JP2005180397A - Thermal acoustic engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal acoustic engine capable of surely generating thermal acoustic self-excited vibration of a working fluid, by always forming a large temperature gradient between both end parts of a heat accumulating means. <P>SOLUTION: This thermal acoustic engine 20 has a columnar gas pipe 21 sealed with the working fluid, a heat accumulator 25 arranged in the columnar gas pipe 21, a high temperature heat exchanger 26 for heating one end part of the heat accumulator 25 with exhaust gas of an internal combustion engine 1 as a heat source, a low temperature heat exchanger 27 constituted for selectively supplying cooling water and air of the internal combustion engine 1 as a refrigerant and cooling the other end part of the heat accumulator 25 by the cooling water or the air, and an ECU 40. The ECU 40 supplies the air to the low temperature heat exchanger 27 when a temperature difference between both end parts of the heat accumulator 25 becomes less than a predetermined value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a thermoacoustic engine that forms a temperature gradient between both ends of a heat storage means arranged in an air column tube and generates thermoacoustic self-excited vibration of a working fluid in the air column tube.

  Conventionally, a refrigerator utilizing a thermoacoustic phenomenon has been proposed (see, for example, Patent Document 1). This refrigerator includes a pipe filled with gas, a stack disposed inside the pipe and sandwiched between a high temperature side heat exchanger and a low temperature side heat exchanger, and a high temperature side at a position asymmetric with the stack. And a regenerator arranged together with the heat exchanger and the low temperature side heat exchanger. This refrigerator generates a self-excited vibration of gas in the stack by forming a temperature gradient between both ends of the stack, and stores it in the regenerator by propagation of standing waves and traveling waves obtained thereby. It is.

  Conventionally, an apparatus for recovering waste heat of an internal combustion engine using a thermoacoustic phenomenon has been proposed (see, for example, Patent Document 2). This device includes a resonance pipe connected to an exhaust gas purification catalytic converter of an internal combustion engine, a stack provided at one end of the resonance pipe, and a transducer provided at the other end of the resonance pipe. In this apparatus, one end of the stack is heated by heat generated from the catalytic converter, and a temperature gradient is applied between both ends of the stack. Thereby, sound waves are generated in the stack, and the energy of the sound waves is converted into electric energy by the transducer.

Japanese Patent No. 3015786 JP 2002-122020 A

  As described above, the waste heat of the internal combustion engine can be converted into cold energy or electric energy by forming a temperature gradient between both ends of the stack using the waste heat of the internal combustion engine. However, in order to reliably generate the above-described self-excited vibration (sound wave) of the working fluid, it is necessary to always form a sufficiently large temperature gradient at both ends of the stack (heat storage means).

  Accordingly, an object of the present invention is to provide a thermoacoustic engine that can always generate a large temperature gradient between both end portions of a heat storage means and reliably generate thermoacoustic self-excited vibration of a working fluid.

  A thermoacoustic engine according to the present invention includes an air column tube in which a working fluid is sealed, and heat storage means disposed inside the air column tube, and both end portions of the heat storage unit using surplus energy of the internal combustion engine. In a thermoacoustic engine that forms a temperature gradient in between and generates thermoacoustic self-excited vibration of the working fluid, a high-temperature heat exchanger that heats one end of the heat storage means using the exhaust gas of the internal combustion engine as a heat source, and cooling of the internal combustion engine Water and air can be selectively supplied as a refrigerant, and a temperature difference between the low-temperature heat exchanger that cools the other end of the heat storage means with cooling water or air and the both ends of the heat storage means is a predetermined value. And a control means for supplying air to the low-temperature heat exchanger when the temperature falls below.

  This thermoacoustic engine includes a high-temperature heat exchanger that uses exhaust gas of an internal combustion engine as a heat source, and generates an internal combustion engine to generate a thermoacoustic self-excited vibration of the working fluid by forming a temperature gradient between both ends of the heat storage means. A low-temperature heat exchanger that can selectively use the cooling water and air as refrigerant. In this thermoacoustic engine, when the temperature difference between both ends of the heat storage means falls below a predetermined value, the control means switches the refrigerant supplied to the low temperature heat exchanger from the cooling water of the internal combustion engine to the air. It is done. As a result, in this thermoacoustic engine, it is possible to always form a large temperature gradient between the both ends of the heat storage means, so that the thermoacoustic self-excited vibration of the working fluid is reliably generated and the desired acoustic output is always obtained. Can be obtained.

  In this case, it is preferable that the control means is configured to supply air to the low-temperature heat exchanger when the temperature of the cooling water exceeds a predetermined value.

  The control means may be configured to supply air to the low-temperature heat exchanger when the temperature difference between the high-temperature heat exchanger and the cooling water falls below a predetermined value.

  Furthermore, the control means may be configured to supply air to the low-temperature heat exchanger when the temperature difference between the low-temperature heat exchanger and the cooling water falls below a predetermined value.

  The control means may be configured to supply air to the low-temperature heat exchanger when the temperature difference between the high-temperature heat exchanger and the low-temperature heat exchanger falls below a predetermined value.

  According to the present invention, it is possible to realize a thermoacoustic engine which can always generate a large temperature gradient between both end portions of the heat storage means and reliably generate the thermoacoustic self-excited vibration of the working fluid.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing an embodiment of a thermoacoustic engine according to the present invention. As shown in the figure, the thermoacoustic engine 20 is applied to, for example, an internal combustion engine 1 used as a travel drive source of a vehicle. First, the internal combustion engine 1 to which the thermoacoustic engine 20 is applied will be briefly described. The internal combustion engine 1 burns a mixture of fuel and air in a combustion chamber 3 formed in the cylinder block 2 and burns it. The piston 4 is reciprocated in the chamber 3 to generate power.

  The intake port of the combustion chamber 3 is connected to the intake manifold 5, and the exhaust port of the combustion chamber 3 is connected to the exhaust manifold 6. In addition, an intake valve Vi that opens and closes an intake port, an exhaust valve Ve that opens and closes an exhaust port, a spark plug 7, and an injector 8 are disposed for each combustion chamber 3 in the cylinder head of the internal combustion engine 1. The intake manifold 5 is connected to a surge tank 9, and an air supply pipe L <b> 1 is connected to the surge tank 9. The air supply pipe L1 is connected to an air intake port (not shown) via the air cleaner 10. Further, a throttle valve 11 is incorporated in the middle of the supply pipe L1 (between the surge tank 9 and the air cleaner 10). On the other hand, the exhaust manifold 6 is connected to an exhaust pipe L2, and a front-stage catalyst device 12a and a rear-stage catalyst device 12b are incorporated in the exhaust pipe L2.

  The thermoacoustic engine 20 of the present invention is used to recover the exhaust heat of the internal combustion engine 1 as described above. The thermoacoustic engine 20 has an air column tube 21 formed of stainless steel or the like so as to have a circular cross section, and inside the air column tube 21 is an operation such as nitrogen, helium, argon, a mixed gas of helium and argon. A fluid (inert gas) is enclosed. As shown in FIG. 1, the air column tube 21 includes a loop portion 22 formed in a substantially rectangular loop shape and a resonance portion 23 connected to one corner portion of the loop portion 22. The resonance part 23 includes a tube part 23a having a circular cross section approximately the same diameter as the loop part 22, and a closed end part 23b connected to the tip of the tube part 23a, and functions as a resonator. The diameter of the closed end portion 23b is gradually increased from the distal end of the tube portion 23a toward the closed end.

  A heat accumulator (heat storage means) 25 is disposed inside the loop portion 22 of the air column tube 21. The heat accumulator 25 has a plurality of narrow flow paths extending in parallel with the axial direction of the air column tube 21 at the arrangement location. As the heat accumulator 25, a honeycomb structure made of ceramic or the like, a thin mesh made of stainless steel or the like arranged at a minute interval, a nonwoven fabric in which metal fibers such as stainless steel are gathered, or the like can be used. A high temperature heat exchanger 26 is disposed adjacent to one end side of the heat accumulator 25, and a low temperature heat exchanger 27 is disposed adjacent to the other end side of the heat accumulator 25. That is, the heat accumulator 25 is arranged in a state of being sandwiched between the high temperature heat exchanger 26 and the low temperature heat exchanger 27.

  Exhaust gas flowing through the exhaust pipe L2 of the internal combustion engine 1 is supplied to the heat transfer tubes constituting the high temperature heat exchanger 26, and the high temperature heat exchanger 26 uses the exhaust gas of the internal combustion engine 1 as a heat source. In the present embodiment, the high-temperature heat exchanger (its heat transfer tube) 26 is incorporated in the exhaust pipe L2 between the front-stage catalyst device 12a and the rear-stage catalyst device 12b, and the high-temperature heat exchanger (its heat transfer tube) 26 An exhaust supply adjustment valve (open / close valve) 15 is provided at the exhaust gas inlet. By closing the exhaust supply adjusting valve 15, the supply of exhaust gas to the high temperature heat exchanger 26 can be stopped.

  The low-temperature heat exchanger 27 is configured to be able to selectively supply cooling water of the internal combustion engine and external air as refrigerants. That is, the low-temperature heat exchanger 27 has a water-cooled heat exchanging unit 27w for circulating cooling water and an air-cooled heat exchanging unit 27a for circulating air. The water-cooled heat exchanger 27w of the low-temperature heat exchanger 27 is incorporated in the cooling system L3 of the internal combustion engine 1, and the air-cooled heat exchanger 27a of the low-temperature heat exchanger 27 is incorporated in the air system L4. In addition, although illustration is abbreviate | omitted, on the surface of the low-temperature heat exchanger 27, the fin for heat radiation is arrange | positioned in multiple numbers.

  As shown in FIG. 1, the cooling system L3 of the internal combustion engine 1 includes a cooling water inflow valve (open / close valve) 31 provided at the fluid inlet of the water cooling heat exchanging portion 27w and a cooling water outflow provided at the fluid outlet. A valve (open / close valve) 32 and a cooling water pump 33 for supplying cooling water to the water cooling heat exchanging unit 27w are included. Therefore, by operating the cooling water pump 33 with the cooling water inflow valve 31 and the cooling water outflow valve 32 opened, the cooling water flowing through the cooling system L3 can be supplied to the water cooling heat exchanging unit 27w. Further, by stopping the cooling water pump 33 and closing the cooling water inflow valve 31 and the cooling water outflow valve 32, the supply of the cooling water to the water cooling heat exchanging portion 27w can be stopped.

  Similarly, the air system L4 includes an air inflow valve 34 (open / close valve) provided at the fluid inlet of the air-cooling heat exchanger 27a, an air outflow valve (open / close valve) 35 provided at the fluid outlet, and air from the surroundings. And an air pump 36 for circulatingly supplying the air-cooled heat exchanger 27a. Therefore, by operating the air pump 36 with the air inflow valve 34 and the air outflow valve 35 being opened, air can be circulated and supplied to the air-cooling heat exchange unit 27a. Further, by stopping the air pump 36 and closing the air inflow valve 34 and the air outflow valve 35, the supply of air to the air cooling heat exchanging portion 27a can be stopped.

  Furthermore, the regenerator 250, the cold storage high temperature heat exchanger 260, and the cold storage low temperature heat exchanger 270 are arranged in the loop portion 22 of the air column tube 21. In this case, the cold storage high-temperature heat exchanger 260 is configured so that one end of the cold storage 250 can be maintained at approximately room temperature (20 to 25 ° C.). The cold storage heat exchanger 270 is disposed adjacent to the low temperature heat exchanger 27 described above, and a predetermined refrigerant is circulated and supplied to the cold storage heat exchanger 270 (its heat transfer tube). In the present embodiment, instead of arranging the regenerator 250 and the high and low temperature heat exchangers 260 and 270 for cold storage inside the loop part 22, a transducer is arranged inside the closed end 23 b of the resonance part 23. Then, acoustic energy may be collected to obtain electrical energy. Further, both the unit such as the regenerator 250 and the transducer may be arranged for the air column tube 21.

  The thermoacoustic engine 20 is controlled by an electronic control unit (hereinafter referred to as “ECU”) 40 that functions as control means of the internal combustion engine 1. The ECU 40 includes a CPU, a ROM, a RAM, an input / output port, a storage device, etc., all not shown. The cooling water inflow valve 31, the cooling water outflow valve 32 and the cooling water pump 33 of the cooling system L3, the air water inflow valve 34 of the air system L4, the air water outflow valve 35 and the air pump 36, and the exhaust gas of the high temperature heat exchanger 26. The exhaust supply adjustment valve 15 and the like provided at the inlet are respectively connected to the input / output ports of the ECU 40, and these are controlled by the ECU 40. In the present embodiment, a water temperature sensor T is installed in the cooling system L3. The water temperature sensor T detects the temperature of the cooling water supplied to the low-temperature heat exchanger 27, and outputs a signal indicating the detected value to the ECU 40. To give.

  When operating the thermoacoustic engine 20 configured as described above, the exhaust gas from the combustion chamber 3 is introduced into the high-temperature heat exchanger 26 of the thermoacoustic engine 20. In addition, the low-temperature heat exchanger 27 (water-cooled heat exchanger 27w) of the thermoacoustic engine 20 is basically supplied with cooling water flowing through the cooling system L3 by the cooling water pump 33.

  Here, since the temperature of the exhaust gas of the internal combustion engine 1 normally reaches about 250 to 500 ° C., one end portion of the heat accumulator 25 is heated by the exhaust gas flowing through the high-temperature heat exchanger 26 to increase the temperature. . On the other hand, the temperature of the cooling water of the internal combustion engine 1 is substantially the atmospheric temperature immediately after the cold start of the internal combustion engine 1 and is approximately 80 to 90 ° C. after the warm-up is completed. Is cooled by cooling water flowing through the low-temperature heat exchanger 27. As a result, a large temperature gradient is formed between both ends of the heat accumulator 25, and as a result, thermoacoustic self-excited vibration (sound wave) of the working fluid is generated.

  When the frequency of the self-excited vibration (sound wave) of the working fluid thus generated matches the frequency in the resonance part 23, a standing wave is formed in the resonance part 23, and in the loop part 22, A traveling wave traveling from the low temperature heat exchanger 27 to the high temperature heat exchanger 26 is formed. Then, due to the traveling wave generated due to the temperature gradient formed between both ends of the regenerator 25, the high temperature heat exchanger 260 for regenerator has a high temperature between both ends of the regenerator 250 of the loop portion 22. Thus, a temperature gradient is formed so that the cold storage low-temperature heat exchanger 270 side has a low temperature.

  At this time, one end of the regenerator 250 is maintained at a substantially normal temperature (20 to 25 ° C.) by the regenerative high-temperature heat exchanger 260, so the other end of the regenerator 250 and the regenerative low-temperature heat exchanger 270 ( The heat transfer tube) drops in accordance with the temperature gradient. As a result, the units of the regenerator 250, the regenerator high-temperature heat exchanger 260, and the regenerator low-temperature heat exchanger 270 operate as a thermoacoustic refrigerator, and the refrigerant flows out of the regenerator low-temperature heat exchanger 270. It becomes possible to take out cold heat.

  As described above, according to the thermoacoustic engine 20, the self-excitation of the working fluid is performed by forming a temperature gradient in the both end pipes of the heat accumulator 25 using the surplus energy (heat energy of the exhaust gas) of the internal combustion engine 1. Vibration can be generated and the energy (acoustic energy) of the vibration can be converted into heat energy (cold heat). However, depending on the operating state of the internal combustion engine 1, the temperature of the cooling water flowing through the cooling system L3 may increase excessively. In such a case, particularly in a high thermal efficiency engine having a relatively low exhaust temperature, a sufficiently large temperature gradient cannot be formed between both ends of the heat accumulator 25, and self-excited vibration (sound wave) of the working fluid is generated. It may be difficult to do so.

  Therefore, in the present embodiment, the refrigerant supply shown in FIG. 2 is performed by the ECU 40 in order to always form a large temperature gradient between the both ends of the heat accumulator 25 and to surely generate the thermoacoustic self-excited vibration of the working fluid. The control routine is repeatedly executed every predetermined time. That is, at the execution timing of the refrigerant supply control routine, the ECU 40 first obtains the temperature of the cooling water supplied to the low-temperature heat exchanger 27 based on the signal from the water temperature sensor T (S10).

When determining the temperature of the cooling water at S10, ECU 40 determines whether the temperature of the coolant determined is the threshold value _{T 0} or more which is determined in advance (S12). The threshold T ₀ is a temperature difference (temperature gradient) between both ends of the heat accumulator 25 during operation of the internal combustion engine 1, that is, a temperature range of the exhaust gas, an ambient environment temperature of the internal combustion engine 1, and cooling water and air. In consideration of the specific heat and the like, the upper limit value for forming a sufficiently large temperature gradient between both end portions of the regenerator 25 is determined in advance (for example, about 60 ° C.) and stored in the storage device.

If the temperature of the cooling water is determined to be the threshold value T ₀ or more at S12, ECU 40, the low temperature heat exchanger 27 cooling water is provided for water cooling heat exchange section 27w of the inlet valve 31 and the cooling water outlet valve 32 is closed (S14), and the cooling water pump 33 of the cooling system L3 is stopped (S16). Then, the ECU 40 opens the air inflow valve 34 and the air outflow valve 35 provided for the air cooling heat exchanging portion 27a of the low temperature heat exchanger 27 (S18), and operates the air pump 36 of the air system L4 (S20). ). Thereby, air taken in from the surroundings by the air pump 36 is supplied to the low-temperature heat exchanger 27 as a refrigerant instead of the cooling water that has been supplied.

On the other hand, when the temperature of the cooling water is determined to be below the threshold value T ₀ at S12, ECU 40 is provided with an air inlet valve 34 and the air outlet relative to the air-cooled heat exchanger portion 27a of the cold heat exchanger 27 The valve 35 is closed (maintained in the closed state) (S22), and the air pump 36 of the air system L4 is stopped (maintained in the stopped state) (S24). Then, the ECU 40 opens (maintains in the open state) the cooling water inflow valve 31 and the cooling water outflow valve 32 provided for the water cooling heat exchanging portion 27w of the low temperature heat exchanger 27 (S26), and the cooling system. The cooling water pump 33 of L3 is operated (maintained in the operating state) (S28). Thereby, cooling water is supplied to the low-temperature heat exchanger 27 as a refrigerant (the supply of cooling water is continued).

Thus, the thermoacoustic engine 20, the temperature of the cooling water flowing through the cooling system L3 is at the threshold value T ₀ or more, even with a cooling water as a coolant for low temperature heat exchanger 27, both end portions of the heat accumulator 25 When it is determined that there is a possibility that a sufficiently large temperature gradient cannot be formed between both ends of the heat accumulator 25 because the temperature difference between them is below a predetermined value, the refrigerant supplied to the low-temperature heat exchanger 27 is The cooling water of the internal combustion engine is switched to air having a temperature lower than that of the cooling water. Thereby, in the thermoacoustic engine 20, since it becomes possible to always form a large temperature gradient between the both ends of the heat accumulator 25, the thermoacoustic self-excited vibration of the working fluid is surely generated, and the desired acoustics are always generated. Output can be obtained.

By the way, as described above, based on the temperature of the cooling water (by comparing the temperature of the cooling water with a predetermined threshold value T ₀ ), the temperature difference between both ends of the heat accumulator 25 falls below a predetermined value. It is possible to determine substantially whether or not the same, but the same determination can be made using the temperature difference between the high-temperature heat exchanger 26 and the cooling water. In this case, in addition to the water temperature sensor T, the thermoacoustic engine 20 includes a temperature sensor Th (see FIG. 1) that detects the temperature of a predetermined portion of the high-temperature heat exchanger 26 (preferably, a portion that heats the heat accumulator 25). Is provided. And ECU40 calculates | requires the temperature difference of the high temperature heat exchanger 26 and cooling water based on the detected value of the water temperature sensor T and the temperature sensor Th, and when the said temperature difference is less than predetermined value, the low temperature heat exchanger 27 is obtained. Air is supplied to the (air-cooling heat exchanger 27a).

  Even if such a configuration is adopted, it is possible to always form a large temperature gradient between both ends of the heat accumulator 25, so that the thermoacoustic self-excited vibration of the working fluid can be reliably generated and always desired. Sound output can be obtained. In this case, instead of providing the high temperature heat exchanger 26 with the temperature sensor Th, a temperature sensor Tcat (see FIG. 1) for detecting the catalyst temperature is provided in the pre-catalyst device 12a and the detected value of the temperature sensor Tcat is increased. The temperature of the heat exchanger 26 may be substituted.

  Moreover, by calculating | requiring the correlation with the temperature difference (temperature gradient) between the both ends of the heat storage 25, even if it uses the temperature difference of the low temperature heat exchanger 27 and cooling water, between the both ends of the heat storage 25 It can be determined whether a large temperature gradient can be formed. In this case, in addition to the water temperature sensor T, the thermoacoustic engine 20 includes a temperature sensor Tc (see FIG. 1) that detects the temperature of a predetermined portion of the low-temperature heat exchanger 27 (preferably, a portion that cools the regenerator 25). Is provided. And ECU40 calculates | requires the temperature difference of the low temperature heat exchanger 27 and cooling water based on the detected value of the water temperature sensor T and the temperature sensor Tc, and when the said temperature difference falls below a predetermined value, the low temperature heat exchanger 27 is obtained. Air is supplied to the (air-cooling heat exchanger 27a). Even if such a configuration is adopted, it is possible to always form a large temperature gradient between both ends of the heat accumulator 25, so that the thermoacoustic self-excited vibration of the working fluid can be reliably generated and always desired. Sound output can be obtained.

  Furthermore, based on the temperature difference between the high temperature heat exchanger 26 and the low temperature heat exchanger 27, it may be determined whether or not a large temperature gradient can be formed between both ends of the heat accumulator 25. In this case, the ECU 40 detects the temperature of a predetermined location of the high temperature heat exchanger 26 (preferably a portion that heats the regenerator 25) and a predetermined location of the low temperature heat exchanger 27 (preferably a regenerator). When the temperature difference between the high temperature heat exchanger 26 and the low temperature heat exchanger 27 is less than a predetermined value, the temperature difference between the high temperature heat exchanger 26 and the low temperature heat exchanger 27 is obtained based on the detected value of the temperature sensor Tc that detects the temperature of the portion 25 that cools 25). Then, air is supplied to the low-temperature heat exchanger 27 (air-cooled heat exchanger 27a). Also in this case, instead of providing the temperature sensor Th in the high-temperature heat exchanger 26, a temperature sensor Tcat (see FIG. 1) for detecting the catalyst temperature is provided in the pre-stage catalyst device 12a or the like, and the detected value of the temperature sensor Tcat is used as the high-temperature heat. The temperature of the exchanger 26 may be substituted.

  The above-described controls for switching between cooling water and air as the refrigerant of the low-temperature heat exchanger 27 are executed after the warm-up of the internal combustion engine 1 is completed. That is, when the exhaust gas of the internal combustion engine 1 is not sufficiently heated, a large temperature gradient is not formed between both end portions of the heat accumulator 25, so that thermoacoustic self-excited vibration of the working fluid may not occur. Therefore, in such a case, it is desirable to stop the operation of the thermoacoustic engine 20, and for example, the operation of the thermoacoustic engine 20 is stopped by closing the exhaust supply regulating valve 15. As a result, the exhaust gas is supplied to the post-catalyst device 12b without recovering its thermal energy, so that the post-catalyst device 12b can be activated at an early stage.

It is a schematic block diagram which shows the thermoacoustic engine by this invention. 3 is a flowchart for explaining a refrigerant supply control routine in the thermoacoustic engine shown in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 12a Front stage catalyst apparatus 12b Rear stage catalyst apparatus 15 Exhaust supply adjustment valve 20 Thermoacoustic engine 21 Air column pipe 22 Loop part 23 Resonance part 23a Pipe part 23b Closed end part 25 Regenerator 26 High temperature heat exchanger 27 Low temperature heat exchanger 27a Air cooling heat exchanging part 27w Water cooling heat exchanging part 31 Cooling water inflow valve 32 Cooling water outflow valve 33 Cooling water pump 34 Air inflow valve 35 Air outflow valve 36 Air pump 250 Regenerator 260 Cold storage high temperature heat exchanger 270 Cold storage low temperature heat exchange L2 Exhaust pipe L3 Cooling system L4 Air system T Water temperature sensor Tc, Th, Tcat Temperature sensor

Claims (5)

It has an air column tube in which a working fluid is sealed, and heat storage means arranged inside the air column tube, and forms a temperature gradient between both ends of the heat storage unit by using surplus energy of the internal combustion engine. In the thermoacoustic engine for generating the thermoacoustic self-excited vibration of the working fluid,
A high-temperature heat exchanger that heats one end of the heat storage means using the exhaust gas of the internal combustion engine as a heat source;
A low-temperature heat exchanger configured to selectively supply cooling water and air of the internal combustion engine as a refrigerant, and cooling the other end of the heat storage means with the cooling water or air;
A thermoacoustic engine comprising: control means for supplying air to the low-temperature heat exchanger when a temperature difference between both ends of the heat storage means falls below a predetermined value.   2. The thermoacoustic engine according to claim 1, wherein air is supplied to the low-temperature heat exchanger when the temperature of the cooling water exceeds a predetermined value.   2. The control unit according to claim 1, wherein when the temperature difference between the high temperature heat exchanger and the cooling water falls below a predetermined value, air is supplied to the low temperature heat exchanger. The described thermoacoustic engine.   2. The control unit according to claim 1, wherein air is supplied to the low-temperature heat exchanger when a temperature difference between the low-temperature heat exchanger and the cooling water falls below a predetermined value. The described thermoacoustic engine. The control means is configured to supply air to the low-temperature heat exchanger when a temperature difference between the high-temperature heat exchanger and the low-temperature heat exchanger falls below a predetermined value. The thermoacoustic engine according to 1.

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