JP2016061534A - Active silencer and blower device including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blower device and an active silencer capable of acquiring a sufficient silence effect by suppressing noise due to an airflow and a standing wave even when a swirl generates at a downstream end part or a strong standing wave generates in a finite length duct by the installation into the blower, in an active silencing structure of a duct structure in an airflow field.SOLUTION: A blower device includes an active silencing air passage 6 inside the blower device 1 and a multiblade fan 3, and the multiblade fan 3 and the active silencing air passage 6 are connected via an enlarged air passage 5 in which an opening area is larger than that of the active silencing air passage 6. A sensor microphone 10 is installed on an installation surface 9 parallel with a rotary shaft 8 of the multiblade fan 3 in the active silencing air passage 6, and on the installation surface 9, an extension surface 13 protruded to the enlarged air passage is provided.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an active silencer that is disposed in an internal air passage and silences noise generated during operation, and an air blower including the active silencer.

  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 internal air passage.

  Conventionally, as this type of active silencer, there has been known one in which a microphone is installed with a space provided in a low-speed airflow range in order to reduce the influence of the airflow in the air passage (see, for example, Patent Document 1).

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

  Conventionally, as an active silencer having a duct structure, an internal original sound reference microphone 111, a silencer speaker 112, and an error microphone, which are sequentially attached at appropriate intervals from the upstream side inside a rectangular duct 101 made of a thin steel plate, respectively. 113 and an arithmetic controller 102 respectively connected to them are known.

  In this type of device, the generated sound propagating in the rectangular duct 101 together with the air flow 103 is detected by the reference microphone 111 for frequency and the like, and the arithmetic controller 102 creates a signal having a phase opposite to that of the original sound. The muffler speaker 112 is released into the rectangular duct 101 and cancels the original sound. The error microphone 113 monitors the internal sound, and the calculation controller 102 causes the muffler speaker 112 to output zero. Is automatically adjusted. As shown in FIG. 6, a microphone section 104 is provided in the corner low-speed airflow range of the square duct 101, and a reference microphone 111 and an error microphone 113 are provided.

  As a result, the reference microphone 111 and the error microphone 113 do not detect the noise generated by the airflow in the duct, but can accurately detect only the noise original sound to be silenced, and the silencer feedback function is provided. improves.

Japanese Utility Model Publication No. 5-11198

  However, when the device described in Patent Document 1 is cut to an appropriate length for inclusion in the air blower body, the air passage expands beyond the downstream end of the duct, that is, a sudden expansion air passage. In this case, a vortex is generated from the downstream end of the duct. When the downstream end of the duct and the reference microphone or error microphone that is the downstream microphone are close to each other, the microphone picks up noise generated by the vortex. In other words, this vortex becomes noise when detecting the original noise, and there is a problem that a sufficient silencing effect cannot be obtained.

  In addition, when an active silencer is mounted on the blower, it is necessary to shorten the duct to limit the dimensions. However, when the duct is short, a strong standing wave is generated in the duct, and the microphone detects the standing wave, so that the effect of the active silencer is deteriorated at a specific frequency.

  Therefore, the present invention solves the above-described problems, and an object of the present invention is to provide an active silencer that suppresses a reduction in the silencing effect due to airflow and standing waves, and a blower provided with the same.

  The present invention includes a square tube-shaped active silencing air passage provided with an upstream microphone, a speaker, and a downstream microphone in this order from the upstream side in the airflow direction, and a rotating shaft that goes straight in the airflow direction. A blower that includes a centrifugal fan that sucks air from a suction port provided vertically, and that connects the centrifugal fan and the active silencing air passage through an enlarged air passage having a larger opening area than the active silencing air passage. An air blower provided with an extended surface in which a downstream microphone is installed on an installation surface parallel to the rotation axis in the active silencing air passage and protruded into the enlarged air passage on the installation surface, and an active silencer used in the air blowing device This achieves the 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.

Configuration outline diagram of blower device according to Embodiment 1 of the present invention Partial enlarged view of the active silencer Side sectional view of the air blower according to Embodiment 2 of the present invention. Configuration outline diagram of conventional active silencer Sectional view of a conventional active silencer

  An air blower according to an embodiment of the present invention includes a square tube-shaped active silencing air path including an upstream microphone, a speaker, and a downstream microphone in this order from the upstream side in the airflow direction, and a direct flow in the airflow direction. A centrifugal fan that sucks air from a suction port provided perpendicular to the rotation axis, and the centrifugal fan and the active silencing air through an enlarged air passage having a larger opening area than the active silencing air passage. A blower connected to a road, wherein the downstream microphone is installed on an installation surface parallel to the rotation axis in the active silencing air passage, and an extension surface protruding from the enlarged air passage is formed on the installation surface. It is provided.

  As a result, the vortex generated at the downstream end as a cause of noise is kept away from the microphone, so that the correlation between the microphones can be improved and the silencing effect can be increased. Further, since the extended surface is provided on a surface parallel to the rotation axis, the air blowing performance is not deteriorated by inhibiting the flow to the suction port. Further, since the extension surface is installed in the empty space so as to avoid the centrifugal fan whose flow direction dimension is not uniform, the size of the blower does not increase. Furthermore, the presence of the suddenly expanding air passage at the downstream end causes a phenomenon that a standing wave is generated in the active silencing air passage and disturbs the detection signals of the upstream microphone and the downstream microphone. On the other hand, since the extension surface makes the length in the active silencing air path direction non-uniform, it is possible to reduce the influence of the standing wave, increase the correlation between the microphones, and increase the silencing effect.

  Moreover, the air blower according to the embodiment of the present invention includes a downstream end portion of the extension surface that is more than a maximum distance between the downstream end portion of the other surface other than the installation surface and the downstream microphone in the active silencing air passage. The minimum distance from the downstream microphone is increased.

  As a result, the downstream end of the downstream microphone installation surface that most affects the downstream microphone detection accuracy is furthest away from the downstream microphone. For this reason, the influence of noise due to the vortex generated at the downstream end can be further reduced, the correlation between the microphones can be increased, and the silencing effect can be increased.

  Further, in the blower device according to the embodiment of the present invention, the two active silencing air paths are arranged in parallel on a plane perpendicular to the rotation axis to form an integrated air path, and the downstream microphones of the respective active silencing air paths and The extension surface is provided only on the surface that is the outside of the integrated air passage.

  Thereby, since the air path width per one of the active silencing air paths can be reduced, a silencing effect up to a higher frequency can be obtained.

  Further, the active silencer according to the embodiment of the present invention is provided with a square tube-shaped active silencer air passage having an upstream microphone, a speaker, and a downstream microphone in this order from the upstream side in the airflow direction, and the downstream microphone. The installation surface is provided with an extended surface that protrudes downstream from the downstream end of the other surface where the downstream microphone is not installed.

  As a result, the vortex generated at the downstream end that causes noise is kept away from the microphone, so that the correlation between the microphones can be improved and the noise reduction effect can be increased. In addition, there is an extension surface to reduce the correlation between the upstream microphone and the downstream microphone due to the occurrence of a standing wave in the active silencing air path due to the opening at the downstream end. Since the lengths of the microphones are made non-uniform, it is possible to reduce the influence of standing waves, increase the correlation between microphones, and increase the silencing effect.

  Further, the active silencer according to the embodiment of the present invention is configured such that the downstream end portion of the extension surface is larger than the maximum distance between the downstream end portion of the other surface other than the installation surface and the downstream microphone in the active silencer air passage. And the minimum distance from the downstream microphone is increased.

  As a result, the downstream end of the downstream microphone installation surface that has the most influence on the downstream microphone detection accuracy is the downstream end of the extended surface farthest from the downstream microphone, thereby reducing the influence of noise caused by vortices generated at the downstream end. It is possible to increase the correlation between microphones and increase the silencing effect.

(Embodiment 1)
Embodiment 1 of the present invention will be described below with reference to FIG. FIG. 1 is a schematic configuration diagram of the blower.

  The blower device 1 according to the first embodiment includes a substantially cubic housing, and includes an air inlet 7, an active silencer air passage 6 as an active silencer, an enlarged air passage 5, a centrifugal fan 50, and an exhaust outlet 2. I have.

  The exhaust port 2 is located on the most downstream side (upward in FIG. 1) in the airflow direction in the blower 1 and communicates with the downstream opening of the centrifugal fan 50.

  The centrifugal fan 50 includes a circular multi-blade fan 3, a motor (not shown) that rotates the multi-blade fan 3, a scroll casing 4 that wraps the multi-blade fan 3, and a rotation that is the center of rotation of the multi-blade fan 3. A shaft 8 is provided. The motor (not shown) is coaxial with the rotary shaft 8 and is arranged so as to be embedded in the space inside the centrifugal fan. Moreover, the rotating shaft 8 is arrange | positioned orthogonally with respect to the flow direction (upper side of FIG. 1).

  The centrifugal fan 50 sucks air upstream from the suction port 51 and discharges air from the exhaust port 2, thereby discharging the air sucked from the suction port 7 to the outside of the blower 1.

  The suction port 51 is provided on the substantially circular side surface of the scroll casing 4 and is provided perpendicular to the rotation shaft 8.

  The air inlet 7 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 6 is provided on the downstream side of the air inlet 7 so that the upstream opening of the active silencing air passage 6 and the air inlet 7 communicate with each other. The active silencing air passage 6 has a hollow rectangular tube shape, and the cross-sectional shape perpendicular to the airflow direction is rectangular. The active silencing air passage 6 includes an installation surface 9 parallel to the rotation axis 8.

  The installation surface 9 includes an error microphone 12 (corresponding to an upstream microphone), a mute speaker 11 (corresponding to a speaker), and a sensor microphone 10 (corresponding to a downstream microphone) in order from the upstream side in the airflow direction. Further, the installation surface 9 is provided with an extension surface 13 protruding in the downstream direction (the enlarged air passage side described later).

  The extended surface 13 is provided in parallel to the rotating shaft 8 to avoid contact with the bulge on the upstream side of the scroll casing 4.

  On the downstream side of the active silencing air path 6, an enlarged air path 5 that connects the downstream opening of the active silencing air path 6 and the centrifugal fan 50 is provided.

  The enlarged air passage 5 has an upstream opening larger than the rectangular cross section of the active silencing air passage 6. In other words, the air passage rapidly expands from the downstream opening of the active silencing air passage 6 to the enlarged air passage 5.

  Next, details of the extension surface 13 will be described with reference to FIG. FIG. 2 is a partially enlarged view of the active silencing device. In the active silencing air passage 6, the downstream end portions (active silencing air passage downstream end portion 14) and the extension surface 13 of three surfaces to which the sensor microphone 10 is not attached are shown. The positional relationship of the extended surface edge part 15 which is a downstream edge part is shown.

  In the blower device 1 according to the present embodiment, the extension distance 16 that is the minimum distance between the sensor microphone 10 and the extended surface end 15 is a reference that is the minimum distance between the sensor microphone 10 and the active silencing airflow downstream end 14. The distance is larger (longer) than the distance 17.

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

  Then, operation | movement and an effect | action of each part at the time of operation | movement of the air blower 1 are demonstrated. When the centrifugal fan 50 is operated in the blower 1, an air flow from the intake port 7 to the exhaust port 2 is generated. At the same time, the noise of the centrifugal fan 50 is radiated from the intake port 7 through the expansion air passage 5 and the active silencing air passage 6.

  Since the active silencing air path 6 has the effect 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 path. Therefore, in the active silencing air passage 6, the sensor microphone 10 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 error microphone 12 that becomes a muffler point from the sound detected by the sensor microphone 10. The prediction is performed based on the correlation between the sensor microphone 10 and the error microphone 12 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 mute speaker 11 to be silenced. Further, in order to prevent the sound transmitted to the error microphone 12 from being shifted from the predicted sound and reducing the muffling effect, the calculation detected by the error microphone 12 is transmitted to the calculation control unit so that the calculation control unit is correlated. To correct. Thereby, the silencing performance is improved.

  In this mechanism, the higher the correlation between the sound detected by the sensor microphone 10 and the sound detected by the error microphone 12, the higher the noise reduction effect. In order to increase this correlation, it is necessary that the same sound as that detected by the sensor microphone 10 is transmitted to the error microphone 12. However, for example, when a sound that can be heard only by one microphone is generated, the correlation is lowered. One of the causes for reducing this correlation is the occurrence of “vortices” at the end, which will be described later.

  Incidentally, the enlarged view of the extension surface 13 in FIG. 2 is a case where the centrifugal fan 50 (not shown) sucks air in the direction of the enlarged air passage 5 (upward in FIG. 2). That is, the airflow flows in the direction from the error microphone 12 toward the sensor microphone 10, and is released to the enlarged air passage 5 at the downstream end portion 14 and the extended surface end portion 15 of the active silencing air passage.

  In general, when an air flow is discharged into an enlarged air passage, a vortex 18 is generated at the end of the air passage. The vortex generates sound because it accompanies pressure changes. This sound is small, that is, a noise signal that can be detected only by a close microphone. In addition, this sound moves downstream in the flow. That is, it is detected by the sensor microphone 10 but not detected by the error microphone 12. The presence of this vortex lowers the correlation between the sensor microphone 10 and the error microphone 12, so that the silencing effect is also reduced.

  Here, in the air blower 1, since the extension surface 13 is extended to the installation surface 9 on which the sensor microphone 10 is installed, the influence is reduced by moving away the adjacent vortex, that is, the noise reduction effect is increased and the noise reduction effect is increased. I can do it.

  Further, in the blower 1, by making the extension distance 16 longer than the reference distance 17, it is possible to reliably obtain the effect of moving away the adjacent vortex, and to increase the correlation and increase the silencing effect. I can do it.

  In addition, since the extended surface 13 is provided on a surface parallel to the rotation shaft 8, that is, at a position that does not interfere with the suction airflow of the centrifugal fan 50 that sucks air from the axial direction, the blowing performance may be reduced. Absent. Further, by providing the extension surface 13 on a surface parallel to the rotation shaft 8, the extension surface 13 can be projected into the empty space of the scroll casing 4 formed by bending, so that the size of the blower device is increased. Can be minimized.

  Further, the boundary between the active silencing air passage 6 and the enlarged air passage 5 is a sudden expansion opening. In such a rapidly expanding shape, a standing wave is generated in the active silencing air path 6 and the sound is amplified or attenuated, thereby reducing the correlation between the position of the sensor microphone 10 and the position of the error microphone 12. Will occur. For example, when a strong standing wave antinode is located at the position of the sensor microphone 10 and a strong standing wave node corresponds to the position of the error microphone 12, the correlation is greatly reduced.

  However, the length of the extension surface 13 from the air inlet 7 to the downstream end portion of the active silencing air passage 6 can be made uneven, that is, the generation of a strong standing wave can be suppressed to reduce the influence of the standing wave. As a result, the correlation between the position of the sensor microphone 10 and the position of the error microphone 12 can be increased, and the silencing effect can be increased.

(Embodiment 2)
In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, detailed description thereof will be omitted, and description will be made with reference to FIG.

  As shown in the side sectional view of the blower in FIG. 3, the blower 20 of the second embodiment is integrally provided with active silencing air paths 21 and 22 adjacent to each other in parallel. Further, the active silencing air passages 21 and 22 have a rectangular cross-sectional shape, and only two surfaces that are parallel to the rotating shaft 8 of the centrifugal fan 50 and outside the active silencing air passages 21 and 22 are provided on the installation surface 9. It is said.

  That is, in the present embodiment, the active silencing air path (active silencing air path 21 + active silencing air path 22) is divided into two air paths. By the way, the lower limit frequency of the sound to which active silencing can be applied in the duct is determined by the formula of sound speed ÷ (2 × wind path width). According to this formula, the silencing frequency range can be expanded by dividing and reducing the wind path width per one wind path.

  Further, since the extension surface 13 is provided in the active silencing air passages 21 and 22, the vortex at the downstream end can be kept away and the influence of the standing wave can be reduced, so that the position of the sensor microphone 10 and the position of the error microphone 12 can be reduced. It is possible to increase the correlation and increase the silencing effect. Moreover, since the extended surface 13 is provided on a surface parallel to the rotation axis, there is no deterioration in the blowing performance due to obstructing the flow to the suction port. Further, since the extension surface 13 is provided only on the outer side surface 52 of the active silencing air passages 21 and 22 and is not provided on the inner side surface 53, the extension surface is provided in an empty space so as to avoid the centrifugal fan 50 whose flow direction dimension is not uniform. It can be installed and the size expansion of the blower can be minimized.

(Other variations)
In addition, you may use the active silencer which was made into the active silencing air path in Embodiment 1, 2 independently.

  In this case, the active silencer is a square cylinder-shaped active silencer including an upstream microphone (error microphone 12), a speaker (silence speaker 11), and a downstream microphone (sensor microphone 10) in this order from the upstream side in the airflow direction. The air path and the installation surface on which the downstream microphone is installed are provided with an extended surface projecting downstream from the downstream end of the other surface on which the downstream microphone is not installed.

  Further, the minimum distance between the downstream end portion of the extension surface and the downstream microphone is made larger than the maximum distance between the downstream end portion of the surface other than the installation surface and the downstream microphone in the active silencing air passage. It is.

  As a result, the vortex generated at the downstream end that causes noise is kept away from the microphone, so that the correlation between the microphones can be improved and the noise reduction effect can be increased. In addition, there is an extension surface to reduce the correlation between the upstream microphone and the downstream microphone due to the occurrence of a standing wave in the active silencing air path due to the opening at the downstream end. Since the lengths of the microphones are made non-uniform, it is possible to reduce the influence of standing waves, increase the correlation between microphones, and increase the silencing effect.

  In addition, since the downstream end of the downstream microphone installation surface that most affects the downstream microphone detection accuracy is the downstream end of the extension surface and the farthest downstream end from the downstream microphone, noise caused by vortices generated at the downstream end The influence can be further reduced, the correlation between the microphones can be increased, and the silencing effect can be increased.

  The air blower according to the present invention can suppress a decrease in the silencing effect even if it is installed in an air current field built in an air conditioner or a ventilation fan, etc. This is useful as an active silencer that can suppress a decrease in the silencing effect.

DESCRIPTION OF SYMBOLS 1 Air blower 2 Exhaust port 3 Multiblade fan 4 Scroll casing 5 Expanded air path 6 Active silencing air path 7 Intake port 8 Rotating shaft 9 Installation surface 10 Sensor microphone 11 Silent speaker 12 Error microphone 13 Extension surface 14 Active silencing air path downstream end Part 15 Extension surface end part 16 Extension distance 17 Reference distance 18 Vortex 20 Air blower 21, 22 Active silencer 50 Centrifugal fan 51 Suction port 52 Outer side 53 Inner side

Claims (5)

An active muffler airflow path with a square tube shape including an upstream microphone, a speaker, and a downstream microphone in this order from the upstream side in the airflow direction,
A rotary shaft that is perpendicular to the flow direction of the airflow, and a centrifugal fan that takes in air from a suction port that is provided perpendicular to the rotary shaft,
A blower device that connects the centrifugal fan and the active silencing air passage through an enlarged air passage having a wider opening area than the active silencing air passage,
The downstream microphone is installed on an installation surface parallel to the rotation axis in the active silencing air path,
The air blower provided with the extended surface which made the said installation surface protrude in the said expansion air path.   The minimum distance between the downstream end portion of the extension surface and the downstream microphone is larger than the maximum distance between the downstream end portion of the surface other than the installation surface in the active silencing air passage and the downstream microphone. The blower according to 1.   Two active silencing air paths are arranged in parallel on a plane perpendicular to the rotation axis to form an integral air path, and the downstream microphone and the extension surface of each active silencing air path are outside the integral air path. The blower according to claim 1 or 2 provided only on the surface. An active muffler airflow path with a square tube shape including an upstream microphone, a speaker, and a downstream microphone in this order from the upstream side in the airflow direction,
An active silencer comprising: an extension surface that protrudes downstream from a downstream end of another surface where no downstream microphone is installed on an installation surface where the downstream microphone is installed.   5. The minimum distance between the downstream end portion of the extension surface and the downstream microphone is larger than the maximum distance between the downstream end portion of the surface other than the installation surface and the downstream microphone in the active silencing air passage. The active silencer as described.

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