JPH11337206A - Sound refrigerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the weight of a device and to provide an increased life for the device, in a sound refrigerating device that a sound wave generating device is arranged in a hollow annular sound device having a peripheral length being an integer times the wavelength of a sound wave and a cold storage apparatus is located in the given position of the sound pipe. SOLUTION: A sound wave generating device is constituted that one set of piezoelectric element pieces 6 and 6 arranged at a distance increased an odd number times 1/4 wavelength of a sound wave and a plurality of sets the elements is disposed along the line, and the piezoelectric element pieces 6 and 6 are connected to a power source 5 through phase regulators 7-77. The phase regulators 7-77 regulate the vibration phase of each piezoelectric piece 6 so that the phases of two sound waves outputted from one set of the piezoelectric pieces 6 and 6 are differed by the odd number times the 1/4 wavelength of a sound wave. The vibration phase of each piezoelectric piece 6 is regulated such that the phases of progress waves in one direction by each set of the piezoelectric element pieces are caused to coincide with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic refrigeration apparatus having a sound wave generator disposed opposite a pipe of an acoustic tube and a regenerator interposed at a predetermined position of the acoustic tube.
In particular, the present invention relates to an acoustic refrigeration apparatus capable of achieving weight reduction and long life.

[0002]

2. Description of the Related Art Conventionally, there is known an acoustic refrigeration apparatus for refrigeration using sound waves (see, for example, Japanese Patent Publication No. 3-46745). For example, the acoustic refrigerator (200) shown in FIG.
02A) is closed, and the other end (202B) is provided with a resonance tube (202) having an opening, and a speaker (201) for generating sound is provided facing the open end (202B) of the resonance tube (202). And resonance tube (202)
Inside, a regenerator (203) in which flat plates are arranged in a plurality of layers is provided.

Here, the frequency of the current applied to the speaker (201) is set to a value at which sound waves resonate in the resonance tube (202). From the speaker (203) to the closed end of the resonance tube (202)
When a sound wave is generated toward (202A), a pressure distribution P as shown in FIG. 11 is formed in the resonance tube (202), and an antinode part having a large pressure fluctuation and a node part having a small pressure fluctuation are formed. And occur alternately. Further, as shown by an arrow W in the figure, the gas displacement also has an antinode and a node. As a result, the regenerator (2
A temperature difference occurs at both ends of 03). Then, the low-temperature end and the high-temperature end of the regenerator (203) perform cooling of the object and heat radiation to the outside via a heat exchanger (not shown), respectively.

The above-described acoustic refrigeration apparatus (200) can be described by a Brayton cycle consisting of four steps of adiabatic compression, isobaric pressure change, adiabatic expansion, and isobaric pressure change of a minute gas mass. However, in the Brayton cycle constituted by the acoustic refrigerator (200),
Heat is absorbed by the difference between the temperature when the gas mass expands and the temperature of the regenerator (203), or is released by the difference between the temperature when the gas mass is compressed and the temperature of the regenerator (203). Therefore, the thermal transfer process is irreversible, and has a disadvantage that the thermal efficiency is lower than that of the Carnot cycle.

Therefore, the applicant has proposed an acoustic refrigeration apparatus in which the thermal transfer process is reversible and a gas cycle close to an ideal gas cycle, the Carnot cycle, can be realized (Japanese Patent Application No. Hei 9-1997). 134993). Based on FIGS. 4 to 9,
The basic structure and principle of the acoustic refrigerator will be described.

As shown in FIG. 4, an acoustic tube (1) through which a sound wave is to be transmitted forms a hollow annular closed-loop conduit. The circumference of the acoustic tube (1) is set to be an integral multiple of the wavelength of the sound wave. In the following example, the length of the center line of the acoustic tube (1) is defined as the circumference. Speaker as sound wave generator
(2) and (3) are attached to the acoustic tube (1) so as to emit acoustic waves into the acoustic tube (1) while being separated from each other by a distance equal to an odd multiple of 音波 wavelength of the acoustic wave. Also, speaker (2)
A sound wave generation control device (50) is connected to (3), and a speaker
(2) The phases of the sound waves emitted from (3) are 1 /
Drive control is performed so as to shift by an odd multiple of four wavelengths.

Next, the operation principle of the acoustic refrigerator is described.
This will be described with reference to FIG. The sound waves radiated from the speakers (2) and (3) enter the acoustic tube (1), branch in two directions, and travel in the acoustic tube (1). And both speakers (2)
Two sound waves emitted from (3) and traveling in the acoustic tube (1) overlap each other. Here, from the relationship between the arrangement intervals of the speakers (2) and (3) and the phase difference between the sound waves, the sound waves 2L and 3L traveling to the left in the drawing have the same phase, are superimposed on each other and amplified, and The sound waves 2R and 3R traveling in the directions have opposite phases and cancel each other. As a result, only the sound wave traveling in one direction (left direction) remains, and the sound wave further goes around in the acoustic tube (1) and is superimposed with the sound wave of the same phase, so that the amplitude is increased similarly to the resonance. Will be.

Next, as shown in FIG. 6, the principle of refrigeration in the case where a cold storage member (40) having good heat exchange properties and a small pressure loss is arranged in an acoustic tube (1) of an acoustic refrigeration apparatus will be described with reference to FIG. This will be described with reference to FIG. The traveling sound wave passing through the cold storage member (40) has a phase shift depending on its position, and when focusing on a minute gas mass located at a certain position, an expansion stroke occurs in the traveling direction of the sound wave at the center position as a boundary. In the opposite direction, a compression stroke occurs. In the expansion step and the compression step, heat is absorbed and released using the cold storage member (40), so that heat is sequentially transferred in the direction opposite to the traveling direction of the sound wave. Since the heat transfer process is reversible, the heat efficiency is higher than that of the conventional acoustic refrigerator.

Further, the gas cycle of the acoustic refrigerator according to the present invention will be described with reference to FIGS. The Carnot cycle includes an isothermal process and an adiabatic process, and is shown as a rectangular cycle diagram of A, H, G, and D in the TS diagram as shown in FIG. Here, A → H indicates an adiabatic expansion stroke (constant entropy), H → G indicates an isothermal expansion stroke, G → D indicates an adiabatic compression stroke, and D → A indicates an isothermal expansion stroke.

As shown in FIG. 9, when a sound wave passes in one direction through a regenerative member having good heat conductivity as a gas mass, the minute gas mass reciprocates and changes pressure at the same time. The pressure change, when the gas mass has moved the most in the sound wave traveling direction,
The pressure rises quickly and is strongly compressed. Here, since the heat storage member has good heat conductivity, isothermal compression is performed. This isothermal compression stroke is indicated by D → A in FIGS. Next, when the gas mass moves in the direction opposite to the sound wave traveling direction, heat is released along the temperature gradient of the cold storage member,
The gas mass is cooled by a substantially equal volume change. This process is indicated by AB in FIGS.

Thereafter, at the end in the direction opposite to the traveling direction of the sound wave, the pressure decreases rapidly and expands strongly. At this time, an isothermal expansion process in which heat is absorbed from the cold storage member is performed.
This process is indicated by B → C in FIGS. 8 and 9.
Even when the gas moves in the direction in which the sound wave travels, there is an equal volume change that absorbs heat along the temperature gradient of the cold storage member. This process is indicated by C → D in FIGS. 8 and 9.

As described above, D → A → B → C → shown in FIG.
One cycle of D makes it possible to transfer heat in the direction opposite to the direction of sound wave travel. Thus, a cycle constituted by the isothermal process and the isostatic process is called a Stirling cycle, and the adiabatic process of the Carnot cycle is an isostatic process. Therefore, according to the acoustic refrigeration apparatus, efficiency equivalent to the Carnot cycle can be obtained.

Further, as shown in an acoustic refrigerator (150) shown in FIG. 10, a plurality of sets of speakers (10A) (10B) and speakers (20A) (20B) which are displaced from each other by an odd multiple of １ ／ wavelength of a sound wave. ),
Speaker (30A) (30B), speaker (40A) (40B), speaker (5
By disposing the (0A) (50B) and the speakers (60A) (60B) at predetermined intervals along the pipeline, it is possible to generate a sound wave traveling in one direction as in the above-described acoustic refrigerator. Thus, the burden on each speaker can be reduced, and the life of the acoustic refrigerator can be prolonged.

[0014]

In the acoustic refrigeration system, the input work for generating a sound wave is proportional to the driving force of the speaker and the stroke of the diaphragm. In a sound wave generator such as a loudspeaker that drives a diaphragm by a linear motor such as a voice coil motor, the driving force per unit weight is relatively small. Absent. In order to reduce the weight of the apparatus, it is necessary to increase the stroke of the diaphragm. However, there is a problem that the service life of the suspension portion of the diaphragm and the seal portions such as the piston seal and the bellows is extremely shortened by increasing the stroke.

An object of the present invention is to provide an acoustic refrigeration apparatus that can achieve a light weight and a long life.

[0016]

In the acoustic refrigeration apparatus according to the present invention, a sound wave generator is provided so as to face a hollow annular acoustic tube whose circumference is an integral multiple of the wavelength of a sound wave. At the same time, a regenerator is interposed at a predetermined position of the pipe of the acoustic tube,
A temperature gradient is formed in the regenerator by the sound waves emitted from the sound wave generator. In the characteristic configuration, the sound wave generator includes a plurality of piezoelectric element pieces arranged along the pipeline on the inner peripheral wall of the acoustic tube at an interval of an odd multiple of 1/4 wavelength of the acoustic wave along the pipeline. The piezoelectric element pieces are connected to a drive control circuit, and the phase of two sound waves emitted from the set of piezoelectric element pieces is set to １ ／ wavelength of the sound wave. , And the vibration phase of each piezoelectric element piece is adjusted so that the phases of the traveling waves in one direction generated by each set of the piezoelectric element pieces match each other.

In the above-described acoustic refrigeration apparatus of the present invention, when each of the piezoelectric element pieces is driven by the drive control circuit, the piezoelectric element pieces vibrate in the radial direction of the acoustic tube to generate sound waves toward the acoustic tube. I do. Here, since a piezoelectric element piece is employed as the sound wave generator, a large pressure P per unit area can be obtained. Further, since the piezoelectric element piece can be disposed on substantially the entire inner peripheral wall of the acoustic tube, the area A of the vibration generating surface becomes large. Therefore, although the stroke of the vibration of the piezoelectric element piece is small, the driving force (pressure P × area A) becomes very large, so that a sufficient input work necessary for generating a sound wave can be obtained. .

The sound waves generated from one set of two piezoelectric element pieces are superposed and amplified in the one direction based on the arrangement interval of the two piezoelectric element pieces and the phase of the generated sound wave, and amplified in the other direction. The traveling sound waves will be canceled. For this reason, only the sound wave traveling in one direction remains in the sound tube, and further goes around the sound tube and is superimposed with the sound wave of the same phase, so that the amplitude is increased like resonance.
The sound waves traveling in only one direction generated by each set of the piezoelectric element pieces are phase-controlled so that the phases thereof coincide with each other, so that these sound waves are combined to generate a traveling wave having a larger amplitude. Will be.

When the traveling wave generated in this manner passes through the regenerator, the pressure and displacement of the minute gas mass located at each location cause a phase shift depending on the location. As a result, the gas mass located at each location expands when located in the traveling direction of the sound wave, and compresses when located in the opposite direction, from the center position of the displacement. In the expansion stroke and the compression stroke, heat is absorbed and released, so that heat is sequentially transferred in the direction opposite to the direction in which the sound wave travels. As a result, the heat transfer process is performed reversibly, and a heat cycle close to the Carnot cycle is realized.

In a specific configuration, the piezoelectric element pieces have a pipe-like shape that can be mounted along the inner peripheral wall of the acoustic tube, and are arranged continuously over substantially the entire length of the conduit of the acoustic tube. In this specific configuration, the piezoelectric element piece vibrates in a direction in which the inner diameter expands and contracts, and generates a sound wave in the acoustic tube. Here, the area of the vibration generating surface is as close as possible to the maximum achievable area, that is, the entire area of the inner peripheral wall of the acoustic tube. As a result, the input work for generating the sound wave is sufficiently large. Become.

In a more specific configuration, a pipe-shaped elastic member is interposed between the inner peripheral wall of the acoustic tube and the piezoelectric element piece. Therefore, the vibration of the vibration surface of the piezoelectric element piece on the acoustic tube side is absorbed by the elastic deformation of the elastic member, and there is no possibility that the piezoelectric element piece is peeled off from the acoustic tube with the vibration.

[0022]

According to the acoustic refrigerator of the present invention,
A piezoelectric element piece is used as the sound wave generator, and the driving force per unit weight of the piezoelectric element piece is very large, so that the weight of the apparatus can be reduced. In addition, since no suspension member or seal member whose life is shortened due to the vibration of the piezoelectric element piece is provided, the life can be extended.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. The acoustic refrigeration apparatus according to the present invention is, in principle, an acoustic refrigeration apparatus (15
0), wherein a plurality of piezoelectric element pieces are arranged on the inner peripheral wall of the acoustic tube in place of the plurality of speakers.

As shown in FIG. 1, the inner peripheral wall of the hollow annular acoustic tube (1) whose peripheral length is an integral multiple of the wavelength of the sound wave has an inner peripheral wall extending in the direction of the pipe.
Eight regions are formed by equally dividing, and a pipe-shaped piezoelectric element piece (6) is continuously arranged in each region with a phase difference of 45 °. These eight piezoelectric element pieces
(6) ... (6) are 0 °, 45 °, 90 °, and 135, respectively.
°, 180 °, 255 °, 270 ° and 315 ° through eight phase adjusters (7) to (77) to perform phase adjustment,
Connected to power supply (5). A cool storage unit (4) is provided at an appropriate position of the acoustic tube (1). The regenerator (4) may be a wire mesh laminate or a porous body made of a material having high thermal conductivity such as copper, copper alloy, iron, stainless steel, or a regenerative member (shown in the drawing) composed of a plurality of parallel plates. (Omitted).

As shown in FIGS. 2A and 2B, each piezoelectric element piece
A pair of ring-shaped electrodes (61) and (61) are fixed to both end surfaces of (6), and by applying an AC voltage (62) to both electrodes (61) and (61), as shown by arrows in the figure. As shown, the piezoelectric element piece (6) can be vibrated in the direction in which the inner diameter increases or decreases.
As shown in FIG. 3, the piezoelectric element piece (6) is attached to the inner peripheral wall of the acoustic tube (1) via a ring-shaped elastic member (8). Vibration on the outer peripheral surface of the piezoelectric element piece (6) is absorbed.

In the acoustic refrigerator shown in FIG.
2 connected to the phase adjuster (7) and the 90 ° phase adjuster (72)
One set of two piezoelectric element pieces (6) and (6), and one set of two piezoelectric element pieces (6) and (6) connected to the 45 ° phase adjuster (71) and the 135 ° phase adjuster (73). And 90 ° phase adjuster (72)
And the two piezoelectric element pieces (6) and (6) connected to the 180 ° phase adjuster (74) form a set, and the 135 ° phase adjusters (73) and 2
Two piezoelectric element pieces connected to a 25 ° phase adjuster (75)
(6) (6) is a set, and the 180 ° phase adjusters (74) and 27
Two piezoelectric element pieces (6) connected to a 0 ° phase adjuster (76)
(6) is a set and 255 ° phase adjuster (75) and 315 °
Two piezoelectric element pieces (6) (6) connected to the phase adjuster (77)
And a pair of two piezoelectric element pieces (6) and (6) connected to the 270 ° phase adjuster (76) and the 0 ° phase adjuster (7) to generate a sound wave.

That is, two piezoelectric element pieces (6) forming one set
(6) are arranged at an interval (90 °) that is an odd multiple of 1/4 wavelength of the sound wave, and the first sound wave emitted from one piezoelectric element piece (6) and the other piezoelectric element piece (6) The two piezoelectric element pieces (6) and (6) are driven so that the phase of the emitted second sound wave differs by an odd number times the quarter wavelength of the sound wave. As a result, the sound wave radiated from each piezoelectric element piece (6) branches in two directions in the acoustic tube (1), and a sound wave traveling in one direction and a sound wave traveling in the other direction along the pipe are generated. . And both piezoelectric element pieces
(6) Based on the arrangement interval of (6) and the phase of the generated sound wave, sound waves traveling in one direction are superimposed and amplified, and sound waves traveling in the other direction are canceled. For this reason,
Only the sound wave traveling in one direction remains in the sound tube (1), and further goes around the sound tube (1) and is superimposed with the sound wave of the same phase, so that the amplitude is increased like resonance.

In the above acoustic refrigeration apparatus, the set of the piezoelectric element pieces (6) and (6) is disposed on the entire circumference of the acoustic tube (1) with a shift of 45 °. The traveling waves generated by each set are subjected to phase adjustment according to the position shift of each set by the phase adjusters (7) to (77), that is, phase adjustment (delay processing) with a shift of 45 °. Therefore, the phases coincide with each other in the process of traveling through the acoustic tube (1). As a result, these traveling waves are combined, and a sound wave having a larger amplitude is generated.

The sound waves generated in this way are stored in the regenerator (4).
, The pressure and displacement of the minute gas mass located at each location in the regenerator (4) cause a phase shift depending on the location. As a result, the gas mass located at each location expands when located in the traveling direction of the sound wave, and compresses when located in the opposite direction, from the center position of the displacement. In the expansion stroke and the compression stroke, heat is absorbed and released, so that heat is sequentially transferred in the direction opposite to the direction in which the sound wave travels. As a result, the heat transfer process is performed reversibly, and a heat cycle close to the Carnot cycle is realized.

In the acoustic refrigeration apparatus of the present invention, as shown in FIG. 1, a plurality of piezoelectric element pieces (6) are disposed by utilizing substantially the entire inner peripheral wall of the acoustic tube (1). Since a wide vibration surface is formed, a large driving force can be obtained by the vibration surface and the high pressure generated by the piezoelectric element piece (6). Further, there is no member having a short life as in the conventional sound wave generator driven by a linear motor. As a result, the weight reduction and long life of the device are realized.

[Brief description of the drawings]

FIG. 1 is a sectional view of an acoustic refrigerator according to the present invention.

FIG. 2 is a partially cutaway front view (a) and a cross-sectional view (b) of a piezoelectric element piece provided in the acoustic refrigerator.

FIG. 3 is a sectional view of an acoustic tube constituting the acoustic refrigerator.

FIG. 4 is a first diagram for explaining the operation principle of the acoustic refrigerator according to the proposal of the applicant.

FIG. 5 is a second diagram of the above.

FIG. 6 is a schematic view showing a basic structure of the acoustic refrigerator.

FIG. 7 is a view for explaining a heat transfer process of the acoustic refrigerator.

FIG. 8 shows a TS representing a refrigeration cycle of the acoustic refrigerator.
FIG.

FIG. 9 is a diagram for explaining the refrigeration cycle.

FIG. 10 is a schematic diagram showing a basic structure of another acoustic refrigerator according to the proposal of the applicant.

FIG. 11 is a sectional view of a conventional acoustic refrigerator.

[Explanation of symbols]

 (1) Acoustic tube (4) Regenerator (5) Power supply (6) Piezoelectric element pieces (7) to (77) Phase adjuster (61) Electrode (8) Elastic member

Claims (3)

[Claims] 1. A sound wave generator is provided to face a pipe of a hollow annular sound tube whose circumference is an integral multiple of the wavelength of a sound wave, and a regenerator is provided at a predetermined position in the pipe of the sound tube. In the acoustic refrigerator, which forms a temperature gradient in the regenerator by the sound waves emitted from the sound wave generator, the sound wave generator is arranged on the inner peripheral wall of the acoustic tube along the pipeline by an odd multiple of 1/4 wavelength of the sound wave. A plurality of sets of piezoelectric element pieces arranged at intervals of are arranged along the pipeline, and these piezoelectric element pieces are connected to a drive control circuit. The phases of two sound waves emitted from the piezoelectric element pieces of the set differ by an odd multiple of 1/4 wavelength of the sound waves, and the phases of traveling waves in one direction generated by each set of the piezoelectric element pieces match each other. Adjusting the vibration phase of each piezoelectric element piece Refrigeration equipment. 2. The acoustic refrigerator according to claim 1, wherein the piezoelectric element piece has a pipe shape that can be mounted along the inner peripheral wall of the acoustic tube, and is disposed continuously over substantially the entire length of the acoustic tube. apparatus. 3. Between the inner peripheral wall of the acoustic tube and the piezoelectric element piece,
The acoustic refrigeration apparatus according to claim 2, wherein a pipe-shaped elastic member is interposed.