Silencing device and air supply system
A silencing device and an air supply system according to an embodiment of the present invention include a resonance silencer provided at a position connected to a space in which the sound source is located within the air supply system in order to silence the noise generated from the sound source in the housing, in which in a case where a resonance wavelength of the resonance silencer alone is denoted by λ, a distance by which the resonance silencer is separated from the sound source is less than λ/2. A fundamental resonance frequency of the resonance silencer is equal to or less than an acoustic upper limit frequency determined according to a size of the housing.
1 . A silencing device that is used in an air supply system having a housing, to silence noise generated from a sound source in the housing, the device comprising:
a resonance silencer provided at a position connected to a space in which the sound source is located within the air supply system,
wherein a distance by which the resonance silencer is separated from the sound source is less than λ/2, with λ being a resonance wavelength of the resonance silencer alone, and
a fundamental resonance frequency of the resonance silencer is equal to or less than an acoustic upper limit frequency of the housing,
a ventilation portion that allows air to be supplied in the air supply system to pass therethrough is provided,
the resonance silencer has an opening portion which is disposed at a position facing the ventilation portion, and
an inside of the resonance silencer communicates, through the opening portion, with the space in which the sound source is located.
2 . The silencing device according to claim 1 ,
wherein first silencing, which is silencing by resonance of the resonance silencer, silences the noise, and the first silencing is fundamental resonance of the resonance silencer.
3 . The silencing device according to claim 2 ,
wherein a portion of the resonance silencer that acts on the noise includes an end portion of the resonance silencer as a portion closest to the sound source,
the noise is silenced by the first silencing and a second silencing by interference of reflected sound produced by reflection of the noise by the resonance silencer with the noise in a region between the sound source and the end portion of the resonance silencer, and
a frequency of the second silencing is higher than a frequency of the first silencing.
4 . The silencing device according to claim 1 ,
wherein an insert consisting of at least one of a foam material, a nonwoven fabric, or a porous material is disposed inside the resonance silencer.
5 . The silencing device according to claim 1 , further comprising:
a silencing body different from the resonance silencer.
6 . The silencing device according to claim 5 ,
wherein a portion of the resonance silencer that acts on the noise includes an end portion of the resonance silencer as a portion closest to the sound source, and
the silencing body is disposed in a region between the sound source and the end portion of the resonance silencer.
7 . The silencing device according to claim 5 ,
wherein the silencing body is formed of at least one of a foam material, a nonwoven fabric, or a porous material.
8 . The silencing device according to claim 5 ,
wherein the silencing body is disposed on an outside of the ventilation portion.
9 . An air supply system comprising:
an air supply system main body including the sound source inside a housing; and
the silencing device according to claim 1 .
10 . The air supply system according to claim 9 ,
wherein the air supply system main body supplies air by rotation of a rotating body.
11 . The air supply system according to claim 10 ,
wherein noise generated from the sound source in the housing includes noise caused by the rotation of the rotating body.
12 . The air supply system according to claim 9 ,
wherein the air supply system main body takes in air from a first end side of the air supply system main body and discharges air on a second end side of the air supply system main body, and
the silencing device is disposed at least on the second end side out of a first end and a second end of the air supply system main body.
13 . The air supply system according to claim 12 ,
wherein the silencing device is disposed on each of the first end side and the second end side of the air supply system main body.
14 . The air supply system according to claim 9 ,
wherein the air supply system main body further includes a rotor of an axial fan,
and
an area of a cross section of the ventilation portion perpendicular to a rotating shaft of the axial fan is smaller than an area of a circle surrounded by a trajectory through which a blade tip of the rotor farthest away from the rotating shaft passes during rotation of the axial fan.
15 . The air supply system according to claim 9 ,
wherein a portion of the resonance silencer that acts on the noise includes an end portion of the resonance silencer as a portion closest to the sound source,
the air supply system main body further includes a rotor of an axial fan,
the silencing device includes a silencing body different from the resonance silencer, and
the silencing body is closer to the rotor than the end portion of the resonance silencer.
16 . The air supply system according to claim 9 ,
wherein the air supply system main body is a blower.
17 . The air supply system according to claim 16 ,
wherein a heat exchanger is provided in the air supply system main body.
18 . The air supply system according to claim 9 ,
wherein the air supply system main body further includes a rotor of an axial fan,
the resonance silencer is an air column resonance type resonator having the opening portion,
the silencing device has a first end wall and a second end wall disposed opposite to each other in an axial direction of a rotating shaft of the axial fan,
a ventilation hole is provided in a central portion of each of the first end wall and the second end wall,
a peripheral portion of the ventilation hole in the second end wall is recessed to a first end wall side,
a silencing body formed of at least one of a foam material, a nonwoven fabric, or a porous material is disposed in a recess portion formed by the recessed peripheral portion of the ventilation hole in the second end wall, and
the silencing body is closer to the rotor than the opening portion.