JP6439139B2 - Blower - Google Patents

Description

  The present invention relates to a blower mainly used for ventilation and air conditioning in a house, a building, etc., and provided with an active silencer for silencing noise generated during operation.

  In recent years, blowers installed for ventilation and air conditioning in homes and office buildings have been required to reduce noise generated during operation. One means for solving such a problem is a method of applying an active silencer.

  Conventionally, as the active silencing unit for ducts, as shown in the cross-sectional view of FIG. 4, a reference microphone 102 of internal original sound, a silencing speaker 103, which are sequentially attached to the inside of the duct 101 at appropriate intervals from the upstream side, An error microphone 104 and an operation controller 105 connected to each of them are known (see, for example, Patent Document 1).

  In this type of device, the generated sound propagating in the duct 101 together with the air flow 106 is detected by the reference microphone 102, and the arithmetic controller 105 generates a signal having a phase opposite to that of the original sound. The original sound emitted from the duct 103 is canceled and silenced, the error microphone 104 monitors the internal sound, and the silencer 103 is adjusted by the arithmetic controller 105 so that the output of the error microphone 104 becomes zero. .

  Such an active silencing unit silences the noise propagating in the one-dimensional sound field, and the noise propagating through the air passage can be controlled up to the frequency propagating through the plane wave.

  However, the frequency propagated by the plane wave varies depending on the duct diameter, and when the duct diameter is large, the upper limit frequency that becomes a plane wave becomes low. If the frequency to be silenced is higher than the upper limit frequency, the noise cannot be assumed to be a one-dimensional sound field and cannot be silenced.

  For this reason, as an active silencing unit for large-diameter ventilation paths, the silencing ventilation path is divided into a combination of small-diameter ducts (small-diameter ducts), and the upper limit frequency of noise propagated by plane waves in each small-diameter duct Is known to control the frequency by increasing the frequency (see, for example, Patent Document 2).

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

  In FIG. 5, the same or similar components as those shown in FIG. 4 are indicated by the same reference numerals.

  As shown in FIG. 5, the large-diameter duct is divided into small-diameter ducts 201, 202, 203, and 204 having the same diameter, and a muffler speaker 103 is installed at the same position of each of the diameter ducts. Further, in the small-diameter duct 201, a reference microphone 102 is installed upstream from the installation position of the muffler speaker 103, and an error microphone 104 is installed downstream. The noise signals detected by the reference microphone 102 and the error microphone 104 are input to the calculation controller 105. The calculation controller 105 generates a drive signal to be output to the mute speaker 103 based on these noise signals, This drive signal is output to the muffler speaker 103 installed in the small-diameter duct, and the noise propagating through each small-diameter duct is silenced by the same canceling sound. At this time, since the large-diameter duct is divided into small-diameter ducts, the upper limit of the frequency propagating by the plane wave can be increased and the sound can be silenced up to a high frequency.

Japanese Utility Model Publication No. 5-11198 JP-A-9-160567

  When considering a blower in which the active silencing unit and the centrifugal fan described in Patent Document 2 are combined, if a centrifugal fan is arranged in series downstream of the active silencing unit, the pressure loss of the air flow between the active silencing unit and the centrifugal fan However, there is a problem that the entire length of the blower becomes long. On the other hand, when the position of the centrifugal fan is changed, the air path becomes complicated and pressure loss of the air current occurs.

  In addition, the space is rapidly expanding downstream of the small-diameter duct outlet. For this reason, if the length of the small-diameter duct is shortened in order to shorten the overall length of the blower, a strong standing wave is generated in the small-diameter duct. Since this standing wave is detected by the reference microphone and the error microphone, there is a problem that the silencing effect is reduced at a specific frequency.

  Therefore, the present invention solves the above-described problem, and provides a blower that achieves compactness while suppressing the pressure loss of the airflow and the reduction of the silencing effect of the active silencer due to the standing wave. Objective.

  In order to achieve the above object, the present invention provides a casing having a suction port for sucking air, a discharge port for exhausting air sucked from the suction port, and a centrifugal impeller for guiding air from the suction port to the discharge port. And a centrifugal fan provided with a motor for rotating the centrifugal impeller, an inlet port through which air flows in, an outlet port having a central axis common to the inlet port, and an outlet port from which the inlet air flows out. An active silencer having a plurality of small air passages including a microphone for detecting sound waves in the air passage up to and a speaker for emitting sound waves in the air passage, and an air passage connecting the outlet and the inlet The plurality of small air passages, the central axes of the small air passages being perpendicular to the suction shaft perpendicular to the suction port, and the central shafts on the upstream side and the downstream side of the suction shaft. Are placed adjacent to each other in parallel, The outlet of the small air passage arranged on the upstream side is made closer to the suction shaft than the outlet of the small air passage arranged on the downstream side, and the outer wall surface of the small air passage arranged on the upstream side is The blower is made to face the suction port, thereby achieving the intended purpose.

  ADVANTAGE OF THE INVENTION According to this invention, the fan which implement | achieved compactness can be provided, suppressing the pressure loss and the fall by the standing wave of the silencing effect of an active silencer.

Side sectional drawing of the air blower of Embodiment 1 of this invention Top sectional view of the blower of Embodiment 1 of the present invention Side sectional view of the blower according to Embodiment 2 of the present invention. Sectional view showing a conventional active silencer A perspective view showing a conventional active silencer

  A blower according to the present invention includes a casing having a suction port for sucking air, a discharge port for exhausting air sucked from the suction port, a centrifugal impeller for guiding air from the suction port to the discharge port, and the centrifugal impeller. A centrifugal fan including a motor to be rotated, an inlet port through which air flows, an outlet port having a central axis common to the inlet port, and an air outlet channel from the inlet port to the outlet port. An active silencer having a plurality of small air passages including a microphone that detects sound waves and a speaker that emits sound waves into the air passage, and a ventilation passage that connects the outlet and the suction port. Adjacent to each other so that the central axis of each small air path is perpendicular to the suction axis perpendicular to the suction port and the upstream and downstream sides of the suction shaft are parallel to each other. And placed on the upstream side A configuration in which an outlet of the air passage is made closer to the suction shaft than an outlet of the small air passage arranged on the downstream side, and an outer wall surface of the small air passage arranged on the upstream side is opposed to the suction port. Have

  As a result, the airflow flowing out from the outlet of the small air passage on the upstream side of the suction shaft of the centrifugal fan of the active silencer does not collide with the airflow flowing out from the outlet of the small air passage on the downstream side of the suction shaft. It can flow to the inlet of the fan casing. Thereby, even if it arrange | positions an active silencer and a centrifugal fan in parallel with the suction-axis direction, the pressure loss of an air current does not increase and it can flow smoothly into the suction port of a centrifugal fan. For this reason, there exists an effect that it can suppress that the full length of an air blower becomes long.

  Moreover, the air blower which concerns on this invention is good also as a structure provided with a sound-absorbing material in the part which opposes the said suction inlet of the said centrifugal fan among the inner wall face of the said ventilation path, and the outer wall face of the said small wind path.

  Thereby, a part of the sound wave emitted from the suction port of the centrifugal fan is reflected on the wall surface and enters the active silencer, thereby inhibiting the formation of the plane wave, thereby suppressing the reduction of the silencing effect. There is an effect that can be done.

  Further, in the blower according to the present invention, a length of the outer wall surface of the small air passage arranged on the upstream side in a direction parallel to the central axis is the outlet of the small air passage arranged on the downstream side. It is good also as a structure longer than the length of the half of one side of the direction parallel to the said suction axis.

  Thereby, since the outer wall surface of the small air passage arranged on the upstream side becomes a shape extending one surface of the small air passage arranged on the downstream side, the space downstream of the outlet in the small air passage arranged on the downstream side is It is not a structure that expands rapidly in all directions. Thereby, it becomes difficult to generate a standing wave, and an effect is obtained that a reduction in the silencing effect of the active silencer due to the standing wave can be suppressed.

(Embodiment 1)
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2.

  As shown in FIG. 1, the blower 1 of the present embodiment includes a scroll casing 4 having a suction port 2 for sucking air and a discharge port 3 for exhausting air, a centrifugal impeller 5, and a centrifugal impeller 5. A centrifugal fan 7 provided with a rotating motor 6, a square duct-shaped active silencer 8, and an air passage 10 connecting the outlet 9 of the active silencer 8 and the suction port 2 of the centrifugal fan 7 are provided.

  As shown in FIGS. 1 and 2, the active silencer 8 is provided with four rectangular small air passages 11 (length: 200 mm) in order to increase the upper limit frequency that can be silenced. A reference microphone 12 that detects noise propagating through the air (corresponding to a microphone that detects sound waves in the air path), a speaker 13 that emits sound in an opposite phase to the noise detected by the reference microphone 12, and emission from the speaker 13 An error microphone 14 for detecting noise attenuated by the generated sound and an arithmetic controller (not shown) for connecting and controlling these are provided. The cross section of the small air passage 11 is a square having a side of 80 mm, and the upper limit frequency f at which each small air passage 11 of the active silencer 8 can mute is f <sonic speed / (2L) depending on the width L of the small air passage 11. If the sound speed is 345 m / s, it is 2156 Hz.

  In the four small air passages 11 of the active silencer 8, the central axis 19 of each small air passage 11 is perpendicular to the suction shaft 20 perpendicular to the suction port 2 of the centrifugal fan 7 and is upstream of the suction shaft 20. Two central shafts 19 are arranged adjacent to each other on the upstream side (left side in FIG. 1) and on the downstream side (right side in FIG. 1) so that the central shafts 19 are arranged in parallel on the side and the downstream side. Then, the outlet 9 of the two small air passages 11 arranged on the upstream side is brought closer to the suction shaft 20 by 50 mm than the outlet 9 of the two small air passages 11 arranged on the downstream side. Thereby, the outer wall surfaces 17 of the two small air passages 11 arranged on the upstream side are opposed to the suction port 2 of the centrifugal fan 7. In addition, the upstream side in the suction shaft 20 here means that it is located farther from the suction port 2 than the downstream side in the suction shaft 20. Moreover, the outer wall surface 17 here refers to the part exposed to the ventilation path 10 among the outer surfaces of the wall which forms the two small air paths 11 on the upstream side.

  With the above configuration, when the centrifugal impeller 5 is rotated by the motor 6 of the centrifugal fan 7 (in this embodiment, the rotational speed is 1000 rpm), the centrifugal impeller 5 boosts the pressure from the inlet 15 of the active silencer 8 respectively. The air flows into the small air passage 11. Then, the inflowing air flows from the outlet 9 of the small air passage 11 through the ventilation passage to the suction port 2 of the centrifugal fan 7 and is exhausted from the discharge port 3. At the same time, noise such as wind noise, turbulent noise, and excessive friction is emitted from the suction port 2 of the centrifugal fan 7. Those noises propagate through the small air passages 11 of the active silencer 8 and are emitted from the inlet 15. When the noise passes through the small air passage 11, the noise is reduced by the silencing effect of the active silencing device 8.

  In the present embodiment, in order to shorten the overall length of the blower 1, the central shaft 19 of each small air passage 11 of the active silencer 8 is perpendicular to the suction shaft 20 perpendicular to the suction port 2 of the centrifugal fan 7. In addition, two central shafts 19 are arranged adjacent to each other on the upstream side and two on the downstream side so as to be parallel to the upstream side and the downstream side of the suction shaft 20. Further, the outlet 9 of the two small air passages 11 arranged on the upstream side is brought closer to the suction shaft 20 by 50 mm than the outlet 9 of the two small air passages 11 arranged on the downstream side.

  That is, the outlet 9 of the two small air passages 11 arranged on the upstream side is closer to the suction shaft 20 than the outlet 9 of the two small air passages 11 arranged on the downstream side. For this reason, an upstream-side small wind path 11 dedicated air path and a downstream-side small wind path 11 dedicated air path are virtually formed in the ventilation path 10, and the air passing through the upstream and downstream small wind paths interferes with each other. There is nothing to do. That is, the airflow flowing from the outlet 9 of the two small air passages 11 arranged on the upstream side through the air passage 10 to the suction port 2 of the centrifugal fan 7 flows in the two small air passages 11 arranged on the downstream side. The air can flow smoothly to the suction port 2 of the centrifugal fan 7 without colliding with the airflow flowing out from the outlet 9. Thereby, an increase in pressure loss can be suppressed.

  The length of the two small air passages 11 arranged on the upstream side in the direction parallel to the central axis 19 of the outer wall surface 17 is 50 mm, and the suction of the outlet 9 of the two small air passages 11 arranged on the downstream side The length of one side of the direction parallel to the shaft 20 is 80 mm, which is half (50%) longer than 40 mm.

  The outer wall surface 17 of the two small air passages 11 arranged on the upstream side plays a role of extending one surface of the two small air passages 11 arranged on the downstream side. At this time, the outer wall surface 17 is parallel to the central axis 19 of the outer wall surface 17. By making the length of the direction longer than half the length of one side in the direction parallel to the suction shaft 20 of the outlet 9 of the small air passage 11, the space downstream of the outlet 9 is rapidly expanded in all directions. The standing wave is less likely to be generated in the small air passage 11, and the standing wave affects the reference microphone 12 and the error microphone 14, and the silencing effect of the active silencer 8 is reduced. It can suppress that it falls.

  In addition, by making the length of the direction parallel to the central axis 19 of the outer wall surface 17 longer than the length of about 20% of the length of one side in the direction parallel to the suction shaft 20 of the outlet 9 of the small air passage 11, It can be considered that the space downstream of the outlet 9 does not suddenly expand in all directions, and the research results show that it is difficult to generate a standing wave. However, in order to obtain an effect reliably, it is desirable to make it longer than 50%.

(Embodiment 2)
In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 3, the air blower 1 b according to the present embodiment absorbs sound at a portion of the inner wall surface 16 of the ventilation path 10 and the outer wall surface 17 of the active silencer 8 that faces the suction port 2 of the centrifugal fan 7. The material 18 is attached.

  With this configuration, part of the sound wave (noise) emitted from the suction port 2 of the centrifugal fan 7 is reflected on the inner wall surface 16 of the ventilation path 10 and the outer wall surface 17 of the active silencer 8, and the small wind of the active silencer 8 is obtained. Since it can suppress entering into the path | route 11, it can suppress that the reflected sound wave inhibits formation of a plane wave in the small wind path 11 of the active silencer 8, and can suppress that the silencing effect falls.

  The blower using the active silencer according to the present invention is useful for an exhaust facility for homes or shops where quietness is required.

DESCRIPTION OF SYMBOLS 1 Blower 2 Suction port 3 Discharge port 4 Casing 5 Centrifugal impeller 6 Motor 7 Centrifugal fan 8 Active silencer 9 Outlet 10 Ventilation path 11 Small wind path 12 Reference microphone 13 Speaker 14 Error microphone 15 Inlet 16 Inner wall surface 17 Outer wall surface 18 Sound absorbing material 19 Central axis 20 Suction axis

Claims (3)

A casing having a discharge port for exhausting air sucked from the suction port and the suction port for sucking the air, a centrifugal impeller to guide air to the discharge port from the suction port, and a motor for rotating the centrifugal impeller A centrifugal fan with
An inlet for flowing the air, an outlet for flowing air flows out, and a microphone for detecting sound waves in the flow air path from the inlet to the outlet, and a speaker for emitting sound waves into the air passage An active silencer with a plurality of small air passages,
An air passage connecting the outlet and the suction port;
Each of the plurality of small air passages has the same length in a direction parallel to the central axis of the air passage from the inlet to the outlet.
The plurality of small air passage, the central axis of each Shokazero is, perpendicular to the vertical suction shaft to the suction port, and, in parallel each central axis upstream and downstream of the pre-Symbol suction shaft Placed adjacent to each other,
The outlet of the small air passage arranged on the upstream side is made closer to the suction shaft than the outlet of the small air passage arranged on the downstream side,
A blower in which an outer wall surface of a small air passage disposed on the upstream side is opposed to the suction port. The blower according to claim 1 , wherein a sound absorbing material is provided in a portion of the inner wall surface of the ventilation path and the outer wall surface of the small air path that faces the suction port of the centrifugal fan. A length in a direction parallel to the central axis of the outer wall surface of the small air passage arranged on the upstream side is in a direction parallel to the suction axis of the outlet of the small air passage arranged on the downstream side. The blower according to claim 1 or 2, wherein the blower is longer than a half of one side.

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