JP2017068231A - Blower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blower capable of improving silencing effect of an active muffler.SOLUTION: The blower has a side space 24 in a part of a long side wall 22 in an active silencing wind path 4. On a wall surface 23 of the side space 24, a reference microphone 17 is disposed; and the distance from the wall surface 23 to an opposing side wall 21 is arranged to be equal to the length of a long side 19 in cross section of a wind path to thereby prevent the correlation from decreasing due to influences by standing waves in a frequency area as a silencing object. Thus, the silencing effect is improved.SELECTED DRAWING: Figure 1

Description

The present invention relates to a blower provided with an active silencer that is arranged in an air passage and silences noise generated during operation of the blower.

  In recent years, in air blowers such as air conditioners and ventilation fans, it has been required to reduce noise generated during operation. As one of means for solving such a problem, there is a method of mounting an active silencer having a duct configuration in an air passage (see, for example, Patent Document 1).

  Hereinafter, the active silencer will be described with reference to FIG.

  Conventionally, as an active silencer having a duct configuration, an internal original sound reference microphone 114, a silencer speaker 115, and an error microphone, which are sequentially provided at appropriate intervals from the upstream side inside a rectangular duct 111 made of a thin steel plate, respectively. 116 and an arithmetic controller 112 connected to each of them are known.

  In this type of apparatus, the generated sound propagating in the rectangular duct 111 together with the air flow 113 is detected by the reference microphone 114, and the arithmetic controller 112 generates a signal having a phase opposite to that of the original sound. The original sound emitted from the loudspeaker 115 is canceled and muted, the error microphone 116 monitors the internal sound, and the mute speaker 115 is set so that the output of the error microphone 116 becomes zero by the arithmetic controller 112. It adjusts automatically.

  Conventionally, as a microphone installation configuration in the active silencer disposed in the duct of the blower, there is a problem that when the microphone picks up noise caused by the airflow, an accurate noise signal cannot be acquired and the silencing effect is reduced. there were. As one means for solving such a problem, a microphone is installed in an expansion chamber in which a part of a duct wall surface is expanded in a cross-sectional direction (for example, see Patent Document 2).

  Hereinafter, the installation configuration of the microphone will be described with reference to FIG.

  As shown in FIG. 5, an expansion chamber 121 is formed by expanding a cross-sectional area perpendicular to the flow direction of the airflow for a part of the wall surface of the duct 120, and a microphone 123 is attached in the expansion chamber 121. As a result, when the airflow flowing in the duct 120 reaches the expansion chamber 121, the cross-sectional area perpendicular to the airflow direction increases, and the wind speed decreases. Furthermore, providing the microphone 123 in the expansion chamber 121 has an effect of preventing the vortex generated by peeling near the wall surface of the duct 120 from reaching the microphone 123. As a result, it is possible to reduce the influence of the air flow on the microphone 123 and to suppress the deterioration of the silencing effect.

Japanese Utility Model Publication No. 5-12308 JP-A-7-162979

  However, in the air blower described in Patent Document 2, the correlation between the reference microphone and the silencing point deteriorates due to the influence of the standing wave whose frequency is determined by the distance between the wall surface where the reference microphone is installed and the opposite duct wall surface. There is a problem that the silencing effect at that frequency is significantly reduced. It has been found that this frequency is a frequency having a half wavelength of the distance between the wall surface where the reference microphone is installed and the opposite duct wall surface.

  On the other hand, in order to obtain a good silencing effect in the duct type active silencing device, it is required that the sound generated by the speaker forms a plane wave inside the duct. The maximum frequency at which this plane wave can be formed is determined by the length of the longest side among the sides constituting the duct, and is the frequency having the longest side length among the sides constituting the duct as a half wavelength. It has been found that due to the formation condition of this plane wave, the formation of the plane wave of the speaker-generated sound becomes insufficient in the frequency band equal to or higher than the maximum mute frequency, and the muffling effect is gradually reduced. That is, as the length of the side of the duct is smaller, the silencing effect can be obtained up to a high frequency.

  Moreover, in order to obtain a desired air volume as a blower, a sufficient cross-sectional area is necessary, and in order to increase the cross-sectional area while satisfying the formation condition of the plane wave, the length of the side obtained from the formation condition of the plane wave is set to one side. In general, the length is a square cross-sectional shape.

  From the above, when the silencing effect was confirmed by providing an active silencer with a duct having a square cross-sectional shape in the blower, it was clear that the correlation in the frequency range targeted for silencing could not be ensured and the silencing effect was reduced. Became.

  As a result of study, in order to reduce the effect of airflow on the reference microphone, the distance between the wall where the reference microphone is installed and the opposite duct wall is less The frequency at which the correlation between the reference microphone and the silence point becomes worse than the length becomes lower than the maximum frequency at which the sound generated by the speaker becomes a plane wave. In other words, the present inventors have found a problem that the frequency of the standing wave that affects the reference microphone is lower than the maximum mute frequency at which the sound generated by the speaker maintains a plane wave as the mute target.

  In other words, there is a standing wave that affects the reference microphone in the frequency range to be silenced, and the correlation between the noise detected by the reference microphone and the noise at the silencing point is reduced, and the noise reduction effect may be reduced. It was revealed.

  Therefore, the present invention solves the above-described problems, and an object of the present invention is to provide a blower that improves the silencing effect of the active silencer while ensuring a desired air volume.

  In order to achieve the above object, the present invention communicates a suction port for sucking air upstream, a discharge port for discharging air sucked from the suction port, and a suction port and a discharge port. An air passage section, an air blowing section that guides air from the suction port to the discharge opening inside the air passage section, an active silencing air path provided upstream of the air passage section, a reference microphone, and a speaker. An active silencing device for silencing the silencing air path, and the active silencing air path is a rectangular tube having a long side and a short side in the air path cross section, and a part of the side wall including the long side is the cylindrical body A side space having a wall surface that protrudes in parallel to the outside of the air source, a reference microphone is disposed on the wall surface, and the distance from the wall surface to the opposite side wall is equal to the length of the long side of the air passage cross section. A device that achieves its intended purpose.

  ADVANTAGE OF THE INVENTION According to this invention, the fall of the silencing effect by an airflow or a standing wave can be suppressed, ensuring a desired air volume.

Configuration schematic diagram of air blower according to Embodiment 1 of the present invention Side sectional drawing of the air blower which concerns on Embodiment 1 of this invention. Sectional drawing of the active silencing air path of the air blower which concerns on Embodiment 1 of this invention Sectional drawing of the active silencing air path of the air blower which concerns on Embodiment 2 of this invention Another arrangement sectional view of the active silencing air passage of the blower according to Embodiment 2 of the present invention Side sectional view of an active silencer mounted on a conventional blower Sectional drawing of the active silencer mounted in the conventional air blower

  The blower according to claim 1 of the present invention communicates the suction port for sucking air on the upstream side in the air flow direction, the discharge port for discharging the air sucked from the suction port, and the suction port and the discharge port. An active silencer having an air passage portion, an air blowing portion that guides air from the suction port to the discharge port inside the air passage portion, an active silencing air passage provided upstream of the air passage portion, a reference microphone, and a speaker An active silencing device that silences the air path, and the active silencing air path is a rectangular tube having a long side and a short side in a cross section of the air path, and a part of the side wall including the long side is a part of the cylindrical body. A side space having a wall surface protruding in parallel to the outside side is provided, a reference microphone is disposed on the wall surface, and the distance from the wall surface to the opposite side wall is equal to the length of the long side of the air path cross section.

  Thus, the distance from the wall surface of the side space where the reference microphone is installed to the side wall of the active silencing air path facing the opposite side wall is equal to the length of the long side of the active silencing air path, thereby facing the wall surface where the reference microphone is installed. The frequency of the standing wave generated between the side walls can be made larger than the maximum frequency at which the sound generated by the speaker satisfies the plane wave. That is, the frequency band in which the correlation deteriorates can be moved to a region higher than the maximum frequency, and as a result, the silencing effect can be improved.

  Further, the blower according to claim 2 includes a suction port for sucking air upstream in the air flow direction, a discharge port for discharging air sucked from the suction port, the suction port and the discharge port. A communicating air passage portion, an air blowing portion that guides air from the suction port to the discharge port inside the air passage portion, an active silencing air passage provided upstream of the air passage portion, and a reference microphone; An active silencer having a speaker and performing silencing in the active silencing air path, wherein the active silencing air path is an elliptical cylinder having an air path cross section having a major axis and a minor axis, and the major axis A part of the side wall that does not intersect with the side wall has a wall surface protruding to the outside of the cylindrical body, the reference microphone is disposed from the wall surface toward the intersection of the long axis and the short axis, and from the wall surface The distance to the opposite side wall is equal to the length of the long axis A.

Thus, the distance from the wall surface of the side space where the reference microphone is installed to the side wall of the active silencing air channel facing the opposite side is equal to the length of the long axis of the active silencing air channel, so that the wall facing the reference microphone is installed. The frequency of the standing wave generated between the side walls can be made larger than the maximum frequency at which the sound generated by the speaker satisfies the plane wave. That is, the frequency band in which the correlation deteriorates can be moved to a region higher than the maximum frequency, and as a result, the silencing effect can be improved.
(Embodiment 1)
Hereinafter, the structure of the air blower according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of the air blower according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the blower 1 according to the first embodiment is formed of a case having a substantially cubic outer shape.

  The blower 1 includes a suction port 2 and a discharge port 6 provided in the housing. In addition, the air blower 1 includes an air passage portion 7 that allows the suction port 2 and the exhaust port 6 to communicate with each other, an active sound deadening air passage 4 as the active sound deadening device 3, and a blower portion 5.

  The discharge port 6 is located on the most downstream side (upward in FIG. 1) in the airflow direction in the blower 1 and communicates with the outlet 8 of the blower unit 5.

  The blower 5 includes a circular multi-blade fan 9, a motor (not shown) that rotates the multi-blade fan 9, a casing 10 that encloses the multi-blade fan 9, and a rotation shaft that is the center of rotation of the multi-blade fan 9. 11. The motor (not shown) is coaxial with the rotary shaft 11 and is arranged in a form embedded in the space inside the blower unit 5. Moreover, the rotating shaft 11 is arrange | positioned orthogonally with respect to the flow direction (from the downward direction of FIG. 1) to the airflow.

  The air blowing unit 5 sucks the air on the upstream side at the inlet 12 opened in the casing 10 and discharges the air from the discharge port 6, thereby discharging the air sucked from the suction port 2 to the outside of the blower 1. The inflow port 12 is provided on the substantially circular side surface of the casing 10 and is provided perpendicular to the rotation shaft 11.

  A plate-like partition wall 13 perpendicular to the airflow direction is arranged on the upstream side of the blower unit 5. The partition wall 13 divides the air passage portion 7 into an upstream side and a downstream side, but also includes an opening 14 that forms a part of the air passage portion 7.

  The suction port 2 is located at the most upstream (downward in FIG. 1) in the air flow direction of the blower 1 and is provided as an opening for sucking air from the outside of the blower 1.

  The active silencing air passage 4 is provided on the downstream side of the suction port 2 so that the upstream opening 15 of the active silencing air passage 4 and the suction port 2 communicate with each other. Further, the downstream opening 16 of the active silencing air passage 4 is provided in communication with the opening 14 of the partition wall 13. The active silencing air passage 4 has a rectangular cross section perpendicular to the airflow direction (details will be described later).

  In other words, the active silencing air passage 4 is arranged on the upstream side of the blower 1 and the blower 5 is arranged on the downstream side.

  Next, the configuration of the active silencing air passage 4 provided with the active silencing device 3 will be described in detail.

  The active silencer 3 includes a speaker 18 and a reference microphone 17 in order from the suction port 2 side in the air flow direction of the active silencer air passage 4. In addition, an arithmetic controller (not shown) that generates an audio signal whose phase and amplitude are adjusted from the signal of the reference microphone 17 and oscillates from the speaker 18 is provided.

  Further, the active silencing air passage 4 has a rectangular cross-sectional shape as already described. That is, it is a hollow rectangular tube, and the air passage cross section is a rectangle having a long side 19 and a short side 20. The length of the long side 19 is set to a half wavelength of the maximum silencing frequency from the plane wave condition so that the sound generated by the speaker 18 becomes a plane wave inside the duct at the maximum silencing frequency. Of the side walls 21 constituting the active silencing air passage 4, a part of the side wall 21 including the long side 19 (hereinafter referred to as the long side wall 22) protrudes in parallel to the outside of the cylindrical body 23. A side space 24 having The side space 24 opens in a substantially rectangular shape with respect to the long side wall 22, and the reference microphone 17 is installed on the wall 23. The distance from the wall surface 23 to the opposite side wall 21 is the same as the length of the long side 19 of the air path cross section.

  In addition, the speaker 18 is brought closer to the suction port 2 side from the central part in the air flow direction of the active silencing air passage 4, and the reference microphone 17 is similarly brought closer to the air blowing part 5 side that is a noise source from the central part. It is installed. As a result, the speaker 18 is disposed at a position farther from the air blowing unit 5 than the reference microphone 17.

  The above is the configuration of the blower device 1 according to the present embodiment.

  Next, the operation and action of each part during operation of the blower 1 will be described with reference to FIG. FIG. 2 is a sectional side view of the air blower 1 according to Embodiment 1 of the present invention.

  In the above configuration, when the blower 5 is operated in the blower 1, an air flow from the suction port 2 to the discharge port 6 is generated. At the same time, the noise of the blower 5 is radiated from the suction port 2 through the active silencing air passage 4.

  Since the active silencing air passage 4 has a function of making the sound pressure into a plane wave that is uniform in the cross-sectional direction, the sound pressure propagates one-dimensionally in the air passage. Therefore, in the active silencer 3, the reference microphone 17 detects noise, and transmits the detected noise as a noise signal to an arithmetic controller (not shown).

  The arithmetic control unit first predicts the sound at the muffle point 25 from the sound detected by the reference microphone 17. The prediction is performed based on the correlation between the reference microphone 17 and the muffler point 25 obtained in advance. Next, an inverted phase signal for canceling the predicted sound is generated, and this signal is generated as a canceling sound from the speaker 18 to be silenced. Thereby, noise is reduced at the silencing point 25.

  In this mechanism, the higher the correlation between the sound detected by the reference microphone 17 and the sound at the silencing point 25, the higher the silencing effect. In order to increase this correlation, it is necessary that the same sound as that detected by the reference microphone 17 is transmitted to the silence point 25. However, for example, if a sound is generated only in one of the reference microphone 17 and the silence point 25, the correlation is lowered.

  One of the factors that reduce this correlation is the generation of vortices due to the airflow. By providing the reference microphone 17 on the wall surface 23 in the side space 24, this problem can be avoided. That is, when the airflow flowing in the active silencing air passage 4 reaches the side space 24, the cross-sectional area perpendicular to the airflow direction increases, so the wind speed decreases and the generation of vortices is suppressed. Furthermore, providing the reference microphone 17 in the side space 24 has an effect of preventing the vortex generated by the separation near the side wall 21 of the active silencing air passage 4 from reaching the reference microphone 17. As a result, the influence of the airflow on the reference microphone 17 can be reduced. The distance between the long side wall 22 and the wall surface 23 is preferably about 5 mm to 10 mm.

  Next, with reference to FIG. 3, an effect of making the distance from the wall surface 23 where the reference microphone 17 is installed, which is a feature of the present embodiment, to the opposite side wall 21 equal to the length of the long side 19 of the air path cross section will be described. explain. FIG. 3 is a cross-sectional view of the active silencing air passage 4 of the air blower 1 according to Embodiment 1 of the present invention.

  As shown in FIG. 3, a side space 24 having a wall surface 23 projecting parallel to the outside of the active silencing air passage 4 is provided in a part of the long side wall 22 of the active silencing air passage 4. A reference microphone 17 is installed. Here, the length a of the long side 19 and the length b of the short side 20 are set such that the length a of the long side 19 is equal to the distance c from the wall surface 23 where the reference microphone 17 is installed to the opposite side wall 21. Is determined. For example, the length a of the long side 19 is 85 mm, and the length b of the short side 20 is 80 mm.

  As described above, the frequency of the standing wave generated in the space between the wall surface 23 where the reference microphone 17 is installed and the opposite side wall 21 is the distance c from the wall surface 23 where the reference microphone 17 is installed to the opposite side wall 21. Is a half-wavelength, and is 2 kHz in this configuration. On the other hand, the maximum frequency at which the generated sound of the speaker 18 becomes a plane wave, that is, the frequency region to be muffled, is a frequency in which the length a of the long side 19 of the active muffler air passage 4 is a half wavelength. Become. That is, by making the length a equal to the distance c, the frequency at which the correlation decreases due to the influence of the standing wave can be increased to the maximum frequency at which the sound generated by the speaker 18 satisfies the plane wave. That is, it is possible to prevent the correlation from deteriorating in the frequency region to be muffled, and as a result, the muffling effect can be improved. Further, since the distance between the long side wall 22 and the wall surface 23 is 5 mm, the air passage cross-sectional area is not greatly reduced from the case where the cross section is square, and the air volume can be secured.

  Here, the length a of the long side 19 and the distance c from the wall surface 23 on which the reference microphone 17 is installed to the opposite side wall 21 are made equal, but the distance c is larger than the length a of the long side 19. Even if it is as small as 5 to 10 mm, it is acceptable. “Equal” includes the range from 5 mm to 10 mm smaller. That is, it is important that the distance c does not exceed the length a. In this case, since the frequency of the standing wave that affects the reference microphone 17 can be made larger than the maximum frequency at which the sound generated by the speaker satisfies the plane wave, the same effect as when the length a and the distance c are equal is obtained. be able to.

  In addition, in the structure which concerns on Embodiment 1, although it is set as the active silencer which does not include an error microphone, it is good also as a structure provided with the error microphone for detecting a mute volume. In this case, the correlativity can be improved by providing a side space 24 on an arbitrary wall surface 23 of the active silencing air passage 4 and providing an error microphone in the side space 24.

  As described above, a part of the long side wall 22 of the active silencing air passage 4 includes the side space 24 having the wall surface 23 protruding in parallel to the outside, the reference microphone 17 is disposed on the wall surface 23, and the wall surface 23. By making the distance from the side wall 21 to the opposite side the same as the length of the long side 19 of the air passage cross section, it is possible to realize the air blower 1 that ensures high noise reduction performance.

  In addition, the long side 19 and the short side 20 of the active silencing air path 4 are not necessarily limited to this. It can be determined by the frequency band in which the active silencing action is performed. In addition, the distance between the long side wall 22 and the wall surface 23 is substantially preferably the above value, but if the silencing performance is obtained, the length of the long side 19 presented in the embodiment is used. The distance calculated from the ratio obtained from a and distance c may be determined so as to be obtained.

(Embodiment 2)
Next, another embodiment will be described.

  As shown in FIG. 4, the active silencing air path 4 of the present embodiment is an elliptical cylinder whose cross section has a long axis 26 and a short axis 27. The length of the long axis 26 is set to a half wavelength of the maximum silencing frequency due to plane wave conditions. And among the side walls 21 constituting the active silencing air passage 4, a part of the side wall that does not intersect with the major axis 26 (in this case, a position that intersects with the minor axis 27) projects the wall surface 23 protruding to the outside of the cylindrical body. A side space 24 is provided. The reference microphone 17 is arranged on the wall surface 23 toward the intersection 28 of the long axis 26 and the short axis 27. The distance f (corresponding to the distance c in the first embodiment) from the wall surface 23 to the opposing side wall 21 through the intersection 28 is the length d of the long axis 26 (the length of the long side 19 in the first embodiment). (equivalent to a)). That is, the wall surface 23 is configured to protrude outward from the side wall 21 by a length corresponding to the difference between the length d of the long axis 26 and the length e of the short axis. For example, when the length d of the major axis 26 is 90 mm and the length e of the minor axis is 80 mm, the wall surface 23 projects from the side wall 21 by 10 mm.

  As a result, the frequency at which the correlation decreases due to the influence of the standing wave can be increased to the maximum frequency that satisfies the plane wave condition. That is, it is possible to prevent the correlation from deteriorating in the frequency region to be muffled, and as a result, the muffling effect can be improved.

  Moreover, by making the air path cross section of the active silencing air path 4 into an elliptical shape, the distance from the point on the side wall 21 to the opposite side wall through the intersection 28 can be made different depending on the position of the point. That is, the distance from the point on the side wall 21 through the intersection 28 to the opposite side wall is not necessarily uniform. In other words, the distance to the opposing side wall 21 on the side wall 21 can be diversified as compared with the case where the air path cross section of the active silencing air path 4 is rectangular. Thereby, the influence of the standing wave which arises in the active silencing air path 4 can further be suppressed, and the silencing effect can be further enhanced. Although the side space 24 is provided on the extended line of the short shaft 27 in FIG. 4, the side space 24 may be provided at a position that does not intersect the short shaft 27 as shown in FIG. Also in this case, the wall surface 23 projects from the side wall 21 to the outside so that the distance f from the wall surface 23 through the intersection 28 to the opposing side wall 21 is equal to the length d of the long axis 26. “Equal” includes the range from 5 mm to 10 mm smaller. That is, it is important that the distance f does not exceed the length d. In this case, since the frequency of the standing wave that affects the reference microphone 17 can be made larger than the maximum frequency at which the generated sound of the speaker satisfies the plane wave, the same effect as when the length d and the distance f are equal is obtained. be able to.

  As described above, the wall surface of the active silencing air passage 4 is an elliptical shape having a major axis 26 and a minor axis 27, and a part of the side wall 21 that does not intersect the major axis 26 protrudes to the outside of the cylindrical body. The reference microphone 17 is arranged from the wall surface 23 toward the intersection 28 of the long axis 26 and the short axis 27, and the distance from the wall surface 23 to the opposite side wall 21 is the length of the long axis 26. By making it equal, the air blower 1 which ensured the high noise reduction performance is realizable.

  The major axis 26 and the minor axis 27 of the active silencing air path 4 are not necessarily limited to this. It can be determined by the frequency band in which the active silencing action is performed. In addition, the distance between the side wall 21 and the wall surface 23 is substantially preferably the above value. However, if the silencing performance is obtained, the ratio obtained from the distance f and the length d presented in the embodiment. The distance f calculated from the above may be determined so as to be obtained.

  INDUSTRIAL APPLICATION This invention is useful as a technique applicable to the air blower which generate | occur | produces noise by ventilation, such as a range hood, an air cleaner, a dehumidifier, and a ventilation fan.

DESCRIPTION OF SYMBOLS 1 Air blower 2 Suction port 3 Active silencer 4 Active silencer air path 5 Air blower 6 Outlet 7 Air path 8 Outlet 9 Multiblade fan 10 Casing 11 Rotating shaft 12 Inlet 13 Partition wall 14 Open 15 Upstream opening 16 Downstream side opening 17 Reference microphone 18 Speaker 19 Long side 20 Short side 21 Side wall 22 Long side side wall 23 Wall surface 24 Side space 25 Silence point 26 Long axis 27 Short axis 28 Intersection

Claims (2)

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 portion communicating the suction port and the discharge port;
A blower unit for guiding air from the suction port to the discharge port inside the air passage unit;
An active silencing air passage provided on the upstream side of the air passage portion;
An active silencer having a reference microphone and a speaker for silencing the active silencer air path;
The active silencing air path is a rectangular tube having a long side and a short side in the air path cross section, and a side having a wall surface in which a part of the side wall including the long side protrudes in parallel to the outside side of the cylindrical body With space,
Placing the reference microphone on the wall;
The air blower characterized in that the distance from the wall surface to the opposing side wall is equal to the length of the long side of the air passage cross section. 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 portion communicating the suction port and the discharge port;
A blower unit for guiding air from the suction port to the discharge port inside the air passage unit;
An active silencing air passage provided on the upstream side of the air passage portion;
An active silencer having a reference microphone and a speaker for silencing the active silencer air path;
The active silencing air path is an elliptical cylinder whose cross section has a major axis and a minor axis, and has a wall surface in which a part of the side wall that does not intersect the major axis protrudes to the outside of the cylinder. With side space,
The reference microphone is arranged from the wall surface toward the intersection of the long axis and the short axis,
The blower characterized in that a distance from the wall surface to the opposing side wall is equal to the length of the long axis.