JP7681979B2 - Fan equipment and air conditioning machines - Google Patents

Description

This disclosure relates to a fan device and an air conditioning machine.

For example, outdoor units of air conditioners and engines used in aircraft have a fan device (ducted fan) with a fan installed inside a duct. By rotating the fan, a fluid flow is created inside the duct. In the case of outdoor units, this flow sends air to the heat exchanger. In the case of engines, the air is sent to the compressor.

However, in fan devices such as those described above, noise (rotation noise) such as NZ noise may occur. NZ noise is noise with a frequency that depends on the product of the fan's rotation speed and the number of fan blades. Depending on the operating conditions of the fan device, this noise may develop and cause energy loss, or it may affect the surrounding environment as an audible problem. Therefore, as exemplified by Patent Document 1 below, a technology has been proposed to cancel out noise by installing an obstacle with circumferential irregularities on the same axis as the fan.

U.S. Pat. No. 8,777,560

However, it is known that the volume of the above-mentioned noise varies depending on the bends in the duct and the placement of other obstacles. In addition, the frequency of the noise changes with changes in the operating conditions. For this reason, even if obstacles such as those described above are uniformly installed, there is a risk that the noise will not be sufficiently reduced.

The present disclosure has been made to solve the above problems, and aims to provide a fan device and air conditioner with further reduced noise.

In order to solve the above problems, the fan device of the present disclosure includes a fan that compresses a fluid by rotating about an axis, a motor that rotates the fan, and a cylindrical duct centered on the axis and surrounding the fan from its outer periphery, wherein an acoustic hole is formed in a wall of the duct at a circumferential position that corresponds to the position of maximum amplitude of a waveform of load fluctuation of the fan that causes NZ noise generated by the fan, and the duct has a cylindrical duct body and a bypass flow path whose upstream end branches off from a midway position of the duct body to the outer periphery of the duct body and whose downstream end communicates with the acoustic hole .
The fan device according to the present disclosure comprises a fan that compresses a fluid by rotating about an axis, a motor that rotates the fan, and a duct that is cylindrical and centered on the axis and surrounds the fan from its outer periphery, wherein an acoustic hole is formed in a wall of the duct at a circumferential position that corresponds to the position of maximum amplitude of a waveform of load fluctuation of the fan that causes NZ noise generated by the fan, and the duct has a first duct located on the upstream side, a second duct arranged spaced apart on the downstream side of the first duct, and a movable duct that is arranged between the first duct and the second duct and supported rotatably about the axis to change the circumferential position of the acoustic hole.

This disclosure makes it possible to provide a fan device and air conditioner with further reduced noise.

1 is a schematic cross-sectional view showing a configuration of an air conditioning machine according to a first embodiment of the present disclosure. 1 is a cross-sectional view of a fan device according to a first embodiment of the present disclosure. 4 is an explanatory diagram showing a graph illustrating a load fluctuation in the circumferential direction of the fan and the relationship with the circumferential position of the acoustic hole. FIG. FIG. 11 is a cross-sectional view showing a modified example of the fan device according to the first embodiment of the present disclosure. FIG. 11 is a cross-sectional view showing a configuration of a duct according to a second embodiment of the present disclosure. FIG. 11 is a cross-sectional view showing a first modified example of a duct according to a second embodiment of the present disclosure. FIG. 11 is a cross-sectional view showing a second modified example of a duct according to a second embodiment of the present disclosure. FIG. 11 is a cross-sectional view showing a configuration of a duct according to a third embodiment of the present disclosure. FIG. 11 is a cross-sectional view showing a configuration of a duct according to a fourth embodiment of the present disclosure.

First Embodiment
(Air conditioning equipment configuration)
Hereinafter, an air conditioning machine 90 and a fan unit 100 according to a first embodiment of the present disclosure will be described with reference to Fig. 1 to Fig. 3. The air conditioning machine 90 is an outdoor unit of an air conditioner. As shown in Fig. 1, the air conditioning machine 90 mainly includes a heat exchanger 200, a fan unit 100, and a housing 300.

The heat exchanger 200 is part of the refrigeration cycle, and exchanges heat between the refrigerant and the air compressed by the fan device 100 (described below). This changes the temperature and phase state of the refrigerant, and the refrigerant is sent to an indoor unit (not shown). The indoor unit changes the room temperature by further exchanging heat between the air in the room and the refrigerant. The heat exchanger 200 is surrounded by a housing 300.

(Configuration of Fan Device)
The fan unit 100 is provided on the upper part of the housing 300. The fan unit 100 pressurizes and sends air, thereby forming a flow of air passing around the heat exchanger 200 inside the housing 300. The fan unit 100 has a fan 1, a motor 2, a motor support 21, and a duct 3.

As shown in FIG. 2, the fan 1 has a cylindrical boss 11 centered on the axis Ac, and a plurality of blades 10 that protrude radially from the outer circumferential surface of the boss 11 and are arranged at intervals in the circumferential direction. The blades 10 are twisted from one side of the axis Ac direction to the other side as they move from the inside to the outside in the radial direction. As a result, when the fan 1 is rotated around the axis Ac, an air flow is generated in the axis Ac direction. In this embodiment, an example is described in which an air flow (main flow Fm) is formed from one side of the axis Ac direction (heat exchanger 200 side) to the other side (fan device 100 side) by rotating the fan 1. In the following description, the side from which the air flows is simply called the "upstream side", and the side from which the air flows is simply called the "downstream side".

The motor 2 is provided to rotate the fan 1 about the axis Ac. The motor 2 has an output shaft that extends on the axis Ac, and this output shaft is fixed to the boss 11 of the fan 1. The motor 2 is also supported and fixed to the inner wall surface of the duct 3, which will be described later, by a motor support part 21.

The duct 3 is cylindrical and covers the fan 1 and the motor 2 from the outer periphery. More specifically, the duct 3 is cylindrical and centered on the axis Ac. The space inside the duct 3 is a flow path F through which air flows. The inner diameter of the duct 3 (flow path F) is constant throughout the entire area in the direction of the axis Ac. One or more acoustic holes H are formed in the wall surface of the duct 3 upstream of the fan 1. The acoustic holes H penetrate the wall surface of the duct 3 in the radial direction. Note that only two acoustic holes H are shown in the example of FIG. 2, but the number of acoustic holes H can be changed depending on the design and specifications. The shape of the acoustic holes H can be circular, rectangular, or polygonal. The acoustic holes H are formed in an area on the fan 1 side that is greater than the diameter of the fan 1, based on the most upstream edge S of the fan 1.

The position of the acoustic hole H in the circumferential direction relative to the axis Ac is determined by the waveform of the load fluctuation when the fan 1 is driven. Here, as shown in FIG. 3, a load fluctuation wave extending in the circumferential direction is formed at the periphery of the fan 1. In other words, the load fluctuation is equivalent to the pressure fluctuation of the air flowing around the fan 1. The load fluctuation is a standing wave, and in the example of FIG. 3, the amplitude is maximum at a certain position P in the circumferential direction. Note that the waveform of the load fluctuation is determined by conditions such as obstacles before and after the duct 3 and bends in the flow path. It is known that the occurrence of such load fluctuations causes noise (NZ sound) by the fan 1. NZ sound is noise in a frequency band that depends on the product of the number of blades 10 of the fan 1 and the rotation speed of the fan 1.

As described above, since the load fluctuation wave is a standing wave, it is possible to cancel out the load fluctuation wave that causes NZ noise by superimposing an acoustic wave that is in the opposite phase to the standing wave. Therefore, the acoustic hole H is formed in a circumferential position that corresponds to the position P of the maximum amplitude of the load fluctuation waveform. The load fluctuation waveform can be obtained by various analysis tools or measurements using an actual machine. The position of the acoustic hole H is determined through such analysis and measurement.

(Action and Effect)
Next, the operation of the fan device 100 according to this embodiment will be described. As shown in Fig. 2, a mainstream Fm is formed in the flow path F of the duct 3 by rotating the fan 1. The load fluctuation of the fan 1 caused by this mainstream Fm generates the NZ sound. Meanwhile, an air flow (side flow Fs) is also formed from the acoustic hole H toward the inside of the flow path F by accompanying this mainstream Fm. This side flow Fs passes through the acoustic hole H and interferes with the fan 1, generating NZ sound with a phase different from that of the NZ sound.

The acoustic hole H is formed at a circumferential position corresponding to the position P of maximum amplitude of the waveform of the load fluctuation of the fan 1, which causes the NZ noise. Therefore, the sound generated by the acoustic hole H cancels out the NZ noise, and the noise of the fan device 100 can be reduced. In particular, in this embodiment, it is possible to reduce noise simply by forming the acoustic hole H in the duct 3. Therefore, noise can be easily reduced by subsequently forming the acoustic hole H in an existing duct 3.

Furthermore, with the above configuration, the acoustic hole H is formed closer to the fan 1 than the diameter of the fan 1 with respect to the most upstream edge S of the fan 1, so that the secondary flow Fs generated from the acoustic hole H can reach the vicinity of the fan 1 smoothly and stably. This makes it possible to further effectively reduce the noise of the fan device 100.

The above describes the first embodiment of the present disclosure. Various changes and modifications can be made to the above configuration without departing from the gist of the present disclosure. For example, in the above first embodiment, a configuration in which air is guided from the outside of the duct 3 through the acoustic hole H has been described. However, the form of the duct 3 is not limited to this, and it is also possible to adopt the configuration shown in FIG. 4 as a modified example. In the example shown in the figure, the duct 3 has a cylindrical duct body 31 and a bypass flow path 32 provided on the outer periphery of the duct body 31. The upstream end of the bypass flow path 32 branches off from the middle of the duct body 31 (flow path F) through the bypass hole H2, and the downstream end is again connected to the flow path F in the duct body 31 through the acoustic hole H.

With the above configuration, a portion of the air can be supplied to the acoustic hole H without impairing the air flow rate in the entire duct 3. This makes it possible to avoid a decrease in performance of the fan device 100 due to the formation of the acoustic hole H. In addition, compared to the case where other fluids are supplied from the acoustic hole H, the possibility of changes in the temperature and humidity of the fluid can be reduced. This makes it possible for the fan device 100 to be suitably applied to mechanical devices that require management of temperature, humidity, etc.

Second Embodiment
Next, a second embodiment of the present disclosure will be described with reference to Fig. 5. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. In this embodiment, the configuration of the duct 3B is different from that in the first embodiment. As shown in Fig. 5, the duct 3B has a first duct 31B, a second duct 32B, a movable duct 33B, and a connection portion 4.

The first duct 31B and the second duct 32B are arranged coaxially with the axis Ac as the center. The first duct 31B is arranged on the upstream side, and the second duct 32B is arranged downstream of the first duct 31B and spaced apart from it. The diameters of the first duct 31B and the second duct 32B are the same. (Note that "same" here means substantially the same, and design tolerances and manufacturing errors are allowed. The same applies to the following explanations.)

The movable duct 33B is provided between the first duct 31B and the second duct 32B. A recess R that is radially recessed and extends circumferentially is formed on the downstream edge of the first duct 31B and the upstream edge of the second duct 32B. The movable duct 33B fits into this recess R from the outer periphery. The movable duct 33B is guided by the recess R and is capable of rotating around the axis Ac. Furthermore, an acoustic hole H that penetrates the wall surface in the radial direction is formed in the wall surface of the movable duct 33B. In other words, the circumferential position of the acoustic hole H can be changed by rotating the movable duct 33B.

One example of a configuration for rotating the movable duct 33B is a mechanism using a magnet and a coil. In this configuration, a magnet is embedded in the wall of the movable duct 33B, and a coil is placed on the outer periphery of the movable duct 33B. When electricity is passed through the coil, an electromagnetic force is generated between the magnet and the coil. This electromagnetic force makes it possible to rotate the movable duct 33B. It is also possible to adopt a configuration in which the movable duct 33B is rotated by a motor or artificial muscle.

The connection part 4 connects the first duct 31B and the second duct 32B in the direction of the axis Ac. In this embodiment, the connection part 4 is located on the inner circumferential side of the movable duct 33B. In addition, multiple connection parts 4 are arranged at intervals in the circumferential direction. The above-mentioned acoustic hole H faces the flow path F from the gap between these connection parts 4.

According to the above configuration, the circumferential position of the acoustic hole H can be changed by rotating the movable duct 33B. This makes it possible to adjust the phase of the sound generated from the acoustic hole H after the fact, even if there is a change in the load fluctuation of the fan that causes the NZ sound, or even if the behavior of the NZ sound is unknown immediately after the manufacture of the fan device 100. In other words, as explained based on FIG. 3 in the first embodiment, the circumferential position of the acoustic hole H can be adjusted in accordance with the change in the position P of the maximum amplitude of the waveform of the load fluctuation. This makes it possible to further effectively reduce the noise of the fan device 100.

Furthermore, according to the above configuration, the first duct 31B and the second duct 32B are connected by providing the connection part 4. This makes it possible to avoid a decrease in the strength of the entire duct 3 due to providing the movable duct 33B at a midpoint of the duct 3. As a result, it is possible to ensure the durability of the fan device 100 for a long period of time.

The above describes the second embodiment of the present disclosure. Note that various changes and modifications can be made to the above configuration without departing from the gist of the present disclosure. For example, in the above second embodiment, an example was described in which the connection portion 4 is located on the inner periphery side of the movable duct 33B. However, as a first modified example, as shown in FIG. 6, it is also possible to configure the connection portion 4B to be located on the outer periphery side of the movable duct 33B. In this case, the above-mentioned recess R is formed on the inner periphery side of the first duct 31B and the second duct 32B.

With this configuration, because the connection portion 4B is provided on the outer periphery of the movable duct, no protrusions or steps are formed on the inner periphery of the movable duct 33B. This allows the fluid to flow more smoothly and stably inside the duct 3C.

Furthermore, it is possible to adopt a configuration that does not include the above-mentioned connection part 4 (4B), as in the duct 3D shown as a second modified example in FIG. 7. In this case, by rotating the movable duct 33D between the first duct 31D and the second duct 32D, it becomes possible to set the circumferential position of the acoustic hole H with a high degree of freedom without being hindered by the connection part 4.

Third Embodiment
Next, a third embodiment of the present disclosure will be described with reference to FIG. 8. The same reference numerals are used for the same configurations as those of the above-mentioned embodiments, and detailed description will be omitted. As shown in FIG. 8, the duct 3E according to this embodiment has a duct body 31E and an intermediate duct 32E. The duct body 31E is cylindrical with the axis Ac at its center. A recess R is formed on the inner peripheral surface of the duct body 31E, which is recessed toward the outer periphery and extends in the circumferential direction. Furthermore, an adjustment hole Hc is formed at a position overlapping with the recess R in the axis Ac direction. In this embodiment, an example in which the shape of the adjustment hole Hc is circular is described, but the shape of the adjustment hole Hc may be rectangular or polygonal.

A cylindrical intermediate duct 32E centered on the axis Ac is fitted from the inner periphery side into the recess R. In other words, the intermediate duct 32E has smaller outer dimensions than the duct body 31E. On the other hand, the inner diameter of the intermediate duct 32E is the same as the inner diameter of the duct body 31E. An acoustic hole H is formed in the intermediate duct 32E. The acoustic hole H is formed at a position corresponding (overlapping) with the above-mentioned adjustment hole Hc in the direction of the axis Ac. In this embodiment, the acoustic hole H is circular like the adjustment hole Hc. Note that the acoustic hole H can also be rectangular or polygonal. The intermediate duct 32E is guided by the recess R and can rotate around the axis Ac.

According to the above configuration, the overlapping area of the acoustic hole H and the adjustment hole Hc changes by rotating the intermediate duct 32E. In other words, the opening area of the acoustic hole H can be adjusted. This changes the flow rate of the secondary flow Fs flowing through the acoustic hole H, and the magnitude of the amplitude of the sound generated from the acoustic hole H can be adjusted. As a result, even if there is a change in the load fluctuation of the fan that causes the NZ sound, or even if the behavior of the NZ sound is unknown immediately after the manufacture of the fan device 100, the amplitude of the sound generated from the acoustic hole H can be adjusted retroactively. This makes it possible to more precisely control or reduce the noise of the fan device 100.

The above describes the third embodiment of the present disclosure. Note that various changes and modifications can be made to the above configuration without departing from the gist of the present disclosure.

<Fourth embodiment>
Next, a fourth embodiment of the present disclosure will be described with reference to Fig. 9. Note that the same components as those in the above-described embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted. As shown in Fig. 9, a duct 3F according to this embodiment has a first duct 31F, a second duct 32F, and a movable duct 33F.

The first duct 31F and the second duct 32F are arranged coaxially with the axis Ac as the center. The first duct 31F is arranged on the upstream side, and the second duct 32F is arranged downstream and spaced apart from the first duct 31F. The diameter dimensions of the first duct 31F and the second duct 32F are the same.

The movable duct 33F is provided between the first duct 31B and the second duct 32B. A recess R that is recessed in the radial direction and extends in the circumferential direction is formed on the downstream edge of the first duct 31B and the upstream edge of the second duct 32B. The movable duct 33B fits into this recess R from the inner circumferential side. The movable duct 33F is guided by the recess R, allowing it to rotate around the axis Ac.

The movable duct 33F has an inner movable duct 331 located on the inner circumference side, and an outer movable duct 332 that covers the inner movable duct 331 from the outer circumference side. An acoustic hole H that penetrates the wall surface in the radial direction is formed in the wall surface of the inner movable duct 331. An adjustment hole Hc is formed in the wall surface of the outer movable duct 332. The acoustic hole H and the adjustment hole Hc are circular. It is also possible for the acoustic hole H and the adjustment hole Hc to be rectangular or polygonal. The acoustic hole H and the adjustment hole Hc are formed at positions corresponding to each other (overlapping) in the direction of the axis Ac. Furthermore, the inner movable duct 331 is capable of rotating relative to the outer movable duct 332 around the axis Ac.

According to the above configuration, first, the circumferential position of the acoustic hole H can be changed by rotating the entire movable duct 33F. This allows the phase of the sound generated from the acoustic hole H to be adjusted. Furthermore, by rotating the outer movable duct 332, the overlapping area of the acoustic hole H and the adjustment hole Hc changes. In other words, the opening area of the acoustic hole H can be adjusted. This allows the amplitude as well as the phase of the sound generated by the acoustic hole H to be adjusted. As a result, even if there is a change in the load fluctuation of the fan that causes the NZ sound, or even if the behavior of the NZ sound is unknown immediately after the manufacture of the fan device 100, the phase and amplitude of the sound generated from the acoustic hole H can be adjusted after the fact. As a result, it is possible to control or reduce the noise of the fan device 100 more precisely.

The fourth embodiment of the present disclosure has been described above. Note that various changes and modifications can be made to the above configuration without departing from the gist of the present disclosure.

As a common feature of each embodiment, in each of the above embodiments, an example in which the fan device 100 is applied to an air-conditioning machine 90 has been described. However, the application of the fan device 100 is not limited to the air-conditioning machine 90, and it can also be suitably applied to turbofan engines and other rotating machines.

<Additional Notes>
The fan device 100 and the air conditioning machine 90 described in each embodiment can be understood, for example, as follows.

(1) The fan device 100 according to the first aspect comprises a fan 1 that rotates around an axis Ac to pump a fluid, a motor 2 that rotates the fan 1, and a duct 3 that is cylindrical and centered on the axis Ac and surrounds the fan 1 from the outer periphery, and an acoustic hole H is formed in the wall of the duct 3 at a circumferential position corresponding to the position P of maximum amplitude of the waveform of the load fluctuation of the fan 1 that causes the NZ noise generated by the fan 1.

According to the above configuration, when fluid flows into the duct 3 through the acoustic hole H, a sound different from the NZ sound is generated. The acoustic hole H is formed at a circumferential position corresponding to the position P of the maximum amplitude of the waveform of the load fluctuation of the fan 1 that causes the NZ sound. Therefore, the sound generated by the acoustic hole H cancels out the NZ sound, and the noise of the fan device 100 can be reduced.

(2) In the fan device 100 according to the second aspect, the acoustic hole H is formed on the fan 1 side from the most upstream edge S of the fan 1 toward the fan 1 rather than the diameter of the fan 1.

With the above configuration, the acoustic hole H is formed closer to the fan 1 than the diameter of the fan 1, so that the acoustic components generated at the acoustic hole H can reach the vicinity of the fan 1 smoothly and stably. This makes it possible to further effectively reduce the noise of the fan device 100.

(3) In the fan device 100 according to the third aspect, the duct 3 has a cylindrical duct body 31 and a bypass flow passage 32 whose upstream end branches off from a position midway through the duct body 31 and whose downstream end communicates with the acoustic hole H.

According to the above configuration, the acoustic hole H is connected to the downstream end of the bypass flow path 32. Furthermore, the upstream end of the bypass flow path 32 branches off from a midway position of the duct body 31. This allows a portion of the fluid to be supplied to the acoustic hole H without impairing the flow rate of the fluid in the entire duct 3. Therefore, it is possible to avoid a decrease in performance of the fan device 100 due to the formation of the acoustic hole H.

(4) In the fan device 100 according to the fourth aspect, the duct 3B has a first duct 31B located on the upstream side, a second duct 32B arranged at a distance downstream of the first duct 31B, and a movable duct 33B arranged between the first duct 31B and the second duct 32B and supported rotatably around the axis Ac to change the circumferential position of the acoustic hole H.

According to the above configuration, the circumferential position of the acoustic hole H can be changed by rotating the movable duct 33B. This makes it possible to adjust the phase of the sound generated by the acoustic hole H after the fact even if there is a change in the load fluctuation of the fan 1 that causes the NZ sound, or even if the behavior of the NZ sound is unknown immediately after the manufacture of the fan device 100.

(5) In the fan unit 100 according to the fifth aspect, the duct 3B further has connection parts 4 that connect the first duct 31B and the second duct 32B in the direction of the axis Ac and are arranged at intervals in the circumferential direction.

According to the above configuration, the first duct 31B and the second duct 32B are connected by providing the connection part 4. This makes it possible to avoid a decrease in the strength of the entire duct 3B due to the provision of the movable duct 33B.

(6) In the fan device 100 according to the sixth aspect, the connection portion 4B is provided on the outer periphery of the movable duct 33C.

With the above configuration, since the connection portion 4B is provided on the outer periphery of the movable duct 33C, no protrusions or steps are formed on the inner periphery of the movable duct 33C. This allows the fluid to flow more smoothly and stably inside the duct 3C.

(7) In the fan device 100 according to the seventh aspect, the movable duct 33F has an inner movable duct 331 in which the acoustic hole H is formed, and an outer movable duct 332 that covers the inner movable duct 331 from the outer periphery and has an adjustment hole Hc formed at a position in the direction of the axis Ac corresponding to the acoustic hole H, and that can change the opening area of the acoustic hole H by rotating around the axis Ac.

According to the above configuration, the circumferential position of the acoustic hole H can be changed by rotating the entire movable duct 33F. This allows the phase of the sound generated from the acoustic hole H to be adjusted. Furthermore, by rotating the outer movable duct 332, the overlapping area of the acoustic hole H and the adjustment hole Hc changes. In other words, the opening area of the acoustic hole H can be adjusted. This allows the amplitude as well as the phase of the sound generated from the acoustic hole H to be adjusted. As a result, even if there is a change in the load fluctuation of the fan 1 that causes the NZ sound, or even if the behavior of the NZ sound is unknown immediately after the manufacture of the fan device 100, the phase and amplitude of the sound generated from the acoustic hole H can be adjusted retroactively.

(8) In the fan device 100 according to the eighth aspect, the duct 3E has a duct body 31E in which the acoustic hole H is formed, and an intermediate duct 32E that is arranged on the inner periphery of the duct body 31E and has an adjustment hole Hc formed at a position in the direction of the axis Ac corresponding to the acoustic hole H, and is supported rotatably around the axis Ac to change the opening area of the acoustic hole H.

According to the above configuration, the overlapping area of the acoustic hole H and the adjustment hole Hc changes by rotating the intermediate duct 32E. In other words, the opening area of the acoustic hole H can be adjusted. This makes it possible to adjust the amplitude of the sound generated from the acoustic hole H. As a result, even if there is a change in the load fluctuation of the fan 1 that causes the NZ sound, or even if the behavior of the NZ sound is unknown immediately after the manufacture of the fan device 100, the amplitude of the sound generated from the acoustic hole H can be adjusted retroactively.

(9) The air conditioning machine 90 according to the ninth aspect includes a fan unit 100 and a heat exchanger 200 that exchanges heat between the fluid pumped by the fan unit 100 and the refrigerant.

The above configuration can further reduce the noise of the air conditioning machine 90.

100 Fan device 1 Fan 2 Motor 3, 3B, 3C, 3D, 3E, 3F Duct 4, 4B Connection part 10 Blade 11 Boss 21 Motor support part 31, 31E Duct body 31B, 31C, 31D, 31F First duct 32B, 32C, 32D, 32F Second duct 32E Intermediate duct 33B, 33C, 33D, 33F Movable duct 32 Bypass flow path 90 Air conditioning machine 200 Heat exchanger 300 Housing 331 Inner movable duct 332 Outer movable duct Ac Axis F Flow path Fm Main flow Fs Subflow H Acoustic hole H2 Bypass hole Hc Adjustment hole R Recess S Edge

Claims (8)

A fan that rotates about an axis to pump a fluid;
A motor for rotating the fan;
a duct having a cylindrical shape centered on the axis and surrounding the fan from an outer periphery side;
Equipped with
an acoustic hole is formed in a wall surface of the duct at a circumferential position corresponding to a position of maximum amplitude of a waveform of load fluctuation of the fan that causes NZ noise generated by the fan;
The duct is
A cylindrical duct body;
a bypass flow passage having an upstream end branching off from a midpoint of the duct body toward the outer periphery of the duct body and having a downstream end communicating with the acoustic hole;
A fan device having the above structure. A fan that rotates about an axis to pump a fluid;
A motor for rotating the fan;
a duct having a cylindrical shape centered on the axis and surrounding the fan from an outer periphery side;
Equipped with
an acoustic hole is formed in a wall surface of the duct at a circumferential position corresponding to a position of maximum amplitude of a waveform of load fluctuation of the fan that causes NZ noise generated by the fan;
The duct is
A first duct located on the upstream side;
a second duct disposed downstream of and spaced from the first duct;
a movable duct disposed between the first duct and the second duct and supported rotatably about the axis to change a circumferential position of the acoustic hole;
A fan device having the above structure. The fan unit according to claim 2 , wherein the duct further includes connection portions that connect the first duct and the second duct in the axial direction and are arranged at intervals in the circumferential direction. The fan device according to claim 3 , wherein the connection portion is provided on an outer periphery of the movable duct. The movable duct is
an inner movable duct having the acoustic hole formed therein;
an outer movable duct that covers the inner movable duct from the outer periphery side, has an adjustment hole formed at a position in the axial direction corresponding to the acoustic hole, and is capable of changing the opening area of the acoustic hole by rotating about the axis;
The fan device according to claim 2 , further comprising: The fan device according to claim 1 , wherein the acoustic hole is formed on a side closer to the fan than a diameter of the fan from an edge on an upstream side of the fan. The duct is
A cylindrical duct body;
a bypass flow passage having an upstream end branching off from a midway position of the duct body and a downstream end communicating with the acoustic hole;
The fan device according to claim 1 , further comprising: A fan device according to any one of claims 1 to 7 ;
a heat exchanger for exchanging heat between the fluid pumped by the fan device and a refrigerant;
An air conditioning machine equipped with:

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