JP2517069Y2 - Resonance / Resonance type silencer elbow - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a resonance / resonance type muffling elbow capable of attenuating noise transmitted in a duct such as an air conditioning equipment or a ventilation equipment.

(Prior Art) Conventionally, as a sound deadening elbow used in a duct such as an air conditioning equipment or a ventilation equipment, a fibrous sound absorbing material is provided over the entire inner surface of the elbow, and a sound absorbing material similar to the inner surface outside the elbow. Can be roughly divided into an air layer and a perforated plate.

(Problems to be solved by the invention) However, the muffling effect was insufficient for noise components in the low frequency range in any of the formats. That is, the noise countermeasure using such a muffling elbow does not necessarily improve the noise disturbance by causing the resonance and the resonance because the noise properties are remarkably low frequency components. Particularly, the resonance effect due to the bending vibration of the perforated plate fixedly provided on the inner surface of the outer corner of the elbow was not sufficient.

In addition, when a sound absorbing material is used on the inner surface of the elbow, not only does the sound absorbing material scatter due to aging and deteriorates the sound deadening effect, but it also causes a trouble in the equipment.

Further, when the sound absorbing material and the air layer are provided on the inner surface of the elbow, a mounting space for the sound absorbing material and the air layer is required, which makes it difficult to install in a narrow place.

The object of the present invention is to eliminate the above-mentioned drawbacks, and it is possible to exert a sound deadening effect in a specific frequency range and to last such a sound deadening effect, especially for a perforated plate fixed on the inner surface of the elbow outer corner. An object of the present invention is to provide a resonance / resonance type silencer elbow using bending vibration.

(Means for Solving the Problems) In order to solve the above problems, the present invention reduces the sound at a specific frequency derived from a theoretical formula based on bending vibration of a plate in an elbow used for air conditioning equipment or ventilation equipment. A resonance / resonance type characterized in that a perforated plate is fixedly provided at a position where an effect is produced along the inner surface of the outer corner portion of the elbow by using a support material for holding the inner surface at a predetermined space and a supporting interval. It is a muffling elbow.

(Function) By providing the perforated plate with a predetermined distance from the elbow outer plate, a resonance effect is generated by the air layer on the back surface of the perforated plate,
In addition, a resonance effect is generated by specifying the distance between the support members that support the perforated plate, and the sound reduction characteristics for sounds in a specific frequency range can be obtained due to the overlapping of these effects.

(Example) Hereinafter, an example of the present invention is described based on a drawing.

1 shows an external perspective view of a muffler elbow according to the present invention, and FIGS. 2 and 3 show a side view and a front view of the elbow shown in FIG. 1, respectively.

The resonance / resonance type sound absorbing elbow 10 according to the present invention is configured by providing a perforated plate 2 arranged along the inner surface of the outer corner portion 1 thereof with a predetermined distance from the inner surface.

The perforated plate 2 has a number of aligned through holes 2a and is spot-welded by using a plurality of crank-shaped support members 3 having both ends bent in opposite directions as shown in FIG. It is fixed to the inner surface of the outer corner portion 1.

The sound-absorbing elbow 10 configured as described above is configured so that the support interval of the support member 3 of the perforated plate attached to the inner surface of the outer corner portion 1 is equal to the bending vibration of the flat plate so as to match the specific frequency range for damping. It is calculated from a theoretical formula based on.

That is, the theoretical formula based on the bending vibration of the flat plate is as follows.

Where f: Resonance frequency Hz C ₁ : Longitudinal wave propagation velocity of perforated plate m / S a: Longitudinal support interval of perforated plate mb: Short side support interval of perforated plate mt: Perforated plate Plate thickness m (issued by Gihodo Publishing Co., Ltd., noise and vibration countermeasure handbook
That is, the elbow 10 of the present invention is provided in a shape in which the resonance / resonance effect can be expected by the perforated plate 2 and the air layer, and the specific frequency is low / medium at which resonance / resonance frequency occurs. The thickness of the air layer and the support interval of the perforated plate are set so as to enter the frequency range.

In the figure, reference numeral “c” indicates the thickness of the air layer,
"W" is the widthwise spacing of the support spacing, "h" is the depthwise spacing of the support spacing, and "t" is the spacing.
Indicates the wall thickness of the support material 3, respectively.

FIG. 4 is a perspective view of a support material applied to the present invention, and FIG. 5 is a result of an experiment using the muffling elbow of the present invention.
It shows the attenuation characteristics of noise energy in comparison with the conventional elbow.

The dimensions of the elbow of the present invention are: * Elbow size: 300 x 300 mm * Perforated plate support interval (h x w): 280 x 170 mm * Perforated plate thickness: 0.8 mm * Perforated plate material: Steel plate The one provided is used, and the resonance frequency obtained from the support interval is 188 Hz, but it appears as 250 Hz in the measured value at 1/1 octave.

On the other hand, the conventional elbow has the same size as that of the present invention and has a sound absorbing material applied to the outer surface.

As is clear from the figure, it was found that the elbow of the present invention has a remarkable noise damping effect at a specific frequency of 250 Hz. This is because the resonance effect generated by the distance between the outer plate of the elbow and the perforated plate, etc., and the resonance effect generated by the supporting distance of the perforated plate and the supporting conditions provided the sound reduction characteristics in the specific frequency range. is there.

That is, when sound is incident on a perforated plate having an air layer behind it, a part of the energy of the sound is converted to thermal energy and attenuated due to internal friction of the plate and loss of the supporting portion. Therefore, the resonance frequency is determined by the thickness of the plate material and the air layer.

Also, when sound enters the perforated plate, the plate itself can be treated simply as a “supported flat plate”, bending vibration is generated in the perforated plate, and part of the sound energy is converted into thermal energy. , Decay. Therefore, the resonance frequency is determined by the support interval and the support condition of the plate material.

(Effects of the Invention) As described above, the resonance / resonance type muffling elbow according to the present invention is centered in the low / medium frequency range by fixing the perforated plate at a predetermined interval on the inner surface of the outer corner of the elbow. The sound reduction effect in the specific frequency range is obtained.

Further, since no sound absorbing material is used, deterioration of the sound reduction effect due to aging and trouble due to scattering of the sound absorbing material do not occur.

Also, since the perforated plate mounting space is provided only at the outer corners of the elbow, it is possible to install in a narrow space.

In addition, because it is a structure that can obtain a sound reduction effect only with a perforated plate,
Manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is an external perspective view of a resonance / resonance type sound absorbing elbow according to an embodiment of the present invention, FIG. 2 is a side view thereof, FIG. 3 is a front view thereof, and FIG. 4 is a support material applied to the present invention. FIG. 5 is a damping characteristic diagram based on an experimental result comparing the silencing elbow of the present invention with a conventional example. 1 ... outer corner, 2 ... perforated plate, 2a ... through hole, 3 ... support material, 10 ... resonance / resonance silencing elbow

Claims (1)

(57) [Scope of utility model registration request] 1. An elbow used for air conditioning equipment or ventilation equipment, wherein a perforated plate is attached along an inner surface of an outer corner portion of the elbow with a support material capable of keeping a predetermined distance from the inner surface, and the support thereof. A resonance / resonance type muffling elbow characterized in that a perforated plate is fixed at a position where a desired resonance frequency derived from a theoretical formula based on bending vibration of the plate is generated by a material.