JP2016176453A - Blower device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blower device which has improved a silencing effect of an active silencer.SOLUTION: Regarding at least two active silencing air passages 11 provided on the upstream side of a blower part 10, central axes 31 of a cross section vertical to an air flow direction in each of the active silencing air passages 11 are arranged in directions being separated from each other toward the downstream side from downstream side opening parts 16 of the active silencing air passages 11. Thus, a blower device is provided which prevents lowering of a silencing effect by a phenomenon of detecting sound generated by a speaker 23 installed in the other active silencing air passage 11, that is cross talk.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an air blower with reduced noise.

  Hereinafter, background art will be described for a range hood as an example of a blower.

  In recent years, with the diversification of the layout of a residence, cases where a kitchen and a living room are provided in the same space are increasing. Accordingly, in order to prevent noise from entering the living room and maintain quietness, the range hood installed in the kitchen is more demanded to reduce noise generated during operation. Moreover, since the frequency characteristics of the noise of the range hood tend to be distributed over a wide area, it is necessary to obtain a silencing effect in a wide frequency range.

As one means for solving such a problem, it is known to mount an active silencer unit constituted by a plurality of small-diameter air passages in a range hood. (For example, refer to Patent Document 1).
Hereinafter, the range hood will be described with reference to FIG.

  As shown in FIG. 8, the conventional range hood is configured to include a blower 102 above the range hood 101, an active silencer unit 103 at the middle position, and a hood 104 below. The active silencing unit 103 is composed of a plurality of small-diameter air passages 107a and 107b provided between the suction port 105 of the blower 102 and the opening 106 of the hood 104. Further, the active silencing device is provided in each of the small-diameter air passages 107a and 107b. 108a and 108b were provided.

  In the active silencer 108a, the downstream microphone 109a, the speaker 110a, and the upstream microphone 111a are arranged in this order from the side close to the suction port 105. Similarly, in the active silencer 108b, the downstream microphone 109b, the speaker 110b, and the upstream microphone 111b are arranged in this order from the side close to the suction port 105.

  Then, the noise generated by the operation of the blower 102 is detected by the downstream microphones 109a and 109b, and the sound of the opposite phase is emitted from the speakers 110a and 110b with respect to the detected noise to generate the noise in the respective small-diameter air passages 107a and 107b. It was intended to reduce noise by canceling out.

  In general, a duct-shaped active silencer can control up to a frequency band in which a plane wave is formed, and it is known that the frequency F varies depending on the duct diameter D. Specifically, the frequency F is determined by F = 0.5 × sound speed / D using sound speed. That is, it is possible to mute over a wide band by reducing the duct diameter.

  Furthermore, by providing the active silencer unit 103 with a plurality of small-diameter air passages, the range hood can secure a sufficient air volume for exhausting oily smoke generated during cooking.

JP 2014-163570 A

  However, in the range hood described in Patent Document 1, a phenomenon (hereinafter referred to as crosstalk) occurs in which control sounds come and go between the plurality of small-diameter air passages 107a and 107b. That is, the control sound transmitted from the speaker 110a of an arbitrary small-diameter air passage 107a is radiated from the opening on the small-diameter air passage 107a blower 102 side. The radiated control sound is reflected, for example, on the side surface of the blower 102 and is transmitted to the adjacent small-diameter air passage 107b, and is detected by the microphone 109b of the small-diameter air passage 107b. As a result, it has been found that the microphone 109 cannot detect only the noise of the small-diameter air passage 107 to be muffled, the mute control becomes unstable, and the muffling effect is reduced.

  That is, there is a problem that the silencing effect is reduced due to the influence of crosstalk caused by providing a plurality of small-diameter air paths.

  Then, this invention solves the said subject, and it aims at providing the air blower which improved the silencing effect of the active silencing unit.

  In order to achieve the above object, the air blower according to the present invention has a suction port for sucking air upstream in the air flow direction, a discharge port for discharging air sucked from the suction port, and the suction port. A blower passage communicating with the discharge port, a blower portion that is provided inside the blower passage and guides air from the suction port to the discharge port, and a plurality of active silencers provided on the upstream side of the blower portion And an active silencer for silencing in the active silencing air path, wherein at least two of the active silencing air paths are perpendicular to the air flow direction in each active silencing air path. The central axis of the cross section is arranged in the direction away from the downstream opening of the active silencing air passage toward the downstream side, thereby achieving the intended purpose.

  ADVANTAGE OF THE INVENTION According to this invention, the air blower which reduced the influence of the crosstalk which arises between several active sound deadening air paths can be provided.

The figure which shows the installation state of the range hood which concerns on Embodiment 1 of this invention. The figure which shows schematic structure of the range hood which concerns on Embodiment 1 of this invention. Side sectional view of the vicinity of the active silencing air passage according to the first embodiment of the present invention. Side sectional view of the range hood according to Embodiment 1 of the present invention. Side sectional view of the active silencer near the conventional range hood Side sectional view of the vicinity of the active silencing air passage of the range hood according to Embodiment 1 of the present invention. Side sectional view of the vicinity of the active silencing air passage of the range hood according to Embodiment 2 of the present invention. Side view of a conventional range hood

  The blower according to the embodiment of the present invention includes a suction port that sucks air upstream in an air flow direction, a discharge port that discharges air sucked from the suction port, and the suction port and the discharge port. An air passage that communicates with the air passage; an air blower that is provided inside the air passage and guides air from the suction port to the discharge port; a plurality of active silencing air passages that are provided upstream of the air blow unit; An air blower comprising an active silencer for silencing in the silencing air path, wherein at least two of the active silencing air paths have a central axis of a cross section perpendicular to the air flow direction in each active silencing air path They are arranged in a direction away from each other toward the downstream side from the downstream opening of the active silencing air passage.

  With this arrangement, the distance between the downstream openings of the active silencing air passage can be increased. As a result, it is possible to prevent a microphone installed in the active silencing air path from detecting a sound generated by a speaker installed in another active silencing air path, that is, a reduction in the silencing effect due to crosstalk. Moreover, the length of the active silencing air passage can be made longer than arranging the two central axes in parallel with the air flow in the air passage. Thereby, the time for calculating the control sound generated from the speaker with respect to the sound detected by the reference microphone can be increased. The fact that the calculation time can be taken long means that the control sound for eliminating the noise can be accurately calculated. That is, since the sound in the active silencing air path can be silenced using precisely calculated control sound with high accuracy, the silencing effect can be enhanced.

  In the blower according to the embodiment of the present invention, at least two of the active silencing air paths are arranged so that the central axes of the active silencing air paths intersect with each other in a side view.

  With this arrangement, the central axis can be separated to the upstream side even in the upstream opening portion of the active silencing air passage. Thereby, the distance of the upstream opening part of an active silencing air path can also be enlarged. Therefore, it is possible to prevent a reduction in the silencing effect due to crosstalk not only on the downstream opening side of the active silencing air passage but also on the upstream opening side. In addition, the length of the active silencing air passage can be further increased by configuring the central axes to intersect. As a result, the calculation time of the control sound can be further increased, and the silencing effect can be further enhanced.

  Further, in the blower device according to the embodiment of the present invention, the active silencer includes a reference microphone that detects a target sound to be erased, the active silencer air passage has a rectangular tube shape, and the reference microphone is disposed. The surface to be made is the most distant surface in the cross section perpendicular to the air passage.

  Thereby, the reference microphones in the at least two active silencing air paths can be arranged at the farthest positions. With this arrangement, the distance between the reference microphone and the downstream opening of the other active silencing air path can be increased. As a result, it is possible to prevent a reduction in the silencing effect due to crosstalk.

  Further, in the blower device according to the embodiment of the present invention, the active silencer includes an error microphone that detects a sound to be erased after processing, and the active silencer air passage has a rectangular tube shape, and the error microphone is The surface to be disposed is a surface facing the surface on which the reference microphone is disposed in the same active silencing air passage.

  With this arrangement, the distance between the reference microphone and the error microphone can be made larger than when the reference microphone and the error microphone are installed on the same surface. Thereby, the calculation time of the control sound can be further increased, and the silencing effect can be further enhanced.

  Further, in the blower device according to the embodiment of the present invention, the active silencer includes an error microphone that detects a sound to be erased after processing, and the active silencer air passage has a rectangular tube shape, and the error microphone is The surface to be arranged is the surface farthest from the cross section perpendicular to the air passage.

  With this arrangement, the distance between the error microphone and the downstream opening of the other active silencing air passage can be increased. As a result, it is possible to prevent a reduction in the silencing effect due to crosstalk.

  Hereinafter, using a range hood as an example of a blower, an embodiment of the present invention will be described for understanding of the present invention. The following embodiments are examples embodying the present invention, and do not limit the technical scope of the present invention. Moreover, the same number is attached | subjected about the same site | part through all the drawings. Furthermore, in each drawing, the description of the details of each part not directly related to the present invention is omitted.

(Embodiment 1)
First, the installation state of the range hood which concerns on this Embodiment is demonstrated using FIG. In addition, FIG. 1 is a figure which shows the installation state of the range hood which concerns on Embodiment 1 of this invention.

  As shown in FIG. 1, the range hood 1 attached to the kitchen is attached above the cooking device 2. The range hood 1 includes a hood portion 3 arranged so as to cover the upper surface of the cooking device 2 and an exhaust portion 4 formed so as to protrude toward the center upper surface side of the hood portion 3. Further, a duct 9 is connected above the exhaust unit 4 (exhaust direction), and constitutes an air passage for exhausting the exhaust from the exhaust unit 4 to the outside of the room, for example. In addition, the one side surface of the range hood 1 when it sees from the arrow X direction in FIG. 1, ie, the surface of the range hood which a cook faces at the time of cooking, is defined as a range hood front. In addition, an operation unit 5 that operates a blower unit described later of the range hood is disposed on the side surface of the hood unit 3 on the front side of the range hood.

  Then, the structure of the range hood 1 which concerns on this Embodiment using FIG. 2 is demonstrated. FIG. 2 is a diagram showing a schematic configuration of the range hood according to Embodiment 1 of the present invention. In addition, in FIG. 2, the state which removed the panel of the range hood front side of the exhaust part 4 is shown in order to use for an understanding, and the baffle plate provided in the collection port of the hood part 3 is represented by the dashed-two dotted line. .

  As shown in FIG. 2, the range hood 1 includes a rectangular parallelepiped exhaust portion 4 and a hood portion 3 below the exhaust portion 4 (downward in the drawing and upstream as described later).

  The exhaust part 4 has a vertically long rectangular parallelepiped shape having a top surface 6, that is, an upper direction of the drawing, and a discharge port 7 opened in a downstream direction, which will be described later, and a suction port 8 opened in the lower part. By connecting the duct 9 to the discharge port 7, the range hood 1 can be communicated outdoors. The duct 9 is not included in the range hood 1. The suction port 8 communicates with the cooking appliance side opening 28 of the hood 3.

  The inside of the exhaust part 4 includes an air passage 40 that communicates the suction port 8 and the exhaust port 7, and an active silencing air passage 11 that is connected to the suction port 8 on the upstream side and divides the upstream side of the air passage into two. I have. A blower unit 10 is provided on the downstream side of the blower passage 40.

  The air blowing unit 10 includes a fan 12, a motor (not shown) that drives the fan 12, and a casing 13 that collects air from the fan 12 and sends the air to the discharge port 7. That is, the air blowing unit 10 is located in the upper part of the exhaust unit 4 and exhausts air in the air passage 40 connecting the suction port 8 and the discharge port 7.

  The hood part 3 includes an exhaust part side opening part 14 communicating with the suction port 8, a cooking equipment side opening part 28 provided on the upstream side of the exhaust part side opening part 14, an exhaust part side opening part 14 and the cooking equipment side The air flow to the hood part 3 constituted by the current plate 41 (shown by a two-dot chain line in the drawing) provided between the openings 28 and the inner periphery of the cooking appliance side opening 28 and the outer periphery of the current plate A collection port 30 serving as an intake port is provided.

  Next, the configuration in the vicinity of the active silencing air path of the range hood 1 according to the present embodiment will be described in detail with reference to FIG. FIG. 3 is a side sectional view of the vicinity of the active silencing air passage according to the first embodiment of the present invention.

  The two active silencing air passages 11 have a rectangular tube shape, and air passages through which air flows from the lower side to the upper side, that is, the height direction are formed. Here, when an active silencing air passage section 34 perpendicular to the air flow direction inside each active silencing air path 11 is defined, a central axis 31 of the active silencing air path section 34 is a central axis of each active silencing air path 11. Matches 31. The central shaft 31 is disposed in a direction inclined away from the downstream opening 16 of the active silencing air passage 11 toward the downstream side, that is, in the direction indicated by the arrow direction 35. In other words, the flow direction of the air in each active silencing air passage 11 is arranged in a direction away from the downstream opening 16 of the active silencing air passage 11 toward the downstream side. Further, each active silencing air passage 11 is surrounded by an inner wall 20, and an inner side wall 21 that is an inner side of a side plate 43 of the exhaust part 4 is located on the outer side of the inner wall 20. It has a configuration that suppresses noise emission to the camera. Each active silencing air passage 11 includes an active silencing portion 26 for silencing inside, and a ventilation intermediate space 17 is provided between the downstream opening 16 of the active silencing air passage 11 and the casing 13. Yes.

  The active silencer 26 includes an error microphone 22 that serves as an upstream microphone, a speaker 23, and a reference microphone 24 that serves as a downstream microphone in order from the suction port 8 side on the inner wall 20 of each of the plurality of active silencer air paths 11. The active silencer 26 includes an arithmetic controller 25 that generates a control signal whose phase and amplitude are adjusted from the signals of the error microphone 22 and the reference microphone 24 and oscillates from the speaker 23.

  The error microphone 22 and the speaker 23 are brought closer to the suction port 8 side from the central part in the height direction of the active silencer air passage 11, and the reference microphone 24 is also brought closer to the air blowing part 10 side that is a noise source from the central part. Installed. The height direction is a direction connecting the discharge port 7 and the suction port 8. As a result, the error microphone 22 and the speaker 23 are disposed farther from the air blowing unit 10 than the reference microphone 24.

  The arithmetic controller 25 is connected to the error microphone 22, the speaker 23, and the reference microphone 24, and is disposed in the space between the inner wall 20 of the active silencing air passage 11 and the inner wall 21 of the exhaust part 4. This space has a rectangular tube shape that goes around the inner wall 21 of the exhaust part 4, and a space independent of the air flow path is formed by the inner wall 20, the inner wall 21, the upstream side plate 42, and the air blowing part side opening end surface 18. It is composed.

  The upstream side plate 42 is a wall surface extending from the upstream end of the active silencing air passage 11 toward the inner wall 21 of the exhaust portion 4, and the blower side opening end surface 18 extends from the downstream end of the active silencing air passage 11 to the exhaust portion 4. It is a wall surface extending in the direction of the inner wall 21.

  As described above, the calculation controller 25 is provided in a space independent of the air passage, so that it is isolated from smoke, oily smoke, steam and the like.

  Then, operation | movement of the range hood 1 is demonstrated using FIG. FIG. 4 is a side sectional view of the range hood according to Embodiment 1 of the present invention.

  The operation of the range hood 1 is performed by the user operating the operation unit 5 shown in FIG. When the range hood 1 is operated, the motor that constitutes the blower unit 10 is driven, and the fan 12 connected to the rotation shaft of the motor rotates to generate an air flow. That is, as indicated by a broken line in FIG. 4, an air flow 44 is generated that flows from the suction port 8 toward the duct 9 with the collection port 30 as an entrance.

  The air flow 44 sucked from the suction port 8 passes through the blower passage in the order of the active silencing air passage 11, the ventilation intermediate space 17, and the blower unit 10, and then passes from the discharge port 7 through the duct 9 to the outside of the exhaust unit 4. Exhausted.

  That is, the range hood 1 can collect and exhaust air containing oil smoke and water vapor rising from below (upstream direction) during cooking as an air flow 44.

  Furthermore, the range hood 1 includes an active silencer 26 in the active silencer air passage 11. The active silencer 26 detects noise radiated from the blower 10 with the reference microphone 24. The noise detected by the reference microphone 24 is transmitted to the arithmetic controller 25 as a noise signal. The arithmetic controller 25 predicts a state when noise passes near the speaker 23 based on the noise signal. The arithmetic controller 25 generates a sound signal having a phase opposite to that of the predicted noise, that is, a control signal, and transmits the control signal to the speaker 23. The speaker 23 emits a control sound based on the control signal, thereby reducing the noise of the blower unit 10 due to the blowing. And the reduced noise is radiated | emitted from the collection port 30. FIG. The reduced noise is detected by the error microphone 22 and transmitted to the arithmetic controller 25 as a correction signal. The arithmetic controller 25 can improve the silencing performance by generating a control signal based on this correction signal thereafter.

  The above is the basic operation of the range hood 1 according to the present embodiment.

  Next, the crosstalk phenomenon solved by the range hood 1 according to the present embodiment will be described with reference to FIG. 5 shows a conventional range hood, that is, the case where each active silencing air passage 211 is arranged so that the central axis 31a and the central shaft 31b of each active silencing air passage 211 are parallel to the air flow of the air passage 40. It is a sectional side view of the vicinity of the active silencing air path 211.

  As described above, the speaker 23a radiates a control sound having an opposite phase into the active silencing air path 211a with respect to the noise detected by the reference microphone 24a. This control sound acts on the noise transmitted through the active silencing air passage 11a, and a reduced sound is radiated from the collection port 30 described with reference to FIG. However, at this time, a part of the control sound generated by the speaker 23a of the active silencing air path 211a is transmitted through the active silencing air path 211a as shown by a dotted line, and is intermediately ventilated from the downstream opening 16a of the active silencing air path 211a. Radiated into the space 17. And the control sound radiated | emitted to the ventilation middle space 17 propagates the inside of the ventilation middle space 17, and penetrate | invades into the adjacent active silencing air path 211b. Then, crosstalk occurs in which the reference microphone 24b and the error microphone 22b in the adjacent active silencing air path 211b detect this control signal. Due to this crosstalk, the two microphones (reference microphone 24b and error microphone 22b) in the adjacent active silencing air path 211b detect sounds larger than the correct noise in the corresponding active silencing air path 211. . Here, “corresponding” refers to microphones installed in each active silencing air path, in other words, in the active silencing air path 211a, the reference microphone 24a and the error microphone 22a, and in the active silencing air path 211b, the reference microphone 24b and the error microphone. 22b. As a result, a louder sound than the correct control sound is output from the speaker 23b in the active silencing air path 211b, and the reference microphone 24a and the error microphone 22a detect the sound, and a louder control sound is generated from the speaker 23a. To do. Since such a phenomenon is repeated between the adjacent active silencing air paths 211, the control of the active silencing unit becomes unstable, and the silencing effect is reduced. This also occurs in the active silencing air path 211a.

  Next, a mechanism for reducing crosstalk in the range hood 1 according to the present invention will be described with reference to FIG. FIG. 6 is a side sectional view of the vicinity of the active silencing air passage 11 of the range hood according to the first embodiment of the present invention.

  The configuration of each part in FIG. 6 is as described with reference to FIG. With this arrangement, the control sound generated by the speaker 23a is radiated from the downstream opening 16a to the ventilation intermediate space 17 and further transmitted to the reference microphone 24b via the downstream opening 16b as shown in FIG. Larger than the range hood. Therefore, the magnitude of the control sound output from the speaker 23a detected by the reference microphone 24b and the error microphone 22b in the adjacent active silencing air passage 11b can be reduced. That is, it is possible to reduce the influence of crosstalk and prevent a reduction in the silencing effect.

  Further, by arranging the active silencing air passages 11 in the direction in which the central shaft 31 is separated from the downstream opening 16 toward the downstream side, the length of each active silencing air passage is longer than that of the conventional range hood shown in FIG. Can be lengthened. Thereby, the time for the arithmetic controller to calculate the control signal for the sound detected by the reference microphone 24 can be lengthened. The fact that the calculation time can be lengthened means that the control sound can be accurately calculated. Further, since the sound in the active silencing air path can be silenced using the precisely calculated control sound, the silencing effect can be enhanced.

  As described above, by arranging the central axes 31 of the two active silencing air paths 11 away from each other on the downstream side, the range hood 1 that ensures high silencing performance can be realized.

(Embodiment 2)
Then, the range hood which concerns on this Embodiment 2 is demonstrated using FIG. FIG. 7 is a side sectional view of the vicinity of the active silencing air passage 11 of the range hood 50 according to the second embodiment of the present invention.

  As shown in FIG. 7, in the range hood 50, when the direction connecting the discharge port 7 and the suction port 8 is a vertical direction, the central axes 31 of the active silencing air paths 51a and 51b intersect each other when viewed from the side. It is arranged. That is, not only the downstream openings 16a and 16b but also the upstream openings 32a and 32b toward the upstream side with respect to the two active silencing air paths 11, the central axes 31 are arranged away from each other, that is, in the arrow direction 45. doing.

  With this arrangement, the distance until the control sound generated by the speaker 23a is radiated from the upstream opening 32a to the ventilation upstream space 33 and transmitted to the upstream opening 32b is larger than that of the conventional range hood shown in FIG. . As a result, the control sound generated by the speaker 23a is reduced also in the upstream opening 32b of the active silencing air passage 51b. That is, it is possible to reduce the influence of crosstalk and prevent a reduction in the silencing effect. The ventilation upstream space 33 is an air passage space that is sandwiched between the current plate 41 and the top plate on the suction port 8 side of the hood portion 3 and guides the collected air to the suction port 8.

  Further, by arranging the central axis 31 so as to intersect in a side view, each active silencing air path is more than the conventional range hood shown in FIG. 5 or the range hood 1 shown in the first embodiment. The length can be increased. Thereby, the time for calculating the control signal can be further increased, and the silencing effect can be further enhanced.

  Furthermore, since the distance between the downstream openings 16a and 16b is also increased, the effect of the range hood 1 of the first embodiment can also be obtained.

  As described above, by arranging the central axes 31 of the respective active silencing air passages 11 so as to intersect each other in a side view, the range hood 50 that ensures high silencing performance can be realized.

(Modification)
As described above, the silencer technology of the range hood has been described as an example in which the silencer is particularly required in the blower. However, the present invention is not limited to the range hood, and can be applied to any air blower that generates noise by air blowing, such as an air purifier, a dehumidifier, or a ventilation fan.

  Moreover, in this Embodiment, although comprised from two active silencing air paths, you may increase the number of active silencing air paths according to the frequency band of the silencing object.

  Since the blower according to the present invention can suppress the occurrence of crosstalk, the blower can be applied not only to a range hood but also to a blower that generates noise by blowing air, such as an air purifier, a dehumidifier, and a ventilation fan. Useful.

1, 50 Range hood (an example of a blower)
DESCRIPTION OF SYMBOLS 2 Cooking device 3 Hood part 4 Exhaust part 5 Operation part 6 Top surface 7 Exhaust port 8 Suction port 9 Duct 10 Air blower part 11, 11a, 11b, 211, 211a, 211b Active silencer 12 Fan 13 Casing 14 Exhaust part side Opening portion 16, 16a, 16b Downstream side opening portion 17 Ventilation intermediate space 18 Blower side opening end surface 20 Inner wall 21 Inner side wall 22, 22a, 22b Error microphone 23, 23a, 23b Speaker 24, 24a, 24b Reference microphone 25 Operation controller 26 Active Silencer 28 Cooking Equipment Side Opening 30 Collection Port 31, 31a, 31b Central Axis 32a, 32b Upstream Opening 33 Ventilation Upstream Space 34 Active Silencing Airflow Cross Section 40 Airflow Path 41 Rectifying Plate 42 Upstream Side Plate 43 Side Plate 44 Air flow 51a, 51b Active silencer

Claims (5)

A suction port for sucking air upstream in the air flow direction;
A discharge port for discharging air sucked from the suction port;
An air passage communicating the suction port and the discharge port;
A blower provided inside the blower passage to guide air from the suction port to the discharge port;
A plurality of active silencing air paths provided on the upstream side of the air blowing section;
An air blower comprising an active silencer for silencing in the active silencer air path,
For at least two of the active silencing air paths, the central axes of the cross sections perpendicular to the air flow direction in the active silencing air paths are arranged away from the downstream opening of the active silencing air path toward the downstream side. Blower. For at least two of the active silencing air paths,
The air blower according to claim 1, wherein the blowers are arranged so that the central axes of the respective active silencing air passages intersect each other in a side view. The active silencer is
With a reference microphone that detects the target sound to be erased,
The active silencing air path is
A square tube shape,
The air blower according to claim 1 or 2, wherein a surface on which the reference microphone is arranged is a surface farthest in a cross section perpendicular to the air flow path. The active silencer is
It has an error microphone that detects the erasure target sound after processing,
The active silencing air path is
A square tube shape,
The air blower according to claim 3, wherein the surface on which the error microphone is disposed is a surface facing the surface on which the reference microphone is disposed in the same active silencing air path. The active silencer is
It has an error microphone that detects the erasure target sound after processing,
The active silencing air path is
A square tube shape,
The air blower according to any one of claims 1 to 3, wherein a surface on which the error microphone is disposed is a surface farthest in a cross section perpendicular to the air flow path.

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