the inner cylinder 26. For this reason, the condensed water does not stay in the exhaust gas heat exchange path 38C and the exhaust gas outlet header 40C of the upper heat exchange unit 30C.

  (3rd Embodiment) The principal part of the exhaust heat recovery system 90 which concerns on FIG. 7 at the 3rd Embodiment of this invention is shown with the sectional side view. As shown in this figure, the exhaust heat recovery system 90 has an exhaust gas outlet header at a position that is offset downstream from the lower heat exchange section exhaust gas outlet hole 58 instead of the condensed water discharge hole 84. It differs from the exhaust heat recovery system 80 according to the second embodiment in that it includes a condensed water discharge hole 92 that allows the 40C and the exhaust gas merging portion 44 to communicate with each other.

  The condensed water discharge hole 92 has an upstream end 92A located downstream of the downstream end 58A of the lower heat exchange part exhaust gas outlet hole 58, and the lower heat exchange part exhaust gas outlet hole 58 in the exhaust gas flow direction. And a portion that does not overlap. Therefore, as shown in FIG. 8A, which is a cross section taken along the line 8A-8A in FIG. 7, the condensed water discharge hole 92 is not formed in the opening region of the lower heat exchange section exhaust gas outlet hole 58, and FIG. As shown in FIG. 8B which is an 8B cross section, the lower heat exchange section exhaust gas outlet hole 58 is not formed in the opening region of the condensed water discharge hole 92.

  The other configuration of the exhaust heat recovery system 90 is the same as the corresponding configuration of the exhaust heat recovery system 80 including a portion not shown.

  Therefore, the exhaust heat recovery system 90 according to the third embodiment can obtain the same effect by the same operation as the exhaust heat recovery systems 10 and 80 according to the first and second embodiments. Further, in the exhaust heat recovery system 90, since the condensed water discharge hole 92 is arranged offset to the downstream side of the lower heat exchange part exhaust gas outlet hole 58, the condensed water discharge hole generated by the upper heat exchange part 30C is used. The condensed water discharged to the exhaust gas merging portion 44 via 92 does not partially enter the lower heat exchange portion 30 </ b> D via the lower heat exchange portion exhaust gas outlet hole 58, on the downstream side. (Exhaust pipe 14, main muffler 20, air).

  That is, in the exhaust heat recovery system 90, a part of the condensed water generated in the upper heat exchange unit 30C is reliably prevented from staying in the lower heat exchange unit 30D. Thus, in the condensed water discharge mode, it is sufficient to discharge only the condensed water generated in the lower heat exchange unit 30D, and the condensed water temporarily discharged to the lower heat exchange unit 30D can be used for a short time. It can be discharged in the discharge mode.

  In addition, in the structure provided with the partition plate 50 which divides the heat exchange part 30 into the upper and lower objects as in the first embodiment, the condensed water discharge hole 60 is offset downstream from the lower heat exchange part exhaust gas outlet hole 58. May be provided.

  (4th Embodiment) The principal part of the exhaust heat recovery system 100 which concerns on FIG. 9 at the 4th Embodiment of this invention is shown with the sectional side view. As shown in this figure, the exhaust heat recovery system 100 includes a communication port 102 provided in the partition plate 50 so as to communicate the upper and lower exhaust gas outlet headers 40A and 40B in place of the condensed water discharge hole 60. Thus, it differs from the exhaust heat recovery system 10 according to the first embodiment.

  As shown in FIG. 10, the communication ports 102 are through holes (windows, cutout portions) penetrating the partition plate 50, and are provided on both the left and right (horizontal direction) sides of the inner cylinder 26 in a front view. . The communication port 102 may be configured as a notch, or may be configured as a non-installation part of the partition plate 50 (such as a gap between the divided partition plates).

  Other configurations of the exhaust heat recovery system 100 are the same as the corresponding configurations of the exhaust heat recovery system 10 including portions not shown. In the following, the operation of the exhaust heat recovery system 100 will be described mainly with respect to the differences from the operation of the exhaust heat recovery system 10.

  In the exhaust heat recovery system 100 having the above-described configuration, when the heat of the exhaust gas is recovered in the engine cooling water in the exhaust heat recovery mode, the exhaust gas is cooled by both the upper heat exchange unit 30A and the lower heat exchange unit 30B and condensed water. Occurs. Condensed water generated in the lower heat exchange unit 30B is temporarily placed in the lower part of the exhaust gas heat exchange path 38B and the exhaust gas outlet header 40B of the lower heat exchange unit 30B, as in the case of the exhaust heat recovery system 10. Stays on. The condensed water generated in the upper heat exchange unit 30A is introduced into the exhaust gas outlet header 40B via the communication port 102, and the lower heat exchange unit 30B together with the condensed water generated in the lower heat exchange unit 30B. The exhaust gas heat exchanging path 38B and the exhaust gas outlet header 40B are temporarily retained.

  When the ECU 72 determines that the condensed water is retained based on information such as the elapsed time and the pressure loss of the lower heat exchange unit 30B, the ECU 72 operates the actuator 70 of the flow path switching valve 24 to discharge the condensed water. Switch to mode. Thereby, the flow of the exhaust gas is concentrated on the lower heat exchange section 30B. Then, the condensed water temporarily staying at the lowest place of the exhaust gas heat exchange path 38B or the exhaust gas outlet header 40B is exhausted from the lower heat exchange section by the strong flow of the exhaust gas generated in the lower heat exchange section 30B. The gas is forcibly discharged to the exhaust gas merging portion 44 via the gas outlet hole 58.

  As described above, in the exhaust heat recovery system 100 according to the fourth embodiment, the heat exchange unit 30 includes the upper heat exchange unit 30A and the lower heat exchange unit 30B that are divided by the partition plate 50. The condensed water retained in the side heat exchange unit 30B can be effectively discharged by the condensed water discharge mode. In addition, since the exhaust heat recovery system 100 does not have the condensed water discharge hole 60, the exhaust gas flow path of the upper heat exchange unit 30A and the flow path of the lower heat exchange unit 30B are formed vertically symmetrically. Thus, in the exhaust heat recovery mode, the exhaust gas is more evenly distributed to the upper heat exchange unit 30A and the lower heat exchange unit 30B in which the exhaust gas branching part 42 is positioned symmetrically, and the heat exchange performance is improved. Further, in the exhaust heat recovery system 100, switching between the normal mode, the exhaust heat recovery mode, and the condensed water discharge mode by the single valve 64 is as described for the exhaust heat recovery system 10.

  In each of the above embodiments, the example in which the bypass flow path 22 is disposed in the axial center portion of the exhaust heat recovery heat exchanger 18 is shown, but the present invention is not limited to this, and for example, exhaust heat recovery The heat exchanger 18 may be configured to include the bypass flow path 22 arranged in parallel on the lateral side of the heat exchanger 18 or may not include the bypass flow path 22.

  Further, in each of the above embodiments, the example in which the cross section of the exhaust gas flow path of the heat exchanger 18 for exhaust heat recovery is formed in a circular shape or an annular shape, but the present invention is not limited to this, for example, The cross-sectional shape of the exhaust gas flow path of the heat exchanger 18 for exhaust heat recovery may be formed in a rectangular shape, a rectangular shape, an elliptic shape, an elliptic shape, or the like.

  Further, in each of the above-described embodiments, the upper heat exchange part exhaust gas outlet hole 56 that communicates the exhaust gas outlet headers 40A, 40C and the exhaust gas merging part 44 is provided at the top of the inner cylinder 26. The present invention is not limited to this, and the upper heat exchange section exhaust gas outlet hole 56 may be disposed at any position in the circumferential direction of the inner cylinder 26. Therefore, for example, the upper heat exchange part exhaust gas outlet hole 56 may be eliminated, and the condensed water discharge holes 60 and 84 may also serve as the upper heat exchange part exhaust gas outlet hole.

It is a sectional side view which shows the principal part of the exhaust heat recovery system which concerns on the 1st Embodiment of this invention. (A) is sectional drawing along the 2A-2A line of FIG. 1, (B) is sectional drawing along the 2B-2B line of FIG. It is a figure which shows the mode switching state of the exhaust heat recovery system which concerns on the 1st Embodiment of this invention, Comprising: (A) is a sectional side view of exhaust heat recovery mode, (B) is a sectional side view of condensed water discharge mode. (C) is a side sectional view of a normal mode. 1 is a system flow diagram showing a schematic overall configuration of an exhaust heat recovery system according to a first embodiment of the present invention. It is a sectional side view which shows the principal part of the exhaust heat recovery system which concerns on the 2nd Embodiment of this invention. FIG. 6 is a cross-sectional view taken along line 6-6 of FIG. It is a sectional side view which shows the principal part of the exhaust heat recovery system which concerns on the 3rd Embodiment of this invention. (A) is sectional drawing along the 8A-8A line of FIG. 7, (B) is sectional drawing along the 8B-8B line of FIG. It is a sectional side view which shows the principal part of the exhaust heat recovery system which concerns on the 4th Embodiment of this invention. FIG. 10 is a cross-sectional view taken along the line 10-10 in FIG. 9.

Explanation of symbols

10 Exhaust heat recovery system (exhaust heat recovery device)
18 Exhaust heat recovery heat exchanger (heat exchanger)
22 bypass flow path 24 flow path switching valve (flow path switching device, regulating valve device)
26 Inner cylinder (inner pipe)
28 Outer tube (outer tube)
30A, 30C Upper heat exchange section (first flow path)
30B, 30D Lower heat exchange section (second flow path)
50 partition plate
52 Upper heat exchange section exhaust gas inlet hole (exhaust gas inlet of the first flow path)
54 Lower heat exchange section exhaust gas inlet hole (exhaust gas inlet of the second flow path)
58 Lower heat exchange section exhaust gas outlet hole (exhaust gas outlet of second flow path)
60 Condensate drain hole (communication port)
64 Valve (Valve)
80/90/100 Exhaust heat recovery system (Exhaust heat recovery system)
82 Partition plate
84.92 Condensate drain hole (communication port)
102 Communication port

Claims (8)

A heat exchanger in which an exhaust gas flow path for performing heat exchange between the exhaust gas and the cooling medium is divided into a first flow path and a second flow path;
A flow rate adjusting means capable of adjusting a ratio of a flow rate of exhaust gas introduced into the first flow path and the second flow path of the heat exchanger;
Exhaust heat recovery device.   The flow rate adjusting means is one of a first state in which the exhaust gas inlets of the exhaust gas are opened at the same opening degree in the first flow path and the second flow path, and the second flow path and the second flow path. The exhaust heat recovery apparatus according to claim 1, wherein the exhaust heat recovery apparatus is an adjustment valve device capable of taking a second state in which an opening degree of one exhaust gas inlet is larger than an opening degree of the other exhaust gas inlet. An exhaust gas inlet opening at an opening portion of each exhaust gas inlet of the first flow path and the second flow path, further comprising a bypass flow path for bypassing the heat exchanger;
The regulating valve device is provided at an exhaust gas inlet of the bypass flow path, and can open and close the bypass flow path, and takes the first state and the second state while closing the bypass flow path. The exhaust heat recovery device according to claim 2, which has a single valve body to be obtained. The heat exchanger has a cylindrical shape that covers the bypass flow path disposed at the axial center along the horizontal direction from the outer peripheral side, and the exhaust gas inlet of the first flow path and the second flow path The exhaust gas inlet is disposed so as to face the direction of gravity on the upstream side of the exhaust gas inlet of the bypass flow path,
The valve body of the regulating valve device is rotated about the axis by rotating around the axis passing through the axis of the bypass flow path and at right angles to both the axial direction and the gravity direction of the bypass flow path. A posture of opening the bypass flow path by movement, and a posture of opening the first flow path and the second flow path at the same opening degree of the exhaust gas while closing the bypass flow path; The exhaust heat recovery apparatus according to claim 3, wherein the exhaust heat recovery apparatus is configured to switch between a posture of opening the second circuit while closing the bypass flow path and the first flow path. The first channel and the partition located on the upper side in the gravitational direction of the partition between the inner tube arranged along the horizontal direction and a part of the inner tube serving as the bypass channel and the outer tube covering the inner tube The heat exchanger having a second flow path located on the lower side of the gravity direction of
The exhaust heat recovery apparatus according to claim 3 or 4, wherein the inner pipe is provided with a communication port that communicates a lower portion in the direction of gravity on the downstream side of the first flow path with the inside of the inner pipe.   The exhaust heat recovery apparatus according to claim 5, wherein the partition wall is disposed below the axis of the heat exchanger.   The exhaust heat recovery apparatus according to claim 5 or 6, wherein the communication port is disposed downstream of the exhaust gas outlet of the second flow path provided in the inner pipe in the exhaust gas flow direction. The first channel and the partition located on the upper side in the gravitational direction of the partition between the inner tube arranged along the horizontal direction and a part of the inner tube serving as the bypass channel and the outer tube covering the inner tube The heat exchanger in which the second flow path located on the lower side in the gravity direction is formed symmetrically in the vertical direction,
The exhaust heat recovery apparatus according to claim 3 or 4, wherein the partition wall is provided with a communication port that communicates the downstream side of the first flow path and the second flow path.

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