JPS6245437B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a silencer. Air blowers are used to ventilate subways, public ditches, and general building equipment. The noise from blowers is emitted from the intake and exhaust ports, causing noise pollution and having a negative impact on the working and living environments. Therefore, a silencer is usually installed between the blower, which is the source of the sound, and the intake and exhaust ports, in order to prevent noise pollution and improve the environment. The present invention relates to a silencer for these ventilation equipment.

Conventional technology When installing a silencer in underground ventilation equipment, the air passage is generally narrow, the cross-sectional area that is originally the installation space for the silencer is small, and inspection passages are often provided, making it difficult to install the silencer. The installation cross-sectional area is further reduced,
The speed of the air passing through the silencer increases, and as a result (1) the pressure loss increases and the output of the drive motor of the fan for the ventilation equipment increases.

(2) Airflow generated noise inside the muffler or on the downstream side becomes louder, and even if the fan noise is reduced within the muffler, the airflow generated sound remains, and in severe cases, a separate muffler is required. , and other problems arose.

Referring to the drawings, FIG. 1 shows an example of a silencer, and FIG. FIG. 1b shows a splitter-shaped air passage 7 divided in the vertical direction and surrounded by sound absorbing material 8. Both have well-known configurations.

Fig. 2 shows a conventional noise muffling device, in which a muffler 3 is installed in an air path 2 surrounded by an air path wall 1, and a walking path 5a for inspection with a sound insulating board 4 with a door is provided on the side thereof. It is being FIG. 3 is a view taken along the line A--A in FIG. 2, where FIG. 3a shows a cell type and FIG. 3b shows a splitter type. Arrow 6 indicates the direction of air flow. In such conventional devices, since the cross-sectional area of the muffler is small, the wind speed is high, the pressure loss is large as described above, and the noise generated by the air flow is large.

Problems to be Solved by the Invention Since the ventilation air passage is narrow and an inspection passage is also provided, the velocity of the air passing through the silencer inevitably increases.
Therefore, the pressure loss of the muffler increases and the running cost also increases. Furthermore, airflow generated noise increases, leading to a reduction in sound volume. This invention seeks to eliminate these drawbacks.

Means for Solving the Problem In order to solve this drawback, the present invention provides a walkway for inspection and a muffler, which are installed together on the same plane perpendicular to the air flow direction as in the past. Airflow will be allowed to pass through the passageway, and a walking passageway and silencer will be installed downstream as well.
By installing a sound insulating board with a door between each silencer, the wind speed inside the silencer can be roughly halved, the pressure loss can be reduced to almost 1/4, and the noise generated by airflow can also be greatly reduced. It is something that

Embodiment FIG. 4 shows a muffling device of the present invention, in which a muffler 3 and a walking path 5b for inspection, which also serves as an air path, are provided on the upstream side of the airflow indicated by an arrow 6, and on the downstream side, a walking path 5b for inspection is installed. A silencer 3' is provided on the side, a passage 5'b is provided on the side of the silencer, and a sound insulating plate 4 with a door is provided between the two. FIG. 5 is a view taken along the line A--A in FIG. 4, where FIG. 5a shows a cell type and FIG. 5b shows a splitter type. In this way, the present invention provides the same effect as when a silencer is attached to the entire air passage, and the wind speed inside the silencer is reduced by approximately half. As seen in the figure, the sound insulating board 4 with the door between the passages does not obstruct the air passage, and the silencers 3 and 3' are placed side by side, making it as if the entire air passage were a silencer.

FIG. 6 and subsequent figures show other embodiments, and the same reference numerals as in FIG. 4 indicate the same parts. In FIG. 6, the number of stacked silencers 3, 3' is further increased by one step, and the sound insulating plate 4 with a door is provided at a slight angle.

7 shows the device shown in FIG. 4 in multiple stages, and FIG. 8 shows the device shown in FIG. 6 in multiple stages.

Effects The advantages of the device of this invention are compared with the conventional device. The pressure loss ΔPmmAq is generally expressed as ΔP=ζγ/2gv ² .

Here, ζ: Pressure loss coefficient γ: Specific weight of air Kgf/m ³ g: Gravitational acceleration m/S ² v: Wind speed in the silencer m/S.

If we use the suffix 1 to indicate the case of the conventional noise muffling device, and the suffix 2 to indicate the case of the present invention, if the ventilation air volume is constant, it can be considered that approximately ζ ₂ ≒ζ ₁ v ₂ ≒ 1/2v ₁ . Equipment pressure loss ΔP ₁
The ratio of pressure loss ΔP ₂ in the case of this invention is: becomes. Therefore, pressure loss is reduced to about 1/4,
This helps reduce running costs and save energy.

On the other hand, airflow generated sound L _A dB(A) is generally expressed as L _A ≈60log ₁₀ v+K.

Here, v: Wind speed in the muffler m/s K: Constant determined by the shape of the muffler If the ventilation air volume is constant, it can be considered that approximately v ₂ ≒ v ₁ /2, so the airflow generated by the conventional muffler The difference between the sound L _A1 dB(A) and the L _A2 dB(A) of the silencer of this invention is L _A1 −L _A2 ≒60log ₁₀ v ₁ +K−(60log ₁₀ v ₂ +K) ≒60log ₁₀ v ₁ − 60log ₁₀ v ₁ /2 = 60log2≒18dB(A), so airflow generated noise can be reduced by about 18dB(A).

[Brief explanation of the drawing]

Fig. 1a shows a cell-type muffler, Fig. 2b shows a splitter-type muffler, Fig. 2 shows a conventional muffler, and Fig. 3 is a view along arrow A-A in Fig. 2. in,
3a shows a cell type, FIG. 3b shows a splitter type, FIG. 4 shows a silencer of the present invention, and FIG. Figure a shows a cell type, and Figure b shows a splitter type.
FIG. 6, FIG. 7, and FIG. 8 are diagrams showing different embodiments, respectively. Explanation of symbols, 1...Air channel wall, 2...Air channel, 3,
3'...Sound silencer, 4...Sound insulating board with door, 5a, 5
b, 5'b... Passage, 6... Air flow direction, 7... Air path in the silencer, 8... Sound absorbing material.

Claims (1)

[Claims] 1. A walking path 5 on the upstream side in the flow direction in the air path 2.
b and a silencer 3, and on the downstream side, a silencer 3' is installed on the side of the walking path 5b, and a walking path 5b is installed on the side of the silencer 3, and an upstream side silencer and a downstream side silencer are installed. A sound deadening device characterized in that a sound insulating board 4 with a door is provided between the containers. 2. The muffling device according to claim 1, characterized in that the muffling device is arranged in multiple stages.