JP2003120581A - Noise reducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an NZ reducing device as additive structure capable of reducing NZ generated by the rotation of a tangential fan without changing the shape of a stabilizer for controlling air flow of an air conditioner. SOLUTION: This device comprises the stabilizer 18 for controlling air flow generated by the rotation of the tangential fan 11 of the air conditioner, which is provided close to the tangential fan 11; and a resonator 20 comprising an opening part 21 and a throat part 22, the opening part 21 being mounted on the stabilizer 18 in opposition to the tangential fan 11. When an NZ of an intended frequency ff is generated by the rotation of the tangential fan 11, a sound wave of natural frequency f0 is generated within the resonator 20 and outputted through the opening part 21. The sound wave of natural frequency f0 is unconformable in impedance to the sound wave of intended frequency ff , and has an equal intensity of reverse phase.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resonator, and more particularly to a structure of an NZ sound reducing device for reducing NZ sound in a fan system such as an air conditioner.

[0002]

2. Description of the Related Art In a system using a blower fan such as an air conditioner, a periodic noise generated from a blower fan, which is generally called a cross flow fan (hereinafter referred to as a tangential fan), is regarded as a problem. This periodic sound is called an NZ sound because it changes according to the number of revolutions (N) of the tangential fan and the number of blades (Z). Conventionally, in order to reduce the NZ noise generated by the tangential fan, a silencer has been installed in the air flow path of the tangential fan to reduce noise.

Here, the configuration of a blower fan for a conventional air conditioner will be described with reference to FIG. FIG. 11 is a side sectional view showing the configuration of the air conditioner 10 using the tangential fan 11. In the figure, white arrows indicate air flow paths. Inside the casing 12 of the air conditioner 10, a plurality of blades 11 rotatably housed in the direction of arrow A are provided.
A tangential fan 11 having w is provided. When the tangential fan 11 rotates, air is sucked from the air suction port 13 provided on the side surface of the casing 12, the air suction port 14 and the air suction port 15 provided on the top surface. The air is heat-exchanged by the heat exchangers 16a, 16b and 16c provided in the casing 12 and cooled or heated. Then, the air that has been heat-exchanged by the heat exchangers 16a to 16c passes through the flow path B formed by the tangential fan 11 and the tip portion 12a of the casing 12 by the rotation of the tangential fan 11, and is air. It is blown out from the discharge port 17. A narrow passage C is formed by the tangential fan 11 and the stabilizer 18 on the downstream side of the passage B in the rotating direction of the tangential fan 11. In this way, the NZ sound was generated when the blades 11w of the tangential fan 11 passed through the narrowly formed flow paths B or C.

As a conventional NZ noise reduction device, Japanese Patent Application Laid-Open No. 7-332284 discloses a technique in which a fanning noise generated in the nose portion of a multiblade blower is silenced by a resonator. Further, Japanese Patent Application Laid-Open No. 7-151059 discloses a technique of reducing the noise of a centrifugal fan by a plurality of Helmholtz resonator cavities having various outer shapes provided in a cutoff device rotor.

[0005]

By the way, the air conditioner 1
In order to improve the performance of 0, it is necessary to bring the stabilizer 18 as close as possible to the tangential fan 11. That is, it is required to reduce the distance between the flow paths C formed between the tangential fan 11 and the stabilizer 18. Since the flow path C is a part that separates intake and discharge of air, it is possible to control the strength of the vortex of the air blown from the air discharge port 17 by controlling the flow of air in this part. it can. The performance of the air conditioner 10 greatly changes depending on how strongly the vortex can be point-controlled. At this time, in the flow path C near the stabilizer 18, a local fluctuation of the air flow occurs, and an NZ sound is generated between the blade 11w of the tangential fan 11 and the stabilizer 18.

As described above, in the air conditioner 10,
When the blades 11w of the tangential fan 11 pass through the positions of B and C where the air passages are formed narrow, an NZ sound which is an unavoidable sound is generated. In particular, regarding noise generated by the current air conditioner 10, the NZ in the flow path C between the tangential fan 11 and the stabilizer 18 is
It is known that the contribution of sound is large. It is stated that the NZ sound in the flow path C formed between the tangential fan 11 and the stabilizer 18 is reduced. Therefore, if the shape of the stabilizer 18 is changed to widen the channel C, the sound generated in the channel C changes. That is,
The level of the NZ sound becomes smaller. However, changing the shape of the stabilizer 18 also changes the performance. That is, by changing the shape of the stabilizer 18, N
Although the Z sound can be reduced, there is a problem that the performance of the air conditioner 10 is deteriorated accordingly. As described above, there has not been provided a device capable of reducing the NZ noise while improving the performance of the air conditioner 10.

The technique disclosed in Japanese Patent Application Laid-Open No. 7-332284 is to set the sound pressure at the opening of the resonator to "0". At this time, the performance of reducing the NZ sound is represented by the product of the area of the opening and the sound pressure due to resonance. Here, in the illustrated resonator, since the area of the opening is not sufficient, the effect of reducing the NZ sound cannot be sufficiently obtained. This resonator is also affected by the air flow. Therefore, even if this technique is applied to the tangential fan 11, the NZ sound reduction performance of the tangential fan 11 cannot be sufficiently exhibited. In addition, Japanese Patent Laid-Open No. 7-1
The technique disclosed in Japanese Patent No. 51059 is one in which a plurality of Helmholtz resonator cavities are rotated and switched by a cut-off device rotor, and this Helmholtz resonator cavity also has a sufficient opening area. Since it is not widely used, the effect of reducing the NZ sound cannot be sufficiently obtained. Furthermore, the techniques disclosed in these publications do not describe any numerical support for reducing the NZ sound.

Therefore, the present invention provides an NZ sound reducing device as an additional structure capable of reducing the NZ sound generated by the rotation of the tangential fan without changing the shape of the stabilizer. To aim.

[0009]

The present invention, which achieves the above object, provides a noise reduction device characterized by the following configuration in order to reduce the noise generated by the rotation of a fan. . The noise reduction device of the present invention includes a stabilizer that controls an air flow generated by rotation of a fan, a volume having a predetermined volume, a throat that is continuous with the volume and has an opening area smaller than that of the volume, and an opening that is continuous with the throat. And a resonator attached to the stabilizer such that the opening faces the fan. Then, this resonator is configured to generate a sound wave having impedance mismatch with a sound wave that constitutes noise and output the sound wave from the opening. Further, in the noise reduction device of the present invention, the resonator is characterized by generating a sound wave having a phase opposite to that of the sound wave of the noise and having the same intensity. With this configuration, the noise generated by the rotation of the fan can be reduced more reliably.

Further, the noise reduction device according to the present invention may have various forms. For example, a variable mechanism that can change the volume of the volume of the resonator can be further provided. This variable mechanism may be arranged such that a piston is provided in the volume portion of the resonator and the piston is moved to change the volume, or the volume is made variable by a screw or the like fitted in the volume portion. I do not care. Further, in the noise reduction device of the present invention, the variable mechanism may have a configuration capable of changing the volumes of the plurality of resonators arranged in the stabilizer simultaneously or independently. The distance between the plurality of resonators may be shorter than the wavelength of noise, but is preferably about 1/4 of the wavelength of noise.

Further, the noise reduction device of the present invention is such that the frequency specifying means for specifying the target frequency of the sound wave constituting the noise and the natural frequency of the sound wave output from the resonator based on the target frequency specified by the frequency specifying means. And a variable mechanism controller that controls the variable mechanism to output the natural frequency specified by the natural frequency specifying means.

Furthermore, the resonator in the noise reduction device of the present invention is characterized in that a plurality of resonator elements are connected to each other. Here, a plurality of the plurality of resonator elements may be directly connected to the stabilizer, and a plurality of openings thereof may be connected to the resonator element attached to the stabilizer, or may be connected in a stepwise manner.

The present invention also provides the following noise reduction device. This noise reduction device has a stabilizer for controlling the air flow generated by the rotation of the fan, a volume part having a predetermined volume, a throat part connected to the volume part and having an opening area smaller than that of the volume part, and an opening part connected to the throat part. And a resonator attached to the stabilizer so that the opening faces the fan, and the resonator is provided on the downstream side of the air flow generated by the rotation of the fan.
In addition, a windshield is provided upstream of the air flow sucked by the rotation of the fan. With this configuration, it is possible to reduce the influence of the air flow caused by the rotation of the fan on the resonator.

Further, the present invention also provides the following noise reduction device. This noise reduction device controls an air flow generated by the rotation of a fan, and a stabilizer having a through hole formed on the upstream side of the air flow generated by the rotation of the fan, a volume part having a predetermined volume, and a volume part having a predetermined volume. Having a throat portion having an opening area smaller than the continuous volume portion and an opening portion connected to the throat portion, a resonator attached to the stabilizer so that the opening portion matches the through hole, and a mesh material covering the stabilizer including the through hole. Equipped with. With this configuration, the NZ sound generated on the upstream side of the airflow generated by the rotation of the fan can be reduced at a position close to the source of the NZ sound.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION [First Embodiment] The present invention will be described in detail below based on the first embodiment shown in the accompanying drawings. FIG. 1 is a side sectional view showing the structure of the NZ sound reducing apparatus according to the first embodiment. As shown in FIG. 1, in the NZ sound reducing apparatus according to the first embodiment, a resonator (acoustic container) 20 is attached to a stabilizer 18 provided near the tangential fan 11. In order to improve the performance of the air conditioner 10 as much as possible, the stabilizer 18 is the tangential fan 11
It is desirable that they be mounted as close to each other as possible. The resonator 20 is provided with an opening 21, a throat 22 and a bottom 23, and a volume is formed by a container surrounding the outer circumference. In the first embodiment, the opening 21 of the resonator 20 is aligned with the surface 18a of the stabilizer 18 facing the tangential fan 11.
The throat portion 22 of the resonator 20 is arranged so as to penetrate the through hole 18b of the stabilizer 18.

First, the principle for reducing the NZ sound in the first embodiment will be described. FIG. 2A is a diagram showing the resonator 20 ′, and FIG. 2B is a diagram showing the state of sound waves inside the acoustic tube 24. FIG Inside the resonator 20 'shown in 2 (a), with respect to sound waves of a frequency f ₀ having propagated from the sound source 27, the resonance frequency f ₀ is generated. When the sound wave of the frequency f ₀ propagated from the sound source 27 reaches the bottom portion 23 ′ of the resonator 20 ′,
It has a mechanism for generating a pressure in the resonator 20 'such that the sound pressure p at the opening 21' becomes zero.

The manner in which the resonant sound wave having the frequency f ₀ is generated will be described with reference to the acoustic tube 24 having the open end 25 and the bottom portion 26 shown in FIG. 2B. First, the sound wave of the frequency f ₀ propagating from the sound source 27 is transmitted to the bottom portion 26 of the acoustic tube 24.
To reach. Then, in the acoustic tube 24, as shown in FIG.
A resonant sound wave having a frequency f ₀ as shown in (b) is generated. The speed at which a sound wave propagates in air is, for example, 340 m / s.
The wavelength λ of this sound wave is also fixed. Therefore, the frequency of the resonant sound wave generated in the acoustic tube 24 can be uniquely obtained, for example, f ₀ . Here, when the particle velocity of the sound wave is u and the sound pressure is p, this resonant sound wave at the bottom portion 26 is p = p _max , u = 0, the sound pressure p has a maximum value, and the particle velocity u is 0. Become.
Further, the resonance sound waves are p = 0 and u = u _max at the opening end 25 because the opening end 25 is open. Here, if the intensity of the sound is intensity I, I can be expressed as I = p × u. The sound pressure p and the particle velocity u are thus balanced.

A sound wave of a certain intensity is generated from the sound source 27. At this time, the influence of the intensity of the resonance sound wave from the resonator 20 'is such that the intensity of the sound wave from the sound source 27 is slightly lowered. Therefore, by intentionally creating an impedance mismatch (hereinafter, impedance mismatching) as described below, the total sound power of the sound wave from the sound source 27 and the resonant sound wave from the resonator 20 'is minimized. Adjust so that

Next, the reduction of sound using impedance mismatching will be described with reference to FIG. 3 and mathematical formulas. Here, the impedance of sound is a complex number representing the pressure and particle velocity of sound. By creating this impedance mismatch, the frequency f ₀ output from the resonator 20 in order to reduce the NZ sound of the frequency f _f from the tangential fan 11 shown in FIG.
The sound of can be derived. FIG. 3 is a diagram showing that a sound for reducing the sound generated from the primary sound source S1 on the flat plate is generated from the secondary sound source S2 provided near the primary sound source S1. . Here, the tangential fan 11 will be described as a primary sound source S1 and the resonator 20 will be described as a secondary sound source S2. Here, the density of air propagating sound (kg / m ³ ) is ρ, the speed of sound (m / s) is c, the wave number (1 / m) is k, the volumetric flow rate of the primary sound source S1 (m ³ / s)
Is q _p and the acoustic power of the sound radiated from this primary sound source S1 is W ₁ , W ₁ is

[0020]

[Equation 1]

[0021] Here, the sound power (W ₁ ) of the primary sound source S1 is W _pp , the component radiated from the primary sound source S1 and affected by the secondary sound source S2 is W _ps , and the component radiated from the secondary sound source S2 is the primary sound source. The component affected by S1 is W _sp , and the acoustic power of the secondary sound source S2 is W _ss . W _ps and W _sp are
It is a component generated by interaction between the primary sound source S1 and the secondary sound source S2. And the primary sound sources S1 and S2
When the acoustic power radiated from two sound sources of the next sound source S2, and W _2, W ₂ is

[0022]

[Equation 2]

It can be expressed as Here, the secondary sound source S
Let q _{s be} the volume flow rate (m ³ / s) of 2 and d be the distance (m) between the primary sound source S1 and the secondary sound source S2.
Expressed using the subscript “*” that indicates a conjugate complex number, W ₂ is

[0024]

[Equation 3]

It can be written as Here, when the sound pressure near the acoustic soft boundary (opening 21 in FIG. 1) is P _s , the transfer impedance is Z _t , and the impedance of the acoustic soft boundary is Z _s , the acoustic soft boundary using the resonator is close to the boundary. For the balance of sound pressure, the relationship shown in Formula 4 is established.

[0026]

[Equation 4]

From this, the volume flow rate q _s of the secondary sound source S2 is

[0028]

[Equation 5]

Can be written as Therefore, the sound reduction effect when using the secondary sound source S2 as the acoustic soft boundary that cancels the acoustic power W ₁ radiated from the primary sound source S1 to reduce the sound is shown by the formulas 1 to 3. The ratio P of the sound power is shown by the equation 6.

[0030]

[Equation 6]

Equation 6 can be simplified by using Equation 5.

[0032]

[Equation 7]

From equation 7,

[0034]

[Equation 8]

When is small, the ratio P of the acoustic powers W ₁ and W ₂ is a small value.

[0036]

[Equation 9]

Minimum value when

[0038]

[Equation 10]

It becomes Here, in the case of causing resonance without impedance mismatch as described with reference to FIG. 2, Z _s becomes 0, and the expression 10 does not hold. However, when a practical resonator is used as an acoustic soft boundary, the kinematic viscosity coefficient (m ³ / s) is ν, the throat length (m) is 1, the throat radius (m) is a, and the throat Area (m
² ) S, the volume (m ³ ) of the resonator is represented by V, and the transfer impedance Z _t and the impedance Z _s of the resonator portion are _expressed by the formulas 11 and 12.

[0040]

[Equation 11]

[0041]

[Equation 12]

Therefore, when the sound is to be reduced by using the resonator, the transfer impedance Z _t calculated by the formula 11 and the impedance Z _s of the acoustic soft boundary calculated by the formula 12 are shown in the formula 7. It is necessary to adjust the power ratio P to be a small value. Specifically, the contents of this adjustment include the distance d between the primary sound source S1 and the secondary sound source S2, the throat length 1 of the resonator, the throat radius a, and the resonator volume V. By appropriately adjusting these, it is possible to design the optimum conditions for reducing the sound by the resonator.

It was found that when the frequency of the resonator for 1NZ was adjusted to 809 Hz using the resonator designed in this way, the sound was reduced at 625 Hz. That is, if it is desired to reduce the sound of 625 Hz generated from the sound piece, the sound output from the resonator may be adjusted to 809 Hz. Similarly, 2NZ 1250H
To reduce the sound of z, the sound of 1624Hz is set to 1 of 3NZ.
To reduce the 875 Hz sound, add 2439 Hz sound to 4
To reduce the sound of NZ 2500Hz, the sound of 3269Hz, and to reduce the sound of 5NZ 3125Hz, 404
It may be adjusted so as to output a 4 Hz sound. However,
There was a tendency to increase the sound slightly before the frequency at which the sound was reduced.

The resonator as described above can be applied as the resonator 20 in the first embodiment. The resonator 20 in the first embodiment is the same as that shown in FIG.
As described by using the equation (1) and the equation (3), the impedance mismatch is designed. Here, if the frequency of the sound wave generated from the tangential fan 11 that is the noise source is the target frequency f _f , and the natural frequency f _{0 of the} sound wave generated from the resonator 20 to reduce the sound of this target frequency f _f , The impedance mismatch can be expressed as f ₀ ≠ f _f . When the opening area of the opening 21 of the resonator 20 is S, the volume of the resonator 20 is V, the thickness of the throat is t, and the distance between the tangential fan 11 and the stabilizer 18 is d, the resonator 20 The natural frequency f ₀ can be expressed as f ₀ = F ₁ (S, V, T) = F ₂ (f _f , d, s). As described above, the sound wave having the frequency f _f generated by the tangential fan 11 has a phase opposite to that of the sound wave, and
A sound of frequency f ₀ having an intensity substantially equal to that of the sound wave of frequency f _f is output. Moreover, the sound wave of the frequency f ₀ is generated with the timing shifted due to the intentional impedance mismatch. With this configuration, even when the stabilizer 18 is brought close to the tangential fan 11, the sound wave of the NZ sound generated from the tangential fan 11 can be reduced. Also,
Noise can be efficiently reduced in the same opening area as compared with the case where the resonator 20 'that does not utilize impedance mismatch is used.

Up to this point, the description has been given based on the side sectional view of the air conditioner 10 shown in FIG. 1, but the positional relationship between the tangential fan 11 and the resonator 20 will be explained based on the perspective view shown in FIG. . FIG. 4A is a diagram showing a case where the tangential fan 11 is regarded as one rod. Here, the length of this tangential fan 11 is about 800 mm. If the target frequency f _f generated from this tangential fan 11 is about 700 Hz, the wavelength of the sound wave of this target frequency f _f is about 50.
It is 0 mm. This wavelength of 500 mm is too long to be controlled by one resonator 20 as it is, so the resonator 20 should be controlled for each quarter wavelength. Therefore, as shown in the figure, the resonators 20a ...
20f are arranged in the stabilizer 18 at intervals of about 125 mm. By the way, the tangential fan 11 cannot be a single rod body having a size of 800 mm in terms of manufacturing. Therefore, when the tangential fan 11 is manufactured, as shown in FIG. 4B, the tangential fan 11 is divided into ten parts, for example, tangential fans 11a to 11j, and manufactured and assembled. The length of each of these tangential fans 11a to 11j is not constant and has a slight difference, but each length is shorter than 125 mm which is a quarter wavelength of the target frequency f _f described above.
mm or less. Therefore, the resonators 20a to 20j are associated with the tangential fans 11a to 11j.
Can be placed.

[Second Embodiment] The second embodiment will be described below with reference to FIGS. 5 and 6. FIG. 5 is a diagram showing a configuration of the resonator 30 and the variable mechanism 40 for reducing the NZ sound according to the second embodiment.
As shown in FIG. 5A, in the second embodiment, the resonator 30 is attached to the stabilizer 18 provided near the tangential fan 11. The resonator 30 is provided with an opening 31 and a throat 32. The resonator 20 of the first embodiment has the fixed bottom portion 23, but the resonator 30 illustrated in the second embodiment has a movable bottom portion. A piston 41 that can be moved by a rod 42 in the direction of the arrow is provided on the side of the resonator 30 that faces the opening 31. The piston 41 forms the bottom of the resonator 30. A seal member 43 such as an O-ring is provided between the piston 41 and the resonator 30 to enhance airtightness. Further, the rod 42 has a rack 44 driven by a pinion 45.
Is provided.

As shown in FIG. 5B, in the second embodiment, the resonator 30 and the variable mechanism 40 shown in FIG. 5A are arranged side by side. As illustrated, the pinion 45a, the rack 44a, the rod 42a, the resonator 30a connected to the piston 41a, and the pinion 45
b, the rack 44b, the rod 42b, and the resonator 30b connected to the piston 41b, the pinions 45a, 45
They are connected by a rotating rod 47 that penetrates b. The adjustment knob 46 is attached to the tip of the rotary rod 47.
Is provided.

The rod 42 of the variable mechanism 40 shown in FIG. 6 is provided with a groove 42a that meshes with the groove inside the rack 44. A fine adjustment knob 48 is provided at the tip of the rod 42.

According to the variable mechanism 40 including the resonator 30 and the piston 41 forming the bottom of the resonator 30 shown in FIG. 5 (a), the pinion 45 meshing with the rack 44 is rotated to rotate the rod 44 in the arrow direction. Can be moved linearly in any direction. With this, the volume of the resonator 30 can be arbitrarily changed. Further, as shown in FIG. 5B, if the pinion 45 of the variable mechanism 40 is connected by the rotary rod 47, all the resonators 3 can be rotated by rotating the adjusting knob 46.
The volume of 0 can be changed at the same time. At this time, when all the resonators 30 have the same design, the displacement amount of the piston 41 may be the same. Also,
If the shape of each resonator 30 is different,
Depending on the displacement amount of each piston 41, the pinion 45
It is necessary to change the diameter of. In addition, the variable mechanism 40
6, the main adjustment of the entire variable mechanism 40 is performed using the pinion 45 that meshes with the rack 44, and the precise fine adjustment of each resonator 30 meshes with the groove inside the rack 44. This can be done with the fine adjustment knob 48.

As described above, according to the second embodiment, the volume of the resonator 30 can be arbitrarily changed by using the variable mechanism 40. By doing so,
NZ that occurs when the tangential fan 11 rotates
It is possible to output the natural frequency that can reduce the sound most efficiently. In addition, each resonator 30
Since it is possible to finely adjust the volume of the NZ sound, it is possible to output an eigen frequency capable of best reducing the NZ sound at the position with respect to the NZ sound having a frequency that is not unique at each position.

[Third Embodiment] The third embodiment will be described below with reference to FIG. FIG. 7 is a diagram showing configurations of the resonator 30 and the variable mechanism 40 for reducing the NZ sound and the control mechanism 50 for controlling the variable mechanism 40 in the third embodiment. In the second embodiment, the variable mechanism 40 adjusts the volume of the resonator 30, but in the third embodiment shown in FIG. 7, a control mechanism 50 for controlling the variable mechanism 40 is further provided. .
Then, although the piston 41 attached to the rod 42 is moved by the pinion 45, the piston 41 is moved by using the pulse motor 55 in the third embodiment. As shown in FIG. 7, the stabilizer 18 provided near the tangential fan 11 includes a resonator 3
0 is attached. A piston 41 that can be moved by a rod 42 in the direction of the arrow is provided as the bottom of the resonator 30.
Between the resonator and the resonator 30 to improve airtightness.
A seal material 43 such as a ring is provided. Between the tangential fan 11 and the stabilizer 18, a sound pressure sensor 51 for detecting the NZ sound generated by the rotation of the tangential fan 11 is provided. A frequency calculator 52, a calculator 53, a variable mechanism controller 54, and a pulse motor 55 are connected to the sound pressure sensor 51.

When the air conditioner 10 is used in a strong state, the rotation speed of the tangential fan 11 increases. Further, when used in a weak state, the rotation speed of the tangential fan 11 decreases. That is, the rotation speed of the tangential fan 11 is not always constant, but changes depending on the usage state of the air conditioner 10. When the rotation speed changes, the frequency of the NZ sound also changes accordingly. In the third embodiment, the natural frequency generated from the resonator 30 is changed by moving the pulse motor 55 and appropriately changing the volume of the resonator 30 according to the NZ sound that changes depending on the rotation speed of the tangential fan 11. Can be changed. The NZ sound generated by the rotation of the tangential fan 11 is detected by the sound pressure sensor 51 and sent to the frequency calculator 52. The frequency calculator 52 detects that the sound detected by the sound pressure sensor 51 has a frequency of, for example, f _f . And this detected frequency f
_f is sent to the calculator 53. The calculator 53 calculates a natural frequency f ₀ for canceling this frequency f _f and sends it to the variable mechanism controller 54. Then, the variable mechanism controller 54 calculates the displacement amount for causing the resonator 30 to generate the natural frequency of f ₀ , and controls the pulse motor 55 to move the piston 41 based on this displacement amount. Then, the pulse motor 55 moves the rod 42 in either direction of the arrow to change the volume of the resonator 30. In the third embodiment, this pulse motor 55
According to this, all variable mechanisms 40 may be controlled, or each variable mechanism 40 may be controlled independently.

As described above, according to the third embodiment, the volume of the resonator 30 can be changed according to the sound pressure of the NZ sound detected by the sound pressure sensor 51.
Then, even when the rotation speed of the tangential fan 11 changes according to the operating condition of the air conditioner 10 and the NZ sound changes, this NZ sound is also changed according to the NZ sound at that time.
It becomes possible to output a sound wave having a natural frequency capable of reducing sound.

[Fourth Embodiment] The fourth embodiment will be described below with reference to FIG. FIG. 8 is a diagram showing the configuration of the resonator 60 for reducing the NZ sound according to the fourth embodiment. In the first to third embodiments, the resonator 30 provided with one opening and one throat has been described, but the tangential fan 11 is described.
The NZ sound generated at 1 is not limited to the frequency of 1NZ, but may be the frequency of 2NZ or 3NZ.
Therefore, in the fourth embodiment, a resonator 60 capable of reducing not only 1NZ NZ sound but also 1NZ to 3NZ NZ sound will be described. The resonator 60 shown in FIG. 8 includes a first resonator 61, a second resonator 62, and a third resonator 63. The first resonator 61 has a throat portion 61a and an opening portion 61b, and the second resonator 62 has a throat portion 62a.
The third resonator 63 is provided with a throat portion 63 a as each element of the resonator 60. The resonator 60 is attached to the stabilizer 18 provided near the tangential fan 11. The elements of each of these resonators 60 are first
It may be attached to the resonator 61 in stages, or a plurality of the first resonators 61 may be attached.

The internal impedance of the first resonator 61 is Z _s1 , the internal impedance of the second resonator 62 is Z _s2 , and the internal impedance of the third resonator 63 is Z _s3 . Then, the total impedance Z _s of the resonator 60 is Z _s = Z _s1 × Z _s2 × Z _s3 . As a result, the first resonator 61 having the internal impedance Zs1 produces 1NZ of NZ sound and the second resonator 62 having the internal impedance Zs2 produces 2N.
The third NZ sound of Z can be reduced by the third resonator 63 having the internal impedance Zs3.

As described above, in the fourth embodiment, the first resonator 61, the second resonator 62, and the third resonator 63 are provided. by this,
The resonator 60 having the one opening 61b can reduce NZ sounds of a plurality of types of frequencies. That is, it is not necessary to provide a plurality of resonators 60 for each NZ sound. In addition, if the resonator 60 has such a configuration, for example, 10 resonators 6 are arranged.
Since all 0s can reduce a plurality of NZ sounds, 2NZ and 3NZ NZ sounds can be reduced without impairing the power for reducing 1NZ NZ sounds.

[Fifth Embodiment] The fifth embodiment will be described below with reference to FIG. FIG. 9 is a diagram showing the configuration of the resonator 70 for reducing the NZ sound according to the fifth embodiment. Resonator 2 explained so far
In Nos. 0, 30, and 60, the opening is provided substantially at the center of the stabilizer 18, but in the fifth embodiment, the opening 71 of the resonator 70 is generated by the tangential fan 11 as shown in FIG. It was provided on the downstream side of the air flow. Further, a windshield 72 is provided in a portion of the opening 71 near the heat exchanger 16a shown in FIG.

Here, the rotation of the tangential fan 11
The influence of the air flow generated by the will be described. Figure 11
The tangential fan 11 rotates as shown in FIG.
And the air is sucked in from the air suction port 13 of the air conditioner 10.
Get caught Then, this air passes through the heat exchangers 16a to 16c.
Then it flows into the tangential fan 11. This
At that time, the flow velocity of the air flow is 2 m / s to 5 m / s. Well
Also, it is generated by the rotation of the tangential fan 11.
The flow velocity of the air flow is 12 m / s. Tanzen Sharfa
In order to reduce the NZ sound generated by the rotation of the rotor 11.
Natural frequency f ₀The sound wave is generated by the particle velocity from the opening 71.
The particle velocity u is affected by the air flow.
If you do, it will be drowned out by this air flow. Tanze
Downstream of the air flow generated by the rotation of the internal fan 11
On the side, the influence of the air flow from the heat exchanger 16a side is large.
However, rather than the opening 71 in the fifth embodiment,
The windshield 72 provided near the heat exchanger 16a is
Of the influence of the particle velocity u on the sound wave by the air flow of
You can

As described above, in the fifth embodiment, the opening 71 having the windshield 72 is provided on the downstream side of the airflow generated by the rotation of the tangential fan 11. As a result, a sound wave having a natural frequency for reducing the NZ sound generated from the resonator 70 is generated by the heat exchanger 16a.
It is no longer affected by the air flow from the side.

[Sixth Embodiment] The sixth embodiment will be described below with reference to FIG. FIG. 10 shows the sixth
80 for reducing NZ sound in the embodiment
It is a figure which shows the structure of. As shown in FIG. 10, in the sixth embodiment, among the stabilizers 18 provided close to the tangential fan 11, the through hole 1 is provided on the upstream side of the air flow generated by the rotation of the tangential fan 11.
8c is provided. Then, the resonator 80 having the opening 81 is attached so that the opening 81 fits into the through hole 18c. The surface of the through-hole 18c of the stabilizer 18 is made of a metal mesh material 90 that is finely meshed with about 80 to 200 mesh.
Is provided.

As described above, the rotation of the tangential fan 11 produces an air flow of 12 m / s. When the opening 81 is provided on the upstream side of the air flow of the tangential fan 11, the sound wave output from the resonator 80 is erased by the influence of the air flow. However, in the sixth embodiment, the mesh material 90 is provided on the surface of the through hole 18c. This mesh material 90
Does not allow air to pass through, but allows sound waves to pass therethrough, and thus allows passing of sound waves having a natural frequency for reducing the NZ sound generated by the rotation of the tangential fan 11.

As described above, in the sixth embodiment, the opening 81 is provided on the downstream side of the air flow generated by the rotation of the tangential fan 11. The mesh member 9 is formed so that the opening 81 is not affected by the air flow.
0 is provided. As a result, the sound wave having a natural frequency for reducing the NZ sound generated from the resonator 80 is not affected by the air flow generated by the rotation of the tangential fan 11.

[0063]

As described above, according to the present invention,
It is possible to provide a resonator capable of reducing the NZ sound generated by the rotation of the tangential fan without changing the shape of the stabilizer. This resonator has a structure for positively generating a particle velocity having a phase opposite to that of the NZ sound and having an impedance of 0.

Also, not only a particular NZ sound,
It is also possible to provide a resonator having a structure capable of reducing a plurality of types of NZ sound.

Further, it is possible to provide a resonator having a structure capable of outputting a sound wave having a natural frequency capable of reducing the NZ sound without being affected by the air flow generated by the rotation of the tangential fan. become able to.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a resonator 20 for reducing an NZ sound according to a first embodiment.

FIG. 2 is a diagram showing a state of sound waves inside a resonator 20 ′ and an acoustic tube 24.

FIG. 3 is a diagram showing how a sound for reducing the sound generated from the primary sound source S1 is generated from the secondary sound source S2.

FIG. 4 is a tangential fan 11 and a resonator 20.
It is a figure which shows the positional relationship with.

FIG. 5 is a diagram showing configurations of a resonator 30 and a variable mechanism 40 for reducing NZ sound according to the second embodiment.

FIG. 6 is a diagram showing configurations of a resonator 30 and a variable mechanism 40 for reducing NZ sound according to the second embodiment.

FIG. 7 shows a resonator 30 and a variable mechanism 40 for reducing the NZ sound according to the third embodiment, and the variable mechanism 4.
It is a figure which shows the structure of the control mechanism 50 which controls 0.

FIG. 8 is a diagram showing a configuration of a resonator 60 for reducing NZ sound according to a fourth embodiment.

FIG. 9 is a diagram showing a configuration of a resonator 70 for reducing NZ sound according to a fifth embodiment.

FIG. 10 is a diagram showing a configuration of a resonator 80 for reducing NZ sound according to a sixth embodiment.

FIG. 11 is a side sectional view of a conventional air conditioner 10.

[Explanation of symbols]

10 ... Air conditioner, 11, 11a, 11b, 11c, 11
d, 11e, 11f, 11g, 11h, 11i, 11j
... tangential fan, 11w ... blade, 12 ... casing, 12a ... tip part, 13 ... air inlet, 14 ... air inlet, 15 ... air inlet, 16a, 16b, 16c ... heat exchanger, 17 ... air Discharge port, 18 ... Stabilizer, 18
a ... Surface, 18b ... Through hole, 18c ... Through hole, 20, 20
', 20a, 20b, 20c, 20d, 20e, 20
f, 20g, 20h, 20i, 20j ... Resonator, 2
1, 21 '... opening, 22 ... throat, 23, 23' ... bottom, 24 ... acoustic tube, 25 ... open end, 26 ... bottom, sound source ...
27, 30 ... Resonator, 31 ... Opening, 32 ... Throat,
40 ... Variable mechanism, 41 ... Piston, 42 ... Rod, 43
... sealing material, 44 ... rack, 45 ... pinion, 46 ... adjusting knob, 47 ... rotary rod, 48 ... fine adjusting knob, 50 ... control mechanism, 51 ... sound pressure sensor, 52 ... frequency calculator, 53 ... operation 54, Variable mechanism controller, 55 ...
Pulse motor, 60 ... Resonator, 61 ... First resonator, 61a ... Throat portion, 61b ... Opening portion, 62 ... Second resonator, 62a ... Throat portion, 63 ... Third resonator, 6
3a ... Throat, 70 ... Resonator, 71 ... Opening, 72 ...
Windshield, 80 ... Resonator, 81 ... Opening, 90 ... Mesh material, S1 ... Primary sound source, S2 ... Secondary sound source

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) F04D 29/46 F04D 29/46 J 29/66 29/66 P (72) Inventor Koji Tanaka 2 Niihama, Arai-cho, Takasago, Hyogo Prefecture 1-1-1, Mitsubishi Heavy Industries, Ltd. Takasago Laboratory F-term (reference) 3H031 AA03 AA11 BA15 CA11 3H034 AA02 AA18 BB02 BB09 BB11 CC04 CC07 DD09 DD26 DD28 DD30 EE06 EE15

Claims (8)

[Claims] 1. A noise reduction device for reducing noise generated by rotation of a fan, comprising: a stabilizer for controlling an air flow generated by rotation of the fan; a volume portion having a predetermined volume; and a volume portion connected to the volume portion. A resonator having a throat portion having an opening area smaller than the volume portion and an opening portion connected to the throat portion, and the resonator attached to the stabilizer so that the opening portion faces the fan,
The noise reduction device according to claim 1, wherein the resonator is configured to generate a sound wave having impedance mismatch with a sound wave forming the noise and output the sound wave from the opening. 2. The noise reduction device according to claim 1, wherein the resonator generates a sound wave having an opposite phase and an intensity equal to that of the noise sound wave. 3. The noise reduction device according to claim 1, further comprising a variable mechanism that changes the volume of the volume section. 4. The noise reduction device according to claim 3, wherein a plurality of the resonators are arranged in the stabilizer, and the variable mechanism changes the volumes of the plurality of resonators simultaneously or independently of each other. 5. A frequency specifying device for specifying a target frequency of a sound wave constituting the noise, and a natural frequency of a sound wave output from the resonator based on the target frequency specified by the frequency specifying means. 4. The noise reduction according to claim 3, further comprising: a natural frequency specifying unit; and a variable mechanism controller that controls the variable mechanism to output the natural frequency specified by the natural frequency specifying unit. apparatus. 6. The noise reduction device according to claim 1, wherein the resonator is formed by connecting a plurality of resonator elements. 7. A noise reduction device for reducing noise generated by rotation of a fan, comprising: a stabilizer for controlling an air flow generated by rotation of the fan; a volume part having a predetermined volume; and a volume part having a predetermined volume. A resonator having a throat portion having a smaller opening area than the continuous volume portion and an opening portion continuous with the throat portion, and the resonator attached to the stabilizer so that the opening portion faces the fan;
The noise reduction is characterized in that the resonator is provided with the opening portion on a downstream side of an air flow generated by rotation of the fan, and a windshield provided on an upstream side of an air flow sucked by the rotation of the fan. apparatus. 8. A noise reduction device for reducing noise generated by rotation of a fan, which controls an air flow generated by the rotation of the fan and penetrates upstream of the air flow generated by the rotation of the fan. A stabilizer having a hole, a volume portion having a predetermined volume, a throat portion connected to the volume portion and having an opening area smaller than that of the volume portion, and an opening portion connected to the throat portion, and the opening portion is A noise reduction device comprising: a resonator attached to the stabilizer so as to match the through hole; and a mesh material that covers the stabilizer including the through hole.