JP2008291777A - Engine exhaust heat recovery device and its method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust heat recovery device effectively heating liquid to be heated even if an exhaust gas temperature is relatively low, and to provide its method. <P>SOLUTION: The exhaust heat recovery device comprises: a heating part 33 heating and gasifying liquid refrigerant Wr by exhaust heat of exhaust gas; a condensing part 37 condensing refrigerant Ws gasified by the heating part 33 by heat exchange; and a heating promoting part 35 which is disposed on a refrigerant passage between the heating part 33 and the condensing part 37, and in which heat accumulating material 36 is disposed to be in contact with the gasified refrigerant Ws. Heat generation reaction is performed between the heat storage material 36 and the gasified refrigerant Ws to increase a temperature of the gasified refrigerant Ws fed to the condensing part 37, and the heat exchange between the liquid Wc to be heated and the gasified refrigerant Ws which passed through the heating promoting part 35 and of which the temperature is increased, in the condensing part 37. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an engine exhaust heat recovery apparatus and method for heating a liquid to be heated (for example, engine cooling water or oil) using exhaust heat of exhaust gas of the engine.

  2. Description of the Related Art Conventionally, an exhaust heat recovery apparatus that heats a liquid to be heated by using exhaust heat of engine exhaust gas is known (see, for example, Patent Document 1).

  Patent Document 1 discloses that the liquid to be heated is engine cooling water. By heating the engine coolant with the exhaust heat recovery device, it is possible to improve the warm-up performance and the heating start-up performance of the heater (heater).

The exhaust heat recovery device disclosed in Patent Document 1 heats and vaporizes a liquid refrigerant with exhaust heat (heating unit). Then, heat is exchanged between the vaporized refrigerant and the liquid to be heated to condense the vaporized refrigerant (condensing unit, referred to as a cooling unit in the document). The liquid to be heated is heated mainly by latent heat released when the vaporized refrigerant condenses. In particular, the apparatus is configured such that the contact area between the refrigerant heat transfer fin and the exhaust gas in the heating section is larger on the downstream side than on the upstream side, whereby the refrigerant receives heat more evenly. The exhaust heat recovery efficiency is improved.
JP 2007-24423

  However, the refrigerant cannot always receive sufficient exhaust heat in the heating unit. For example, since the exhaust gas temperature is low immediately after the engine is started, the amount of exhaust heat received by the refrigerant is considerably smaller than that in the warm state. However, the time when there is a request for heating of the liquid to be heated is usually when the exhaust gas temperature immediately after starting the engine is low.

  In this way, the fact that the temperature of the essential exhaust heat is low when the demand for receiving exhaust heat is the highest is the actual situation. Under such circumstances, even if the exhaust heat recovery efficiency is increased as in Patent Document 1, The effect must be limited.

  The present invention has been made in view of the above circumstances, and provides an exhaust heat recovery apparatus and method that can effectively heat a liquid to be heated even when the exhaust gas temperature is relatively low. Objective.

The invention according to claim 1 for solving the above-mentioned problem is an exhaust heat recovery device that heats a liquid to be heated using exhaust heat generated by exhaust gas from an engine, and heats a liquid refrigerant with the exhaust heat. Provided on the refrigerant passage between the heating unit and the condensing unit, and can be brought into contact with the vaporized refrigerant. And a heating promoting part in which a heat storage material is disposed, and the heat storage material raises the temperature of the vaporized refrigerant sent to the condensing unit by performing an exothermic reaction with the vaporized refrigerant. Yes,
The vaporized refrigerant whose temperature has risen through the heating promoting part exchanges heat with the liquid to be heated in the condensing part.

  According to a second aspect of the present invention, in the exhaust heat recovery apparatus for an engine according to the first aspect, the heating promoting portion is disposed so as to receive the exhaust heat, and the heating portion communicates with the heating promoting portion. A first passage valve that opens and closes the passage is provided on one passage, and the first passage valve is opened when there is a heating request for the liquid to be heated and is closed when there is no heating request. Is characterized by performing the reverse reaction of the exothermic reaction by receiving the exhaust heat in a state in which the first passage valve is closed.

  According to a third aspect of the present invention, in the engine exhaust heat recovery apparatus according to the first or second aspect of the present invention, as the circulation path of the vaporized refrigerant, the first is led from the heating unit to the condensing unit via the heating promoting unit. And a second path that bypasses the heating promoting section and is guided to the condensing section from the heating section, and the vaporized refrigerant passes through the first path when there is a heating request for the heated liquid. When there is no heating request, the second path is passed.

  According to a fourth aspect of the present invention, in the exhaust heat recovery apparatus for an engine according to any one of the first to third aspects, a space in which the refrigerant is water and water vapor that is a vaporized refrigerant flows, and the intake air of the engine And a suction passage valve for opening and closing the negative pressure suction passage, wherein the suction passage valve starts operation of at least the exhaust heat recovery device in an engine drive state. The valve is opened for a predetermined period thereafter.

  The invention according to claim 5 is the engine exhaust heat recovery apparatus according to any one of claims 1 to 4, wherein the refrigerant is water, and a main component of the heat storage material is magnesium oxide. And

  The invention according to claim 6 is the engine exhaust heat recovery apparatus according to any one of claims 1 to 5, wherein the liquid to be heated is engine coolant, and the engine coolant is circulated as a circuit. A radiator circuit that passes through the radiator, a bypass circuit that bypasses the radiator, and a radiator circuit valve that closes the radiator circuit when the engine is cold, the exhaust heat recovery device being connected to the bypass circuit, To do.

  The invention according to claim 7 is an exhaust heat recovery method for heating a liquid to be heated by utilizing exhaust heat generated by exhaust gas from an engine, wherein the liquid refrigerant is heated by the exhaust heat and vaporized, and the vaporized refrigerant Is brought into contact with a heat storage material that performs an exothermic reaction with the vaporized refrigerant, and the temperature of the vaporized refrigerant is increased by the heat generated by the exothermic reaction. It is characterized by heat exchange and condensation.

  According to the first aspect of the present invention, as will be described below, the liquid to be heated can be effectively heated even when the exhaust gas temperature is relatively low.

  According to the configuration of the present invention, the refrigerant cycle of evaporation (vaporization) of the refrigerant in the heating unit → heat exchange between the refrigerant and the liquid to be heated in the condensation unit → condensation (liquefaction) of the refrigerant is performed. The liquid to be heated can be effectively heated even by a relatively low temperature vaporized refrigerant by heat exchange using the latent heat.

  Furthermore, in this invention, the heating promotion part provided with the thermal storage material is provided between the heating part and the condensation part. This heat storage material raises the temperature of the vaporized refrigerant sent to the condensing part by performing an exothermic reaction with the vaporized refrigerant. In this way, since the temperature of the refrigerant during heat exchange can be increased compared to the case where no heat storage material is provided, the heated liquid can be effectively heated even when the exhaust gas temperature is relatively low.

  According to the second aspect of the present invention, as will be described below, it is easy to downsize the apparatus or make it maintenance-free.

  Since there is a limit to the amount of the heat storage material that can be accommodated in the heating promoting portion, when only the exothermic reaction is performed, the limit is eventually reached and no further exothermic reaction is performed. Accordingly, it is necessary to accommodate a large amount of heat storage material or frequently change the heat storage material in order to delay the limit point.

  However, according to the present invention, the reverse reaction of the exothermic reaction is performed by applying exhaust heat to the heat storage material after the exothermic reaction. That is, the heat storage material can be returned to the state before the exothermic reaction (hereinafter referred to as regeneration). By appropriately performing this regeneration, the same heat storage material can be repeatedly subjected to an exothermic reaction. Therefore, the amount of necessary heat storage material is relatively small, and the apparatus can be downsized. In addition, frequent replacement of the heat storage material is not required, so that maintenance can be easily performed.

  In this regeneration, if the first passage valve is opened, there is a possibility that an exothermic reaction may be performed simultaneously with the supply of the refrigerant from the heating unit. Therefore, in the present invention, during regeneration, the first passage valve is closed to stop the supply of refrigerant. Thereby, only a reverse reaction is performed and appropriate regeneration can be realized.

  According to the third aspect of the present invention, as described below, when there is no request for heating the liquid to be heated, it is possible to suppress unnecessary heating.

  The vaporized refrigerant is passed through the first path when there is a request to heat the liquid to be heated. Thereby, heat exchange at high temperature is performed as described above, and the liquid to be heated is effectively heated.

  On the other hand, the refrigerant passes through the second path when there is no request for heating of the liquid to be heated. Thereby, an unnecessary exothermic reaction of the heat storage material is suppressed, and thus an unnecessary temperature rise of the refrigerant can be suppressed. Therefore, unnecessary heating of the liquid to be heated can be suppressed.

  In addition to the condensing unit that exchanges heat between the refrigerant and the liquid to be heated, a condensing unit that condenses the refrigerant may also be provided on the second path. In that case, heat exchange itself between the refrigerant and the liquid to be heated can be suppressed, and unnecessary heating of the liquid to be heated can be further suppressed.

  Further, when the refrigerant passes through the second passage at the time of regeneration, the passage through the second path during regeneration may be prohibited (when heating or regeneration is not in progress). Through the second path).

  According to the invention of claim 4, the space in which the vaporized refrigerant (water vapor) flows can be decompressed with a simple configuration. Since the water is easily evaporated by this reduced pressure, the exothermic reaction can be further promoted.

  According to the fifth aspect of the present invention, as will be described below, the reaction of the heat storage material suitable for the exhaust heat recovery of the engine can be performed.

Magnesium oxide, which is the main component of the heat storage material, hydrates with water (steam) to become magnesium hydroxide (MgO + H ₂ O → Mg (OH) ₂ ). This hydration reaction is performed at a water vapor temperature of about 70 to 80 ° C. This is a temperature that can be achieved even with a relatively low temperature exhaust gas immediately after engine startup. And by this hydration reaction, the water vapor | steam which passes along a thermal storage material rises to about 150-230 degreeC. Therefore, the water vapor temperature during heat exchange can be effectively increased.

  As described above, normally, the heating requirement for the liquid to be heated increases when the exhaust gas temperature immediately after the engine is started is low. According to the present invention, since the water vapor temperature of the refrigerant can be increased in such a case, it is convenient to meet the heating requirement of the liquid to be heated.

  On the other hand, the reverse reaction (regeneration) of the hydration reaction is a dehydration reaction of magnesium hydroxide. This dehydration reaction is performed at about 300 ° C. Since the exhaust gas temperature when the engine is warm is 400 ° C. or higher, the temperature is sufficient to cause this dehydration reaction. That is, the heat storage material can be properly regenerated.

  Thus, the heat storage material of the present invention behaves as if the heat is stored when the exhaust gas temperature is high and the stored heat is released when the exhaust gas temperature is low. Also, the high-temperature exhaust heat at the time of heat storage (regeneration) is heat that should be discarded as it is, but that heat is stored and taken out when there is a request for heating of the liquid to be heated and used effectively. It can also be said.

  The heat storage material of the present invention is a heat storage material suitable for an exhaust heat recovery device of an engine because the reaction temperature at the time of heat storage or heat dissipation is conveniently matched to the exhaust gas temperature when it is desired to perform them. ing.

  According to the invention of claim 6, as described below, the warm-up performance of the engine can be effectively improved.

  A circuit that circulates the engine coolant includes a radiator circuit that passes through the radiator, a bypass circuit that bypasses the radiator, and a radiator circuit valve that closes the radiator circuit when the engine is cold (generally a thermostat is used) Is conventionally known. By circulating the cooling water only to the bypass circuit during the cold time, it is possible to promote an increase in the cooling water temperature after the cold start and improve the warm-up performance.

  Furthermore, in the present invention, since the exhaust heat recovery device of the engine is connected to the bypass circuit, the rise of the coolant temperature can be further promoted and the warm-up performance can be further improved.

  In addition, when the heater is connected to this bypass circuit, the heating start-up performance of the heater can also be improved.

  Furthermore, if the cooling water is guided to the exhaust heat recovery device only when there is a request for heating of the engine cooling water using an appropriate switching valve or the like, unnecessary heating of the engine cooling water can be more reliably suppressed. Can do.

  According to the seventh aspect of the present invention, as will be described below, the liquid to be heated can be effectively heated even when the exhaust gas temperature is relatively low.

  According to the configuration of the present invention, the refrigerant cycle of evaporation (vaporization) of refrigerant → heat exchange between the refrigerant and the liquid to be heated → condensation (liquefaction) of the refrigerant is performed. Even if the temperature difference of the refrigerant is relatively low, the liquid to be heated can be effectively heated by heat exchange using the latent heat.

  Further, in the present invention, the vaporized refrigerant is allowed to react with the heat storage material that performs an exothermic reaction with the vaporized refrigerant, and the temperature of the vaporized refrigerant is increased by the heat generated by the exothermic reaction. By carrying out like this, the temperature of the refrigerant | coolant at the time of heat exchange can be raised compared with the case where a heat storage material is not provided. Therefore, even when the exhaust gas temperature is relatively low, the liquid to be heated can be effectively heated.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic circuit diagram of engine cooling water including an exhaust heat recovery apparatus according to the first embodiment of the present invention. Circuits through which engine coolant circulates are roughly divided into a radiator circuit 18 that passes through the radiator 9 and a bypass circuit 11 that bypasses the radiator 9. Further, a thermostat 6 (radiator circuit valve) is provided for closing the radiator circuit 18 when the coolant temperature is equal to or lower than a predetermined value.

  First, the bypass circuit 11 will be described. When the thermostat 6 is closed when the engine is cold, the coolant circulates only through the bypass circuit 11.

  The bypass circuit 11 enters the engine body 2 from the water pump 5 and exits the engine body 2 via the cylinder block 3 and the cylinder head 4. Thereafter, the bypass circuit 11 branches in parallel to the cold first path 14, the cold second path 15, and the cold third path 16. The first cold path 14 passes through the vicinity of the EGR valve 7 and the throttle body 8. Since these are well-known members, they will be briefly described. The EGR valve 7 is a valve provided on an EGR passage for performing EGR (exhaust gas recirculation). The throttle body 8 is a member provided with a throttle valve that adjusts the intake air amount of the engine according to the load.

  The cold second path 15 passes in the vicinity of the heater 10 for heating.

  The exhaust heat recovery device 30 is connected to the cold third path 16. The exhaust heat recovery device 30 is a device that heats the liquid to be heated (in this embodiment, engine cooling water) using the exhaust heat of the exhaust gas flowing through the exhaust pipe 25. The cooling water is sent from the cold third path 16 to the cooling water out path 22 via the switching valve 21 (three-way valve). The cooling water heated by the exhaust heat recovery device 30 is returned from the cooling water in-passage 23 to the cold third passage 16.

  The cold first path 14, the cold second path 15, and the cold third path 16 finally merge and return to the water pump 5.

  When the cooling water is cold, it circulates only through the bypass circuit 11 (including the cold first, second, and third paths 14, 15 and 16), so that the heat received by the engine main body 2 is received by the engine main body 2. The temperature is efficiently transmitted to the low temperature portion, the EGR valve 7 and the throttle body 8, and these are quickly raised to an appropriate temperature. (Warm-up). In addition, heat is supplied to the heater 10 to quickly start up the heating. Further, by passing the cooling water through the exhaust heat recovery device 30, the temperature rise of the cooling water can be further promoted, and the warm-up performance and the heating start-up performance can be improved. Details of the exhaust heat recovery device 30 will be described later.

  On the other hand, the radiator circuit 18 is a circuit for passing cooling water through the radiator 9. When the engine is warm (when the cooling water temperature is equal to or higher than a predetermined value), the cooling water circulates through the radiator circuit 18 by opening the thermostat 6. The radiator circuit 18 branches from the bypass circuit 11 after exiting the cylinder head 4, passes through the radiator 9, returns to the water pump 5 via the thermostat 6. Since the cooling water exchanges heat with the outside air (running wind) by the radiator 9 and is efficiently cooled, the engine main body 2 is appropriately cooled when warm.

  In addition, the switching valve 21 is configured to block the cooling water out path 22 during the warm time so that the cooling water is not guided to the exhaust heat recovery device 30. Thereby, the unnecessary temperature rise of cooling water is suppressed.

  FIG. 2 is a perspective view schematically showing the exhaust heat recovery device 30 and the vicinity thereof. The exhaust heat recovery device 30 is disposed in the middle of the exhaust pipe 25. The exhaust heat recovery device 30 receives the exhaust gas 27 from the upstream side exhaust pipe 25a, receives heat, and sends it to the downstream side exhaust pipe 25b. The exhaust heat recovery device 30 is preferably provided at a relatively upstream position of the exhaust pipe 25. For example, when the catalyst device is provided at the most upstream position of the engine exhaust pipe, it is preferably provided immediately downstream thereof.

  In the present embodiment, the cooling water inlet 61 and the cooling water outlet 63 are led out from the upper surface of the main body of the exhaust heat recovery apparatus 30. The cooling water inlet 61 is connected to the cooling water out path 22 (FIG. 1), and the cooling water outlet 63 is connected to the cooling water in path 23 (FIG. 1), respectively, and exchanges the cooling water Wc with these. A fourth passage 44 (described later) is led out to the outside of the exhaust heat recovery device 30 on the side of the main body, and a condenser 37b is provided in the fourth passage 44. A negative pressure suction passage 47 described later is led out to the outside of the main body side of the exhaust heat recovery device 30. The negative pressure suction passage 47 communicates with a negative pressure generating portion (not shown) of the intake system of the engine, and the air A in the exhaust heat recovery device 30 is sucked out by the negative pressure as necessary to reduce the pressure. It has come to be. A condenser 48 is provided in the negative pressure suction passage 47.

  FIG. 3 is a schematic diagram of the exhaust heat recovery device 30. This schematic diagram substantially corresponds to a longitudinal sectional view of the exhaust heat recovery device 30 (a sectional view in a plane perpendicular to the axial direction of the exhaust pipe 25). The exhaust heat recovery device 30 has a two-chamber structure, and includes a lower first chamber 31 and an upper second chamber 32.

  The first chamber 31 is a part connected to the exhaust pipe 25 (the approximate position is indicated by a two-dot chain line), and the exhaust gas 27 flowing in from the upstream exhaust pipe 25a passes through the first chamber 31 and is exhausted downstream. The tube 25b can be pulled out. In FIG. 3, the flow direction of the exhaust gas 27 is a direction perpendicular to the paper surface.

  A large number of fins 34 for efficiently receiving the exhaust heat of the exhaust gas 27 are arranged inside the first chamber 31, and a heating unit 33 is formed. A liquid refrigerant (in this embodiment, water Wr) is stored in the lower part of the heating unit 33 (the bottom of the first chamber 31). The vaporized refrigerant (water vapor Ws in the present embodiment) evaporates and rises from the water Wr that has received the exhaust heat at the lower part of the heating unit 33, and passes through the gaps of the fins 34 while receiving the exhaust heat at the heating unit 33. It is comprised so that it may escape above 33.

  In the upper part of the first chamber 31, there is provided a heating promoting portion 35 containing a granular heat storage material 36 (in this embodiment, magnesium oxide MgO is a main component). The heating unit 33 and the heating promotion unit 35 are communicated with each other through the first passage 41. The first passage 41 is provided with a first passage valve 51 for opening and closing the first passage 41.

  In the second chamber 32, a first condensing part 37a is disposed. The 1st condensing part 37a comprises the condensing part 37 as a whole with the 2nd condenser 37b mentioned later. The condensing unit 37 is a part that condenses the water vapor Ws by heat exchange (returns to the water Wr).

  A cooling water inlet 61 and a cooling water outlet 63 are provided to communicate the first condensing part 37a with the outside (upper part) of the main body of the exhaust heat recovery device 30. The cooling water inlet 61 and the cooling water outlet 63 are connected to each other through the heat exchange passage 62 inside the first condensing part 37a. Accordingly, the cooling water Wc introduced from the cooling water inlet 61 is led out to the cooling water outlet 63 through the heat exchange passage 62 (indicated by a white arrow). A large number of fins 38 are arranged in the heat exchange passage 62 in order to increase the heat exchange efficiency between the water vapor Ws and the cooling water Wc.

  The heating unit 33 and the first condensing unit 37 a are communicated with each other through the second passage 42. The second passage 42 is provided with a second passage valve 52 for opening and closing the second passage 42. The connecting portion between the second passage 42 and the first condensing part 37a is preferably provided on the downstream side of the first condensing part 37a (one end side in the row direction of the fins 38).

  On the other hand, the heating promoting part 35 and the first condensing part 37 a are communicated with each other through the third passage 43. A third passage valve 53 for opening and closing the third passage 43 is provided. The connecting portion between the third passage 43 and the heating promoting portion 35 is desirably provided at a position farther than the connecting portion between the first passage 41 and the heating promoting portion 35. As shown in the drawing, both connecting portions are connected to the heating promoting portion 35. It is more desirable to provide it near the both ends. The connecting portion between the third passage 43 and the first condensing portion 37a is upstream of the first condensing portion 37a (opposite the fin 38 group with respect to the connecting portion between the second passage 42 and the first condensing portion 37a). Side).

  The downstream side of the first condensing part 37 a and the lower part of the first chamber 31 (location where the water Wr is stored) are communicated with each other through the fourth passage 44. The fourth passage 44 passes through the outside of the main body side of the exhaust heat recovery device 30. A fourth passage valve 54 for opening and closing the fourth passage 44 is provided on the upstream side of the fourth passage 44 (position close to the first condensing portion 37a). A second condensing part 37 b is provided downstream of the fourth passage valve 54. The second condenser 37b is an air-cooled condenser, and condenses the water vapor Ws by exchanging heat between the external air of the exhaust heat recovery device 30 and the water vapor Ws. The fourth passage 44 returns the condensed water Wr to the water Wr reservoir of the heating unit 33.

  In addition, a negative pressure suction passage 47 that communicates the downstream side of the first condensing unit 37 a and the outside of the main body of the exhaust heat recovery device 30 is provided. As described above, the negative pressure suction passage 47 communicates with the negative pressure generating portion of the engine intake system. The negative pressure suction passage 47 is provided with a suction passage valve 55 for opening and closing it. An air-cooled condenser 48 is provided on the upstream side of the suction passage valve 55 (side close to the first condensing part 37a). The condenser 48 exchanges heat between the external air of the exhaust heat recovery device 30 and the air A sucked under negative pressure, and condenses the water vapor Ws contained in the air A.

  Next, the operation of the exhaust heat recovery device 30 will be described. Table 1 is a table | surface which shows the operation | movement pattern of each valve 51-55.

  Table 1 shows the operation patterns of the valves 51 to 55 for each of the five preset modes (decompression, initial stage, heat supply, regeneration, warm). “◯” indicates valve opening, and “×” indicates valve closing.

  Each mode will be described with reference to Table 1. No. In each of the modes marked with 1 to 5, this No. Are executed by an unillustrated control unit (for example, incorporated in the engine control unit ECU). Specifically, opening / closing control of each of the valves 51 to 55 is performed.

  No. The first depressurization mode is a mode in which the air A in the exhaust heat recovery apparatus 30 is evacuated from the negative pressure suction passage 47 to depressurize the internal pressure of the apparatus. The decompression mode is executed for a predetermined period immediately after the cold start of the engine (also immediately after the start of the operation of the exhaust heat recovery device 30). This predetermined period may be a preset time or may be performed until a time when the pressure is reduced to a predetermined atmospheric pressure by providing a separate pressure sensor or the like.

  In the decompression mode, the suction passage valve 55 is opened as shown in Table 1. As a result, the exhaust heat recovery device 30 communicates with the negative pressure portion of the engine intake system and is evacuated. At that time, as shown in Table 1, all the other valves 51 to 54 are also opened, so that the air A is quickly extracted from each part in the exhaust heat recovery device 30. In the decompression mode, the atmospheric pressure in the exhaust heat recovery apparatus 30 is decompressed to about 260 mmHg (≈347 hPa).

  Since the air A to be evacuated passes through the condenser 48, the water vapor Ws contained in the air A is condensed by the condenser 48 and returned to the exhaust heat recovery device 30. Therefore, the water vapor Ws as the refrigerant is prevented from leaking outside the exhaust heat recovery device 30.

  The suction passage valve 55 is opened only in this decompression mode, and is closed in other modes.

  No. The initial mode 2 is a mode in which the required portion of water vapor Ws is filled at an early stage, and is usually executed following the decompression mode. In the initial mode, as shown in Table 1, the fourth passage valve 54 and the suction passage valve 55 are closed, and the other valves are opened.

  When the engine is started, the heating unit 33 receives the exhaust heat of the exhaust gas 27, the water Wr evaporates, and a large amount of water vapor Ws is generated. In order to operate the exhaust heat recovery apparatus 30 stably, it is desirable to fill the apparatus with water vapor Ws at an early stage. On the other hand, in the initial stage of operation, the second condensing part 37b is hardly required, so the fourth passage 44 has a waste volume. Therefore, by closing the fourth passage valve 54 and shutting off the fourth passage 44, the filling volume of the water vapor Ws is reduced and early filling is achieved.

  The execution time of the initial mode is relatively short and is executed as necessary (this may be omitted in some cases).

  No. The third heat supply mode is the most characteristic and important mode, and is a mode in which the temperature of the water vapor Ws is further increased by the heating promotion unit 35. The heat supply mode is executed following the pressure reduction mode or the initial mode when there is a heating request for the cooling water Wc, that is, when the temperature of the cooling water Wc is equal to or lower than a predetermined value. In the heat supply mode, as shown in Table 1, the second passage valve 52 and the suction passage valve 55 are closed, and the other valves are opened.

  In the heat supply mode, the cooling water Wc is guided to the cooling water out path 22 by the switching valve 21 (FIG. 1). Therefore, the flow of the cooling water Wc (white arrow) that flows from the cooling water inlet 61 to the cooling water outlet 63 via the heat exchange passage 62 occurs. Note that the cooling water Wc may flow through the heat exchange passage 62 from the decompression mode or the initial mode before the heat supply mode.

  In FIG. 3, the flow of the water vapor Ws in the heat supply mode is indicated by arrows. In the heat supply mode, the first path 40 through which the water vapor Ws is guided from the heating unit 33 to the condensing unit 37 via the heating promoting unit 35 is formed. Specifically, the water vapor Ws is evaporated from the water Wr and receives the exhaust heat of the exhaust gas 27 while ascending the heating unit 33. Then, it is guided to the heating promoting part 35. And a hydration reaction is caused with magnesium oxide (MgO) which is a main component of the heat storage material 36 accommodated in the heating promotion part 35. The hydration reaction is represented by the following chemical formula (Formula 1).

MgO + H ₂ O → Mg (OH) ₂ (Formula 1)
This hydration reaction is an exothermic reaction, and the heat raises the temperature of the water vapor Ws in the reaction remaining portion that passes through the heating promoting portion 35 to 150 to 230 ° C. The steam Ws whose temperature has risen is guided to the first condensing part 37a through the third passage 43, and is condensed by exchanging heat with the cooling water Wc flowing through the heat exchange passage 62. If there is water vapor Ws that has not been condensed, it is guided to the fourth passage 44, condensed in the second condensing part 37b, and returned to the water Wr storage part.

  On the other hand, the cooling water Wc heat-exchanged with the high-temperature steam Ws in the heat exchange passage 62 rises in temperature, and is returned to the bypass circuit 11 (cold third path 16) through the cooling water in-path 23. Thereby, the temperature rise of the cooling water Wc can be further promoted, and the warm-up performance can be further improved. Moreover, the heating start-up performance of the heater 10 can also be improved.

  In the experiment by the inventors of the present application, it was confirmed that when this embodiment is applied when the warm-up time of the conventional structure is about 5 minutes, the warm-up time can be shortened to about 1 minute.

No. The regeneration mode 4 is a mode in which the heat storage material 36 undergoes the reverse reaction (dehydration reaction) of (Equation 1). Magnesium hydroxide (Mg (OH) ₂ ) is generated by the hydration reaction shown in (Formula 1), but magnesium oxide is gradually consumed only in the heat supply mode, and finally the hydration of (Formula 1). It becomes impossible to make a reaction. Therefore, by appropriately performing the regeneration mode, the magnesium hydroxide is returned to magnesium oxide, that is, regenerated.

  The regeneration mode is executed when there is no heating request for the cooling water Wc, that is, when the temperature of the cooling water Wc is equal to or higher than a predetermined value (for example, the temperature at which the thermostat 6 opens). In the regeneration mode, as shown in Table 1, the third passage valve 53 and the fourth passage valve 54 are opened, and the other valves are closed.

  Further, in the regeneration mode, since the heating request for the cooling water Wc has already disappeared, the switching valve 21 (FIG. 1) blocks the cooling water out path 22. Therefore, the flow of the cooling water Wc that passes from the cooling water inlet 61 to the cooling water outlet 63 via the heat exchange passage 62 does not occur.

In FIG. 4, the flow of water vapor Ws in the regeneration mode is indicated by arrows. In the heating promotion unit 35, the first passage valve 51 is closed, the supply of the water vapor Ws is stopped, and the exhaust heat at a high temperature of 400 ° C. or higher is received. Therefore, magnesium hydroxide (Mg (OH)) generated in the heat supply mode The dehydration reaction ₂ ) is performed. The dehydration reaction is represented by the following scientific formula (Formula 2).

Mg (OH) ₂ → MgO + H ₂ O (Formula 2)
By this dehydration reaction, water vapor Ws of about 150 ° C. is generated. The water vapor Ws is guided to the first condensing part 37a through the third passage 43. As described above, since the flow of the cooling water Wc is not formed in the heat exchange passage 62, heat exchange with the cooling water Wc is suppressed. Accordingly, condensation in the first condensing unit 37a is also suppressed. Therefore, a lot of water vapor Ws is guided to the fourth passage 44, condensed in the second condensing part 37b, and returned to the water Wr storage part.

  On the other hand, since heat exchange in the heat exchange passage 62 is suppressed, an unnecessary temperature rise of the cooling water Wc is suppressed.

  Looking at the operation of the heat storage material 36 in the above heat supply mode and regeneration mode, the heat storage material 36 stores the exhaust heat of the high temperature exhaust gas 27 in the regeneration mode and stores heat in the heat supply mode in which the exhaust gas temperature is low. Acts as if it releases heat. The high-temperature exhaust heat in the regeneration mode is heat that should be discarded as it is, but it can be said that the heat is stored and taken out in the heat supply mode in which the cooling water Wc is required to be heated and effectively used.

  The heat storage material 36 is a heat storage material suitable for the exhaust heat recovery device 30 because the reaction temperature at the time of heat storage and heat dissipation conveniently matches the exhaust gas temperature when it is desired to perform them.

  No. The warm mode No. 5 is a mode that is performed when there is no request to heat the cooling water Wc and when the regeneration mode is not performed (usually after the regeneration mode). In the warm mode, as shown in Table 1, the second passage valve 52 and the fourth passage valve 54 are opened, and the other valves are closed.

  In the warm mode, similarly to the regeneration mode, the switching valve 21 (FIG. 1) blocks the cooling water out path 22. Therefore, the flow of the cooling water Wc that passes from the cooling water inlet 61 to the cooling water outlet 63 via the heat exchange passage 62 does not occur.

  In FIG. 5, the flow of the water vapor Ws in the warm mode is indicated by arrows. In the warm mode, the second path 50 through which the water vapor Ws is guided from the heating unit 33 to the condensing unit 37 by bypassing the heating promoting unit 35 is formed. Specifically, the water vapor Ws that is vaporized from the water Wr and rises in the heating unit 33 is guided to the fourth passage 44 via the second passage 42 (without passing through the heating promoting portion 35 and the first condensing portion 37a). And it is condensed by the 2nd condensation part 37b, and is returned to the storage part of the water Wr.

  By doing so, unnecessary reaction in the heating promoting part 35 and unnecessary temperature rise of the cooling water Wc are suppressed.

  Next, a second embodiment according to the present invention will be described.

  FIG. 6 is a perspective view schematically showing the exhaust heat recovery device 80 of the second embodiment and its vicinity. In addition, in the following drawings, the same code | symbol is attached | subjected about the same or similar member as previous embodiment, and the duplication description is abbreviate | omitted.

  The basic configuration of the exhaust heat recovery device 80 is the same as that of the exhaust heat recovery device 30 of the first embodiment. However, as shown in FIG. 6, the cooling water inlet 61 and the cooling water outlet 63 include the exhaust heat recovery device 80. This is mainly different from the exhaust heat recovery device 30 in that it is derived from the side surface of the main body.

  FIG. 7 is a schematic diagram of the exhaust heat recovery device 80 and corresponds to FIG. 3 of the first embodiment. The exhaust heat recovery device 30 has a two-chamber structure, and includes a first chamber 31 connected to the exhaust pipe 25 and a second chamber 32 protruding to the side thereof.

  Inside the first chamber 31, a heating unit 33 is disposed below, and a heating promotion unit 35 is disposed above. The heating unit 33 and the heating promotion unit 35 are connected to each other by a first passage 41 via a first passage valve 51. It is communicated.

  The second chamber 32 is provided with a first condensing part 37a (near the arrangement range of the fins 38). In addition, a cooling water inlet 61 and a cooling water outlet 63 that communicate the first condensing part 37a and the outside of the main body (side part) of the exhaust heat recovery device 80 are provided.

  The configurations of the heat exchange passage 62 and the fins 38 are the same as those in the first embodiment, but in the present embodiment, these axial directions or arrangement directions are vertical.

  The heating promoting part 35 and the first condensing part 37 a are communicated with each other through the third passage 43. Further, the heating promoting part 35 and the storage part for the water Wr below the first chamber 31 and the second chamber 32 are communicated with each other through the fourth passage 44 via the second condensing part 37b. A third passage valve 56 is provided at the branch point between the third passage 43 and the fourth passage 44.

  The third passage valve 56 is a three-way valve, and in the illustrated state, the left passage is closed and the first condensing part 37a and the fourth passage 44 are communicated (left x), and the right passage is closed. The state in which the heating promoting part 35 and the first condensing part 37a are communicated (right x), and the state in which the lower passage is closed and the heating promoting part 35 and the fourth passage 44 are communicated (lower x). It can be switched in three ways.

  The heating unit 33 and the first condensing unit 37 a are communicated with each other through the second passage 42 via the second passage valve 52.

  Further, a negative pressure suction passage 47 that communicates between the first condensing unit 37 a and the outside of the main body of the exhaust heat recovery device 80 is provided. The negative pressure suction passage 47 is provided with a condenser 48 and a suction passage valve 55.

  Next, the operation of the exhaust heat recovery device 80 will be described. Table 2 is a table showing operation patterns of the first passage valve 51, the second passage valve 52, the third passage valve 56, and the suction passage valve 55.

  In Table 2, the object of each mode is the same as in the first embodiment. The operations of the first passage valve 51, the second passage valve 52, and the suction passage valve 55 are the same as those in Table 1 of the first embodiment. The operation of the third passage valve 56 (three-way valve) provided in place of the third passage valve 53 and the fourth passage valve 54 of the first embodiment is unique to this embodiment.

  No. In the pressure reduction mode 1, the suction passage valve 55 is opened as shown in Table 2, and the exhaust heat recovery device 80 communicates with the negative pressure portion of the engine intake system and is evacuated. At that time, as shown in Table 2, the first and second passage valves 51 and 52 are opened, and the third passage valve 56 is set to (left x). The air A is extracted (the air A in the heating accelerating unit 35 is guided to the second chamber 32 from the second passage 42 together with the air A in the heating unit 33 and from there to the negative pressure suction passage 47). .

  No. In the second initial mode, as shown in Table 2, the first and second passage valves 51 and 52 are opened, the third passage valve 56 is set to (right x), and the suction passage valve 55 is closed.

  By shutting off the fourth passage 44 by the third passage valve 56, early filling of the water vapor Ws is achieved. Also in this embodiment, the initial mode is executed as necessary and may be omitted in some cases.

  No. 3, the first passage valve 51 is opened, the second passage valve 52 and the suction passage valve 55 are closed, and the third passage valve 56 is (right x) as shown in Table 2. It is said.

  In FIG. 7, the flow of the water vapor Ws in the heat supply mode is indicated by arrows. In the heat supply mode, the first path 40 through which the water vapor Ws is guided from the heating unit 33 to the condensing unit 37 (first condensing unit 37a) through the heating promoting unit 35 is formed. And in the heating promotion part 35, the hydration reaction shown to (Formula 1) is performed. The water vapor Ws whose temperature has risen is guided to the first condensing part 37a through the third passage 43, is condensed by exchanging heat with the cooling water Wc flowing through the heat exchange passage 62, and returned to the storage part of the water Wr.

  On the other hand, the temperature of the cooling water Wc is promoted by exchanging heat with the high-temperature steam Ws in the heat exchange passage 62. Therefore, the warm-up performance can be further improved. Moreover, the heating start-up performance of the heater 10 can also be improved.

  No. In the regeneration mode 4, as shown in Table 2, the first and second passage valves 51 and 52 and the suction passage valve 55 are closed, and the third passage valve 56 is set to (lower x).

  In FIG. 8, the flow of water vapor Ws in the regeneration mode is indicated by arrows. In the heating promotion unit 35, the supply of the water vapor Ws is stopped by closing the first passage valve 51, and the dehydration reaction shown in (Expression 2) is performed. The generated steam Ws at about 150 ° C. is guided to the second condensing part 37 b through the fourth passage 44. Then, it is condensed and returned to the water Wr reservoir.

  On the other hand, the flow of the cooling water Wc is not formed in the heat exchange passage 62, and the high-temperature water vapor Ws is not guided to the first condensing part 37a, so that an unnecessary temperature rise of the cooling water Wc is suppressed.

  No. In the warm mode 5, as shown in Table 2, the first passage valve 51 and the suction passage valve 55 are closed, the second passage valve 52 is opened, and the third passage valve 56 is (left x). It is said.

  In FIG. 9, the flow of the water vapor Ws in the warm mode is indicated by arrows. In the warm mode, the second path 50 through which the water vapor Ws is guided from the heating unit 33 to the condensing unit 37 (second condensing unit 37b) bypassing the heating promoting unit 35 is formed. Specifically, the water vapor in the heating unit 33 is once led from the second passage 42 to the second chamber 32 and partly condensed in the first condensing unit 37 a, but most of the second condensation passes through the fourth passage 44. Guided to part 37b. Then, it is condensed and returned to the water Wr reservoir.

  By doing so, unnecessary reaction in the heating promoting part 35 and unnecessary temperature rise of the cooling water Wc are suppressed.

  Next, a third embodiment according to the present invention will be described.

  FIG. 10 is a schematic diagram of the exhaust heat recovery device 90 of the third embodiment, and corresponds to FIG. 7 of the second embodiment. The exhaust heat recovery device 90 is a more simplified structure of the exhaust heat recovery device 80 of the second embodiment, and the main feature is that the fourth passage 44 and the second condensing part 37b are omitted. Different from the recovery device 80.

  Accordingly, a third passage valve 57 (open / close valve) is provided instead of the third passage valve 56 (three-way valve). The third passage valve 57 is a valve that opens and closes the third passage 43 that allows the heating promoting unit 35 and the condensing unit 37 in the second chamber 32 to communicate with each other.

  Next, the operation of the exhaust heat recovery device 80 will be described. Table 3 is a table showing operation patterns of the first to third passage valves 51, 52, 57 and the suction passage valve 55.

  In Table 3, the purpose of each mode is the same as in the second embodiment. The operations of the first passage valve 51, the second passage valve 52, and the suction passage valve 55 are the same as those in Table 2 of the second embodiment. The operation of the third passage valve 57 provided in place of the third passage valve 56 of the second embodiment is unique to this embodiment.

  No. In the pressure reduction mode 1, the suction passage valve 55 is opened as shown in Table 3, and the exhaust heat recovery device 90 is communicated with the negative pressure portion of the engine intake system and evacuated. At that time, as shown in Table 3, all the other valves 51, 52, and 57 are opened, so that the air A is quickly extracted from each part in the exhaust heat recovery device 90. The air A in the heating accelerating portion 35 is led to the second chamber 32 from both the second passage 42 and the third passage 43, and from there to the negative pressure suction passage 47.

  No. In the initial mode 2, the suction passage valve 55 is closed and all other valves 51, 52, 57 are opened as shown in Table 3. In the present embodiment, since there is no portion (initial waste volume portion) corresponding to the fourth passage 44 of the second embodiment, the water vapor Ws can be quickly filled only by closing the suction passage valve 55. Also in this embodiment, the initial mode is executed as necessary and may be omitted in some cases.

  No. In the third heat supply mode, as shown in Table 3, the first passage valve 51 and the third passage valve 57 are opened, and the second passage valve 52 and the suction passage valve 55 are closed.

  In FIG. 10, the flow of the water vapor Ws in the heat supply mode is indicated by arrows. In the heat supply mode, the first path 40 through which the water vapor Ws is guided from the heating unit 33 to the condensing unit 37 via the heating promoting unit 35 is formed. And in the heating promotion part 35, the hydration reaction shown to (Formula 1) is performed. The water vapor Ws whose temperature has risen is guided to the condensing unit 37 through the third passage 43, is condensed by exchanging heat with the cooling water Wc flowing through the heat exchanging passage 62, and is returned to the storage unit of the water Wr.

  On the other hand, the temperature of the cooling water Wc is promoted by exchanging heat with the high-temperature steam Ws in the heat exchange passage 62. Therefore, the warm-up performance can be further improved. Moreover, the heating start-up performance of the heater 10 can also be improved.

  No. In the regeneration mode 4, as shown in Table 3, the third passage valve 57 is opened, and all other valves are closed.

  In FIG. 11, the flow of water vapor Ws in the regeneration mode is indicated by arrows. In the heating promotion unit 35, the supply of the water vapor Ws is stopped by closing the first passage valve 51, and the dehydration reaction shown in (Expression 2) is performed. The generated steam Ws at about 150 ° C. is guided to the condensing unit 37 through the third passage 43.

  Here, the flow of the cooling water Wc in the heat exchange passage 62 is not formed, and heat exchange between the water vapor Ws and the cooling water Wc is suppressed. However, since the second chamber 32 is not directly subjected to exhaust heat and does not reach a very high temperature, for example, heat exchange between the water vapor Ws and the outside air is performed through the wall surface of the second chamber 32. Thereby, the water vapor Ws is condensed in the condensing unit 37 and returned to the water Wr reservoir. The present embodiment is suitable for the case where the water vapor Ws is condensed in the condensing unit 37 without providing a condenser.

  No. In the warm mode 5, as shown in Table 3, the second passage valve 52 is opened and all other valves are closed.

  In FIG. 12, the flow of the water vapor Ws in the warm mode is indicated by arrows. In the warm mode, the second path 50 through which the water vapor Ws is guided from the heating unit 33 to the condensing unit 37 by bypassing the heating promoting unit 35 is formed. Specifically, the water vapor in the heating unit 33 is guided to the condensing unit 37 through the second passage 42. In the same manner as in the regeneration mode, the water is condensed in the condensing unit 37 and returned to the water Wr reservoir.

  By doing so, unnecessary reaction in the heating promoting part 35 and unnecessary temperature rise of the cooling water Wc are suppressed.

  As mentioned above, although each embodiment of this invention was described, the said embodiment can be suitably changed in the range which does not deviate from the summary of this invention. For example, although magnesium oxide MgO is mentioned as the main component of the heat storage material 36 in the above embodiment, other materials having the same heat storage action, such as zeolite, may be used. Further, the coolant is not necessarily water.

  In each of the above embodiments, the liquid to be heated is the cooling water Wc. However, this may be engine oil or automatic transmission oil (ATF).

  The refrigerant gas path, the type and arrangement of the valves, and the like may be set as appropriate, and may be other than the above-described embodiments.

1 is a schematic circuit diagram of engine cooling water including an exhaust heat recovery device according to a first embodiment of the present invention. It is a perspective view which shows typically the said waste heat recovery apparatus and its vicinity. It is a figure which shows the flow of the water vapor | steam in heat supply mode while it is a schematic diagram of the said waste heat recovery apparatus. It is a figure which shows the flow of the water vapor | steam in the regeneration mode of the said waste heat recovery apparatus. It is a figure which shows the flow of the water vapor | steam in the warm mode of the said waste heat recovery apparatus. It is a perspective view which shows typically the waste heat recovery apparatus which concerns on 2nd Embodiment of this invention, and its vicinity. It is a figure which shows the flow of the water vapor | steam in heat supply mode while it is a schematic diagram of the waste heat recovery apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows the flow of the water vapor | steam in the regeneration mode of the waste heat recovery apparatus of 2nd Embodiment. It is a figure which shows the flow of the water vapor | steam in the warm mode of the waste heat recovery apparatus of 2nd Embodiment. It is a figure which shows the flow of the water vapor | steam in heat supply mode while being a schematic diagram of the waste heat recovery apparatus which concerns on 3rd Embodiment of this invention. It is a figure which shows the flow of the water vapor | steam in the regeneration mode of the waste heat recovery apparatus of 3rd Embodiment. It is a figure which shows the flow of the water vapor | steam in the warm mode of the waste heat recovery apparatus of 3rd Embodiment.

Explanation of symbols

2 Engine body 6 Thermostat (radiator circuit valve)
DESCRIPTION OF SYMBOLS 9 Radiator 11 Bypass circuit 18 Radiator circuit 25 Exhaust pipe 27 Exhaust gas 30 Waste heat recovery apparatus 33 Heating part 35 Heating promotion part 36 Heat storage material (magnesium oxide is a main component)
37 Condensing portion 40 First path 41 First path 47 Negative pressure suction path 50 Second path 51 First path valve 55 Suction path valve 80 Waste heat recovery device 90 Waste heat recovery device Wc Engine cooling water (liquid to be heated)
Wr water (liquid refrigerant)
Ws Water vapor (vaporized refrigerant)

Claims (7)

An exhaust heat recovery device that heats a liquid to be heated using exhaust heat from exhaust gas from an engine,
A heating unit that heats and vaporizes the liquid refrigerant with the exhaust heat, and
A condensing unit for condensing the refrigerant vaporized in the heating unit by heat exchange;
A heating promotion part provided on a refrigerant passage between the heating part and the condensing part and provided with a heat storage material so as to be in contact with the vaporized refrigerant;
The heat storage material raises the temperature of the vaporized refrigerant sent to the condensing unit by performing an exothermic reaction with the vaporized refrigerant,
The exhaust heat recovery apparatus for an engine, wherein the vaporized refrigerant whose temperature has increased through the heating promoting portion exchanges heat with the liquid to be heated in the condensing portion. The heating promotion part is arranged to receive the exhaust heat,
A first passage valve for opening and closing the first heating passage and the heating promotion portion is provided on a first passage communicating with the heating portion and the heating promotion portion.
The first passage valve is opened when there is a heating request for the liquid to be heated and closed when there is no heating request,
The exhaust heat recovery apparatus for an engine according to claim 1, wherein the heat storage material performs the reverse reaction of the exothermic reaction by receiving the exhaust heat in a state where the first passage valve is closed. As a circulation path of the vaporized refrigerant, a first path led from the heating part to the condensing part via the heating promoting part, and a first path led from the heating part to the condensing part bypassing the heating promoting part. With two routes,
3. The engine according to claim 1, wherein the vaporized refrigerant is passed through the first path when there is a request to heat the liquid to be heated, and is passed through the second path when there is no request for heating. Waste heat recovery device. The refrigerant is water,
A negative pressure suction passage that connects a space in which water vapor that is a vaporized refrigerant flows and a negative pressure generating portion of an intake system of the engine;
A suction passage valve for opening and closing the negative pressure suction passage,
The exhaust heat of the engine according to any one of claims 1 to 3, wherein the suction passage valve is opened at least for a predetermined period after the operation of the exhaust heat recovery device is started in the engine driving state. Recovery device. The refrigerant is water;
The engine exhaust heat recovery apparatus according to any one of claims 1 to 4, wherein a main component of the heat storage material is magnesium oxide. The heated liquid is engine cooling water,
As a circuit through which the engine coolant circulates, a radiator circuit that passes through a radiator, a bypass circuit that bypasses the radiator, and a radiator circuit valve that closes the radiator circuit when the engine is cold,
6. The exhaust heat recovery apparatus for an engine according to claim 1, wherein the exhaust heat recovery apparatus is connected to the bypass circuit. An exhaust heat recovery method for heating a liquid to be heated using exhaust heat from exhaust gas from an engine,
The liquid refrigerant is heated with the exhaust heat and vaporized,
The vaporized refrigerant is allowed to react with a heat storage material that performs an exothermic reaction with the vaporized refrigerant, and the temperature of the vaporized refrigerant is increased by heat generated by the exothermic reaction.
An exhaust heat recovery method for an engine, wherein the vaporized refrigerant whose temperature has been increased is condensed by exchanging heat with the liquid to be heated.

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