JP2006002738A - Waste heat recovery device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably generate and maintain sound waves due to a thermoacoustic phenomenon even when the temperature of exhaust gas discharged from an internal combustion engine changes.
[Solution]
The exhaust heat recovery apparatus 40 of the present invention includes an acoustic tube 42, a prime mover 46 that generates sound waves, and a drive device 44 that is driven by the sound waves generated by the prime mover 46. The prime mover 46 is arranged at one end of the first heat accumulator, the first heat accumulator, absorbs heat from the exhaust gas and heats one end of the first heat accumulator, and the first heat accumulator. It can be comprised by the 1st low-temperature heat exchanger which is arrange | positioned at the other end and absorbs heat from the other end of the first heat accumulator and releases the heat to the outside. The temperature of the exhaust gas is measured by the temperature sensor 31, and the flow rate of the exhaust gas supplied to the first high-temperature heat exchanger of the prime mover 46 is adjusted based on the measured temperature.
[Selection] Figure 1

Description

  The present invention relates to a technique for recovering (effectively using) thermal energy from exhaust gas of an internal combustion engine (for example, an engine mounted on an automobile). Specifically, the present invention relates to a thermoacoustic apparatus that uses the thermal energy of exhaust gas.

  As a technique for recovering thermal energy from exhaust gas of an internal combustion engine, use of a thermoacoustic phenomenon has been studied. The thermoacoustic phenomenon refers to various phenomena that occur when sound waves (vibration flow) propagate through a narrow channel having a temperature gradient in thermal contact with a wall. In a narrow channel (for example, a space whose channel radius is about the thermal boundary layer of the fluid), heat exchange is performed between the solid wall forming the channel and the vibrating fluid (fluid carrying sound waves). When a temperature gradient exists in the traveling direction of the sound wave, the vibrating fluid is heated and cooled by displacing the temperature gradient in addition to the cyclic compression and expansion. Thus, the oscillating fluid undergoes a thermodynamic process such as compression, expansion, heating, and cooling, which enables energy conversion between heat and sound. Unlike the energy conversion by other heat engines, this energy conversion by the thermoacoustic phenomenon has an advantage that a highly efficient thermodynamic cycle (Stirling cycle) can be realized without requiring a moving part such as a piston. For this reason, an apparatus for converting and recovering heat energy of exhaust gas into sound energy using a thermoacoustic phenomenon has been developed (Patent Document 1).

The apparatus described in Patent Document 1 includes a resonance tube, a sound wave generator disposed at one end of the resonance tube, and a transducer disposed at the other end of the resonance tube. The sound wave generator includes a heat accumulator (the portion forming the narrow flow path described above), a high temperature heat exchanger disposed at one end of the heat accumulator, and a low temperature heat exchanger disposed at the other end of the heat accumulator. Consists of. A catalytic converter is disposed around the high-temperature heat exchanger, and heat radiation fins project from the outer peripheral surface of the low-temperature heat exchanger. A rare gas such as air or helium is sealed as a working fluid in the resonance tube.
Exhaust gas discharged from the internal combustion engine is purified by a catalytic converter and then exhausted from the muffler. When the exhaust gas is purified by the catalytic converter, the temperature of the exhaust gas rises due to the reaction heat. The heat energy of the exhaust gas whose temperature has risen is transmitted to one end of the heat accumulator through the high temperature heat exchanger, and thereby one end of the heat accumulator is heated. On the other hand, the other end of the heat accumulator is cooled by a low temperature heat exchanger provided with heat radiation fins. Therefore, the temperature of the end of the heat accumulator on the high temperature heat exchanger side becomes high, and the temperature of the end of the heat accumulator on the low temperature heat exchanger side becomes low (that is, a temperature gradient is given to the heat accumulator). When the temperature of the high-temperature heat exchanger exceeds a certain seaside temperature (for example, 200 to 300 ° C. when the working fluid is atmospheric pressure air), the working fluid in the regenerator starts to vibrate alone (thermoacoustic self-excited vibration). . When sound waves are generated in the resonance tube by the thermoacoustic self-excited vibration, the sound waves are converted into mechanical vibrations by a transducer disposed at the other end of the resonance tube, and then converted into electrical energy for use (collection).
JP 2002-120929

As is clear from the above description, in order to generate sound waves by the thermoacoustic phenomenon, it is necessary to give an appropriate temperature gradient to the heat accumulator. That is, it is necessary to supply a sufficient amount of heat from the exhaust gas to the high-temperature heat exchanger and to heat the end of the heat accumulator so as to be at or above the critical temperature. In addition, after sound waves are generated by the thermoacoustic phenomenon, it is necessary to continue supplying an appropriate amount of heat from the exhaust gas to the high-temperature heat exchanger in order to maintain the sound waves due to the thermoacoustic phenomenon.
On the other hand, the temperature of the exhaust gas discharged from the internal combustion engine (that is, the heat energy of the exhaust gas) varies greatly depending on the operating condition of the internal combustion engine. For example, the exhaust gas temperature of the internal combustion engine is low immediately after the start of the operation of the internal combustion engine and rises with time. Further, it varies greatly depending on the load of the internal combustion engine. In particular, in an internal combustion engine such as an automobile engine, the engine speed (engine load) changes greatly according to the driver's accelerator operation, and the exhaust gas temperature also changes greatly. Therefore, in order to generate sound waves by the exhaust gas discharged from the internal combustion engine and maintain the sound waves, the amount of heat supplied to the high-temperature heat exchanger is appropriately set regardless of whether or not the temperature of the exhaust gas has changed. It is necessary to control the amount.
However, in the conventional exhaust heat recovery apparatus described above, when the temperature of the exhaust gas discharged from the internal combustion engine changes, the amount of heat supplied to the high temperature heat exchanger changes accordingly. For this reason, sound waves could not be stably generated in the acoustic tube, and thus the heat energy of the exhaust gas could not be recovered stably.

  The present invention has been made in view of the above-described circumstances, and can stably generate and maintain sound waves due to a thermoacoustic phenomenon even when the temperature of exhaust gas discharged from an internal combustion engine changes. It is an object of the present invention to provide an exhaust heat recovery device that can stably recover (use) the thermal energy of exhaust gas.

An exhaust heat recovery device of the present invention is an exhaust heat recovery device that recovers thermal energy of exhaust gas exhausted from an internal combustion engine, and includes an acoustic tube, a first heat accumulator disposed in the acoustic tube, and a first heat storage device. A first high-temperature heat exchanger that is disposed at one end of the heater and absorbs heat from the exhaust gas and heats one end of the first heat accumulator; and the other end of the first heat accumulator disposed at the other end of the first heat accumulator A first low-temperature heat exchanger that absorbs heat from the first heat exchanger and releases the heat to the outside; and a drive device that is disposed at a position away from the first heat accumulator in the acoustic tube and is driven by sound waves generated by the first heat accumulator. Prepare. And it has further the control means which adjusts the exhaust gas flow rate supplied to a 1st high temperature heat exchanger based on the temperature sensor which detects the temperature of exhaust gas, and the exhaust gas temperature detected by the temperature sensor.
In this exhaust heat recovery device, one end of the first heat accumulator is heated by the first high-temperature heat exchanger, while the other end of the first heat accumulator is cooled by the first low-temperature heat exchanger, and thereby the temperature of the heat accumulator is increased. A gradient is given. The exhaust gas flow rate supplied to the first high-temperature heat exchanger is adjusted according to the exhaust gas temperature discharged from the internal combustion engine. That is, the first high temperature heat exchanger according to the exhaust gas temperature so that the amount of heat supplied from the exhaust gas to the first high temperature heat exchanger (the amount of heat supplied to one end of the first heat accumulator) becomes an appropriate amount. The exhaust gas flow rate supplied to the is adjusted. For this reason, even if the temperature of the exhaust gas discharged from the internal combustion engine changes, an appropriate amount of heat is supplied to the first high-temperature heat exchanger. For this reason, an appropriate temperature gradient is stably given to the first heat accumulator, and sound waves are stably generated from the first heat accumulator. The sound energy of the sound wave generated by the first heat accumulator is used (recovered) by a driving device (for example, an energy conversion device such as a transducer) disposed at a position away from the first heat accumulator by a predetermined distance.

  In the exhaust heat recovery apparatus, an auxiliary heating device is further provided at the end of the first heat accumulator on the first high temperature heat exchanger side, and the control means is based on the exhaust gas temperature detected by the temperature sensor. It is preferable to heat the end of the first heat accumulator on the first high temperature heat exchanger side. According to such a configuration, even when the temperature of the exhaust gas discharged from the internal combustion engine is too low (for example, when starting up immediately after the start of operation), the end of the first heat accumulator is moved by the auxiliary heating device. It is heated and can quickly generate sound waves from the first regenerator.

Moreover, as a drive device, it can be set as the refrigerator driven with the sound wave which generate | occur | produced with the 1st heat storage, for example. That is, the drive device is arranged at (1) the second heat accumulator and (2) the high temperature side end of the second heat accumulator, absorbs heat from the high temperature side end of the second heat accumulator, and heats the outside. A second high-temperature heat exchanger that discharges, and (3) a second heat exchanger that is disposed at the low-temperature end of the second regenerator, absorbs heat from the object to be cooled, and releases heat to the low-temperature end of the second regenerator. 2 low temperature heat exchanger. In such a configuration, a second high-temperature heat exchanger, a second heat accumulator, and a second low-temperature heat exchanger are sequentially formed in the traveling direction of the sound wave generated in the first heat accumulator, and the sound energy of the sound wave traveling in the second heat accumulator The second low temperature heat exchanger is cooled. For this reason, a cooling target object (for example, refrigerant | coolant etc.) can be cooled with a 2nd low-temperature heat exchanger.
When a refrigerator is used as the driving device, the driving device further includes a second temperature sensor that detects the temperature of the object to be cooled that has been cooled by the second low-temperature heat exchanger, and the control means detects the exhaust gas temperature detected by the temperature sensor and the first temperature. It is preferable to adjust the flow rate of the exhaust gas supplied to the first high-temperature heat exchanger based on the temperature of the cooling target detected by the two-temperature sensor. According to such a configuration, the amount of heat supplied to the first high temperature heat exchanger is adjusted according to the temperature of the object to be cooled (that is, the cooling capacity of the first low temperature heat exchanger is adjusted). Therefore, sound waves due to the thermoacoustic phenomenon can be stably generated, and at the same time, the object to be cooled can be cooled with an appropriate cooling capacity.

Hereinafter, the best modes for carrying out the exhaust heat recovery apparatus according to the present application will be listed.
(Mode 1) The acoustic tube is provided with a prime mover that generates sound waves and a refrigerator that cools the object to be cooled by the sound energy of the sound waves generated by the prime mover. The prime mover includes a heat accumulator and a pair of heat exchangers disposed at both ends of the heat accumulator. The refrigerator is also constituted by a heat accumulator and a pair of heat exchangers arranged at both ends of the heat accumulator.
(Mode 2) One heat exchanger (high temperature heat exchanger) of the prime mover performs heat exchange with the exhaust gas and heats one end of the heat accumulator. The other heat exchanger (low temperature heat exchanger) of the prime mover performs heat exchange with cooling water (or air), and cools the other end of the heat accumulator (for example, maintains it at room temperature). A sound wave traveling from the low-temperature heat exchanger to the high-temperature heat exchanger side is generated in the regenerator of the prime mover.
(Mode 3) The sound wave generated in the prime mover travels from one heat exchanger (high temperature heat exchanger) of the refrigerator toward the other heat exchanger (low temperature heat exchanger). The high-temperature heat exchanger of the refrigerator performs heat exchange with cooling water (or air), and cools one end of the heat accumulator (for example, maintains at normal temperature). The low-temperature heat exchanger of the refrigerator exchanges heat with the object to be cooled to cool the object to be cooled.
(Mode 4) The exhaust gas pipe of the internal combustion engine is provided with a temperature sensor for measuring the temperature of the exhaust gas. A branch pipe is provided in the exhaust gas pipe of the internal combustion engine, and the branch pipe is connected to a high-temperature heat exchanger of the prime mover. The branch pipe is provided with a flow control valve, and the flow rate of the exhaust gas flowing through the branch pipe is adjusted by the flow control valve. The control unit adjusts the opening degree of the flow control valve based on the exhaust gas temperature detected by the temperature sensor.
(Mode 5) The fuel in the fuel tank is supplied to the internal combustion engine by a fuel pump. The low temperature heat exchanger of the refrigerator cools return fuel out of the fuel discharged from the fuel pump. The cooled return fuel is returned into the fuel tank to cool the fuel tank.
(Mode 6) The fuel in the fuel tank is supplied to the internal combustion engine by a fuel pump. The low-temperature heat exchanger of the refrigerator cools the fuel evaporative gas (evaporative gas) in the fuel tank. The cooled and liquefied fuel is returned to the fuel tank.
(Mode 7) A turbo engine is used as the internal combustion engine. The low temperature heat exchanger of the refrigerator cools the supercharged air from the turbocharger. The cooled air is supplied to the engine.
(Mode 8) The low-temperature heat exchanger of the refrigerator cools the exhaust gas for EGR (exhaust gas recirculation). The cooled exhaust gas is resupplied to the engine.
(Mode 9) The low-temperature heat exchanger of the refrigerator cools the refrigerant. The cooled refrigerant is used for cooling an air conditioner in a vehicle cabin, an in-vehicle refrigerator, or a freezer for a freezer.

First Embodiment An exhaust heat recovery apparatus (thermoacoustic cooling apparatus) according to an embodiment of the present invention will be described with reference to the drawings. The thermoacoustic cooling device of the present embodiment is mounted on an automobile, collects the thermal energy of exhaust gas discharged from the automobile engine, and cools the return fuel by the collected thermal energy.

  FIG. 1 shows a schematic configuration of a thermoacoustic cooling device according to the present embodiment. As shown in FIG. 1, the thermoacoustic cooling apparatus includes an acoustic tube 42 (a loop tube formed of metal or resin), and a working gas (for example, atmospheric pressure air, pressurized helium— Argon mixed gas or the like). The acoustic tube 42 is provided with a prime mover 46 and a refrigerator 44.

  The prime mover 46 includes a heat accumulator and a pair of heat exchangers disposed at both ends of the heat accumulator, as will be described in detail later. A branch pipe 30 branched from the exhaust pipe 26 is connected to one heat exchanger of the prime mover 46 (hereinafter also referred to as prime mover side high temperature heat exchanger). Exhaust gas discharged from the engine flows through the exhaust pipe 26, and part of the exhaust gas flowing through the exhaust pipe 26 flows through the branch pipe 30. The prime mover-side high-temperature heat exchanger recovers heat from the exhaust gas flowing through the branch pipe 30 and heats one end of the heat accumulator with the recovered heat. The exhaust gas whose heat has been recovered by the prime mover side high temperature heat exchanger (that is, the cooled exhaust gas) is returned to the exhaust pipe 26. The temperature of the exhaust gas flowing through the exhaust pipe 26 is measured by the temperature sensor 31. The exhaust gas temperature measured by the temperature sensor 31 is input to the control unit 32. The control unit 32 adjusts the flow rate of the exhaust gas flowing through the branch pipe 30 by controlling the flow rate control valve 28 provided in the branch pipe 30. This adjusts the amount of thermal energy recovered by the prime mover side high temperature heat exchanger.

  A hot water pipe 24 is connected to the other heat exchanger of the prime mover 46 (hereinafter also referred to as prime mover side low temperature heat exchanger). In the circulation path of the hot water pipe 24, one heat exchanger (hereinafter also referred to as a refrigerator-side high-temperature heat exchanger) of the radiator (radiator) 22 and the refrigerator 44 is interposed. The cooling water flowing through the hot water pipe 24 is dissipated by the radiator 22 and its temperature decreases. The cooling water whose temperature has been reduced by the radiator 22 flows through the hot water pipe 24 to the refrigerator-side high-temperature heat exchanger and the prime mover-side low-temperature heat exchanger, and performs heat exchange with these heat exchangers (that is, these heats). Cool the exchanger). Thus, one end (low temperature side end) of the regenerator of the prime mover 46 and one end (high temperature side end) of the refrigerator 44 are cooled to the cooling water temperature. The cooling water that has flowed through the prime mover side low temperature heat exchanger is returned to the radiator 22.

  A return fuel pipe 16 branched from the fuel discharge pipe 18 via the pressure regulating valve 14 is connected to the other heat exchanger of the refrigerator 44 (hereinafter also referred to as a refrigerator-side low-temperature heat exchanger). A fuel pump 12 is connected to one end of the fuel discharge pipe 18, and the fuel pump 12 is disposed in the fuel tank 10. The other end of the fuel discharge pipe 18 is connected to an injector (not shown) that injects fuel into the engine. The fuel pump 12 sucks and boosts the fuel in the fuel tank 10 and discharges the boosted fuel to the fuel discharge pipe 18. The pressure of the fuel flowing through the fuel discharge pipe 18 is adjusted by the pressure regulating valve 14, and the fuel after pressure adjustment is supplied to the engine (injector). The fuel returned to the fuel tank 10 by the pressure adjustment by the pressure regulating valve 14 flows through the return fuel pipe 16. The fuel flowing through the return fuel pipe 16 is returned to the fuel tank 10 through the refrigerator-side low-temperature heat exchanger. The temperature of the return fuel that has passed through the refrigerator-side low-temperature heat exchanger is measured by a temperature sensor 34 disposed in the return fuel pipe 16. The return fuel temperature measured by the temperature sensor 34 is input to the control unit 32.

In the thermoacoustic cooling device described above, the heat energy of the exhaust gas is recovered by the high temperature side heat exchanger of the prime mover 46, and one end of the regenerator of the prime mover 46 is heated by the recovered thermal energy. On the other hand, the other end of the regenerator of the prime mover 46 is cooled by cooling water flowing through the hot water pipe 24. For this reason, a temperature gradient is generated in the regenerator of the prime mover 46, and sound waves are generated from the prime mover 46 due to this temperature gradient (thermoacoustic self-excited vibration).
The sound waves generated by the prime mover 46 travel from the low temperature heat exchanger of the prime mover 46 toward the high temperature heat exchanger, and travel in the refrigerator 44 from the high temperature heat exchanger side to the low temperature heat exchanger side. The refrigerator 44 is disposed at a position away from the prime mover 46 by a predetermined distance (specifically, disposed so that the node of the sound wave generated by the prime mover 46 becomes the position of the high temperature heat exchanger of the refrigerator 44). Have been). For this reason, a reverse Stirling cycle is executed in the regenerator of the refrigerator 44, and heat is pumped up in the direction opposite to the traveling direction of the sound wave. Thereby, the low temperature heat exchanger of the refrigerator 44 is cooled, and the return fuel flowing through the low temperature heat exchanger is cooled. The cooled return fuel flows into the fuel tank 10 and directly cools the fuel tank 10. For this reason, it is possible to suppress the evaporation of fuel in the fuel tank 10, thereby reducing fluctuations in the air-fuel ratio of the engine, reducing the size of the canister, and further suppressing the occurrence of vapor lock of the fuel pump 12. be able to.

Next, the structures of the prime mover 46 and the refrigerator 44 will be described in detail with reference to FIGS. Since the motor 46 and the refrigerator 44 have the same structure, the configuration of the motor 46 will be described in detail here.
As shown in FIG. 2, the prime mover 46 includes a heat accumulator 190, a high temperature heat exchanger 180 disposed at one end of the heat accumulator 190, and a low temperature heat exchanger 170 disposed at the other end of the heat accumulator 190. Is done. As the heat accumulator 190, a laminate of thin plates of metal or ceramics, a honeycomb structure of metal or ceramics, or the like can be used. For example, a stainless mesh or a ceramic honeycomb can be used. A heat insulating material 176 (for example, ceramics or phenol resin) is disposed around the heat accumulator 190.

The high-temperature heat exchanger 180 includes a heat transfer plate 184 that abuts one end (the lower end in the figure) of the heat accumulator 190 and a heat exchange unit 182 provided on the upper surface of the outer periphery of the heat transfer plate 184. For the heat transfer plate 184, a honeycomb-like or lattice-like wire net formed of a high conductor (for example, Cu or the like) can be used. The heat transfer plate 184 is attached to the acoustic tube 42 via heat insulating materials 176 and 178.
The heat exchange unit 182 is provided so as to surround the outer periphery of the heat accumulator 190 as shown in FIG. A branch pipe 30 is connected to the heat exchanging part 182 so that exhaust gas flows in the heat exchanging part 182. A plurality of fins 186 projecting on the heat transfer plate 184 are arranged in the heat exchanging portion 182 as shown well in FIG. 5 (however, illustration of the fins 186 is omitted in FIG. 3). ). The fins 186 improve the efficiency of heat exchange between the exhaust gas flowing in the heat exchange unit 182 and the heat transfer plate 184. A heat insulating material 176 is disposed on the outer periphery of the heat exchanging portion 182 with a slight space therebetween.

The low-temperature heat exchanger 170 is also configured by a heat transfer plate 173 that is in contact with the other end (upper end in the figure) of the heat accumulator 190 and a heat exchange portion 172 formed on the peripheral edge 171 of the heat transfer plate 173 (FIG. 2). reference). The heat transfer plate 173 can be a honeycomb-like or lattice-like wire mesh formed of a high conductor, and is attached to the acoustic tube 42 via heat insulating materials 174, 176. In the state where the heat transfer plate 173 is attached to the acoustic tube 42, the peripheral edge 171 protrudes from the outer peripheral surface of the acoustic tube 42. Therefore, the heat exchanging part 172 formed on the peripheral edge 171 of the heat transfer plate 173 also protrudes from the outer peripheral surface of the acoustic tube 42.
The heat exchange part 172 is provided so as to surround the outer periphery of the acoustic tube 42 as shown in FIG. A hot water pipe 24 is connected to the heat exchanging part 172 so that cooling water flows through the heat exchanging part 172. As shown in FIGS. 6 and 7, a spiral guide blade 172 b is provided in the heat exchange unit 172. Therefore, the cooling water flowing in the heat exchanging portion 172 is guided by the guide vanes 172b and flows spirally (arrows shown in the drawing), thereby improving the cooling capacity of the heat exchanging portion 172.
In the refrigerator 44, the high temperature heat exchanger 180 described above is used as a low temperature heat exchanger, and the low temperature heat exchanger 170 described above is used as a high temperature heat exchanger.

The thermoacoustic cooling device described above is controlled by the control unit 32. The control process performed by the control unit 32 will be described based on the flowchart shown in FIG.
As shown in FIG. 8, first, the control unit 32 sets the load of the flow control valve (exhaust gas control valve) 28 to 0% (S10). The flow control valve 28 of this embodiment has a load characteristic as shown in FIG. That is, the exhaust gas flow rate Q flowing through the branch pipe 30 is “0” when the load of the flow control valve 28 is 0 to 20%, and branches according to the load when the load of the flow control valve 28 is 20 to 80%. The exhaust gas flow rate Q flowing through the pipe 30 also increases. When the load of the flow control valve 28 becomes 80% or more, the exhaust gas flow rate Q flowing through the branch pipe 30 becomes constant at the maximum flow rate. In step S10, since the load of the flow control valve 28 is set to 0%, the exhaust gas flow rate Q flowing through the branch pipe 30 is also “0”.

Next, the control unit 32 reads the temperature (exhaust gas temperature) measured by the temperature sensor 31 and the temperature (return fuel temperature) measured by the temperature sensor 34 (S12).
In step S13, the target exhaust gas temperature is set based on the measured value (return fuel temperature) of the temperature sensor 34 read in step S12. Here, the target exhaust gas temperature is an exhaust gas temperature necessary for obtaining a desired cooling capacity in a state where the load of the flow control valve 28 becomes a reference value (for example, a load of 60%). Therefore, when the return fuel temperature is high and it is desired to increase the cooling capacity of the refrigerator 44, it is necessary to supply a large amount of heat to the prime mover 46, so the target exhaust gas temperature is set high. Conversely, when the return fuel temperature is too low and it is desired to reduce the cooling capacity of the refrigerator 44, the target exhaust gas temperature is set low.

Next, the control unit 32 determines the load of the flow control valve 28 based on the set target exhaust gas temperature and the measured value (measured exhaust gas temperature) of the temperature sensor 31 read in step S12 (S14-30). . Specifically, first, threshold values L1, L2, H1, and H2 are set based on measured values (exhaust gas temperature) measured by the temperature sensor 31 (see FIG. 10). In the present embodiment, the threshold values L2 and H2 are set in the first temperature range around the measured exhaust gas temperature, and the threshold values L1 and H1 are set in the second temperature range (wider than the first temperature range). Set. For example, if the measured exhaust gas temperature is T, L2 = T−t1, H2 = T + t1, L1 = T−t2, and H2 = T + t2 (where t1 <t2).
When the threshold values L1, L2, H1, and H2 are determined, the load of the flow control valve 28 is determined based on these threshold values L1, L2, H1, and H2 and the target exhaust gas temperature set in step S13. That is, when the target exhaust gas temperature is higher than the threshold value H1 (YES in step S14), the load of the flow control valve 28 is set to 100% (S16). If the target exhaust gas temperature is between the threshold values H2 and H1 (YES in step S22), the load on the flow control valve 28 is increased by 5% (S24). On the other hand, when the target exhaust gas temperature is lower than the threshold value L1 (YES in step S18), the load of the flow control valve 28 is set to 0% (S20). When the target exhaust gas temperature is between the threshold values L1 and L2 (YES in step S26), the load of the flow control valve 28 is reduced by 5%. When the target exhaust gas temperature is between the threshold values L2 and H2 (NO in step S26), the load of the flow control valve 28 is maintained in that state. When the load of the flow control valve 28 is determined, the control unit 32 drives the flow control valve 28 so as to achieve the determined load. As a result, the flow rate of the exhaust gas flowing through the high-temperature heat exchanger of the prime mover 46 is adjusted (that is, the amount of heat energy recovered by the prime mover is adjusted).

  FIG. 10 schematically shows the relationship between the measured exhaust gas temperature, the set target exhaust gas temperature, and the load of the flow control valve 28 determined based on these. As is clear from FIG. 10, the load on the flow control valve 28 increases as the target exhaust gas temperature is higher than the measured exhaust gas temperature. Accordingly, a large amount of exhaust gas flows through the high-temperature heat exchanger of the prime mover 46, and a large amount of heat energy is recovered by the high-temperature heat exchanger of the prime mover 46. In FIG. 10, the load of the flow control valve 28 when the target exhaust gas temperature falls within the range of the threshold values L2 to H2 is simply displayed in a straight line.

  As is apparent from the above description, in this embodiment, when the measured exhaust gas temperature is too low compared to the target exhaust gas temperature (for example, immediately after starting the engine), the load of the flow control valve 28 is 100. %, And a large amount of exhaust gas is supplied to the prime mover 46. For this reason, the high-temperature heat exchanger of the prime mover 46 can be heated in a short time, and sound waves can be generated in the acoustic tube 42. After the sound wave is generated from the prime mover 46 and the cooling of the return fuel is started by the refrigerator 44, the load of the flow control valve 28 is adjusted based on the measured return fuel temperature and exhaust gas temperature, and the prime mover 46 An appropriate amount of heat is supplied to the high-temperature heat exchanger. For this reason, even if the exhaust gas temperature changes in accordance with the engine load or the like, sound waves having an appropriate acoustic intensity are stably generated from the prime mover 46.

  In the embodiment described above, an auxiliary heating device such as a heater is further provided in the vicinity of the high-temperature heat exchanger of the prime mover 44, and one end of the regenerator of the prime mover 44 (the end on the high-temperature heat exchanger side) is arranged by this auxiliary heating device. Part) may be heated. By using the auxiliary heating device, the prime mover 44 can be appropriately heated even when the exhaust gas temperature is low, and sound waves can be generated from the prime mover 44.

  Further, in the above-described embodiment, the low-temperature heat exchanger of the prime mover and the high-temperature heat exchanger of the refrigerator are water-cooled heat exchangers that are cooled by cooling water. However, as shown in FIG. An air-cooled heat exchanger can also be used. FIG. 12 shows an example in which an air-cooled heat exchanger is used for the low-temperature heat exchanger of the prime mover (or the high-temperature heat exchanger of the refrigerator). The right side of FIG. 12 shows an example in which a honeycomb-shaped heat radiating plate 192a is used as the heat transfer plate 194a that is in contact with the heat accumulator 210 (see FIG. 13A), and the left side of FIG. An example is shown in which a plurality of heat radiation fins 192b are provided on the heat transfer plate 194b that abuts (see FIG. 13B). By using an air-cooled heat exchanger as shown in FIGS. 12 and 13, it is possible to eliminate the need for hot water piping required when a water-cooled heat exchanger is used. The cooling capacity of these air-cooled heat exchangers can be adjusted by the area of the heat radiating plate 192a and the heat radiating fins 192b.

Further, the structure of the high-temperature heat exchanger of the prime mover (or the low-temperature heat exchanger of the refrigerator) is not limited to the above-described embodiment, and various structures can be adopted. For example, as shown in FIGS. 12, 14, and 15, a heat exchange unit 202 may be provided on the outer edge 203 of the heat transfer plate 204. A plurality of fins 205 can be provided in the heat exchanging section 202 substantially perpendicular to the axial direction of the acoustic tube 42. A heat insulating material 207 is disposed around the heat exchange unit 202.
In addition, when such a structure is employ | adopted, unlike the structure shown in FIG. 2, a heat exchanger cannot be attached to the acoustic tube 42 using a screw | thread etc. FIG. Therefore, as shown in FIGS. 12 and 14, the heat exchanger 200 can be attached to the acoustic tube 42 by a stopper 206. The stopper 206 can be provided at an appropriate position on the outer periphery of the heat exchange unit 202 (see FIG. 14).

Second Example Next, a thermoacoustic cooling device according to a second example will be described with reference to FIG. In addition, the description about the part which concerns on the same structure as 1st Example is abbreviate | omitted, and it demonstrates centering on a different part from 1st Example.
As shown in FIG. 16, the thermoacoustic cooling device 43 of the second embodiment cools the fuel evaporative gas (evaporative gas) evaporated in the fuel tank 10. That is, the fuel tank 10 and the low temperature heat exchanger of the refrigerator 49 are connected by the gas pipe 13. A fan 11 is disposed at a gas inlet (end on the fuel tank 10 side) of the gas pipe 13. As the fan 11 rotates, air (fuel evaporative gas) in the fuel tank is sent into the gas pipe 13. The air flowing through the gas pipe 13 is cooled by the low temperature heat exchanger of the refrigerator 49. As a result, the fuel evaporative gas contained in the air is liquefied, and the liquefied fuel (cooled fuel) is returned to the fuel tank 10 through the pipe 15. Also in the second embodiment, since the evaporation of the fuel in the fuel tank 10 is suppressed, effects such as suppression of fluctuations in the air-fuel ratio of the engine, miniaturization of the canister, and suppression of vapor lock of the fuel pump 12 can be achieved. In the thermoacoustic cooling device 43 of the second embodiment, a resonance tube 51 is attached to the acoustic tube 45 as shown in FIG.

Third Example Next, a thermoacoustic cooling device according to a third example will be described with reference to FIG. The thermoacoustic cooling device 90 of the third embodiment cools the supercharged air from the turbocharger 68. As shown in FIG. 17, a surge tank 60 and an intake manifold 62 are provided in an intake system 58 of an engine 64 (gasoline engine). The surge tank 60 stores air sucked through the air cleaner 52. The amount of air flowing from the air cleaner 52 to the surge tank 60 is adjusted by the opening of the throttle 56. Air in the surge tank 60 is supplied to the engine 64 through the intake manifold 62.

  The exhaust system 72 of the engine 64 is provided with an exhaust manifold 66 and a catalyst device 70. A turbocharger 68 is interposed between the exhaust manifold 66 and the catalyst device 70. The exhaust gas processed by the catalyst device 70 is exhausted to the outside through the exhaust pipe 71. A branch pipe 74 is provided in the exhaust pipe 71. The flow rate of the exhaust gas flowing through the branch pipe 74 is adjusted by the flow rate control valve 76. A motor 88 (high temperature heat exchanger) of the thermoacoustic cooling device 90 is connected to the circulation path of the branch pipe 74. The high temperature heat exchanger of the prime mover 88 recovers thermal energy in the exhaust gas, thereby generating sound waves from the prime mover 88. The air supercharged by the turbocharger 68 is supplied to the refrigerator 92 (low temperature heat exchanger) of the thermoacoustic cooling device 90. The supercharged air cooled by the refrigerator 92 is returned to the intake system 58 through the intake pipe 57. Note that cooling water flowing through the hot water pipe 96 is supplied to the low-temperature heat exchanger of the prime mover 88 and the high-temperature heat exchanger of the refrigerator 92. A radiator 94, a pump 86, and a flow rate control valve 82 are disposed in the circulation path of the hot water pipe 96. The radiator 94 cools the cooling water flowing through the hot water pipe 96, the pump 86 sends the cooling water cooled by the radiator 94 to the hot water pipe 96, and the flow control valve 82 adjusts the amount of cooling water flowing through the hot water pipe 96. In addition, by improving the cooling capacity of the low-temperature heat exchanger of the prime mover 88 and the high-temperature heat exchanger of the refrigerator 92, a temperature control device such as the radiator 94 can be omitted from the circulation path of the hot water pipe 96.

  In the third embodiment, the temperature of the exhaust gas flowing through the branch pipe 74 is measured by the temperature sensor 78, the temperature of the cooling water flowing through the hot water pipe 96 is measured by the temperature sensor 98, and the supercharger cooled by the refrigerator is used. The temperature of the air is measured by the temperature sensor 100. The temperatures measured by these temperature sensors 78, 98 and 100 are input to the control unit 84. The control unit 84 can control the flow rate control valve 76, the pump 86, and the flow rate control valve 82 based on the input temperature. For example, the flow control valve 76, the pump 86, and the flow control valve 82 are controlled so that the temperature of the supercharged air supplied to the engine 64 becomes a constant value. Thereby, the emission discharged from the engine 64 can be controlled.

As is apparent from the above description, in the third embodiment, the supercharged air of the turbocharger 68 is cooled by the thermoacoustic cooling device 90, so that a conventionally required large intercooler can be eliminated. For this reason, the whole apparatus can be made compact.
Further, since the thermoacoustic cooling device 90 has a high cooling capacity, it is possible to supply supercharged air having a lower temperature than the intercooler to the engine 64. For this reason, it is possible to improve the intake charging efficiency and the engine output.
Furthermore, since the heat energy in the exhaust gas is recovered by the prime mover 88 of the thermoacoustic cooling device 90, and the exhaust gas is thereby cooled, the exhaust loss can be reduced and the exhaust noise can be reduced.
The supercharged air cooling system described above can also be applied to a system for cooling supercharged air of a diesel engine. In this case, the throttle body provided in the intake system of the engine can be eliminated.

(4th Example) Next, the thermoacoustic cooling device which concerns on 4th Example is demonstrated with reference to FIG. The thermoacoustic cooling device 90 of the fourth embodiment cools exhaust gas for EGR (exhaust gas recirculation). Although the fourth embodiment is different from the third embodiment in that the EGR gas is cooled, the schematic configuration is the same as that of the third embodiment. Therefore, here, the description will focus on the differences from the third embodiment.
As shown in FIG. 18, the exhaust manifold 66 is provided with an EGR branch pipe 54. The EGR branch pipe 54 is connected to a refrigerator 92 (low temperature heat exchanger) of the thermoacoustic cooling device 90 and cooled by the low temperature heat exchanger of the refrigerator 92. The EGR gas cooled by the refrigerator 92 flows into the surge tank 60 through the EGR branch pipe 54. The flow rate of the EGR gas flowing through the EGR branch pipe 54 is adjusted by the EGR valve 99. In the fourth embodiment, since the EGR gas is cooled by the thermoacoustic cooling device 90, the EGR cooler conventionally required can be eliminated.

Fifth Example Next, a thermoacoustic cooling device according to a fifth example will be described with reference to FIG. The thermoacoustic cooling device 110 of the fifth embodiment cools the refrigerant of the air conditioner that cools the interior of the automobile.
As shown in FIG. 19, the refrigerator 112 (low temperature heat exchanger) of the thermoacoustic cooling device 110 is disposed in the circulation path of the refrigerant pipe 104. A pump 108 is disposed in the circulation path of the refrigerant pipe 104, and the refrigerant flows through the refrigerant pipe 104 by operating the pump 108. In addition, a heat exchange unit 102 that performs heat exchange with the cooling air is provided in the circulation path of the refrigerant pipe 104. The heat exchange unit 102 is arranged in the duct 100. A blower 106 is disposed at the rear end of the duct 100, and the air blown from the blower 106 is blown into the vehicle interior through the heat exchange unit 102. Therefore, the refrigerant flowing through the refrigerant pipe 104 is cooled by the low-temperature heat exchanger of the refrigerator 112 and exchanges heat with the air blown out from the blower 102 by the heat exchange unit 102. As a result, the air blown from the blower 102 is cooled and blown into the passenger compartment.
In the fifth embodiment, since the thermoacoustic cooling device 110 is used for the air conditioner for the passenger compartment of the automobile, unlike the case where the compression type refrigerator is used, the compressor is unnecessary, and the case where the absorption type refrigerator is used. In contrast, a compressor, a generator, a pump, etc. can be dispensed with. For this reason, an apparatus is comprised simply and it can improve the reliability and durability of an apparatus.

  In the embodiment shown in FIG. 19, the thermoacoustic cooling device is used as an air conditioner in the passenger compartment. However, the thermoacoustic cooling device is used to cool the refrigerant of other devices mounted in the automobile. You can also. For example, as shown in FIG. 20, a thermoacoustic cooling device 150 can be used to cool the refrigerant for the in-vehicle refrigerator 130. Furthermore, as shown in FIG. 21, it can also be used for a refrigeration system 164 that cools the freezer 162 of the freezer 160 (note that reference numeral 166 in FIG. 21 denotes an engine).

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
In addition, the technical elements described in the present specification or drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

It is a schematic block diagram of the thermoacoustic cooling device which concerns on 1st Example. It is a figure which shows the structure of the motor | power_engine (refrigerator) of the thermoacoustic cooling device shown in FIG. It is the III-III sectional view taken on the line of FIG. It is the IV-IV sectional view taken on the line of FIG. It is a figure which expands and shows the heat exchange part of the high temperature heat exchanger shown in FIG. It is a figure which expands and shows the heat exchange part of the low-temperature heat exchanger shown in FIG. It is a figure which shows typically the flow of the cooling water in the heat exchange part shown in FIG. It is a flowchart of the process performed with the control unit of the thermoacoustic cooling device which concerns on 1st Example. It is a graph which shows the load characteristic of a flow control valve. It is a graph which shows the relationship between the load of the flow control valve determined in a control unit, target exhaust gas temperature, and measured exhaust gas temperature. It is a figure which shows the modification of the thermoacoustic cooling device which concerns on 1st Example. It is a figure which shows the structure of the motor | power_engine (refrigerator) of the thermoacoustic cooling device shown in FIG. It is a top view of the low-temperature heat exchanger shown in FIG. It is sectional drawing of the high temperature heat exchanger shown in FIG. It is a figure which expands and shows the heat exchange part of the high temperature heat exchanger shown in FIG. It is a figure which shows schematic structure of the thermoacoustic cooling device which concerns on 2nd Example. It is a figure which shows schematic structure of the thermoacoustic cooling device which concerns on 3rd Example. It is a figure which shows schematic structure of the thermoacoustic cooling device which concerns on 4th Example. It is a figure which shows schematic structure of the thermoacoustic cooling device which concerns on 5th Example. It is a figure which shows the modification of the thermoacoustic cooling device which concerns on 5th Example. It is a figure which shows the other modification of the thermoacoustic cooling device which concerns on 5th Example.

Explanation of symbols

10: Fuel tank 24: Hot water pipe 26: Exhaust pipe 28: Flow control valve 30: Branch pipe 31: Temperature sensor 32: Control unit 34: Temperature sensor 42: Acoustic pipe 44: Refrigerator 46: Motor

Claims (4)

An exhaust heat recovery device that recovers thermal energy from exhaust gas of an internal combustion engine,
An acoustic tube;
A first heat accumulator disposed in the acoustic tube;
A first high-temperature heat exchanger disposed at one end of the first heat accumulator and absorbing heat from the exhaust gas to heat one end of the first heat accumulator;
A first low-temperature heat exchanger that is disposed at the other end of the first heat accumulator, absorbs heat from the other end of the first heat accumulator, and releases heat to the outside;
A drive device disposed at a position away from the first heat accumulator in the acoustic tube and driven by sound waves generated by the first heat accumulator;
A temperature sensor for detecting the temperature of the exhaust gas;
And a control means for adjusting a flow rate of the exhaust gas supplied to the first high-temperature heat exchanger based on the exhaust gas temperature detected by the temperature sensor.   An auxiliary heating device is further provided at the end of the first heat accumulator on the first high-temperature heat exchanger side, and the control means uses the auxiliary heating device to change the first heat accumulator temperature based on the exhaust gas temperature detected by the temperature sensor. The exhaust heat recovery apparatus according to claim 1, wherein the end portion on the high temperature heat exchanger side is heated.   The drive device is arranged at (1) the second heat accumulator and (2) the high temperature side end of the second heat accumulator, and absorbs heat from the high temperature side end of the second heat accumulator to release the heat to the outside. A second high temperature heat exchanger, and (3) a second low temperature which is disposed at the low temperature side end of the second heat accumulator and absorbs heat from the object to be cooled and releases the heat to the low temperature side end of the second heat accumulator. The exhaust heat recovery apparatus according to claim 1, further comprising a heat exchanger.   The apparatus further comprises a second temperature sensor for detecting the temperature of the cooling object cooled by the second low-temperature heat exchanger, and the control means detects the exhaust gas temperature detected by the temperature sensor and the cooling object detected by the second temperature sensor. The exhaust heat recovery apparatus according to claim 3, wherein the flow rate of the exhaust gas supplied to the first high-temperature heat exchanger is adjusted based on the temperature of the exhaust gas.

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