JP7761826B2 - thermoacoustic engine - Google Patents

Description

The present invention relates to a thermoacoustic engine capable of converting thermal energy into acoustic energy.

Patent Document 1 discloses a thermoacoustic engine equipped with a prime mover capable of converting thermal energy into acoustic energy. The prime mover has a heat accumulator housed in a pipe extending in a predetermined direction, a heater arranged side by side on one side of the heat accumulator in the predetermined direction, and a cooler arranged side by side on the other side of the heat accumulator in the predetermined direction. The internal space of the pipe is filled with gas as a working fluid. The heater is heated using waste heat (exhaust gas, wastewater, etc.) generated in a factory, for example. The cooler is cooled using cooling water, for example. This creates a temperature gradient in the heat accumulator in the predetermined direction. The thermal energy is then converted into acoustic energy by the thermoacoustic phenomenon, and the working fluid in the pipe undergoes self-excited vibrations, generating sound waves. This acoustic energy is used, for example, in power generation systems, cooling systems, etc.

Patent No. 6233835

Generally, connecting multiple prime movers (in other words, multiple energy conversion units) in series can further amplify acoustic energy. However, for example, in a configuration in which multiple prime movers (multiple energy conversion units) are simply arranged side by side in a predetermined direction, as in Patent Document 1, there is a risk that the thermoacoustic engine will become larger in that direction. Furthermore, in such a configuration, for example, in order to compact the supply path that supplies the heating medium to the heater and/or the supply path that supplies the cooling medium to the cooler, it is possible to branch the supply paths for each medium from a single supply source. In such a configuration, temperature variations may occur between the supply paths when the heating medium or cooling medium is supplied. As a result, the temperature difference between the heaters and coolers cannot be made uniform between multiple prime movers, which may affect the amplification rate of acoustic energy.

The object of the present invention is to avoid problems that can arise in thermoacoustic engines in which multiple energy conversion units are connected in series.

The thermoacoustic engine of the first invention is a thermoacoustic engine equipped with a prime mover configured to convert thermal energy into acoustic energy, wherein the prime mover has a first energy conversion unit, a second energy conversion unit separate from the first energy conversion unit, and a connecting pipe unit connecting the first energy conversion unit and the second energy conversion unit in series, and the first energy conversion unit has a first pipe line forming a first passage through which a working fluid passes, a first heat accumulator housed in the first passage and configured to heat and cool the working fluid, a first heater arranged next to one side of the first heat accumulator in a predetermined direction, and a first cooler arranged next to the other side of the first heat accumulator in the predetermined direction, and the second energy conversion unit is configured to convert the thermal energy into acoustic energy. The system comprises a second pipe forming a second passage through which a working fluid passes, a second heat accumulator housed in the second passage and configured to heat and cool the working fluid, a second heater arranged side by side on one side of the second heat accumulator in the predetermined direction, and a second cooler arranged side by side on the other side of the second heat accumulator in the predetermined direction, wherein the connecting pipe portion is arranged in a position at least partially overlapping with the first energy conversion unit and the second energy conversion unit in the predetermined direction, the first heater and the second heater are arranged in a position at least partially overlapping with each other in the predetermined direction, and the first cooler and the second cooler are arranged in a position at least partially overlapping with each other in the predetermined direction.

In the present invention, even though the first energy conversion unit and the second energy conversion unit are connected in series, they are not arranged linearly in the predetermined direction. This prevents the prime mover and thermoacoustic engine from becoming too large in the predetermined direction. Furthermore, because the first heater and the second heater are arranged to at least partially overlap in the predetermined direction, the first heater and the second heater can be simultaneously heated by a single heating medium flow path extending in a direction intersecting the predetermined direction. Furthermore, because the first cooler and the second cooler are arranged to at least partially overlap in the predetermined direction, the first cooler and the second cooler can be simultaneously cooled by a single cooling medium flow path extending in a direction intersecting the predetermined direction. This allows the heating medium flow path and the cooling medium flow path to be made compact. This reduces temperature variations during supply of the heating medium or cooling medium, and stably equalizes the temperature difference between the heater and the cooler. This allows for stable amplification of acoustic energy. In this way, problems that can arise in a thermoacoustic engine in which multiple energy conversion units are connected in series can be avoided.

The thermoacoustic engine of the second invention is the thermoacoustic engine of the first invention, characterized in that at least a portion of the connecting pipe section is composed of at least a portion of the member constituting the first pipe line and at least a portion of the member constituting the second pipe line.

This invention allows for a more compact prime mover. Furthermore, heat can be efficiently transferred between the first energy conversion unit and the second energy conversion unit via the connecting pipe.

The thermoacoustic engine of the third invention is the thermoacoustic engine of the first or second invention, characterized in that the first pipe is tubular, and the second pipe is arranged radially outside the first pipe.

In this invention, the first energy conversion unit can be positioned radially inside the second energy conversion unit. This allows the prime mover to be made even more compact.

A fourth aspect of the present invention is a thermoacoustic engine according to the third aspect of the present invention, further comprising a heating medium flow path through which a heating medium flows that heats the first heater and the second heater. The heating medium flow path has a first heating flow path portion disposed radially outside the second pipe line and extending in the predetermined direction, and a second heating flow path portion formed upstream of the first heating flow path portion in the flow direction of the heating medium and extending in the circumferential direction of the second pipe line, and the flow path resistance of the second heating flow path portion is lower than the flow path resistance of the first heating flow path portion.

In the present invention, the pressure loss of the heating medium in the second heating flow path portion can be made smaller than the pressure loss of the heating medium in the first heating flow path portion. This makes it easier for the heating medium to temporarily accumulate in the second heating flow path portion before flowing from the second heating flow path portion into the first heating flow path portion. This makes it easier for the flow rate and temperature of the heating medium in the second heating flow path portion to be uniform in the circumferential direction. This allows for a substantially isothermal heating medium to flow uniformly through the first heating flow path portion, allowing the first heater and second heater to be heated evenly in the circumferential direction. This makes it possible to achieve a uniform temperature distribution in the circumferential direction of the first heater and second heater.

The thermoacoustic engine of the fifth invention is the thermoacoustic engine of the third or fourth invention, further comprising a cooling medium flow path through which a cooling medium flows to cool the first cooler and the second cooler, the cooling medium flow path having a first cooling flow path portion disposed radially outside the second pipe line and extending in the predetermined direction, and a second cooling flow path portion formed upstream of the first cooling flow path portion in the flow direction of the cooling medium and extending in the circumferential direction of the second pipe line, wherein the flow path resistance of the second cooling flow path portion is lower than the flow path resistance of the first cooling flow path portion.

In this invention, the pressure loss of the cooling medium in the second cooling flow path portion can be made smaller than the pressure loss of the cooling medium in the first cooling flow path portion. This makes it easier for the cooling medium to temporarily accumulate in the second cooling flow path portion before flowing from the second cooling flow path portion into the first cooling flow path portion. This makes it easier for the flow rate and temperature of the cooling medium in the second cooling flow path portion to be uniform in the circumferential direction. This allows a cooling medium with approximately the same temperature to flow uniformly through the first cooling flow path portion, thereby cooling the first cooler and the second cooler evenly in the circumferential direction. This makes it possible to achieve a uniform temperature distribution in the circumferential direction of the first cooler and the second cooler.

The thermoacoustic engine of the sixth invention is the thermoacoustic engine of the first or second invention, characterized in that the first energy conversion unit, the connecting pipe unit, and the second energy conversion unit are connected in an S-shape.

The present invention allows the thermoacoustic engine to be made compact in a specific direction using a simple structure.

1 is a schematic plan view of a thermoacoustic engine according to an embodiment of the present invention. FIG. 1 is a conceptual diagram of a conventional prime mover. FIG. 1 is a conceptual diagram of a prime mover according to an embodiment of the present invention. FIG. 2A is a perspective view of the motor, and FIG. 2B is a view of the motor viewed from a predetermined direction. FIG. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 1A to 1D are cross-sectional views of components included in the prime mover. FIG. 10 is a conceptual diagram of a prime mover according to a modified example. FIG. 10 is a conceptual diagram of a prime mover according to another modified example.

(Outline of thermoacoustic engine)
Next, an embodiment of the present invention will be described. First, an overview of a thermoacoustic engine 1 according to this embodiment will be described with reference to the plan view of FIG. 1 . The thermoacoustic engine 1 is configured to convert thermal energy into acoustic energy (sound wave energy) by utilizing a known thermoacoustic phenomenon. The thermoacoustic engine 1 includes, for example, a prime mover loop 11, an amplifier unit 3, and an output unit 4. Roughly speaking, the prime mover loop 11 converts thermal energy into acoustic energy (in other words, generates acoustic energy). The generated acoustic energy is amplified by the amplifier unit 3 and converted into another type of energy by the output unit 4.

The prime mover loop 11 includes a prime mover 12 (details of which will be described later) and a loop pipe 13. The prime mover 12 and loop pipe 13 are filled with a working fluid (a working gas such as air or helium).

As shown in Figure 1, the prime mover 12 extends in a predetermined direction and converts thermal energy into acoustic energy. Specifically, by creating a temperature gradient in a predetermined direction in the prime mover 12, thermal energy is converted into acoustic energy through the thermoacoustic phenomenon, causing the working fluid to self-excited vibrate. This generates sound waves.

The loop tube 13 is configured to propagate sound waves generated by the motor 12, circulate acoustic energy within the loop tube 13, and send it to the amplifier unit 3. The loop tube 13 has tube sections 13a, 13b, 13c, 13d, and 13e. Tube section 13a is connected to one end of the motor 12 in a predetermined direction. Tube section 13a extends to one side in the predetermined direction and branches in a direction approximately perpendicular to the predetermined direction. Tube section 13b is connected to the branched portion of tube section 13a and extends on the opposite side from the amplifier unit 3. Tube sections 13c, 13d, and 13e are further connected to tube section 13b. The end of tube section 13e is connected to the other end of the motor 12 in the predetermined direction.

The amplifier unit 3 is configured to amplify the acoustic energy circulated from the motor loop 11 and send it to the output unit 4. The amplifier unit 3 has a pipe section 14, a motor 15, and a pipe section 16. One end of the pipe section 14 is connected to the branched portion of the pipe section 13a of the motor loop 11. The other end of the pipe section 14 is connected to one end of the motor 15. The motor 15 has a configuration similar to that of, for example, the motor 12 (details of which will be described later). One end of the pipe section 16 is connected to the motor 15. The other end of the pipe section 16 is connected to the output unit 4.

The output unit 4 is configured to be able to convert acoustic energy into another type of energy. The output unit 4 may include, for example, a known linear generator. Alternatively, the output unit 4 may include a known thermoacoustic cooler. For details, see, for example, Japanese Patent No. 6233835.

(Schematic configuration of a conventional prime mover)
Before describing the configuration of the prime mover 12 of this embodiment, a schematic configuration of a conventional prime mover 101 will be described with reference to the conceptual diagram in FIG. 2 . FIG. 2 is a conceptual cross-sectional view of the prime mover 101 cut along a plane parallel to a predetermined direction. The prime mover 101 includes, for example, a substantially cylindrical pipe 102, a heat accumulator 103, a heater 104, and a cooler 105. In FIG. 2 , the radial direction of the pipe 102 is simply referred to as the radial direction. The prime mover 101 is configured to generate a temperature gradient in a predetermined direction in the heat accumulator 103 by the heater 104 and the cooler 105. As a result, the working fluid in the heat accumulator 103 exchanges thermal energy with the heat accumulator 103, which allows the working fluid to self-excite and generate sound waves.

The conduit 102 is formed, for example, from metal. The conduit 102 accommodates a heat storage device 103, a heater 104, and a cooler 105 inside in the radial direction. The heat storage device 103 has, for example, a ceramic honeycomb structure with numerous thin tube-shaped passages penetrating in a predetermined direction. The heater 104 is disposed on one side of the heat storage device 103 in the predetermined direction. The heater 104 has, for example, numerous mesh plates (not shown) stacked at a fine pitch in a predetermined direction. Alternatively, the heater 104 may have a honeycomb structure (not shown) having a structure similar to that of the heat storage device 103. A heating medium flow path (not shown) for flowing a heating medium is provided on the radial outside of the heater 104 (for example, on the radial outside of the conduit 102). The cooler 105 is disposed on the other side of the heat storage device 103 in the predetermined direction. Like the heater 104, the cooler 105 also has a number of mesh plates (not shown). Alternatively, the cooler 105 may also have a honeycomb structure (not shown) similar to that of the heat accumulator 103. A cooling medium flow path (not shown) for flowing a cooling medium is provided on the radial outside of the cooler 105 (for example, radially outside of the pipe 102).

Generally, acoustic energy can be further amplified by connecting multiple prime movers 101 in series. However, simply arranging multiple prime movers 101 in a predetermined direction may result in the thermoacoustic engine 1 becoming larger in size in that direction. Furthermore, in such a configuration, for example, when a heating medium or cooling medium is supplied through multiple supply paths branching from a single supply source, temperature variations may occur between the supply paths when the heating medium or cooling medium is supplied. This may prevent uniform heating of the heaters 104 and cooling of the coolers 105 between the multiple prime movers 101, potentially affecting the amplification rate of acoustic energy. Therefore, to avoid such problems, the prime mover 12 of this embodiment has the following configuration.

(Configuration of the prime mover)
The configuration of the prime mover 12 will first be described with reference to Fig. 3. Fig. 3 is a conceptual cross-sectional view of the prime mover 12 cut along a plane parallel to a predetermined direction. To make the drawing easier to see, a first heat accumulator 27, a first heater 28, a first cooler 29, a second heat accumulator 31, a second heater 32, a second cooler 33, a third heater 38, and a third cooler 39, which will be described later, are hatched in Fig. 3.

The prime mover 12 has a first energy conversion unit 21, a second energy conversion unit 22, and a connecting pipe unit 23. The first energy conversion unit 21, the second energy conversion unit 22, and the connecting pipe unit 23 all extend in a predetermined direction. The first energy conversion unit 21 and the second energy conversion unit 22 are connected by the connecting pipe unit 23. In this embodiment, the first energy conversion unit 21, the second energy conversion unit 22, and the connecting pipe unit 23 are arranged approximately coaxially (i.e., have approximately the same central axis).

The first energy conversion section 21 has a substantially cylindrical pipe 26 (the first pipe of the present invention), a first heat accumulator 27, a first heater 28, and a first cooler 29. In FIG. 3, the radial direction of the pipe 26 is simply referred to as the radial direction. A first passage A1, which is a passage for the working fluid, is formed within the pipe 26. The first passage A1 accommodates the first heat accumulator 27, the first heater 28, and the first cooler 29 (i.e., the first passage A1 can also be referred to as the first accommodation space). The first heat accumulator 27, like the conventional heat accumulator 103 described above, is formed of, for example, a ceramic honeycomb structure. The first heater 28 and the first cooler 29, like the conventional heater 104 and cooler 105 described above, are formed of a number of mesh plates. Similar to the prime mover 101, the first energy conversion unit 21 is configured to heat and cool the working fluid in the first heat accumulator 27 by generating a temperature gradient in a predetermined direction in the first heat accumulator 27 using the first heater 28 and the first cooler 29.

The second energy conversion section 22 includes a conduit 30 having an inner diameter larger than the outer diameter of the conduit 26 described above, a conduit 34 having an inner diameter larger than the outer diameter of the conduit 30, a second heat accumulator 31, a second heater 32, and a second cooler 33. Conduits 30 and 34 correspond to the second conduit of the present invention. Conduits 30 and 34 are arranged approximately coaxially with conduit 26. A second passage A2, which is a passage for the working fluid, is formed between conduits 30 and 34. The second passage A2 accommodates the second heat accumulator 31, the second heater 32, and the second cooler 33 (i.e., the second passage A2 can also be referred to as a second accommodation space). Similar to the conventional heat accumulator 103 described above, the second heat accumulator 31 is formed, for example, of a ceramic honeycomb structure. The second heater 32 and second cooler 33 are formed from a number of mesh plates, similar to the conventional heater 104 and cooler 105 described above. Similar to the prime mover 101, the second energy conversion unit 22 is configured to heat and cool the working fluid in the second heat accumulator 31 by generating a temperature gradient in a predetermined direction in the second heat accumulator 31 using the second heater 32 and second cooler 33.

The connecting pipe section 23 includes a pipe 36 having an inner diameter larger than the outer diameter of the pipe 26 described above, a pipe 37 having an inner diameter larger than the outer diameter of the pipe 36 and smaller than the inner diameter of the pipe 30, a third heater 38, and a third cooler 39. Pipes 36 and 37 are arranged approximately coaxially with pipes 26, 30, and 34. A third passage A3, which is a passage for the working fluid, is formed between pipes 36 and 37. The third passage A3 accommodates the third heater 38 and the third cooler 39 (i.e., the third passage A3 can also be referred to as a third accommodation space). The third heater 38 and the third cooler 39 are formed of multiple mesh plates, similar to the conventional heater 104 and cooler 105 described above. The connecting pipe section 23 is disposed radially between the first energy conversion section 21 and the second energy conversion section 22. Furthermore, conduits 36 and 37 are configured so that the other end of the first energy conversion unit 21 in the predetermined direction communicates with one end of the second energy conversion unit 22 in the predetermined direction. As a result, first passage A1, second passage A2, and third passage A3 are connected in series as a single passage. More specifically, first passage A1 and second passage A2 are connected via third passage A3. The components constituting conduit 36 may be separate from the components constituting conduit 26. Alternatively, conduits 36 and 26 may be formed from the same components. The components constituting conduit 37 may be separate from the components constituting conduit 30. Alternatively, conduits 37 and 30 may be formed from the same components.

In the prime mover 12, the first heater 28, second heater 32, and third heater 38 are arranged in positions where they overlap each other in a predetermined direction. More specifically, the third heater 38 is arranged radially outward of the first heater 28. The second heater 32 is arranged further radially outward than the third heater 38. The first cooler 29, second cooler 33, and third cooler 39 are arranged in positions where they overlap each other in a predetermined direction. More specifically, the third cooler 39 is arranged radially outward of the first cooler 29. The second cooler 33 is arranged further radially outward than the third cooler 39. The first heat accumulator 27 and second heat accumulator 31 are arranged in positions where they overlap each other in a predetermined direction, sandwiching the third passage A3 between them.

In addition, a heating medium flow path (not shown in FIG. 3) for flowing a heating medium and a cooling medium flow path (not shown in FIG. 3) for flowing a cooling medium are provided radially outward from the pipe 34. The heating medium flow path is positioned so as to overlap with the second heater 32 in a predetermined direction. The cooling medium flow path is positioned so as to overlap with the second cooler 33 in a predetermined direction.

When the heating medium flows through the heating medium flow path, heat from the heating medium is transferred to the second heater 32 via pipe 34. This heats the second heater 32. Furthermore, heat from the second heater 32 is transferred to the third heater 38 via pipes 30 and 37, heating the third heater 38. Furthermore, heat from the third heater 38 is transferred to the first heater 28 via pipes 26 and 36, heating the first heater 28. This heat transfer effectively heats the first heater 28 and the third heater 38, which are located radially inward of the second heater 32. Furthermore, when the cooling medium flows through the cooling medium flow path, heat from the second cooler 33 is released to the cooling medium via pipe 34. Heat from the third cooler 39 is released to the second cooler 33 via pipes 30 and 37. Heat from the first cooler 29 is released to the third cooler 39 via the pipes 26 and 36. By releasing the heat in this manner, the first cooler 29 and the third cooler 39, which are positioned radially inward of the second cooler 33, are also effectively cooled.

In the prime mover 12 configured as described above, the first energy conversion unit 21 is housed radially inside the second energy conversion unit 22. This means that the first energy conversion unit 21 and the second energy conversion unit 22 are arranged at approximately the same position in a predetermined direction. Furthermore, the other end of the first energy conversion unit 21 and one end of the second energy conversion unit 22 are connected by the connecting pipe 23. This means that the first passage A1 of the first energy conversion unit 21, the second passage A2 of the second energy conversion unit 22, and the third passage A3 of the connecting pipe 23 are connected in series as a single passage. This makes it possible to amplify acoustic energy while preventing the prime mover 12 from becoming too large in the predetermined direction.

(Detailed structure of the prime mover 12)
Next, an example of a detailed structure for realizing the above-described prime mover 12 will be described with reference to FIGS. 4( a) to 7(d). FIG. 4(a) is a perspective view of the prime mover 12. FIG. 4(b) is a view of the prime mover 12 as seen from one side in a predetermined direction. FIG. 5 is an exploded perspective view of the prime mover 12. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 4(b). In FIG. 6, some of the components are omitted for clarity (details will be described later). FIG. 7(a) is a cross-sectional view of a first heat accumulator 43 (described later). FIG. 7(b) is a cross-sectional view of a second heat accumulator 44 (described later). FIG. 7(c) is a cross-sectional view of a high-temperature side heat exchanger 45 (described later). FIG. 7(d) is a cross-sectional view of a low-temperature side heat exchanger 46 (described later). In FIGS. 7(c) and 7(d), the diameters of through holes 45d, 46d (described later), etc., are exaggerated for clarity. However, please note that such illustration does not necessarily mean that the through holes 45d, 46d, etc. are larger than the through hole 43b (described below) of the first heat storage device 43 and the through hole 44c (described below) of the second heat storage device 44.

As shown in Figures 4(a) to 6, the outer portion of the prime mover 12 has a substantially cylindrical case 40, a lid 41, and a lid 42. In Figures 4(a) to 6, the radial direction of the case 40 is simply referred to as the radial direction. As shown in Figures 5 and 6, the interior of the prime mover 12 houses a first heat accumulator 43, a second heat accumulator 44, a high-temperature side heat exchanger 45, a low-temperature side heat exchanger 46, a first passage member 47, a second passage member 48, and a third passage member 49. The case 40 to the third passage member 49 form the first energy conversion unit 21a, the second energy conversion unit 22a, the connecting pipe section 23a, the heating medium flow path CH, and the cooling medium flow path CC (see Figure 6). The first energy conversion unit 21a, the second energy conversion unit 22a, and the connecting pipe unit 23a (see FIG. 6) correspond to the first energy conversion unit 21, the second energy conversion unit 22, and the connecting pipe unit 23 (see FIG. 3), respectively. The first energy conversion unit 21a, the second energy conversion unit 22a, and the connecting pipe unit 23a are arranged approximately coaxially. The heating medium flow path CH is a flow path through which the heating medium flows from the entrance to the exit of the motor 12. The cooling medium flow path CC is a flow path through which the cooling medium flows from the entrance to the exit of the motor 12.

As shown in FIG. 4(a), the case 40 extends in a predetermined direction. A lid 41 is disposed on one side of the case 40 in the predetermined direction. A lid 42 is disposed on the other side of the case 40 in the predetermined direction. Furthermore, as shown in FIG. 6, a first heat accumulator 43, a second heat accumulator 44, a high-temperature side heat exchanger 45, and a low-temperature side heat exchanger 46 are housed radially inside the case 40. A second passage member 48 is housed radially inside the lid 41. A first passage member 47 and a third passage member 49 are housed radially inside the lid 42.

The case 40 is, for example, a substantially cylindrical member made of metal. As shown in FIG. 6 , the inner diameter of the central portion of the case 40 in the predetermined direction is smaller than the inner diameters of both side portions of the case 40 in the predetermined direction. That is, a small-diameter portion 40a is formed in the central portion of the case 40 in the predetermined direction. The first heat accumulator 43 and the second heat accumulator 44 are housed radially inside the small-diameter portion 40a. A heating medium flow path CH1 is formed at the radially outer end of the small-diameter portion 40a on one side in the predetermined direction, and extends over substantially the entire circumferential direction of the motor 12 (a direction perpendicular to the predetermined direction and the radial direction; hereinafter simply referred to as the circumferential direction). The heating medium flow path CH1 is part of the heating medium flow path CH. An outlet CHb of the heating medium flow path CH1 is formed at the radially outer end of the small-diameter portion 40a. A cooling medium flow path CC1 is formed at the radially outer end of the small-diameter portion 40a on the other side in the predetermined direction, and extends over substantially the entire circumferential direction. The coolant flow channel CC1 is part of the coolant flow channel CC. The outlet CCb of the coolant flow channel CC1 is formed in the small diameter portion 40a.

In the case 40, a first large diameter section 40b is arranged on one side of the small diameter section 40a in a predetermined direction. A high-temperature side heat exchanger 45 is housed radially inside the first large diameter section 40b. A second large diameter section 40c is arranged on the other side of the small diameter section 40a in the predetermined direction. A low-temperature side heat exchanger 46 is housed radially inside the second large diameter section 40c.

The lid 41 is a generally disk-shaped member made of metal, for example. As shown in FIG. 6, the lid 41 is attached to one end of the case 40 in a predetermined direction. The lid 41 has an opening 41a, a working fluid passage portion 41b, and a heating medium flow path CH2 (the second heating flow path portion of the present invention). The opening 41a, the working fluid passage portion 41b, and the heating medium flow path CH2 all extend over the entire circumferential area. The opening 41a is located approximately in the center of the lid 41 in the radial direction. The opening 41a penetrates the lid 41 in a predetermined direction. The working fluid passage portion 41b is formed to allow gas to move inside the motor 12. The working fluid passage portion 41b is open on the other side in the predetermined direction. A second passage member 48 is housed in the working fluid passage portion 41b. The diameter of the radially inner end of the working fluid passage portion 41b is approximately the same as the diameter of the inner circumferential wall 45a (described below) of the high-temperature side heat exchanger 45 (see FIG. 6). The inner diameter of the radially outer end of the working fluid passage portion 41b is approximately the same as the inner diameter of the inner circumferential wall 45c (described below) of the high-temperature side heat exchanger 45 (see FIG. 6). The heating medium flow path CH2 is part of the heating medium flow path CH. The heating medium flow path CH2 is formed to allow the heating medium to flow in the circumferential direction. The other side of the heating medium flow path CH2 in a predetermined direction is open. An inlet CHa of the heating medium flow path CH2 is formed at the radially outer end of the lid 41.

The lid 42 is a generally disk-shaped member made of metal, for example. As shown in FIG. 6 , the lid 42 is attached to the other end of the case 40 in a predetermined direction. The lid 42 has an opening 42a, a gas passage 42b, and a coolant flow path CC2 (the second cooling flow path portion of the present invention). The opening 42a, the gas passage 42b, and the coolant flow path CC2 all extend over the entire circumferential area. The opening 42a is formed to allow gas to move between the inside and outside of the engine 12. The opening 42a is located at the other end of the lid 42 in the predetermined direction and approximately in the center of the lid 42 in the radial direction. The opening 42a is connected to the gas passage 42b in the axial direction. The gas passage 42b is formed to allow gas to move within the engine 12. The gas passage 42b is located on one axial side of the opening 42a and is open on one side in the predetermined direction. The gas passage portion 42b accommodates a first passage member 47 and a third passage member 49. The inner diameter of the radially outer end of the gas passage portion 42b is approximately the same as the inner diameter of the inner circumferential wall 46c (described below) of the low-temperature side heat exchanger 46 (see FIG. 6). The coolant flow path CC2 is part of the coolant flow path CC. The coolant flow path CC2 is formed to allow the coolant to flow in the circumferential direction. The other side of the coolant flow path CC2 in a predetermined direction is open. An inlet CCa of the coolant flow path CC2 is formed at the radially outer end of the lid 42.

The first heat accumulator 43 corresponds to the first heat accumulator 27 described above. The first heat accumulator 43 is a substantially cylindrical member extending in a predetermined direction and is made of a ceramic material. An outer peripheral wall 43a is formed on the radially outer side of the first heat accumulator 43. A large number of elongated through holes 43b penetrating in a predetermined direction are formed in the portion radially inward of the outer peripheral wall 43a. Note that in Figure 6, only the outer peripheral wall 43a of the first heat accumulator 43 is shown to make it easier to see the path of the working fluid, and the first heat accumulator 43 is indicated by hatching similar to that in Figure 3.

The second heat accumulator 44 corresponds to the second heat accumulator 31 described above. The second heat accumulator 44 is a substantially cylindrical member extending in a predetermined direction and is made of a ceramic material, similar to the first heat accumulator 43. The second heat accumulator 44 has an outer peripheral wall 44a that forms the outer peripheral surface and an inner peripheral wall 44b that forms the inner peripheral surface. The inner diameter of the second heat accumulator 44 is larger than the outer diameter of the first heat accumulator 43 and is disposed parallel to the first heat accumulator 43 at substantially the same position in the predetermined direction. A large number of elongated through holes 44c that penetrate in a predetermined direction are formed in the radially inner portions of the outer peripheral wall 44a and the inner peripheral wall 44b. Note that in Figure 6, only the outer peripheral wall 44a and inner peripheral wall 44b are shown to make the path of the working fluid easier to see, and the second heat accumulator 44 is indicated by hatching similar to that in Figure 3.

The high-temperature side heat exchanger 45 is a component that primarily forms the first heater 28a, second heater 32a, and third heater 38a (see FIG. 6). The first heater 28a, second heater 32a, and third heater 38a correspond to the first heater 28, second heater 32, and third heater 38 (see FIG. 3), respectively. The high-temperature side heat exchanger 45 is a generally cylindrical component extending in a predetermined direction. The high-temperature side heat exchanger 45 is formed of a metal with good thermal conductivity (copper, aluminum, etc.). The high-temperature side heat exchanger 45 is formed with inner peripheral walls 45a, 45b, and 45c, radially outward, over the entire circumferential area. The inner diameter of inner peripheral wall 45a is larger than the outer diameter of inner peripheral wall 45b. The inner diameter of inner peripheral wall 45b is larger than the outer diameter of inner peripheral wall 45c. Inner peripheral wall 45a functions as part of pipeline 34 (see Figure 3) in a predetermined direction. Inner peripheral wall 45b functions as part of pipelines 30, 37 (see Figure 3) in a predetermined direction. Inner peripheral wall 45c functions as part of pipelines 26, 36 (see Figure 3) in a predetermined direction.

As shown in FIG. 7(c), a large number of elongated through-holes 45d penetrating in a predetermined direction are formed in a portion of the high-temperature side heat exchanger 45 radially inward of the inner circumferential wall 45c. This portion functions as the first heater 28a, which corresponds to the first heater 28 (see FIG. 3). Similarly, a through-hole 45e is formed in a portion of the high-temperature side heat exchanger 45 radially outward of the inner circumferential wall 45c and radially inward of the inner circumferential wall 45b. This portion functions as the third heater 38a, which corresponds to the third heater 38 (see FIG. 3). Similarly, a through-hole 45f is formed in a portion of the high-temperature side heat exchanger 45 radially outward of the inner circumferential wall 45b and radially inward of the inner circumferential wall 45a. This portion functions as the second heater 32a, which corresponds to the second heater 32 (see FIG. 3).

In addition, multiple heating medium flow paths CH3 (first heating flow path portions of the present invention) through which the heating medium flows in a predetermined direction are provided radially outward from the inner circumferential wall 45a (see Figure 6). The heating medium flow paths CH3 are part of the heating medium flow path CH. The heating medium flow paths CH3 are located downstream of the heating medium flow path CH2 in the flow direction of the heating medium. In other words, the heating medium flow path CH2 is located upstream of the heating medium flow path CH3 in the flow direction of the heating medium. The heating medium flow path CH3 has an inner circumferential wall 45a, an outer circumferential wall 45g formed radially outward from the inner circumferential wall 45a, and multiple partition wall portions 45h (see Figure 7(c)). The outer circumferential wall 45g is located at the radially outermost position of the high-temperature side heat exchanger 45. The partition wall portions 45h are plate-shaped portions extending in a predetermined direction and are arranged side by side at predetermined intervals in the circumferential direction. The partition wall portions 45h guide the heating medium in a predetermined direction. Note that in FIG. 6, only the inner circumferential walls 45a, 45b, 45c and the outer circumferential wall 45g of the high-temperature side heat exchanger 45 are shown to make it easier to see the paths of the working fluid and heating medium. In FIG. 6, the first heater 28a, the second heater 32a, and the third heater 38a are indicated by hatching similar to that in FIG. 3.

Each of the heating medium flow channels CH3 formed by the multiple partition wall portions 45h may be formed, for example, narrower than the heating medium flow channels CH2. Conversely, the heating medium flow channels CH2 may be wider than the heating medium flow channels CH3. Specifically, the cross-sectional area of the heating medium flow channel CH2 perpendicular to the circumferential direction may be wider than the cross-sectional area of each heating medium flow channel CH3 perpendicular to a predetermined direction (the axial direction of the high-temperature side heat exchanger 45). This allows the flow resistance of the heating medium flow channel CH2 to be smaller than the flow resistance of each heating medium flow channel CH3 (the effect of this will be described later).

The low-temperature side heat exchanger 46 is a component that primarily forms the first cooler 29a, second cooler 33a, and third cooler 39a (see FIG. 6). The first cooler 29a, second cooler 33a, and third cooler 39a correspond to the first cooler 29, second cooler 33, and third cooler 39, respectively. Like the high-temperature side heat exchanger 45, the low-temperature side heat exchanger 46 is a generally cylindrical component extending in a predetermined direction and formed from a metal with good thermal conductivity (copper, aluminum, etc.). The low-temperature side heat exchanger 46 is formed with inner peripheral walls 46a, 46b, and 46c, radially outward, over the entire circumferential area. The inner diameter of inner peripheral wall 46a is larger than the outer diameter of inner peripheral wall 46b. The inner diameter of inner peripheral wall 46b is larger than the outer diameter of inner peripheral wall 46c. The inner peripheral wall 46a functions as part of the pipeline 34 (see Figure 3) in a predetermined direction. The inner peripheral wall 46b functions as part of the pipelines 30, 37 (see Figure 3) in a predetermined direction. The inner peripheral wall 46c functions as part of the pipelines 26, 36 (see Figure 3) in a predetermined direction.

As shown in FIG. 7(d), a large number of elongated through holes 46d penetrating in a predetermined direction are formed in a portion of the low-temperature side heat exchanger 46 radially inward of the inner circumferential wall 46c, similar to the high-temperature side heat exchanger 45. This portion functions as a first cooler 29a corresponding to the first cooler 29 (see FIG. 3). Similarly, a through hole 46e is formed in a portion of the low-temperature side heat exchanger 46 radially outward of the inner circumferential wall 46c and radially inward of the inner circumferential wall 46b. This portion functions as a third cooler 39a corresponding to the third cooler 39 (see FIG. 3). Similarly, a through hole 46f is formed in a portion of the low-temperature side heat exchanger 46 radially outward of the inner circumferential wall 46b and radially inward of the inner circumferential wall 46a. This portion functions as a second cooler 33a corresponding to the second cooler 33 (see FIG. 3).

Additionally, multiple cooling medium flow paths CC3 (first cooling medium flow path portions of the present invention) through which the cooling medium flows in a predetermined direction are provided radially outward from the inner circumferential wall 46a (see FIG. 6). The cooling medium flow paths CC3 are part of the cooling medium flow path CC. The cooling medium flow paths CC3 are located downstream of the cooling medium flow path CC2 in the direction of the cooling medium flow. In other words, the cooling medium flow path CC2 is located upstream of the cooling medium flow path CC3 in the direction of the cooling medium flow. The cooling medium flow path CC3 includes the inner circumferential wall 46a, an outer circumferential wall 46g formed radially outward from the inner circumferential wall 46a, and multiple partition wall portions 46h (see FIG. 7(d)). The outer circumferential wall 46g is located at the radially outermost position of the low-temperature side heat exchanger 46. The partition wall portions 46h are plate-shaped portions extending in a predetermined direction and are arranged side by side at predetermined intervals in the circumferential direction. The partition wall portions 46h guide the cooling medium in a predetermined direction. Note that with regard to the low-temperature side heat exchanger 46, in Figure 6, only the inner circumferential walls 46a, 46b, 46c and the outer circumferential wall 46g are shown to make it easier to see the paths of the working fluid and cooling medium. In Figure 6, the first cooler 29a, second cooler 33a, and third cooler 39a are indicated by hatching similar to that in Figure 3.

Each of the cooling medium flow channels CC3 formed by the multiple partition wall portions 46h may be formed, for example, narrower than the cooling medium flow channels CC2. Conversely, the cooling medium flow channels CC2 may be wider than the cooling medium flow channels CC3. Specifically, the cross-sectional area of the cooling medium flow channel CC2 perpendicular to the circumferential direction may be wider than the cross-sectional area of each cooling medium flow channel CC3 perpendicular to a predetermined direction (the axial direction of the low-temperature side heat exchanger 46). This allows the flow channel resistance of the cooling medium flow channel CC2 to be smaller than the flow channel resistance of each cooling medium flow channel CC3 (the effect of this will be described later).

The first energy conversion unit 21a has a first heat accumulator 43, a first heater 28a, and a first cooler 29a. The outer peripheral wall 43a of the first heat accumulator 43, the inner peripheral wall 45c of the high-temperature side heat exchanger 45, and the inner peripheral wall 46c of the low-temperature side heat exchanger 46 function as a conduit 26a, corresponding to the above-mentioned conduit 26 (see FIG. 3). A first passage A1, which is a passage for the working fluid, is formed within the conduit 26a. The first passage A1 houses the first heat accumulator 43, the first heater 28a, and the first cooler 29a. Similar to the prime mover 101, the first energy conversion unit 21a is configured to heat and cool the working fluid in the first heat accumulator 43 by generating a temperature gradient in a predetermined direction in the first heat accumulator 43 using the first heater 28a and the first cooler 29a.

The second energy conversion unit 22a has a second heat storage device 44, a second heater 32a, and a second cooler 33a. The outer peripheral wall 44a of the second heat storage device 44, the inner peripheral wall 45a of the high-temperature side heat exchanger 45, and the inner peripheral wall 46a of the low-temperature side heat exchanger 46 function as a conduit 34a corresponding to the conduit 34 (see FIG. 3). The inner peripheral wall 44b of the second heat storage device 44, the inner peripheral wall 45b of the high-temperature side heat exchanger 45, and the inner peripheral wall 46b of the low-temperature side heat exchanger 46 function as a conduit 30a corresponding to the conduit 30 (see FIG. 3). A second passage A2, which is a passage for the working fluid, is formed in the space surrounded by the conduits 34a and 30a. The second passage A2 houses the second heat storage device 44, the second heater 32a, and the second cooler 33a. Similar to the motor 101, the second energy conversion unit 22a is configured to heat and cool the working fluid in the second heat accumulator 44 by generating a temperature gradient in a predetermined direction in the second heat accumulator 44 using the second heater 32a and second cooler 33a.

The connecting pipe section 23a has a third heater 38a and a third cooler 39a. The inner circumferential wall 44b of the second heat accumulator 44, the inner circumferential wall 45b of the high-temperature side heat exchanger 45, and the inner circumferential wall 46b of the low-temperature side heat exchanger 46 function as a conduit 37a corresponding to the conduit 37 (see FIG. 3). The outer circumferential wall 43a of the first heat accumulator 43, the inner circumferential wall 45c of the high-temperature side heat exchanger 45, and the inner circumferential wall 46c of the low-temperature side heat exchanger 46 function as a conduit 36a corresponding to the conduit 36 (see FIG. 3). A third passage A3, which is a passage for the working fluid, is formed in the space surrounded by the conduits 37a and 36a. The third passage A3 houses the third heater 38a and the third cooler 39a. Here, at least a portion of the components constituting conduit 37a also function as conduit 30a, and at least a portion of the components constituting conduit 36a also function as conduit 26a (see Figure 6). In other words, at least a portion of connecting pipe section 23a is composed of at least a portion of the components constituting conduit 26a and at least a portion of the components constituting conduit 30a.

The first passage member 47 is a member that allows working fluid to move between the first energy conversion section 21a and the connecting pipe section 23a. The first passage member 47 has, for example, a ring portion 47a formed over the entire circumferential area and multiple protrusions 47b extending radially outward from the ring portion 47a (see FIG. 6). The inner and outer diameters of the ring portion 47a are approximately the same as the inner and outer diameters of the inner circumferential wall 46c of the low-temperature side heat exchanger 46. The first passage member 47 is housed radially inside the third passage member 49 (see FIG. 6).

The second passage member 48 is a member that allows working fluid to move between the connecting pipe portion 23a and the second energy conversion portion 22a. The second passage member 48 has, for example, a ring portion 48a formed over the entire circumferential area and multiple protrusions 48b extending radially inward from the ring portion 48a (see FIG. 6). The inner and outer diameters of the ring portion 48a are approximately the same as the inner and outer diameters of the inner circumferential wall 45b of the high-temperature side heat exchanger 45. The second passage member 48 is housed within the working fluid passage portion 41b of the lid 41 (see FIG. 6).

The third passage member 49 is a member that allows working fluid to move between the second energy conversion unit 22a and the outside of the prime mover 12. The third passage member 49 has, for example, a ring portion 49a formed over the entire circumferential area, multiple protrusions 49b extending radially outward from the ring portion 49a, and a disk portion 49c connected to the other end of the ring portion 49a in a predetermined direction (see FIG. 6). The inner and outer diameters of the ring portion 49a are approximately the same as the inner and outer diameters of the inner circumferential wall 46b of the low-temperature side heat exchanger 46. The third passage member 49 is housed within the gas passage portion 42b of the lid 42 (see FIG. 6).

(Flow of heating medium and cooling medium)
The flow of the heating medium in the heating medium flow channel CH will be described. The heating medium flows in a predetermined direction (axial direction of the high-temperature side heat exchanger 45) through an inlet CHa located farther from the first heat accumulator 43 and the second heat accumulator 44. The heating medium then passes through the heating medium flow channels CH2, CH3, and CH1 in this order and flows out through an outlet CHb located closer to the first heat accumulator 43 and the second heat accumulator 44. This results in a uniform temperature distribution in the radial direction of the high-temperature side heat exchanger 45, allowing the first heater 28a, the second heater 32a, and the third heater 38a to be heated evenly in the radial direction. This allows for stable generation of sound waves. Furthermore, the inlet CHa is located farther from the first heat accumulator 43 and the second heat accumulator 44. This reduces heat loss due to heat transfer to the small diameter portion 40a of the case 40, which would occur if the inlet CHa were located closer. This allows for more stable generation of sound waves.

Furthermore, as described above, by making the flow resistance of the heating medium flow path CH2 smaller than the flow resistance of each heating medium flow path CH3, the following effects are achieved. That is, the pressure loss of the heating medium in the heating medium flow path CH2 is smaller than the pressure loss of the heating medium in each heating medium flow path CH3. As a result, the heating medium is more likely to be temporarily stored in the heating medium flow path CH2 before flowing from the heating medium flow path CH2 into the heating medium flow path CH3. This makes it easier to uniformize the flow rate and temperature of the heating medium in the heating medium flow path CH2. This allows the heating medium to flow uniformly at approximately the same temperature through the multiple heating medium flow paths CH3, thereby heating the first heater 28a, the second heater 32a, and the third heater 38a evenly in the circumferential direction. This therefore makes it possible to uniformize the temperature distribution in the circumferential direction of the high-temperature side heat exchanger 45.

The flow of the cooling medium in the cooling medium flow channel CC will now be described. The cooling medium flows in a predetermined direction (axial direction of the low-temperature side heat exchanger 46) through an inlet CCa located farther from the first heat accumulator 43 and the second heat accumulator 44. The cooling medium then passes through cooling medium flow channels CC2, CC3, and CC1 in that order, and flows out through an outlet CCb located closer to the first heat accumulator 43 and the second heat accumulator 44. This results in a uniform temperature distribution in the radial direction of the low-temperature side heat exchanger 46, allowing the first cooler 29a, the second cooler 33a, and the third cooler 39a to be cooled evenly in the radial direction. This allows for stable generation of sound waves. Furthermore, by locating the inlet CCa farther from the first heat accumulator 43 and the second heat accumulator 44, heat transfer from the small diameter portion 40a of the case 40, which would occur if the inlet CCa were located closer, can be suppressed, resulting in more stable generation of sound waves.

Furthermore, as described above, by making the flow resistance of the coolant flow channel CC2 smaller than the flow resistance of each coolant flow channel CC3, the following effects are achieved. That is, the pressure loss of the coolant in the coolant flow channel CC2 is smaller than the pressure loss of the coolant in each coolant flow channel CC3. This makes it easier for the coolant to temporarily accumulate in the coolant flow channel CC2 before flowing from the coolant flow channel CC2 into the coolant flow channel CC3. This makes it easier to uniform the flow rate and temperature of the coolant in the coolant flow channel CC2. This allows a coolant of approximately the same temperature to flow uniformly through the multiple coolant flow channels CC3, thereby cooling the first cooler 29a, the second cooler 33a, and the third cooler 39a evenly in the circumferential direction. This therefore makes it possible to uniform the temperature distribution in the circumferential direction of the low-temperature side heat exchanger 46.

As described above, the first energy conversion unit 21a and the second energy conversion unit 22a are arranged so that they at least partially overlap in a predetermined direction. Furthermore, at least a portion of the connecting pipe portion 23a is arranged so that it overlaps with the first energy conversion unit 21a and the second energy conversion unit 22a in the predetermined direction. Thus, even though the first energy conversion unit 21a and the second energy conversion unit 22a are connected in series, they are not arranged linearly in the predetermined direction. This prevents the prime mover 12 and the thermoacoustic engine 1 from becoming larger in the predetermined direction. Furthermore, because the first energy conversion unit 21a and the second energy conversion unit 22a are arranged so that they at least partially overlap in the predetermined direction, a single heating medium flow path CH can simultaneously heat the first heater 28a and the second heater 32a. Furthermore, with this configuration, a single cooling medium flow path CC extending in a direction intersecting the predetermined direction can simultaneously cool the first cooler 29a and the second cooler 33a. This allows the heating medium flow path CH and the cooling medium flow path CC to be compact. This reduces temperature variations when supplying the heating medium or cooling medium, and stably equalizes the temperature difference between the heater and the cooler. This allows for stable amplification of acoustic energy. As described above, this avoids the problems that arise in a thermoacoustic engine 1 in which multiple prime movers 12 are connected in series in a predetermined direction.

In addition, the pipes 37a and 36a of the connecting pipe section 23a are formed by parts of the high-temperature side heat exchanger 45, low-temperature side heat exchanger 46, first heat accumulator 43, and second heat accumulator 44 of the prime mover 12. This allows the prime mover 12 to be made more compact in the radial direction. Furthermore, heat can be efficiently transferred between the first energy conversion section 21a and the second energy conversion section 22a via the connecting pipe section 23.

Furthermore, the first energy conversion unit 21a can be positioned radially inside the second energy conversion unit 22a. This allows the prime mover 12 to be made even more compact in the radial direction.

Furthermore, the flow resistance of the heating medium flow path CH2 is smaller than the flow resistance of each heating medium flow path CH3. This allows the pressure loss of the heating medium in the heating medium flow path CH2 to be smaller than the pressure loss of the heating medium in each heating medium flow path CH3. As a result, the heating medium is more likely to be temporarily stored in the heating medium flow path CH2 before flowing from the heating medium flow path CH2 into the heating medium flow path CH3. This makes it easier to uniformize the flow rate and temperature of the heating medium in the heating medium flow path CH2. This allows the heating medium to flow uniformly at approximately the same temperature through the multiple heating medium flow paths CH3, allowing the first heater 28a, second heater 32a, and third heater 38a to be heated evenly in the circumferential direction. This allows the temperature distribution in the circumferential direction of the high-temperature side heat exchanger 45 to be uniform.

Furthermore, the flow resistance of the cooling medium flow path CC2 is smaller than the flow resistance of each cooling medium flow path CC3. This allows the pressure loss of the cooling medium in the cooling medium flow path CC2 to be smaller than the pressure loss of the cooling medium in each cooling medium flow path CC3. This makes it easier for the cooling medium to temporarily accumulate in the cooling medium flow path CC2 before flowing from the cooling medium flow path CC2 into the cooling medium flow path CC3. This makes it easier to uniformize the flow rate and temperature of the cooling medium in the cooling medium flow path CC2. This allows a cooling medium of approximately the same temperature to flow uniformly through the multiple cooling medium flow paths CC3, thereby cooling the first cooler 29a, the second cooler 33a, and the third cooler 39a evenly in the circumferential direction. This allows for a uniform temperature distribution in the circumferential direction of the low-temperature side heat exchanger 46.

Furthermore, in the high-temperature side heat exchanger 45, the first heater 28a of the first energy conversion unit 21a and the second heater 32a of the second energy conversion unit 22a are formed as part of the high-temperature side heat exchanger 45. This makes it easier to assemble the prime mover 12 compared to when the first heater 28a and the second heater 32a are formed from separate components.

Furthermore, in the low-temperature side heat exchanger 46, the first cooler 29a of the first energy conversion unit 21a and the second cooler 33a of the second energy conversion unit 22a are formed as part of the low-temperature side heat exchanger 46. This makes it easier to assemble the prime mover 12 compared to when the first cooler 29a and the second cooler 33a are constructed from separate components.

Next, we will explain modifications to the above embodiment. However, parts with the same configuration as the above embodiment will be assigned the same reference numerals and their description will be omitted as appropriate.

(1) In the above embodiment, the high-temperature side heat exchanger 45 is arranged on one side of the first heat accumulator 43 and the second heat accumulator 44 in a predetermined direction, and the low-temperature side heat exchanger 46 is arranged on the other side of the first heat accumulator 43 and the second heat accumulator 44 in the predetermined direction. However, this is not limited to this. In other words, the positions of the high-temperature side heat exchanger 45 and the low-temperature side heat exchanger 46 may be interchanged.

(2) The positions at which the inlet CHa, outlet CHb, inlet CCa, and outlet CCb (see FIG. 6) are formed are not limited to those described above. For example, the inlet CHa and inlet CCa may be formed in the case 40 (small diameter portion 40a). Alternatively, the outlet CHb may be formed in the lid 41, and the outlet CCb may be formed in the lid 42. Alternatively, for example, the inlet CHa, outlet CHb, inlet CCa, and outlet CCb may all be formed in the case 40.

(3) In the above-described embodiments, the first energy conversion unit 21, the second energy conversion unit 22, and the connecting pipe unit 23 are arranged substantially coaxially. However, this is not limited to this. In other words, the first energy conversion unit 21, the second energy conversion unit 22, and the connecting pipe unit 23 do not necessarily have to be arranged coaxially. Furthermore, in the above-described embodiments, the conduit 26 is arranged radially inside the conduits 30 and 34. In other words, the first energy conversion unit 21 is arranged radially inside the second energy conversion unit 22. However, this is not limited to this. For example, as shown in FIG. 8 , in the prime mover 50, the first energy conversion unit 51, the second energy conversion unit 52, and the connecting pipe unit 53 may be connected so as to be arranged in an S-shape. Even with this configuration, the size of the thermoacoustic engine 1 in a predetermined direction can be suppressed. The first energy conversion unit 51 may include a tubular conduit 56 (a first conduit of the present invention), a first heat accumulator 57, a first heater 58, and a first cooler 59. The second energy conversion unit 52 may include a tubular conduit 61 (a second conduit of the present invention), a second heat accumulator 62, a second heater 63, and a second cooler 64. The connecting pipe unit 53 may include a tubular conduit 65, a third heater 66, and a third cooler 67. The conduit 65 may be disposed so as to be in contact with the conduits 56 and 61. Alternatively, the conduit 65 may be formed integrally with the conduits 56 and 61, for example, by welding. As shown in FIG. 8 , the conduits 56, 61, and 65 may be connected to form a substantially S-shaped configuration. In this modified example, the first heater 58, the second heater 63, and the third heater 66 are arranged in positions where they at least partially overlap in a predetermined direction. Furthermore, the first cooler 59, the second cooler 64, and the third cooler 67 are arranged in positions where they at least partially overlap in a predetermined direction. This makes it possible to prevent the thermoacoustic engine 1 from becoming too large in the predetermined direction. Furthermore, in this modified example, the simple structure makes it possible to prevent the thermoacoustic engine 1 from becoming too large in the predetermined direction.

The pipes 56, 61, and 65 may have a substantially circular cross section. Alternatively, the pipes 56, 61, and 65 may have a substantially rectangular cross section. When the cross section is substantially rectangular, the contact area between the outer surface of pipe 65 and the outer surface of pipe 56, and the contact area between the outer surface of pipe 65 and the outer surface of pipe 61 are large. Therefore, heat can be efficiently transferred between the first energy conversion unit 51 and the second energy conversion unit 52 via pipe 65.

(4) As a further modification of the modification (3) described above, as shown in FIG. 9, the prime mover 70 may be configured as follows. Instead of the above-described conduits 56, 61, and 65, a single conduit 68 curved in a substantially S-shape may be provided. Even with this configuration, the size of the thermoacoustic engine 1 in a predetermined direction can be prevented from increasing.

(5) In the above embodiments, for example, the connecting pipe portion 23 has the third heater 38 and the third cooler 39, but this is not limited to this. For example, instead of the third heater 38, a member that transfers heat between the first heater 28 and the second heater 32 may be provided. Instead of the third cooler 39, a member that transfers heat between the first cooler 29 and the second cooler 33 may be provided.

(6) In the above-described embodiments, the prime mover 12, etc., has two energy conversion units (e.g., the first energy conversion unit 21 and the second energy conversion unit 22). However, this is not limited to this. That is, the number of energy conversion units may be more than two. For example, a connecting pipe unit (not shown) similar to the connecting pipe unit 23 may be provided further radially outward from the second energy conversion unit 22. Furthermore, a third energy conversion unit (not shown) may be provided radially outward from the connecting pipe unit.

(7) In the above embodiments, the prime mover 12, 50, or 70 is provided in the prime mover loop 11, but this is not limited to this. The prime mover 12, 50, or 70 may also be provided in the amplifier section 3. If the output section 4 has a thermoacoustic cooler (not shown), the prime mover 12, 50, or 70 may also be provided in the output section 4.

(8) In the above embodiments, the thermoacoustic engine 1 includes a prime mover loop 11, an amplifier unit 3, and an output unit 4, but this is not limited to this. The thermoacoustic engine 1 may include only a prime mover loop 11 equipped with a prime mover 12, 50, or 70. Alternatively, the thermoacoustic engine 1 may include only an amplifier unit 3 equipped with a prime mover 12, 50, or 70.

REFERENCE SIGNS 1 thermoacoustic engine 12 prime mover 21 first energy conversion section 22 second energy conversion section 23 connecting pipe section 26 pipe line (first pipe line)
27 First heat storage device 28 First heater 29 First cooler 30 Pipe line (second pipe line)
31 Second heat storage device 32 Second heater 33 Second cooler 34 Pipe line (second pipe line)
51 First energy conversion section 52 Second energy conversion section 53 Connection pipe section A1 First passage A2 Second passage CC Cooling medium flow path CC2 Cooling medium flow path (second cooling flow path portion)
CC3 Coolant flow path (first cooling flow path portion)
CH heating medium flow path CH2 heating medium flow path (second heating flow path portion)
CH3 Heating medium flow path (first heating flow path portion)

Claims (3)

A thermoacoustic engine comprising a prime mover configured to convert thermal energy into acoustic energy,
the prime mover includes a first energy conversion unit, a second energy conversion unit separate from the first energy conversion unit, and a connecting pipe unit connecting the first energy conversion unit and the second energy conversion unit in series,
The first energy conversion unit is
a first conduit forming a first passage through which the working fluid passes;
a first heat accumulator accommodated in the first passage and configured to heat and cool the working fluid;
a first heater arranged next to the first heat accumulator on one side in a predetermined direction;
a first cooler arranged next to the first heat accumulator on the other side in the predetermined direction,
The second energy conversion unit is
a second conduit forming a second passage through which the working fluid passes;
a second heat accumulator accommodated in the second passage and configured to heat and cool the working fluid;
a second heater arranged next to the second heat accumulator on the one side in the predetermined direction;
a second cooler arranged next to the second heat accumulator on the other side in the predetermined direction,
the connecting pipe portion is disposed at a position at which the connecting pipe portion at least partially overlaps the first energy conversion portion and the second energy conversion portion in the predetermined direction,
the first heater and the second heater are disposed at positions where they at least partially overlap in the predetermined direction,
the first cooler and the second cooler are disposed at positions where they at least partially overlap in the predetermined direction,
A thermoacoustic engine, characterized in that at least a portion of the connecting pipe portion is composed of at least a portion of a member constituting the first pipe line and at least a portion of a member constituting the second pipe line. the first pipe is tubular,
The thermoacoustic engine according to claim 1 , wherein the second pipe is disposed outside the first pipe in a radial direction of the first pipe. a medium flow path through which a heating medium for heating the first heater and the second heater or a cooling medium for cooling the first cooler and the second cooler flows;
The medium flow path is
a first flow path portion disposed radially outward of the second pipe and extending in the predetermined direction;
a second flow path portion formed upstream of the first flow path portion in the flow direction of the medium and extending in a circumferential direction of the second pipe,
3. The thermoacoustic engine according to claim 2, wherein a flow resistance of the second flow passage portion is lower than a flow resistance of the first flow passage portion.