JP2005351222A - Thermal acoustic engine and method for operating the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve startability and operation continuity of a thermal acoustic engine by surely and quickly generating thermal acoustic self-excited vibration of working fluid. <P>SOLUTION: The thermal acoustic engine 20 includes a gas column pipe 21 filled with working fluid, a heat accumulator 25 arranged in the gas column pipe 21. Temperature gradient is formed between both end parts of the heat accumulator 25 to generate thermal acoustic self-excited vibration of working fluid. The thermal acoustic engine 20 includes working fluid pipes L4, L5 for forcedly vibrating working fluid in the gas column pipe 21 at a time of start and when thermal acoustic self-excited vibration becomes dissipating, a pump 28, a working fluid storage tank 29 and an opening/closing valve 30. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  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 exhaust 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.

  Furthermore, conventionally, a thermoacoustic generator that generates a pressure gradient in the gas in the loop pipe by forming a temperature gradient between both ends of the heat storage section in the loop pipe and generates electric power in accordance with a traveling wave generated by the pressure vibration. Has also been proposed (see, for example, Patent Document 3). This thermoacoustic generator has a starter / generator including a linear motor and a piston cylinder. The starter / generator functions as a starter motor when the thermoacoustic generator is activated, and reciprocally moves the piston cylinder to apply pressure vibration to the gas at an arbitrary frequency to generate self-oscillation of the gas in the loop tube. When pressure vibration due to self-excited oscillation occurs in the loop tube, the starter / generator functions as a generator that generates power in accordance with traveling waves generated by the pressure vibration.

Japanese Patent No. 3015786 JP 2002-122020 A Japanese Patent Laid-Open No. 2003-324932

  As described above, by utilizing the thermoacoustic phenomenon, various waste heats can be recovered to obtain electric energy and cold energy. However, it is not always easy to satisfactorily generate thermoacoustic self-excited vibration of the working fluid in order to start power generation or the like. In addition, when performing power generation using thermoacoustic phenomenon, the self-excited vibration of the working fluid is likely to disappear for some reason. It needs to be generated (reproduced) promptly. That is, the conventional apparatus using the thermoacoustic phenomenon still has room for improvement in terms of startability and operation sustainability.

  In this case, self-excited vibration can be generated relatively early if the piston cylinder is reciprocated in the loop pipe to give pressure vibration to the gas as in the conventional example. However, if the piston is arranged in the loop pipe, the movement of the working fluid in the loop pipe is hindered by the piston after the occurrence of vibration, so that a desired sound output or the like cannot be obtained. Further, even if the piston cylinder is reciprocated in the loop pipe in a state where the self-excited vibration of the working fluid is likely to disappear, it is difficult to reliably and quickly reproduce the thermoacoustic self-excited vibration of the working fluid.

  Therefore, the present invention can reliably and promptly generate the thermoacoustic self-excited vibration of the working fluid, and can reliably generate the thermoacoustic engine having good startability and operation sustainability, and the thermoacoustic self-excited vibration of the working fluid. An object of the present invention is to provide an operation method for promptly generating a thermoacoustic engine that is generated promptly.

  The thermoacoustic engine according to the present invention has an air column tube in which a working fluid is enclosed, and heat storage means disposed inside the air column tube, and operates by forming a temperature gradient between both ends of the heat storage unit. In a thermoacoustic engine that generates thermoacoustic self-excited vibration of a fluid, the working fluid in the air column tube is forced by flowing the working fluid into the air column tube or flowing the working fluid out of the air column tube. It is provided with the forced vibration means to vibrate.

  The thermoacoustic engine includes forced vibration means for forcibly vibrating the working fluid in the air column tube by flowing the working fluid into the air column tube or letting the working fluid flow out of the air column tube. Therefore, if the forced vibration means is activated when the thermoacoustic engine starts or when the self-excited vibration of the working fluid is likely to disappear for some reason, the thermoacoustic self-excited vibration of the working fluid is reliably and promptly Can be generated or reproduced. Thereby, this thermoacoustic engine has a favorable startability and driving | operation sustainability. Further, the forced vibration means for allowing the working fluid to flow into or out of the air column tube can be arranged so as not to hinder the progress of the working fluid in the air column tube.

  In this case, it is preferable that the connection portion between the forced vibration means and the air column tube substantially coincides with the antinode position of the pressure vibration standing wave in the air column tube.

  That is, the working fluid flows into the air column tube in the vicinity of the antinode position of the pressure vibration standing wave in the air column tube, or the working fluid flows out of the air column tube to Since the pressure change can be effectively applied, the thermoacoustic self-excited vibration of the working fluid can be surely and promptly generated or regenerated.

  Moreover, the connection location of the forced vibration means and the air column tube may substantially coincide with the antinode position of the velocity fluctuation standing wave in the air column tube.

  As described above, the working fluid is allowed to flow into the air column tube in the vicinity of the antinode of the velocity fluctuation standing wave in the air column tube, or the working fluid is allowed to flow out of the air column tube to be changed into the working fluid in the air column tube. On the other hand, since it is possible to effectively change the speed, it is possible to reliably and promptly generate or regenerate the thermoacoustic self-excited vibration of the working fluid.

  Furthermore, the forced vibration means may be connected to the air column tube in the vicinity of the heat storage means.

  As described above, the working fluid is caused to flow into the air column tube in the vicinity of the heat storage means, or the working fluid is caused to flow out from the air column tube, so that the phase of the pressure vibration and the phase of the velocity vibration are approximately the same. A traveling wave can be quickly generated and reproduced.

  Further, the forced vibration means is preferably operated based on the natural vibration period of the air column tube.

  That is, the working fluid is allowed to flow into the air column tube so as to synchronize with the thermoacoustic self-excited vibration of the working fluid generated due to the temperature gradient formed between both ends of the heat storage means, or By allowing the working fluid to flow out from the thermodynamic self-excited vibration of the working fluid, it becomes possible to quickly grow or regenerate the working fluid.

  Furthermore, the working fluid is a mixed fluid obtained by mixing a plurality of fluids, and the forced vibration means causes a fluid having a relatively large molecular weight to flow into the air column tube among the plurality of fluids. It is preferable to flow out from the column tube.

  Since the momentum of the fluid can be sufficiently secured if the molecular weight of the fluid flowing into or out of the air column tube is relatively large, the amount of fluid flowing into or out of the air column tube Even if the number is reduced, the working fluid in the air column can be effectively vibrated.

  The operation method of the thermoacoustic engine according to the present invention includes 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. A method for operating a thermoacoustic engine that generates thermoacoustic self-excited vibration of a working fluid, wherein the working fluid is caused to flow into or out of the air column tube under a predetermined condition. Thus, the working fluid in the air column tube is forcibly vibrated.

  ADVANTAGE OF THE INVENTION According to this invention, the thermoacoustic self-excited vibration of a working fluid can be generate | occur | produced reliably and rapidly, the thermoacoustic engine which has favorable startability and driving | operation sustainability, and the thermoacoustic self-excited vibration of a working fluid is ensured. In addition, it is possible to realize an operation method that generates the thermoacoustic engine satisfactorily by generating it quickly.

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

[First Embodiment]
FIG. 1 is a schematic configuration diagram showing a first 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, and a transducer (converting sound wave energy (acoustic energy) into electrical energy is provided at the closed end of the closed end portion 23b. (Sound / electrical conversion means) 24 is arranged.

  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 copper 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 pipe) 26 is incorporated in the exhaust pipe L2 between the front-stage catalyst apparatus 12a and the rear-stage catalyst apparatus 12b. The heat transfer tubes constituting the low-temperature heat exchanger 27 are incorporated in the cooling system L3 of the internal combustion engine 1, and the low-temperature heat exchanger 27 uses the cooling water flowing through the cooling system L3 as a heat source (cold heat source). . In the present embodiment, an exhaust gas supply adjustment valve 15 is provided at the exhaust gas inlet of the high temperature heat exchanger (its heat transfer tube) 26, and the exhaust gas supply adjustment valve 15 is closed to thereby prevent the high temperature heat exchanger 26. The supply of exhaust gas can be stopped. However, the exhaust supply adjustment valve 15 may be omitted so that the exhaust gas is constantly supplied from the internal combustion engine 1 to the high-temperature heat exchanger 26. Similarly, the cooling system L3 includes an on-off valve 16. By closing the on-off valve 16, the supply of cooling water to the low-temperature heat exchanger (its heat transfer tube) 27 can be stopped.

  On the other hand, a working fluid storage tank (working fluid storage means) 29 is connected to the air column tube 21 (the tube portion 23a in this embodiment) of the thermoacoustic engine 20 via a working fluid tube L4 having a pump 28 in the middle. Has been. The pump 28 can suck the working fluid in the air column tube 21 and pump it into the working fluid storage tank 29, and a predetermined amount of working fluid is introduced into the working fluid storage tank 29 in advance. Also, one end of a working fluid pipe L5 having an on-off valve (normally closed) 30 is connected to the working fluid storage tank 29 in the middle. The other end of the working fluid pipe L5 is located near the corner portion located on the opposite side of the closed end portion 23b across the pipe portion 23a among the four corner portions of the air column tube 21, specifically, the loop portion 22. It is connected. The working fluid storage tank 29 is provided with a pressure sensor 31 for detecting the pressure of the working fluid therein.

  By operating the pump 28 with the on-off valve 30 of the working fluid pipe L5 closed, the working fluid pressurized by the pump 28 is introduced into the working fluid storage tank 29 via the working fluid pipe L4. Then, by opening the on-off valve 30 (intermittently) with the relatively high pressure working fluid stored in the working fluid storage tank 29, the high pressure working fluid is supplied to the air column pipe via the working fluid pipe L5. The pressure change and speed change (mainly pressure change) can be given to the working fluid in the air column tube 21. That is, the working fluid pipes L4 and L5, the pump 28, the working fluid storage tank 29, the on-off valve 30 and the like function as forced vibration means for forcibly vibrating the working fluid in the air column pipe 21.

  Furthermore, a movable tube 35 having an outer diameter smaller than the inner diameter of the tube portion 23a is slidably disposed inside the distal end of the tube portion 23a of the resonance portion 23. An actuator (fluid pressure cylinder) 36 for moving the moving tube 35 in parallel with the tube portion 23a is disposed inside the closed end portion 23b. The actuator 36 is connected to a fluid source (not shown) via an on-off valve 37, and the pipe length of the resonance unit 23 can be changed by operating the on-off valve 37 to activate the actuator 36. That is, the moving tube 35 and the actuator 36 function as a frequency setting unit that can change the resonance frequency of the working fluid in the air column tube 21.

  The thermoacoustic engine 20 includes an electronic control unit (hereinafter referred to as “ECU”) 40 that functions as control means. The ECU 40 includes a CPU, a ROM, a RAM, an input / output port, a storage device, etc., all not shown. The above-described exhaust supply adjustment valve 15, the on-off valve 16 of the cooling system L3, the pump 28, the on-off valve 30 of the working fluid pipe L5, the on-off valve 37 for the actuator 36, etc. are connected to the input / output ports of the ECU 40, respectively. These are controlled by the ECU 40. The pressure sensor 31 of the working fluid storage tank 29 is connected to the input / output port of the ECU 40. The pressure sensor 31 detects the pressure of the working fluid in the working fluid storage tank 29 and gives a signal indicating the detected value to the ECU 40. Further, a pressure sensor 34 is installed at a predetermined location of the air column tube 21. The pressure sensor 34 is also connected to an input / output port of the ECU 40. The sensor 34 detects the pressure of the working fluid in the air column tube 21, and gives a signal indicating the detected value to the ECU 40.

  In the thermoacoustic engine 20 configured as described above, the internal combustion engine 1 is operated with the exhaust supply regulating valve 15 and the on-off valve 16 being opened, and the exhaust gas from the combustion chamber 3 has passed through the pre-catalyst device 12a. Thereafter, the operation starts when it passes through the high-temperature heat exchanger 26. In this case, since the temperature of the exhaust gas that has passed through the pre-stage catalyst device 12a reaches about 900 ° C. at the maximum, one end of the heat accumulator 25 is heated by the exhaust gas flowing through the high-temperature heat exchanger 26. Raise the temperature. On the other hand, the low-temperature heat exchanger 27 of the thermoacoustic engine 20 has cooling water at a relatively low temperature (generally atmospheric temperature immediately after the cold start of the internal combustion engine 1 and approximately 80 to 90 ° C. after completion of warm-up). Therefore, the other end of the heat accumulator 25 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 generated in this way matches the resonance frequency in the resonance part 23, a standing wave is formed in the resonance part 23. Further, a traveling wave traveling from the low temperature heat exchanger 27 to the high temperature heat exchanger 26 is formed in the loop portion 22. And the vibration part of the transducer 24 arrange | positioned at the closed end part 23b is vibrated by the standing wave formed in the resonance part 23. FIG. The transducer 24 converts standing wave energy (acoustic energy) in the resonance unit 23 into electric energy, and the obtained electric energy is supplied to a predetermined electric load via a controller (not shown). Thereby, according to the thermoacoustic engine 20 of this invention, the exhaust heat of the internal combustion engine 1 can be collect | recovered efficiently, and the electric power for predetermined | prescribed electric loads can be obtained. Instead of arranging the transducer 24 in the resonance unit 23, a unit of a heat accumulator, a high temperature heat exchanger, and a low temperature heat exchanger is arranged in the loop unit 22, and the exhaust heat energy recovered by the thermoacoustic engine 20 is used. Then, the unit may be operated as a refrigerator.

  If the thermoacoustic engine 20 as described above is used, the exhaust heat (waste heat) of the internal combustion engine 1 can be recovered. However, the thermoacoustic self-excited vibration of the working fluid is generated satisfactorily and the thermoacoustic is generated. It is not always easy to start the engine 20 quickly. Further, during the operation of the thermoacoustic engine 20, the self-excited vibration of the working fluid may be likely to disappear for some reason (for example, the temperature gradient between both ends of the heat accumulator 25 is reduced). For this reason, in this embodiment, while starting the thermoacoustic engine 20 satisfactorily, the forced excitation routine shown in FIG. 2 is executed by the ECU 40 in order to keep the operation sustainability good.

  As shown in FIG. 2, the ECU 40 first determines whether or not there is a start request for the thermoacoustic engine 20 (S10). When it is determined that there is a request to start the thermoacoustic engine 20, the ECU 40 opens the exhaust supply adjustment valve 15 provided at the exhaust gas inlet of the high-temperature heat exchanger 26 and the opening / closing valve 16 of the cooling system L3. At the same time, based on a signal from the pressure sensor 31 of the working fluid storage tank 29, it is determined whether or not the pressure of the working fluid in the working fluid storage tank 29 is equal to or higher than a predetermined threshold (S12).

  When it is determined in S12 that the pressure of the working fluid in the working fluid storage tank 29 is lower than the threshold value, the ECU 40 turns on the pump 28 of the working fluid pipe L4 with the on-off valve 30 of the working fluid pipe L5 closed. Operate (S14). As a result, the working fluid pressurized by the pump 28 via the working fluid pipe L4 is introduced into the working fluid storage tank 29, and the pressure of the working fluid in the working fluid storage tank 29 increases. The ECU 40 operates the pump 28 of the working fluid pipe L4 in S14 until it is determined that the pressure of the working fluid in the working fluid storage tank 29 is equal to or higher than the threshold value.

If an affirmative determination is made in S14, the ECU 40 stops the pump 28 in S16 (or keeps it in a stopped state), and the natural vibration period T of the air column tube 21 that is previously known as a signal from the pressure sensor 34. Based on ₀ , the on-off valve 30 of the working fluid pipe L5 is intermittently opened and closed until a predetermined time elapses (S18). In S18, as shown in FIG. 3, the ECU 40 synchronizes with the thermoacoustic self-excited vibration of the working fluid generated due to the temperature gradient formed between both ends of the heat accumulator 25 (see the broken line in FIG. 3). In other words, the on-off valve 30 is intermittently opened at a timing at which the amplitude of the thermoacoustic self-excited vibration generated due to the temperature gradient becomes substantially maximum. As a result, the working fluid is allowed to intermittently flow into the air column pipe 21 from the working fluid storage tank 29, and the working fluid in the air column pipe 21 can be forcedly and effectively vibrated. As a result, since thermoacoustic self-excited vibration can be generated and grown quickly, the thermoacoustic engine 20 can be started extremely well.

  Also, under such a configuration, when the working fluid is allowed to flow into the air column tube 21, the blowing direction of the working fluid can be set appropriately and easily so that the thermoacoustic self-excited vibration is amplified. . Further, in the present embodiment, as shown in FIG. 1, the corner portion of the loop portion 22 located on the opposite side of the closed end portion 23b across the tube portion 23a is formed in the pressure oscillation standing in the air column tube. It becomes the belly position of the wave. And the working fluid pipe | tube L5 which comprises a forced vibration means is connected to the air column pipe 21 in the location substantially corresponded with the antinode position of the said pressure vibration standing wave. That is, in this embodiment, the working fluid is caused to flow into the air column tube 21 from the working fluid storage tank 29 in the vicinity of the antinode position of the pressure vibration standing wave. As a result, a pressure change can be effectively applied to the working fluid in the air column tube 21, so that thermoacoustic self-excited vibration of the working fluid can be generated and grown reliably and quickly.

  The working fluid pipes L4 and L5, the pump 28, the working fluid storage tank 29, the on-off valve 30 and the like for flowing the working fluid into the air column pipe 21 obstruct the progress of the working fluid in the air column pipe 21. It is possible to arrange so that there is no. Therefore, in this embodiment, the self-excited vibration of the working fluid in the air column tube 21 is not attenuated as in the case where the piston is arranged in the air column tube 21 (loop portion 22), for example. The generated self-excited vibration of the working fluid will grow well.

  When the on-off valve 30 is controlled for a predetermined time in S18, the ECU 40 returns to S10 and determines again whether or not there is a start request for the thermoacoustic engine 20. Once the thermoacoustic engine 20 has been started, a negative determination is made here. In this case, the ECU 40 determines whether or not there is a stop request for the thermoacoustic engine 20 (S20). If it is determined in S20 that there is no stop request for the thermoacoustic engine 20, the ECU 40 calculates the pressure amplitude of the working fluid that self-oscillates in the air column tube 21 based on the signal from the pressure sensor 34. It is determined whether the pressure amplitude is below a predetermined threshold (S22). In S22, the ECU 40 acquires the maximum pressure and the minimum pressure of the working fluid that self-oscillates in the air column tube 21 based on the signal from the pressure sensor 34, and based on these maximum pressure and minimum pressure. The pressure amplitude of the working fluid in the air column tube 21 is obtained.

  If it is determined in S22 that the pressure amplitude of the working fluid that vibrates in the air column tube 21 is below the threshold value, the self-excited vibration of the working fluid in the air column tube 21 is likely to disappear for some reason. It is considered to be. Therefore, when an affirmative determination is made in S22, the ECU 40 executes the processes of S12 to S18 described above. Thereby, in the thermoacoustic engine 20, when the self-excited vibration of the working fluid in the air column tube 21 is likely to disappear for some reason, an operation that occurs due to a temperature gradient formed between both end portions of the heat accumulator 25. The working fluid is intermittently flowed into the air column tube 21 from the working fluid storage tank 29 so as to synchronize with the thermoacoustic self-excited vibration of the fluid (see the broken line in FIG. 3).

  As a result, it is possible to forcibly and effectively vibrate the working fluid in the air column tube 21 to quickly regenerate the thermoacoustic self-excited vibration. Also in this case, in the present embodiment, the working fluid is caused to flow into the air column tube 21 in the vicinity of the antinode position of the pressure vibration standing wave in the air column tube 21. Thus, the pressure change can be effectively applied, and the thermoacoustic self-excited vibration of the working fluid can be regenerated reliably and promptly.

  If it is determined in S22 that the pressure amplitude of the working fluid that self-oscillates in the air column tube 21 is not less than a predetermined threshold value, the ECU 40 returns to S10 and repeats the processes after S10. When it is determined in S20 that there is a stop request for the thermoacoustic engine 20, the ECU 40 ends this routine and executes a process for stopping the thermoacoustic engine 20. In the thermoacoustic engine 20 of the present embodiment, a pump 28 that can suck in the working fluid in the air column tube 21 and pump it into the working fluid storage tank 29 is used, but is not limited thereto. is not. In other words, a pump that can suck the working fluid in the working fluid storage tank 29 and introduce it into the air column tube 21 may be employed as the pump 28.

Under such a configuration, when the pump 28 is operated with the on-off valve 30 of the working fluid pipe L5 closed, the working fluid in the working fluid storage tank 29 is transferred to the air column pipe 21 via the working fluid pipe L4. In this way, the inside of the working fluid storage tank 29 is depressurized. Then, by opening the on-off valve 30 (intermittently) in a state where the inside of the working fluid storage tank 29 is decompressed, the working fluid in the air column tube 21 is supplied to the working fluid storage tank 29 via the working fluid pipe L5. The pressure change and the speed change can be given to the working fluid in the air column tube 21. Also, under such a configuration, if the working fluid storage tank 29 is depressurized in advance, the working fluid in the air column pipe 21 is allowed to flow out to the working fluid storage tank 29 simply by opening the on-off valve 30. Therefore, it is possible to reduce power consumption at the time of starting.
As described above, the forced vibration means including the working fluid pipes L4 and L5, the pump 28, the working fluid storage tank 29, the on-off valve 30 and the like allows the working fluid to flow out from the air column pipe 21 to the outside. Also good.

[Second Embodiment]
Hereinafter, the thermoacoustic engine according to the second embodiment of the present invention will be described with reference to FIG. Note that the same reference numerals are given to the same elements as those described in relation to the first embodiment described above, and redundant descriptions are omitted.

  A thermoacoustic engine 20 </ b> A shown in FIG. 4 has basically the same configuration as the thermoacoustic engine 20 of the first embodiment, and a mixture of fuel and air inside the combustion chamber 3 formed in the cylinder block 2. Is applied to the internal combustion engine 1 that generates power by reciprocating the piston 4 in the combustion chamber 3. In the thermoacoustic engine 20A of FIG. 4, frequency setting means including a moving tube and an actuator are omitted. Then, in the thermoacoustic engine 20A, the connection portion between the working fluid pipe L5 and the air column pipe 21 constituting the forced vibration means and the antinode position of the velocity fluctuation standing wave in the air column pipe 21 are substantially matched. It is configured.

  That is, in the present embodiment, as shown in FIG. 4, the closed end portion 23 b of the resonance portion 23 is the antinode position of the velocity fluctuation standing wave formed in the air column tube 21. Then, as shown in FIG. 4, the working fluid pipe L5 that constitutes the forced vibration means has a closed end 23b (the end face) of the resonance part 23 that substantially coincides with the antinode position of the velocity pressure vibration standing wave. It is connected. Therefore, in the present embodiment, when processing similar to the forced vibration routine of FIG. 2 is executed, the working fluid flows from the working fluid storage tank 29 into the air column tube 21 in the vicinity of the antinode position of the speed fluctuation standing wave. Will be allowed to flow. As a result, it is possible to effectively change the speed of the working fluid in the air column tube 21, and the thermoacoustic self-excited vibration of the working fluid can be generated, grown and regenerated reliably and quickly. It becomes possible.

  Further, as shown in FIG. 4, in the thermoacoustic engine 20A, the tip of the working fluid pipe L5 is formed to extend in the axial direction of the resonance section 23 (pipe section 23a). As described above, when the working fluid is allowed to flow into the air column tube 21 near the antinode position of the velocity fluctuation standing wave, the working fluid flows along the axial direction of the resonance unit 23 (pipe unit 23a). As a result, the speed change can be more effectively applied to the working fluid in the air column tube 21. Further, if the tip of the working fluid pipe L5 is formed in this way, it is possible to prevent the working fluid pipe L5 from inhibiting the progress of the working fluid in the air column pipe 21. In the thermoacoustic engine 20A of FIG. 4, the forced vibration means including the working fluid pipes L4 and L5, the pump 28, the working fluid storage tank 29, the on-off valve 30 and the like removes the working fluid from the air column pipe 21 to the outside. Needless to say, it may be discharged.

[Third Embodiment]
Hereinafter, a thermoacoustic engine according to a third embodiment of the present invention will be described with reference to FIG. The same elements as those described in relation to the first embodiment described above are denoted by the same reference numerals, and redundant description is omitted.

  The thermoacoustic engine 20B shown in FIG. 5 also has basically the same configuration as the thermoacoustic engine 20 of the first embodiment, and a mixture of fuel and air inside the combustion chamber 3 formed in the cylinder block 2 is also provided. Is applied to the internal combustion engine 1 that generates power by reciprocating the piston 4 in the combustion chamber 3. In the thermoacoustic engine 20 </ b> B, the working fluid pipe L <b> 5 constituting the forced vibration means is connected to the air column pipe 21 in the vicinity of the heat accumulator 25.

  That is, in the present embodiment, the working fluid pipe L5 is bent so that the tip thereof extends in the direction from the low temperature heat exchanger 27 toward the high temperature heat exchanger 26, and the heat accumulator 25 is interposed via the low temperature heat exchanger 27. Are connected to the loop portion 22 so as to face each other. Thereby, in the thermoacoustic engine 20B, when processing similar to the forced vibration routine of FIG. 2 is executed, the air column tube is directed from the low temperature heat exchanger 27 toward the high temperature heat exchanger 26 in the vicinity of the heat accumulator 25. The working fluid is caused to flow into 21 (loop portion 22). In this way, by causing the working fluid to flow into the air column tube 21 (loop portion 22) in the vicinity of the heat accumulator 25, a traveling wave in which the phase of the pressure vibration and the phase of the velocity vibration substantially coincide with each other quickly. Can be generated. Therefore, also in the thermoacoustic engine 20B, the thermoacoustic self-excited vibration of the working fluid can be generated, grown, and reproduced reliably and promptly.

  Also in this embodiment, if the tip of the working fluid pipe L5 is formed as described above, it is possible to suppress the progress of the working fluid in the air column pipe 21 from being hindered by the working fluid pipe L5. Further, by flowing the working fluid from the low temperature heat exchanger 27 toward the high temperature heat exchanger 26, the startability of the thermoacoustic engine 20B can be reduced without impairing the temperature gradient formed between both ends of the heat accumulator 25. Driving sustainability can be improved. In the thermoacoustic engine 20B of FIG. 5 as well, the forced vibration means including the working fluid pipes L4 and L5, the pump 28, the working fluid storage tank 29, the on-off valve 30 and the like supplies the working fluid from the air column pipe 21. Needless to say, it may flow out to the outside.

[Fourth Embodiment]
Hereinafter, a thermoacoustic engine according to a fourth embodiment of the present invention will be described with reference to FIG. The same elements as those described in relation to the first embodiment described above are denoted by the same reference numerals, and redundant description is omitted.

  The thermoacoustic engine 20 </ b> C shown in FIG. 6 has basically the same configuration as the thermoacoustic engine 20 of the first embodiment, and a mixture of fuel and air inside the combustion chamber 3 formed in the cylinder block 2. Is applied to the internal combustion engine 1 that generates power by reciprocating the piston 4 in the combustion chamber 3. In this thermoacoustic engine 20C, a mixed gas of helium and argon is used as the working fluid, and the thermoacoustic engine 20C is a means for changing the mixing ratio of helium and argon in the working fluid in the air column tube 21. have.

  That is, a working fluid recovery pipe L6 having a pump 38 and an on-off valve 39 capable of sucking the working fluid in the air column pipe 21 in the air column pipe 21 (in this embodiment, the pipe portion 23a) of the thermoacoustic engine 20C. The fluid separation device 50 is connected via The fluid separation device 50 includes a container 51 that can store a fluid therein, and a separation membrane 52 that partitions the internal space of the container 51 into two fluid storage chambers 51A and 51H. The working fluid recovery pipe L6 described above is connected to one fluid storage chamber 51A of the container 51. The fluid storage chamber 51 </ b> A is connected to the air column pipe 21 (in the present embodiment, the pipe portion 23 a) via a fluid introduction pipe L <b> 7 having a first supply valve (open / close valve) 53. The other fluid storage chamber 51H of the container 51 is connected to the air column tube 21 (in this embodiment, the tube portion 23a) via a fluid introduction tube L8 having a second supply valve (open / close valve) 54. .

  The separation membrane 52 that partitions the inside of the container 51 can pass only helium in the working fluid and separate it from argon. In the present embodiment, a porous membrane formed of polyimide, cellulose acetate, polynullphen, polyamide, polyetherimide, or the like is employed as the separation membrane 52. The separation membrane 52 formed of any of these materials regulates the passage of argon (molecular weight = 40) having a relatively high molecular weight, while allowing passage of helium (molecular weight = 4) having a molecular weight smaller than that of argon. To do. As the separation membrane 52, a porous glass hollow fiber membrane having a large number of minute pores of about 0.3 to 1.0 nm and capable of concentrating helium to about 500 times that of nitrogen may be employed. .

  As shown in FIG. 6, the pump 38 and the open / close valve 39 of the working fluid recovery pipe L6, the first supply valve 53 of the fluid introduction pipe L7, the second supply valve 54 of the fluid introduction pipe L8, and the like are respectively input / output of the ECU 40. These are connected to the ports, and these are controlled by the ECU 40. The pump 38, the on-off valve 39, the working fluid recovery pipe L6, the fluid separation device 50, the first and second supply valves 53 and 54, and the fluid introduction pipes L7 and L8 are used for the working fluid in the air column pipe 21. The helium and argon are recovered and separated into helium and argon, and the separated helium and argon function as means that can be individually resupplied into the air column tube 21.

  That is, when the on-off valve 39 of the working fluid recovery pipe L6 is opened and the pump 38 of the working fluid recovery pipe L6 is operated for a predetermined time, a predetermined amount of the working fluid is sucked out from the air column pipe 21 by the pump 38, The fluid is introduced into the fluid storage chamber 51A of the container 51 constituting the fluid separation device 50 via the working fluid recovery pipe L6. As described above, the inside of the container 51 is partitioned into the fluid storage chamber 51A and the fluid storage chamber 51H by the separation membrane 52 that allows only helium in the working fluid to pass therethrough and separates it from argon. For this reason, when the working fluid is introduced from the air column tube 21 into the fluid storage chamber 51A of the container 51, only helium in the working fluid passes through the separation membrane 52 and flows into the fluid storage chamber 51H. On the other hand, since argon in the working fluid cannot pass through the separation membrane 52, it stays in the fluid storage chamber 51A. As a result, the working fluid recovered from the air column tube 21 is separated into helium and argon by the fluid separation device 50, and argon is stored in the fluid storage chamber 51A and helium is stored in the fluid storage chamber 51H. become.

  After operating the pump 38 for a predetermined time in this way, the first supply valve (Ar supply valve) 53 of the fluid introduction pipe L7 is opened, and the second supply valve (He supply valve) 54 of the fluid introduction pipe L8 is opened. When closed (maintained in the closed state), argon (only) is introduced into the air column tube 21 from the fluid separation device 50 (fluid storage chamber 51A) via the fluid introduction tube L7. In addition, after the pump 38 is operated for a predetermined time, the first supply valve (Ar supply valve) 53 of the fluid introduction pipe L7 is closed (maintained in the closed state), and the second supply valve of the fluid introduction pipe L8 ( When the (He supply valve) 54 is opened, helium (only) is introduced into the air column tube 21 from the fluid separation device 50 (fluid storage chamber 51H) via the fluid introduction tube L8.

  In the thermoacoustic engine 20C, a fluid blowing pipe L9 is branched from the fluid introduction pipe L7 between the fluid storage chamber 51A for argon and the first supply valve 53. The fluid blowing pipe L9 has a fluid blowing valve 55 that is controlled to be opened and closed by the ECU 40. The fluid blowing pipe L9 closes the resonance portion 23 that substantially coincides with the antinode position of the velocity fluctuation standing wave formed in the air column pipe 21. The end 23b is connected to the air column tube 21. The tip of the fluid blowing tube L9 is bent so as to extend in the axial direction of the resonance portion 23 (tube portion 23a). Thereby, the fluid is caused to flow into the air column tube 21 along the axial direction of the resonance portion 23 (tube portion 23a) from the fluid blowing tube L9, so that the working fluid in the air column tube 21 is more effective. It is possible to change the speed. Moreover, if the tip of the fluid blowing pipe L9 is formed in this way, it is possible to suppress the progress of the working fluid in the air column pipe 21 from being blocked by the fluid blowing pipe L9.

  In the thermoacoustic engine 20 </ b> C configured as described above, the forced excitation routine shown in FIG. 7 is executed by the ECU 40 in order to keep the startability and the operation sustainability favorable. Also in this case, as shown in FIG. 7, the ECU 40 first determines whether or not there is a start request for the thermoacoustic engine 20C (S30). When determining that there is a request to start the thermoacoustic engine 20C, the ECU 40 opens the exhaust supply adjustment valve 15 provided at the exhaust gas inlet of the high-temperature heat exchanger 26 and the opening / closing valve 16 of the cooling system L3. Further, the on-off valve 39 of the working fluid recovery pipe L6 is opened, and the pump 38 of the working fluid recovery pipe L6 is operated for a predetermined time (S32). As a result, the working fluid recovered from the air column tube 21 by the pump 38 is separated into helium and argon, and argon is stored in the fluid storage chamber 51A and helium is stored in the fluid storage chamber 51H.

When the process of S32 is executed, the ECU 40 closes the on-off valve 39 and stops the pump 38, and further, based on the signal from the pressure sensor 34 and the natural vibration period T ₀ of the air column tube 21 that has been previously known. Then, the fluid blowing valve 55 of the fluid blowing pipe L9 is intermittently opened and closed for a predetermined time (S34). In S34, the ECU 40 is generated so as to synchronize with the thermoacoustic self-excited vibration of the working fluid generated due to the temperature gradient formed between both ends of the heat accumulator 25, that is, due to the temperature gradient. The fluid blowing valve 55 is intermittently opened at a timing at which the amplitude of the thermoacoustic self-excited vibration becomes substantially maximum. As a result, argon (only) is allowed to flow intermittently into the air column tube 21 from the fluid separation device 50 (fluid storage chamber 51A) via the fluid blowing tube L9, and the working fluid in the air column tube 21 is forced. And can be vibrated effectively. As a result, the thermoacoustic self-excited vibration can be quickly generated and grown, and the thermoacoustic engine 20C can be started very well.

  Here, the molecular weight of argon contained in the working fluid is “40”, whereas the molecular weight of helium contained in the working fluid is “4”. Considering these points, in the thermoacoustic engine 20C, in order to forcibly excite the working fluid in the air column tube 21, argon having a molecular weight larger than that of helium is caused to flow into the air column tube 21. It is done. That is, if the molecular weight of the fluid flowing into the air column tube 21 is relatively large, the momentum of the fluid can be sufficiently secured. Therefore, even if the inflow amount of argon into the air column tube 21 is reduced, the air column tube 21. It is possible to effectively vibrate the working fluid inside. In consideration of the momentum of the fluid flowing into the air column tube 21, the fluid blowing tube L 9 is provided in the air column tube 21 in order to effectively change the speed with respect to the working fluid in the air column tube 21. It is preferable to be connected to the air column tube 21 at the antinode position of the formed velocity pressure vibration standing wave.

  When the fluid injection valve 55 is controlled for a predetermined time in S34, the ECU 40 returns to S30 and determines again whether or not there is a start request for the thermoacoustic engine 20C. Once the start of the thermoacoustic engine 20C has been executed, a negative determination is made here, and in this case, the ECU 40 determines whether or not there is a stop request for the thermoacoustic engine 20C (S36). If it is determined in S36 that there is no stop request for the thermoacoustic engine 20C, the ECU 40 calculates the pressure amplitude of the working fluid that self-oscillates in the air column tube 21 based on the signal from the pressure sensor 34. It is determined whether or not the pressure amplitude is below a predetermined threshold value (S38).

  If it is determined in S38 that the pressure amplitude of the working fluid that self-oscillates in the air column tube 21 is below the threshold value, the self-excited vibration of the working fluid in the air column tube 21 is likely to disappear for some reason. It is considered to be. Therefore, when an affirmative determination is made in S38, the ECU 40 executes the processes of S32 and S34 described above. Thereby, in the thermoacoustic engine 20C, when the self-excited vibration of the working fluid in the air column tube 21 is likely to disappear for some reason, the operation that occurs due to the temperature gradient formed between the both ends of the heat accumulator 25. Argon (only) is allowed to flow intermittently into the air column tube 21 from the fluid separation device 50 (fluid storage chamber 51A) so as to synchronize with the thermoacoustic self-excited vibration of the fluid.

  As a result, also in the thermoacoustic engine 20C, the working fluid in the air column tube 21 can be forcibly and effectively vibrated to quickly regenerate the thermoacoustic self-excited vibration. If it is determined in S38 that the pressure amplitude of the working fluid that self-oscillates in the air column tube 21 is not below a predetermined threshold, the ECU 40 returns to S30 and repeats the processing from S30 onward. When it is determined in S36 that there is a stop request for the thermoacoustic engine 20C, the ECU 40 ends the routine and executes a process for stopping the thermoacoustic engine 20C.

  If the above-described separation membrane is used, only a fluid having a relatively large molecular weight (for example, argon) among a plurality of fluids included in the working fluid is synchronized with, for example, thermoacoustic self-excited vibration from the air column tube 21. Needless to say, a mechanism for forcibly oscillating the working fluid in the air column tube 21 can be easily configured.

1 is a schematic configuration diagram showing a first embodiment of a thermoacoustic engine according to the present invention. 2 is a flowchart for explaining a procedure for forcibly exciting a working fluid in an air column tube in the thermoacoustic engine of FIG. 1. It is a time chart for demonstrating the procedure for forcibly exciting the working fluid in an air column pipe in the thermoacoustic engine of FIG. It is a schematic block diagram which shows 2nd Embodiment of the thermoacoustic engine by this invention. It is a schematic block diagram which shows 3rd Embodiment of the thermoacoustic engine by this invention. It is a schematic block diagram which shows 4th Embodiment of the thermoacoustic engine by this invention. It is a flowchart for demonstrating the procedure for forcibly exciting the working fluid in an air column pipe in the thermoacoustic engine of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 20, 20A, 20B, 20C Thermoacoustic engine 21 Air column tube 24 Transducer 25 Heat storage device 26 High temperature heat exchanger 27 Low temperature heat exchanger 28, 38 Pump 29 Working fluid storage tank 30, 39 On-off valve 31, 34 Pressure Sensor 50 Fluid separation device 51A, 51H Fluid storage chamber 52 Separation membrane 55 Fluid injection valve L9 Fluid injection pipe

Claims (7)

An air column tube in which the working fluid is sealed, and heat storage means disposed inside the air column tube, and a temperature gradient is formed between both end portions of the heat storage unit so that the thermoacoustic self-excitation of the working fluid is performed. In a thermoacoustic engine that generates vibration,
And a forced vibration means for forcibly oscillating the working fluid in the air column tube by flowing the working fluid into the air column tube or by letting the working fluid flow out from the air column tube. A thermoacoustic engine.   2. The thermoacoustic engine according to claim 1, wherein a connection portion between the forced vibration means and the air column tube substantially coincides with an antinode position of a pressure vibration standing wave in the air column tube.   2. The thermoacoustic engine according to claim 1, wherein a connection portion between the forced vibration means and the air column tube substantially coincides with an antinode position of a velocity fluctuation standing wave in the air column tube.   The thermoacoustic engine according to claim 1, wherein the forced vibration means is connected to the air column tube in the vicinity of the heat storage means.   The thermoacoustic engine according to any one of claims 1 to 4, wherein the forced vibration means is operated based on a natural vibration period of the air column tube.   The working fluid is a mixed fluid obtained by mixing a plurality of fluids, and the forced vibration means causes a fluid having a relatively large molecular weight to flow into the air column tube among the plurality of fluids, or The thermoacoustic engine according to claim 1, wherein the thermoacoustic engine is caused to flow out of the air column tube. An air column tube in which the working fluid is sealed, and heat storage means disposed inside the air column tube, and a temperature gradient is formed between both end portions of the heat storage unit so that the thermoacoustic self-excitation of the working fluid is performed. A method of operating a thermoacoustic engine that generates vibration,
The working fluid in the air column tube is forcibly vibrated by flowing the working fluid into the air column tube or flowing out the working fluid from the air column tube under a predetermined condition. How to operate a thermoacoustic engine.

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