JP2010163899A - Exhaust heat recovery device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress temperature rise of cooling water when the temperature of exhaust heat is high, while promoting the temperature rise of cooling water when the cooling water temperature is low by causing the cooling water to efficiently recover the exhaust heat. <P>SOLUTION: In cold starting, exhaust gas is guided to an exhaust bypass passage 27a since an exhaust communication pipe 22 is closed by an exhaust changeover valve 28, and exhaust heat is recovered by cooling water flowing in a heat exchange passage 27b formed on the outer circumference thereof. Since a heat-insulated space 29 formed within an outer cylinder pipe 24 is blocked by an external air shutoff valve 31 operated in conjugation with the exhaust changeover valve 28, the exhaust heat can be efficiently recovered. When the cooling water temperature rises, the exhaust changeover valve 28 and the external air shutoff valve 31 are opened, the exhaust gas is discharged through the exhaust communication pipe 22, and external air is also introduced to the heat-insulated space 29. Therefore, the rise of the cooling water temperature can be suppressed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust heat recovery apparatus that uses the heat of exhaust gas to quickly raise the temperature of a cooling water after startup.

  Conventionally, exhaust gas heat (hereinafter referred to as “exhaust heat”) is recovered by engine cooling water, and the recovered heat is circulated to the engine and the heater of the air conditioning system to complete early warm-up of the engine, and the passenger compartment. There has been proposed an exhaust heat recovery device that supplements the heating of the house.

For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2001-30741), a branch pipe is bypass-connected to an exhaust pipe, and a heat exchanger through which engine coolant flows is arranged in the branch pipe, and the branch pipe is further provided. An on-off valve is installed upstream of the heat exchanger, and when the temperature of the heat exchanger becomes higher than the specified value, this branch pipe is closed to cut off the supply of exhaust gas to the heat exchanger and prevent abnormal overheating of the heat exchanger Techniques to do this are disclosed.
JP 2001-30741 A

  By the way, in general, in a vehicle in which an engine is mounted on the front portion of the vehicle body, an exhaust pipe extending from the engine is guided rearward through the lower surface of the vehicle body floor. Therefore, since the exhaust pipe is constantly exposed to the outside air, the exhaust heat is radiated from the exhaust pipe to the outside. In particular, during traveling, the vehicle is cooled by the traveling wind, so that heat loss occurs, and there is a problem that exhaust heat recovery efficiency by engine cooling water is reduced.

  As a countermeasure, it is conceivable to form a heat insulating space around the exhaust pipe to suppress the generation of heat loss. However, the exhaust heat after the completion of warm-up is high in temperature, and there is a disadvantage that the engine cooling water is overheated by this exhaust heat.

  In view of the above circumstances, the present invention makes it possible to efficiently recover the exhaust heat to the engine cooling water when the engine cooling water temperature is low and promote the temperature rise, and when the exhaust heat becomes high, the engine cooling water An object of the present invention is to provide an exhaust heat recovery device capable of suppressing the temperature rise.

  In order to achieve the above object, the exhaust heat recovery apparatus according to the present invention includes a first pipe through which exhaust gas flows, a second pipe that bypasses the first pipe, and a low temperature of engine cooling water. A first valve body that closes the first conduit and guides the exhaust gas to the second conduit; a heat exchanger that is disposed adjacent to the second conduit and through which engine coolant flows; , An outer tube that covers the outer periphery of the heat exchange unit, and a heat insulating space formed between the outer tube and the heat exchange unit, in conjunction with the first valve body, the first valve body is the The first valve body is cut off when the first pipe line is closed, and the first valve body is provided with a second valve body opened when the first pipe line is opened.

  According to this invention, the 2nd which operate | moves in conjunction with the 1st valve body which opens and closes the 1st pipe line in the heat insulation space formed between the outer cylinder pipe which covers the outer periphery of a heat exchange part, and a heat exchange part. Since the valve body is opened and closed, when the engine coolant temperature is low, the introduction of outside air to the heat insulation space is suppressed by shutting off the second valve body, and exhaust heat is efficiently recovered from the engine coolant. Can be made. On the other hand, when the engine cooling water temperature reaches a predetermined temperature or higher, by opening the second valve body, outside air flows into the heat insulation space, and the temperature rise of the engine cooling water can be suppressed.

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

[First Embodiment]
1 to 5 show a first embodiment of the present invention. FIG. 1 shows a schematic configuration diagram of an engine cooling system provided with an exhaust heat recovery device.

  Reference numeral 1 in FIG. 1 denotes an engine, which is disposed at the front of a vehicle (not shown). An exhaust pipe 2 extending from the engine 1 extends along the bottom surface of the vehicle body floor toward the vehicle body rear side. Reference numeral 3 denotes a muffler.

  Reference numeral 11 denotes an engine cooling system, which includes an engine cooling water (hereinafter simply referred to as “cooling water”) main passage 12 and a cooling water sub-passage 13 as an engine cooling water passage. The cooling water main passage 12 is circulated and connected to an upstream end and a downstream end of a water jacket 1 a formed in the engine 1, a radiator 14 is interposed, and a water pump 15 is disposed downstream of the radiator 14. Is intervening. In this embodiment, an engine drive type is adopted as the water pump 15, but the water pump 15 may be a motor drive type.

  Further, a thermostat valve 16 is interposed between the water pump 15 and the radiator 14. The cooling water sub-passage 13 has a downstream end communicating with the thermostat valve 16 of the cooling water main passage 12 and the water pump 15, and an upstream end upstream of the radiator 14 of the cooling water main passage 12. Branch connected to. The thermostat valve 16 is closed when the cooling water temperature is equal to or lower than the set temperature, and shuts off the cooling water circulating through the cooling water main passage 12, while being opened when the cooling water temperature is equal to or higher than the set temperature. The cooling water is also circulated to the cooling water main passage 12 side. Reference numeral 14a denotes a radiator fan.

  A heater core 17 as heat receiving means is interposed in the cooling water sub-passage 13. The heater core 17 heats the air supplied to the passenger compartment using the heat of the cooling water flowing through the cooling water sub-passage 13 as a heat source. The heater core 17 is disposed in the air duct of the air conditioner and passes through the air duct. Thus, the inside air or the outside air supplied to the vehicle interior is warmed.

  Furthermore, an exhaust heat recovery device 21 is disposed on the downstream side of the heater core 17 in the cooling water sub-passage 13. The exhaust heat recovery device 21 performs heat exchange using a temperature difference between the heat of exhaust gas flowing through the exhaust pipe 2 (exhaust heat) and the temperature of cooling water (cooling water temperature). For example, in warm-up operation after cold start, the temperature of exhaust gas rises earlier than that of cooling water. For this reason, the exhaust heat recovery device 21 collects the exhaust heat in the cooling water, whereby the temperature rise of the cooling water can be promoted.

  As shown in FIGS. 2 to 5, the exhaust heat recovery device 21 has an exhaust communication pipe 22 as a first conduit at the center thereof, an exhaust heat exchanger 23 provided on the outer periphery thereof, and an outer periphery thereof. An outer tube 24 is disposed on the side. The exhaust communication pipe 22 is interposed in the middle of the exhaust pipe 2, and both ends thereof are joined to the exhaust pipe 2 by an airtight body. The exhaust heat exchanger 23 has a double structure in which an inner member 25 and an outer member 26 are overlapped, and both the members 25 and 26 are made of a heat transfer material such as iron. In the figure, the exhaust gas flows from the left side to the right side of the figure. Therefore, the left side of the figure is upstream.

  The inner member 25 is formed in a cylindrical shape surrounding the outer periphery of the exhaust communication pipe 22, and both ends thereof are narrowed and fixed to the exhaust communication pipe 22 in a state of being kept airtight by means such as welding. . Further, the outer member 26 is disposed on the outer periphery of the inner member 25, and both ends thereof are narrowed and fixed to both end portions of the inner member 25 in a state of being kept airtight by means such as welding. . In a space surrounded by the inner wall of the inner member 25 and the outer periphery of the exhaust pipe 2, an exhaust bypass passage 27a as a second pipe is formed in an annular shape, and the outer wall of the inner member 25 and the inner wall of the outer member 26 are formed. A heat exchanging passage 27b as a heat exchanging portion is formed in an annular shape in a space surrounded by. The exhaust heat exchanger 23 may be an integrally molded product.

  Further, an upstream exhaust port 22a and a downstream exhaust port 22b are formed in the exhaust communication pipes 22 positioned on the upstream side and the downstream side of the exhaust bypass passage 27a. Both the exhaust ports 22 a and 22 b are configured by a plurality of punching holes formed in a strip shape along the outer periphery of the exhaust communication pipe 22.

  Further, an exhaust switching valve 28 as a first valve body formed in a butterfly shape is disposed between the exhaust ports 22 a and 22 b of the exhaust communication pipe 22. The exhaust switching valve 28 rotates integrally with the rotating shaft 28a around the rotating shaft 28a. When the exhaust communication pipe 22 is closed by the exhaust switching valve 28, as shown by an arrow B in FIG. The exhaust gas flowing into the exhaust communication pipe 22 flows from the upstream exhaust port 22a into the exhaust bypass passage 27a, and flows out from the downstream exhaust port 22b of the exhaust switching valve 28 to the exhaust communication pipe 22 side. On the other hand, as shown in FIG. 3, when the exhaust switching valve 28 is fully opened, most of the exhaust gas flows through the exhaust communication pipe 22 as indicated by an arrow B.

  Further, the outer tube 24 covering the exhaust communication pipe 22 and the exhaust heat exchanger 23 is opened on both sides thereof in the front-rear direction of the vehicle body, and the positions where it slightly enters inward from the front opening end and the rear opening end. A heat insulating space 29 is formed between the inner wall of the outer tube 24 and the outer wall of the exhaust communication pipe 22 and the exhaust heat exchanger 23, supported by the exhaust communication pipe 22 via stays 29 a and 29 b.

  An inflow port 23a and an outflow port 23b communicating with the heat exchange passage 27b are provided on the upstream side and the downstream side of the outer periphery of the exhaust heat exchanger 23, and both the ports 23a and 23b are connected to the outer tube. 24 is protruded from the outer periphery of the outer tube 24. Further, the ports 23 a and 23 b are connected in the middle of the cooling water sub-passage 13, and the heat exchange passage 27 b constitutes a part of the cooling water sub-passage 13. Accordingly, as shown by arrows B in FIGS. 1, 2 and 3, the cooling water flowing out from the heater core 17 flows into the heat exchange passage 27b from the inflow port 23a, and the cooling water downstream from the outflow port 23b. It is discharged into the auxiliary passage 13.

  A thermoactuator 30 is fixed to the cooling water sub-passage 13 connected to the outflow port 23b. A cooling water introduction passage 30a communicating with the cooling water sub-passage 13 is formed in the thermoactuator 30, and a thermowax (for example, paraffin, for example) built in the thermoactuator 30 is formed by the cooling water passing through the cooling water introduction passage 30a. Wax) 30b thermally expands or contracts. And the rod 30c (refer FIG. 5) provided in the thermo actuator 30 advances / retreats using the thermal expansion or thermal contraction of this thermo wax 30b.

  An opening 24a formed at the upstream end of the outer tube 24 is enlarged in diameter, and a hub 31a of an outside air shut-off valve 31 as a second valve body is formed on the outer periphery of the exhaust communication pipe 22 positioned at the opening 24a. Is supported to move forward and backward. Further, a stopper 32 is fixed to the inner periphery of the base side of the opening 24a whose diameter is increased in the outer tube 24. The stopper 32 restricts the movement of the outside air shut-off valve 31 in the downstream direction, and the outer edge of the outside air shut-off valve 31 is brought into contact with the stopper 32, thereby blocking the inflow of outside air into the heat insulating space 29. Further, a return spring 33 is interposed between the outside air shutoff valve 31 and the stay 29a, and the outside air shutoff valve 31 is always urged by the return spring 33 in the opening direction as shown in FIG. .

  Further, as shown in FIG. 5, an operation lever 34 fixed to the rotary shaft 28a of the exhaust gas switching valve 28 is connected to the rod 30c of the thermoactuator 30 via a link mechanism 35a. Further, the hub 31a of the outside air shutoff valve 31 is connected to a rod 30c provided on the thermoactuator 30 via a link mechanism 35b. Therefore, the operation lever 34 and the outside air shutoff valve 31 are opened and closed in conjunction with each other.

  As described above, the rod 30c of the thermoactuator 30 moves back and forth due to thermal expansion or contraction of the built-in thermowax 30b. When the temperature of the cooling water is low and the thermowax 30b is thermally contracted, the rod 30c is retracted. Then, the operating lever 34 and the outside air shut-off valve 31 are pulled through the link mechanisms 35a and 35b connected to the rod 30c, respectively, and the exhaust gas switching valve 28 and the outside air shut-off valve 31 are closed. On the other hand, when the cooling water temperature rises and the thermowax 30b is thermally expanded, the operating lever 34 is pushed via the link mechanism 35a, and the pulling force on the outside air shutoff valve 31 is released, and the exhaust switching valve 28 and the outside air shutoff are released. The valves 31 are opened with each other.

  Next, the operation of the present embodiment having such a configuration will be described. When the engine 1 is cold, such as when starting after being left for a long time, the cooling water is naturally also cold. Therefore, the thermowax 30b of the thermoactuator 30 provided on the downstream side of the exhaust heat recovery device 21 is thermally contracted. However, the rod 30c interlocked with the operation of the thermowax 30b is retracted.

  Accordingly, the operation lever 34 connected to the rod 30c via the link mechanism 35a rotates the exhaust switching valve 28 in the clockwise direction of FIG. Is blocked. Furthermore, since the outside air shutoff valve 31 connected to the rod 30c via the link mechanism 35b is pulled against the urging force of the return spring 33, the outer peripheral edge thereof is brought into contact with the stopper 32, The heat insulation space 29 is blocked (see FIG. 2).

  Then, when the driver turns on the starter switch (not shown) and starts the engine 1, the water pump 15 is driven and the cooling water circulates. At this time, since the cooling water is cold, the thermostat valve 16 is closed, and therefore most of the cooling water circulates in the cooling water sub-passage 13 side. A heat exchange passage 27b of the exhaust heat recovery device 21 is interposed in the middle of the cooling water sub-passage 13, and the cooling water circulating in the cooling water sub-passage 13 is a heat exchange passage as shown by an arrow A in FIG. It is circulated through 27b.

  Exhaust gas discharged from the engine 1 passes through the exhaust pipe 2 and is discharged through the muffler 3. In the middle of the exhaust pipe 2, an exhaust communication pipe 22 provided in the exhaust heat recovery device 21 is provided in an integrated state, and the exhaust communication pipe 22 is connected to the exhaust switching valve 28 as described above. 2, the exhaust gas discharged from the engine 1 passes through the outer periphery of the exhaust communication pipe 22 from the upstream exhaust port 22a opened before the exhaust switching valve 28, as indicated by an arrow B in FIG. The exhaust gas flows into the exhaust bypass passage 27a formed at the bottom, passes through the exhaust bypass passage 27a, and returns to the exhaust communication pipe 22 through the downstream exhaust port 22b opened on the downstream side of the exhaust switching valve 28.

  Since the temperature of the exhaust gas after starting the engine 1 rises faster than the temperature of the cooling water, a temperature difference occurs, and the heat of the exhaust gas flowing through the exhaust bypass passage 27a causes the exhaust bypass passage 27a to The cooling water flowing through the heat exchange passage 27b isolated through the inner member 25 is heated. As a result, the temperature of the cooling water is raised early, the warm-up time is shortened, and the heat generation of the heater core 17 is promoted to be used for heating the vehicle interior.

  Furthermore, since the upstream of the heat insulation space 29 formed between the exhaust heat exchanger 23 and the outer tube 24 disposed on the outer periphery thereof is blocked by the outside air shutoff valve 31, for example, Even if the vehicle travels during machine operation, the outside air does not flow through the heat insulation space 29, so that the heat insulation state is maintained, the exhaust heat can be efficiently recovered in the cooling water, and the temperature rise of the cooling water is further promoted. be able to.

  Thereafter, when the cooling water temperature further rises and the thermowax 30b of the thermoactuator 30 is thermally expanded, the rod 30c interlocked with the thermowax 30b gradually protrudes, and is connected to the rod 30c via the link mechanisms 35a and 35b. The exhaust gas switching valve 28 and the outside air shutoff valve 31 are gradually opened. Then, when the cooling water temperature reaches a predetermined temperature (for example, 75 to 85 [° C.]), as shown in FIG. 3, the exhaust gas switching valve 28 and the outside air shutoff valve 31 are fully opened.

  As a result, as shown by an arrow B in FIG. 3, most of the exhaust gas is discharged to the outside through the exhaust communication pipe 22. Further, since the outside air shutoff valve 31 is open, as indicated by an arrow C, the outside air passes between the opening 24a formed in the outer tube 24 and the outside air shutoff valve 31 and is introduced into the heat insulating space 29. Is done. Therefore, even if the exhaust heat becomes high temperature, the heat does not stay in the heat insulation space 29, and the temperature rise of the cooling water can be suppressed. Therefore, during traveling, the cooling water and the exhaust gas can be more efficiently cooled by the outside air flowing through the heat insulating space 29.

  As described above, in the present embodiment, in the cold start and the warm-up operation after the start, when the thermowax 30b of the thermoactuator 30 is thermally contracted, the exhaust gas switching valve 28 of the exhaust heat recovery device 21 is in communication with the exhaust gas. Since the pipe 22 is shut off and the exhaust gas is guided to the exhaust bypass passage 27a side, the outside air shut-off valve 31 is closed to shut off the heat insulation space 29, so that the cooling water is cooled by the exhaust gas flowing through the exhaust bypass passage 27a. Can be efficiently heated.

  In addition, after the cooling water is heated to a predetermined temperature, the exhaust switching valve 28 communicates with the exhaust communication pipe 22 and the outside air shutoff valve 31 is opened to introduce outside air into the heat insulating space 29. The temperature rise of water can be suppressed.

  Furthermore, in the present embodiment, the operations of the exhaust switching valve 28 and the outside air shut-off valve 31 are mechanically controlled by the operation of the thermoactuator 30 disposed on the downstream side of the heat exchange passage 27b. By doing so, it can be attached to an existing vehicle relatively easily, and high versatility can be obtained.

[Second Embodiment]
6 and 7 show a second embodiment of the present invention. In the first embodiment described above, the outside air shutoff valve 31 provided in the exhaust heat recovery device 21 is disposed on the upstream side of the outer tube 24, but in this embodiment, the outside air shutoff valve 31 is disposed in the heat insulating space 29. It is arranged on the downstream side.

  That is, the outer tube 24 according to the present embodiment is obtained by disposing the outer tube 24 of the first embodiment with respect to the exhaust communication tube 22 so that the upstream side and the downstream side are reversed. This is the same as the first embodiment described above.

[Third Embodiment]
8 and 9 show a third embodiment of the present invention. In the first and second embodiments described above, the open / close operation of the exhaust gas switching valve 28 and the outside air shutoff valve 31 of the exhaust heat recovery device 21 is mechanically opened and closed using the thermoactuator 30, but this embodiment Then, both the valves 28 and 31 are controlled electronically. The exhaust heat recovery device 21 has a configuration in which a water temperature sensor 42 is provided in place of the thermoactuator 30 of the first and second embodiments, the link mechanisms 35a and 35b are omitted, and each valve 28 31, an exhaust electric actuator 43 and an outside air electric actuator 44 are connected in series, and the valves 28 and 31 are operated by the electric actuators 43 and 44.

  The electronic control unit (ECU) 41 is mainly composed of a microcomputer having a CPU, ROM, RAM, input / output interface, etc. (not shown), and a control program, fixed data, and the like are stored in the ROM. The ECU 41 outputs an operation signal to both the electric actuators 43 and 44 based on the cooling water temperature detected by the water temperature sensor 42 and discharged from the side of the outflow port 23b communicating with the heat exchange passage 27b.

  Specifically, the control of the electric actuators 43 and 44 executed by the ECU 41 is executed according to the flowchart shown in FIG.

  This flowchart is executed for each preset calculation cycle. First, the cooling water temperature detected by the water temperature sensor 42 in step S1 is compared with a preset warm-up completion temperature to check whether the warm-up is complete. When it is determined that the cooling water temperature is warming up below the warm-up completion temperature, the process proceeds to step S2 and outputs a close signal for closing the exhaust switching valve 28. Then, the process proceeds to step S3 and the outside air shutoff valve 31 is turned on. After outputting the closing signal to close the valve, the routine is exited.

  The exhaust gas switching valve 28 employed in this embodiment is always urged in the valve opening direction by a return spring (not shown), while the outside air shutoff valve 31 is always urged in the valve opening direction by the urging force of the return spring 33. It is energized. Accordingly, the exhaust switching valve 28 is fully opened when the exhaust electric actuator 43 is OFF, and is fully closed when it is ON. Further, the outside air shutoff valve 31 is fully opened when the outside air electric actuator 44 is OFF, and is fully closed when it is ON.

  The close signal (ON signal) output from the ECU 41 is energized to the exhaust electric actuator 43 and the outside air electric actuator 44, and each of the electric actuators 43 and 44 is operated so that the exhaust switching valve 28 and the outside air cutoff valve 31 are operated. Are closed (the state shown in FIGS. 2 and 6).

  On the other hand, when it is determined in step S1 that the cooling water temperature has exceeded the warm-up completion temperature, the process proceeds to step S4, and after outputting an opening signal for opening the exhaust switching valve 28, the process proceeds to step S5. An open signal for opening the outside air shutoff valve 31 is output, and the routine is exited.

  When an open signal (OFF signal) is output from the ECU 41 to the exhaust electric actuator 43 and the outside air actuator 44, the energization of both the electric actuators 43 and 44 is cut off, and the exhaust switching valve 28 is returned to a return spring (not shown). And the outside air shut-off valve 31 is opened by the urging force of the return spring 33 (the state shown in FIGS. 3 and 7). Note that the exhaust gas in the fully closed state or the fully open state of the valves 28 and 31, the flow of outside air in the heat insulating space 29, and the temperature change of the cooling water are the same as those in the first and second embodiments described above. Description is omitted.

  According to the present embodiment, the exhaust switching valve 28 and the outside air shut-off valve 31 are opened / closed according to the cooling water temperature detected by the water temperature sensor 42. Therefore, the opening / closing of the valves 28, 31 is cooled. It can be accurately controlled according to the water temperature. Furthermore, the opening / closing timing of the valves 28 and 31 can be finely adjusted for each vehicle type.

  In this embodiment, the exhaust switching valve 28 and the outside air shutoff valve 31 are opened and closed by different electric actuators 43 and 44. However, the valves 28 and 31 may be opened and closed by one actuator. .

[Fourth Embodiment]
10 and 11 show a fourth embodiment of the present invention. In the first to third embodiments described above, the exhaust heat exchanger 23 is formed in an annular shape on the outer periphery of the exhaust communication pipe 22 that is integrated with the exhaust pipe 2. The exhaust communication pipe 51, which is integrated into the first pipe, is branched into an exhaust main passage 51a as a first pipe and an exhaust sub-passage 51b as a second pipe. The heat exchanger 52 of FIG. Further, as in the first and second embodiments, an outer tube 24 is disposed on the outer periphery of the exhaust communication tube 22, and a heat insulating space 29 is formed between the outer tube 24 and the exhaust communication tube 22. The heat insulation space 29 can be freely opened and closed by an outside air shutoff valve 31. The configuration of the outside air cutoff valve 31 is the same as that of the first embodiment described above.

  The inflow port 52 a and the outflow port 52 b of the heat exchanger 52 are connected to the middle of the cooling water sub-passage 13, and the cooling water passes through the heat exchanger 52 and circulates in the cooling water sub-passage 13. Further, an exhaust switching valve 53 serving as a first valve body is disposed at a branch portion on the upstream side of the exhaust main passage 51a and the exhaust sub passage 51b of the exhaust communication pipe 22. A lever (not shown) and an outside air shut-off valve 31 fixed to a rotating shaft 53a provided at the base of the exhaust gas switching valve 53 are provided with link mechanisms 35a and 35b (see FIG. 5) as in the first embodiment. Via the rod 30c of the thermoactuator 30.

  When the engine 1 (see FIG. 1) is cold, the thermowax 30b of the thermoactuator 30 is thermally contracted, so the rod 30c interlocked with the thermowax 30b is connected to the exhaust switching valve via the link mechanisms 35a and 35b. A lever fixed to the rotary shaft 53a of 53 and the outside air shutoff valve 31 are pulled. As a result, as shown in FIG. 10, the exhaust switching valve 53 closes the inflow port of the exhaust main passage 51a and opens the inflow port of the exhaust sub-passage 51b.

  When the driver turns on the starter switch (not shown) and starts the engine 1, most of the cooling water is circulated through the cooling water sub-passage 13 (see FIG. 1) by driving the water pump 15.

  On the other hand, the exhaust gas of the engine 1 flows out in the direction of the muffler 3 (see FIG. 1) through the exhaust sub-passage 51b as indicated by the arrow B because the exhaust main passage 51a of the exhaust communication pipe 22 is closed. . The cooling water circulating through the cooling water sub-passage 13 enters the heat exchanger 52 through the inflow port 52a of the heat exchanger 52 and is discharged from the outflow port 52b as shown by the arrow A. Since the temperature rise of the exhaust gas is faster than that of the cooling water, the cooling water passing through the heat exchanger 52 is heated to recover the exhaust heat, and the warm-up time can be shortened.

  In this case, since the outside air shut-off valve 31 closes the heat insulation space 29, unnecessary heat release of the heat of the exhaust gas flowing through the exhaust sub passage 51b to the atmosphere is suppressed, and the temperature of the cooling water is increased efficiently. be able to.

  Thereafter, when the cooling water temperature further rises, the thermowax 30b of the thermoactuator 30 thermally expands, and the rod 30c protrudes, the exhaust switching valve 53 is exhausted via the link mechanism 35a as shown by the one-dot chain line in the figure. The sub passage 51b is closed and the main exhaust passage 51a is opened. As a result, the exhaust gas passes through the exhaust main passage 51a and is discharged to the outside. At the same time, the outside air shutoff valve 31 is opened via the link mechanism 35 b, and the outside air is introduced into the heat insulating space 29. Therefore, heat is not trapped in the heat insulating space 29 and the cooling water is not unnecessarily heated.

  As described above, in this embodiment, the heat exchanger 52 is provided in the exhaust sub-passage 51b so that the exhaust gas is directly passed therethrough, so that the exhaust heat can be recovered more efficiently by the cooling water. Note that if an existing heat exchanger 52 is employed, cost reduction can be realized.

  In the present embodiment, the exhaust switching valve 53 and the outside air shutoff valve 31 may be opened and closed with a single link mechanism. Further, the exhaust gas switching valve 53 may be disposed at the junction of the exhaust main passage 51a and the exhaust sub-passage 51b on the downstream side of the exhaust communication pipe 22. Similarly, the outside air shutoff valve 31 may be disposed on the downstream side of the outer tube 24.

[Fifth Embodiment]
12 to 14 show a fifth embodiment of the present invention. This embodiment is a modification of the second embodiment described above. In addition, about the structure same as 2nd Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the second embodiment, the structure is such that the middle of the cooling water sub-passage 13 is connected to the inflow port 23a and the outflow port 23b that protrude outward from the outer periphery of the exhaust heat exchanger 23. In the embodiment, a part of the cooling water sub-passage 13 as the engine cooling water passage connected to the inflow port 23a and the outflow port 23b, specifically, the cooling connected to the inflow port 23a of the exhaust heat exchanger 23. The heat upstream space 29 formed between the outer tube 24 and the exhaust communication pipe 22 is inserted between the water upstream passage 13 and the water cooling passage 13 connected to the outflow port 23b. In this way, it is guided in the upstream direction of the exhaust pipe 2.

  That is, the opening end 29c (see FIG. 12) side of the outer tube 24 of the exhaust heat exchanger 23 in the vehicle body front direction extends along the exhaust pipe 2 to the engine 1 side. The cooling water sub-passage 13 connected to both the ports 23a and 23b is inserted into the heat insulating space 29 at the nearest part connected to both the ports 23a and 23b. The cooling water sub-passage 13 inserted into the heat insulating space 29 extends to the engine 1 side along the exhaust pipe 2 and is exposed to the outside from the opening end 29c.

  The outer tube 24 is formed in a cross-sectional shape that can accommodate the two cooling water sub-passages 13 in the heat insulation space 29. As shown in FIG. 14, in the present embodiment, the outer tube 24 is formed in a cross-sectional boat shape. Two cooling water sub-passages 13 are accommodated along the exhaust pipe 2 on the stern side.

  The opening / closing operations of the exhaust gas switching valve 28 and the outside air shutoff valve 31 are the same as those in the second embodiment, and thus the description thereof is omitted.

  In the present embodiment, since the cooling water sub-passage 13 is inserted into the heat insulating space 29 formed in the exhaust heat exchanger 23, the heat radiation of the cooling water flowing through the cooling water sub-passage 13 during the warm-up operation is suppressed. Since the heat from the exhaust gas flowing through the exhaust pipe is received by the cooling water, the cooling water temperature can be raised earlier. When the cooling water temperature reaches a predetermined temperature (for example, 75 to 85 [° C.]), the outside air shut-off valve 31 is fully opened and the outside air is introduced into the heat insulating space 29, so that the cooling water is heated more than necessary. There is nothing.

  As a result, according to the present embodiment, the temperature of the cooling water can be raised more efficiently during the warm-up operation than in the second embodiment described above. The exhaust heat exchanger 23 includes an exhaust communication pipe 51 integrated in the middle of the exhaust pipe 2 as shown in the fourth embodiment, an exhaust main passage 51a, and an exhaust sub-passage 51b as a second pipe. The heat exchanger 52 may be installed in the exhaust sub-passage 51b.

Schematic configuration diagram of an engine cooling system equipped with an exhaust heat recovery device according to the first embodiment Same sectional side view of exhaust heat recovery device The sectional side view according to the state of FIG. IV-IV sectional view of Fig. 3 Same schematic diagram of drive system of exhaust heat recovery device Sectional side view of the exhaust heat recovery apparatus according to the second embodiment FIG. 6 is a sectional side view according to the state of FIG. Configuration diagram of control system of exhaust heat recovery apparatus according to third embodiment Flow chart showing switching control between exhaust switching valve and outside air shutoff valve Sectional side view of the exhaust heat recovery apparatus according to the fourth embodiment XI-XI cross section of Figure 10 Schematic configuration diagram of a vehicle equipped with an exhaust heat recovery device according to a fifth embodiment Sectional view equivalent to FIG. XIV-XIV cross section of Fig. 13

1 ... Engine,
2 ... exhaust pipe,
11 ... Engine cooling system,
13 ... cooling water sub-passage,
17 ... Heater core,
21. Exhaust heat recovery device,
22, 51 ... exhaust communication pipe,
22a: upstream exhaust port,
22b: downstream exhaust port,
23. Exhaust heat exchange part,
23a ... Inflow port,
23b ... Outflow port,
24 ... outer tube,
24a ... opening,
25. Inner member,
26: outer member,
27a ... exhaust bypass passage,
27b ... heat exchange passage,
28, 53 ... exhaust switching valve,
29 ... Insulated space,
30 ... Thermo actuator,
30b ... Thermo wax,
30c ... Rod,
31 ... Outside air shutoff valve,
35a, 35b ... link mechanism,
42 ... Water temperature sensor,
43 ... Exhaust actuator,
44 ... Actuator for outside air,
51a ... exhaust main passage,
51b ... exhaust sub-passage,
52 ... Heat exchanger

Claims (7)

A first conduit through which exhaust gas flows;
A second pipeline bypassing the first pipeline;
A first valve body that closes the first pipe and guides the exhaust gas to the second pipe when the temperature of the engine coolant is low;
A heat exchanging portion that is disposed adjacent to the second pipe and through which engine coolant flows;
An outer tube covering the outer periphery of the heat exchange part;
The heat insulation space formed between the outer tube and the heat exchanging portion is interlocked with the first valve body, and is shut off when the first valve body closes the first conduit, An exhaust heat recovery apparatus comprising: a second valve body that opens when the one valve body opens the first conduit. The second pipe is formed on an outer periphery of the first pipe;
The exhaust heat recovery apparatus according to claim 1, wherein the heat exchange unit is disposed on an outer periphery of the second pipe line. The second conduit is provided adjacent to the first conduit;
The exhaust heat recovery apparatus according to claim 1, wherein the heat exchange unit is disposed in the second pipe line. Both ends of the outer tube are opened in the front-rear direction of the vehicle body,
The exhaust heat recovery apparatus according to any one of claims 1 to 3, wherein the second valve body is disposed on one of a front opening end and a rear opening end of the outer tube. . The first valve body and the second valve body are driven by a thermoactuator having a thermowax that thermally expands or contracts at a temperature of the engine cooling water. The exhaust heat recovery device according to claim 1. An electric actuator for opening and closing the first valve body and the second valve body;
Control means for operating the electric actuator;
A water temperature sensor for detecting the temperature of the engine cooling water,
The control means outputs a signal for closing the first valve body and the second valve body to the electric actuator when it is determined that the engine cooling water temperature detected by the water temperature sensor is a low temperature below a set temperature. The exhaust heat recovery apparatus according to any one of claims 1 to 4, wherein the exhaust heat recovery apparatus is any one of claims 1 to 4. The at least one part of the engine-cooling-water path | route which is connected to the said heat exchange part and distribute | circulates the said engine-cooling water is penetrated by the said heat insulation space, The any one of Claims 1-6 characterized by the above-mentioned. Exhaust heat recovery device.

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