JP4774609B2 - Multi-wing fan - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multiblade fan, and more particularly to a multiblade fan that suppresses audible sound generated from an impeller.
[0002]
[Prior art]
Multi-blade fans such as sirocco fans are used in various applications. The multiblade fan is composed of a casing and an impeller, and blows air by rotating the impeller with an external motor or the like. A small multi-blade fan is used for indoor air circulation and ventilation in a small domestic air cleaner or air conditioner.
[0003]
Household air cleaners and the like have a large resistance to ventilation inside the device due to restrictions on the device size. Moreover, the scale of the processing chamber is large with respect to the equipment size. For this reason, the multiblade fan used for these apparatuses is required to have a high static pressure.
[0004]
[Problems to be solved by the invention]
It is known that a multiblade fan can have a high static pressure by narrowing a gap between a casing and an impeller.
[0005]
However, a multiblade fan whose gap is narrowed by increasing the static pressure tends to generate an unusual noise called nz sound. The nz sound is generated by the interference with the blades of the impeller at the tongue portion where the casing extends to the blower opening. In other words, the rotation of the impeller causes a pressure fluctuation when the blade passes near the tongue. For this reason, a nz sound having a frequency based on the period of pressure fluctuation is generated. Assuming that the rotation speed of the multiblade fan is n rotations per minute and the number of impeller blades is z, the frequency f (Hz) of the nz sound generated from the multiblade fan is expressed as f = n × z / 60. Is done.
[0006]
As the gap between the casing and the impeller becomes narrower, the pressure fluctuation caused by the blades increases, so the nz sound increases. However, a multi-blade fan used for a home air cleaner or the like is required to suppress abnormal noise as much as possible. Thus, the small multi-blade fan is required to have contradictory functions of high static pressure and suppression of abnormal noise.
[0007]
The subject of this invention is providing the multiblade fan which suppresses the audible sound which generate | occur | produces from an impeller, aiming at high static pressure.
[0008]
[Means for Solving the Problems]
The multiblade fan of Claim 1 is provided with the casing, the impeller, and the drive part. A casing has a tongue part in a ventilation part. The impeller is provided inside the casing and has a plurality of blades. The drive unit rotates the impeller. The casing has a plurality of protrusions arranged in the rotation direction of the impeller on the tongue. The interval between the blades is an integral multiple of the interval between the plurality of protrusions. In the multiblade fan, the frequency of the nz sound generated by the interference between the plurality of protrusions on the tongue and the blades when the impeller rotates is 8 kHz or more.
[0009]
When the multiblade fan rotates, the plurality of protrusions on the tongue of the casing interfere with the blades of the impeller to cause pressure fluctuations, and as a result, nz sounds are generated. However, here, the frequency of the nz sound of the multiblade fan is set to 8 kHz or more which is difficult for humans to hear. The human audible frequency region is generally said to be 20 Hz to 20 kHz. However, high frequency components and low frequency components are difficult to hear even at audible frequencies. For this reason, it becomes difficult to hear the nz sound generated from the multiblade fan of the present invention.
[0010]
The nz sound is generated by pressure fluctuation due to interference between the blade and the tongue. For this reason, the frequency of nz sound can be made high by increasing the frequency of a pressure fluctuation. Here, a plurality of protrusions are arranged on the tongue in the rotational direction of the impeller, and nz sound is generated by interference between the blades and the protrusions.
[0011]
Here, conditions are provided for the interval between the protrusions. When the blade interval is N times (N: integer) with respect to the protrusion interval, the frequency f (Hz) of the nz sound is f = n × z × N / 60. For this reason, the frequency of the nz sound can be increased without increasing the number of blades.
[0012]
The multiblade fan according to claim 2 includes a casing, an impeller, and a drive unit. A casing has a tongue part in a ventilation part. The impeller is provided inside the casing and has a plurality of blades. The drive unit rotates the impeller. One or a plurality of auxiliary blades are provided between the blades. The casing has a plurality of protrusions arranged in the blowing direction on the tongue. The interval between the blades and the auxiliary blades or the interval between the auxiliary blades is an integral multiple of the interval between the plurality of protrusions. The multi-blade fan is configured such that when the impeller rotates , the frequency of the nz sound generated by the interference between the plurality of protrusions on the tongue , the blade and the auxiliary blade becomes 8 kHz or more. The total number of blades is set.
[0013]
When the multiblade fan rotates, the tongue of the casing and the blade of the impeller interfere with each other, resulting in a pressure fluctuation, and as a result, nz sound is generated. However, here, the frequency of the nz sound of the multiblade fan is set to 8 kHz or more which is difficult for humans to hear. The human audible frequency region is generally said to be 20 Hz to 20 kHz. However, high frequency components and low frequency components are difficult to hear even at audible frequencies. For this reason, it becomes difficult to hear the nz sound generated from the multiblade fan of the present invention.
[0014]
When the rotational speed of the impeller of the multiblade fan is n rotations per minute and the number of blades is z, the frequency f (Hz) of the nz sound generated from the multiblade fan is expressed as f = n × z / 60. The That is, in order to increase the frequency of the nz sound, the number of blades may be increased or the number of rotations may be increased.
[0015]
Here, the frequency of the pressure fluctuation in the tongue is increased by providing auxiliary blades between the blades. The auxiliary blade is a small blade-like object that does not contribute much to the air flow, and contributes to pressure fluctuation due to interference with the tongue. Thereby, the frequency of nz sound becomes high compared with the case where the auxiliary | assistant blade | wing is not provided. When auxiliary blades are added to an impeller in which the number of blades is set so that the frequency of the nz sound is 8 kHz or more, if the number of auxiliary blades is z ₁ , the nz generated from the multiblade fan The frequency f (Hz) of sound is f = n × (z + z ₁ ) / 60. Here, the frequency of the nz sound is set to be 8 kHz or more by increasing the total number of blades and auxiliary blades.
[0016]
Here, conditions are provided for the interval between the protrusions. When auxiliary blades are provided on the impeller, the frequency of the nz sound when the interval between the auxiliary blades or the interval between the auxiliary blades is N times (N: integer) the interval between the plurality of protrusions. f (Hz) is f = n × (z + z ₁ ) × N / 60. As a result, the frequency of the nz sound can be increased without increasing the number of blades and auxiliary blades.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The exploded perspective view of the air cleaner 1 which concerns on one Embodiment of this invention is shown in FIG. A sirocco fan 10 which is a multi-blade fan is used for air circulation of the air purifier 1.
[0018]
In the air cleaner 1, an outer frame is formed by a front casing 1a, a rear casing 1b, a front panel 2, and the like, and a sirocco fan 10 is disposed between the front casing 1a and the rear casing 1b. The sirocco fan 10 is for circulating air. And between the front panel 2 and the sirocco fan 10, the pre filter 3, the ionization part 4, the roll filter 5, and the photocatalyst part 7 are provided in order from the upstream of the air circulation direction. These members are for purifying the air passing through the air purifier 1. The roll filter 5 is held by the filter case 6.
[0019]
A cross-sectional view of the sirocco fan 10 is shown in FIG.
[0020]
The sirocco fan 10 includes a casing 11, an impeller 20, and a motor 21. As shown in FIG. 1, the motor 21 is supported by the front casing 1a via the support member 15, so that the entire sirocco fan 10 is supported by the front casing 1a. A plurality of blades 22 are provided on the outer peripheral portion of the impeller 20.
[0021]
The casing 11 is a substantially cylindrical case that covers the impeller 20. The motor 21 is fixed to one side of the casing 11. Further, the casing 11 has an opening 14 for taking in air that has passed through the inside of the air cleaner 1 from the front panel 2, and an air outlet that blows out air that has been taken in from the opening 14 and pushed out by the impeller 20. 12 are provided. Further, a tongue portion 11 a is provided at a bent portion that continues from the casing 11 to the air blowing port 12.
[0022]
Next, the operation will be described.
[0023]
When the impeller 20 of the sirocco fan 10 is rotated in the direction of arrow R in FIG. 2 by the motor 21, the air inside the sirocco fan 10 is pushed out by the blades 22. Thereby, indoor air is taken in from the slit provided in the front panel 2. The air taken into the air purifier 1 is removed by the pre-filter 3 from relatively large dust and dust contained therein, and sent to the ionization unit 4. In the ionization unit 4, dirt particles in the air are charged, and the dirt particles charged in the ionization unit 4 are collected by the roll filter 5. The air that has passed through the ionization unit 4 and the roll filter 5 is sent to the photocatalyst unit 7. In the photocatalyst unit 7, the light source lamp 8 that emits light including ultraviolet rays is irradiated to decompose bacteria, odor components, and the like in the air. Thereafter, the air is blown by the sirocco fan 10 from the upper surface of the air cleaner 1 into the room in the direction of the arrow in FIG.
[0024]
The nz sound during operation as described above will be described.
[0025]
The sirocco fan 10 emits an nz sound that is an interference sound due to a pressure fluctuation caused by the interference between the blade 22 of the impeller 20 and the tongue 11a. The frequency f (Hz) of the nz sound is expressed by f = n × z / 60 when the rotation speed of the impeller 20 is n rotations per minute and the number of the blades 22 is z. The smaller the distance between the impeller 20 and the tongue 11a, the greater the nz sound. This is because the pressure fluctuation due to the interference between the impeller 20 and the tongue portion 11a becomes large.
[0026]
Since the sirocco fan 10 of the present embodiment is set so that the frequency of the nz sound is 8 kHz, it is almost inaudible to the user of the air cleaner and can realize substantial noise reduction.
[0027]
<Other embodiments>
(A)
The impeller 20 of the sirocco fan 10 according to the present embodiment is provided with a plurality of blades 22 having the same shape for blowing air. However, by increasing the number of blades 22 to increase the frequency of the nz sound, the air blowing efficiency may be reduced. This is because the ventilation efficiency of the blades 22 decreases. For this reason, it is not preferable to increase the frequency of the nz sound by increasing the blades 22 indefinitely because the static pressure of the sirocco fan 10 is lowered.
[0028]
Here, the frequency of the nz sound can be increased by increasing the frequency of pressure fluctuation. Specifically, by providing one or a plurality of auxiliary blades between the blades 22 of the impeller 20, the frequency of pressure fluctuation can be increased, and as a result, the frequency of the nz sound can be increased.
[0029]
The frequency f (Hz) of the nz sound is f = n × (z + z ₁ ) / 60 when the blade 22 of the impeller 20 is z, the auxiliary blade 23 is z ₁ and the rotation speed is n rotations per minute. The frequency of the nz sound is higher than when there is no auxiliary blade.
[0030]
FIG. 3 is a cross-sectional view of the sirocco fan 10 according to this modification in the vicinity of the tongue 11a. In this modification, two auxiliary blades 23 are provided between the blades 22 as shown in FIG. The auxiliary blades 23 are blades for causing pressure fluctuations, and are small blade-like objects that do not contribute much to air blowing. If the number of blades 22 and auxiliary blades 23 is, for example, 50 blades of the blades 22 of the impeller 20 and 100 blades of the auxiliary blades 23, the rotation number is 3200 rotations per minute, The frequency of the nz sound is 8 kHz, which is higher than about 2.7 kHz, which is the frequency of the nz sound when there is no auxiliary blade.
[0031]
(B)
In the tongue portion 11a of the sirocco fan 10 in the present embodiment, nz sound is generated due to pressure fluctuation due to interference with the blade 22 or the auxiliary blade 23.
[0032]
Here, by providing an object that causes pressure fluctuation in the tongue portion 11a, the frequency of pressure fluctuation can be increased and the frequency of the nz sound can be increased.
[0033]
FIG. 4 is a cross-sectional view in the vicinity of the tongue portion 11a of the sirocco fan 10 of the present modification. In this modification, five protrusions 13 are provided on the tongue portion 11a as shown in FIG. At this time, the protrusions 13 are provided so that the interval L between the blades 22 is N times (N: an integer) the installation interval S of the protrusions 13.
[0034]
The frequency f (Hz) of the nz sound generated thereby is f = n × z × N / 60 when the rotation speed of the impeller 20 is n rotations per minute and the number of blades 22 is z. For example, when the number of blades 22 of the impeller 20 is 50 and N is 3 (see FIG. 4), if the rotation speed is 3200 rotations per minute, the frequency of the nz sound is 8 kHz. Accordingly, the frequency of the nz sound can be increased also by providing the protrusions 13 without increasing the number of blades 22.
[0035]
Similarly to (A) above, by providing the auxiliary blade 23 between the blades 22 of the impeller 20, the frequency of the nz sound can be increased similarly.
[0036]
FIG. 5 is a cross-sectional view of the sirocco fan 10 of this modification in the vicinity of the tongue portion 11a. Protrusions provided on the tongue 11a are provided as shown in FIG. At this time, the protrusions 13 are provided so that the distance L between the blades 22 and the auxiliary blades 22 is N times (N: an integer) the installation interval S of the protrusions 13.
[0037]
The frequency f (Hz) of the nz sound generated thereby is f = n × (z + z ₁ ) when the rotation speed of the impeller 20 is n rotations per minute, the number of the blades 22 is z and the number of the auxiliary blades 23 is z _1. × N / 60. For example, when the number of blades 22 of the impeller 20 and the auxiliary blade 22 is 60 and N is 2 (see FIG. 5), if the rotation speed is 2000 rotations per minute, the frequency of the nz sound is 8 kHz. It becomes.
[0038]
【The invention's effect】
In the multiblade fan according to the first aspect, since the nz sound is 8 kHz or higher, it is difficult to hear the nz sound generated from the multiblade fan, and the influence on humans can be suppressed even when the nz sound is generated greatly.
[0039]
In addition, since the tongue has a plurality of protrusions, the number of pressure fluctuations can be increased compared to when there is no protrusion. Thereby, the frequency of nz sound can be made high.
[0040]
Furthermore, since the interval between the blades is an integral multiple of the interval between the plurality of protrusions, the frequency of the nz sound can be clearly increased.
[0041]
In the multiblade fan according to the second aspect, since the nz sound is 8 kHz or more, it is difficult to hear the nz sound generated from the multiblade fan, and the influence on humans can be suppressed even when the nz sound is generated greatly.
[0042]
Moreover, since the auxiliary | assistant blade | wing is provided between blade | wings, the frequency of a pressure fluctuation can be increased compared with the case where there is no auxiliary | assistant blade | wing. Thereby, the frequency of nz sound can be made high.
[0043]
Furthermore, since the interval between the blades and the auxiliary blades or the interval between the auxiliary blades is an integral multiple of the interval between the plurality of protrusions, the frequency of the nz sound can be clearly increased.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of an air cleaner according to an embodiment.
FIG. 2 is a cross-sectional view of a sirocco fan.
FIG. 3 is a cross-sectional view of the vicinity of the tongue of a sirocco fan in which auxiliary blades are provided between the blades of the impeller.
FIG. 4 is a cross-sectional view of the vicinity of the tongue of a sirocco fan in which a protrusion is provided on the tongue.
FIG. 5 is a cross-sectional view of the vicinity of the tongue of a sirocco fan in which auxiliary blades are provided between the blades of the impeller and protrusions are provided on the tongue.
[Explanation of symbols]
1 Air cleaner 10 Sirocco fan (multi-blade fan)
11 casing 11a tongues 12 wind outlet 13 protrusions 20 impeller 21 motor (driving unit)
22 blade 23 auxiliary blade

Claims (2)

A casing having a tongue in the blower, and
An impeller provided inside the casing and having a plurality of blades;
A drive unit for rotating the impeller;
With
The casing has a plurality of protrusions arranged in the rotation direction of the impeller on the tongue,
The interval between the blades is an integral multiple of the interval between the plurality of protrusions;
When the impeller rotates, the frequency of the nz sound generated by the interference between the plurality of protrusions of the tongue and the blade is 8 kHz or more.
Multi-wing fan. A casing having a tongue in the blower, and
An impeller provided inside the casing and having a plurality of blades;
A drive unit for rotating the impeller;
With
One or more auxiliary blades are provided between the blades;
The casing has a plurality of protrusions arranged in the blowing direction on the tongue,
The interval between the blades and the auxiliary blades or the interval between the auxiliary blades is an integer multiple of the interval between the plurality of protrusions,
When the impeller is rotated, a plurality of projections of the tongue, such that the frequency of the blade and the auxiliary blade and, nz sound caused by the interference of the above 8 kHz, the auxiliary blade and the blade And the total number is set,
Multi-wing fan.

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