JPH06346900A - Suspention type ventilating device - Google Patents

Abstract

PURPOSE:To provide a suspention type ventilating device fitted with a muffler effective with simple structure. CONSTITUTION:A suspention type ventilating device is fitted with a muffler formed of a casing part 3 around an axial blower 15, and duct parts 12, 3 for an air inflow port and an air outflow port. In this case, the muffler is of double structure formed of inner cylinders 10, 11, 12 and outer cylinders 4, 5, 6. The inner cylinder is a cylinder of circular cross section formed of porous material, and the outer cylinder is formed of a cylinder of elliptic cross section. A space between the inner cylinder and the outer cylinder is filled with sound absorbing material or left as a cavity, or the inner cylinder is covered with sound absorbing material of appropriate thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hanging type ventilation device capable of reducing the noise generated by a blower and the noise generated by gas and fluid.

[0002]

2. Description of the Related Art Conventionally, axial blowers have been used for various purposes. For example, in exhaust gas ventilation in a tunnel of a motorway, a required number of axial blowers are installed near the ceiling of the tunnel to unidirectionally blow air from the entrance to the exit of the tunnel. In this ventilation, noise generated from a large number of axial blowers becomes considerably large, and it is desired to reduce this noise.

For this reason, since it is installed in a tunnel, it is necessary to develop a silencer capable of obtaining the required volume reduction while being restricted by space. Conventionally, a silencer for a hanging type ventilation device used for a tunnel or the like has a circular tubular cross section. This is the space
This is because it is subject to restrictions due to cost, production costs, etc. As a method for reducing noise, a method of increasing the length of the muffler more than twice as long as usual and increasing the volume reduction has been adopted.

From such a situation, the actual utility model Sho 61-232
Japanese Unexamined Patent Publication No. 0 discloses a technique in which a resonance silencer for the purpose of reducing the ZN frequency (the rotation frequency of the blower × the number of blades) is incorporated into the silencer. Further, as a special method, Japanese Patent Application Laid-Open No. 59-99097 discloses a technique of reducing the noise by adjusting the phase of the noise generated from each of the two blades to cause interference.

[0005]

However, in the conventional silencer, although the high-frequency sound is sufficiently attenuated by the sound absorbing layer, the Z of the ventilation fan axial flow blower having a relatively low frequency is used.
The noise component of N frequencies remains without being sufficiently reduced. Therefore, the noise after passing through the silencer has a particularly large ZN frequency component, and since this is a relatively low frequency component, noise cannot be easily reduced and becomes a problem as noise pollution, which causes further noise Noise reduction is desired.

Further, the technique of doubling the length of the conventional silencer has problems such as an increase in manufacturing cost and an increase in space required for mounting. Further, if the muffler is lengthened, the pressure loss of the muffler increases and the required shaft power increases, so there is a limit to the length of the muffler. There is also a method to improve the volume reduction of low frequency sound by thickening the sound absorbing layer of the current muffler, but there is a limit to the installation space and the sound absorbing layer of the muffler is spread over the entire circumference of the outer cylinder. If the thickness is larger than the current one, the height becomes high, which is not preferable for practical use.

On the other hand, in the technique disclosed in Japanese Utility Model Publication No. 61-2320, the structure is complicated, and in order to obtain a sufficient noise reduction effect, it is necessary to enlarge the muffler, which is not realistic. Further, it is difficult to sufficiently reduce the noises on the inlet side and the outlet side of the blower at the same time by the technique disclosed in JP-A-59-99097.

Further, in the hanging type ventilation device used in the tunnel, soot and dust such as exhaust gas of an automobile adhere to the surface of the flow path inside the muffler, and the sound reducing effect of the muffler decreases, so that the muffler is activated at regular intervals. There is a problem that it is necessary to remove the ventilation device and replace the sound absorbing material filling the inside of the muffler to clean the surface of the flow path, which makes maintenance complicated and the cost high.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to eliminate the above-mentioned problems and to provide a hanging type ventilation device having a simple structure and a silencer having an excellent silencing effect. And

[0010]

In order to solve the above-mentioned problems, the present invention hangs a silencer, which is composed of a casing part around an axial blower and duct parts of an air inlet and an air outlet. In the type ventilation device, the silencer has a double structure of an inner cylinder 10 and an outer cylinder 4, as shown in FIG.
Reference numeral 0 denotes a cylinder having a circular cross-sectional shape and is made of a porous material, and outer cylinder 4 is made of a cylinder having an elliptical cross-sectional shape, and inner cylinder 10
It is characterized in that the space between the outer cylinder 4 and the outer cylinder 4 is filled with the sound absorbing material 16.

As shown in FIG. 4, the silencer has a double structure of an inner cylinder 10 and an outer cylinder 4. The inner cylinder 10 is a cylinder having a circular cross section and is made of a porous material. The cylinder 4 is configured by a cylinder having an elliptical cross section, and has a structure in which the space between the inner cylinder 10 and the outer cylinder 4 is hollow.

As shown in FIG. 5, the silencer has a double structure of an inner cylinder 10 and an outer cylinder 4. The inner cylinder 10 is a cylinder having a circular cross section and is made of a porous material. Reference numeral 4 denotes a structure in which a cross-sectional shape is an elliptical cylinder, a sound absorbing material 16 having an appropriate thickness is attached to the outer circumference 4 of the inner cylinder 10, and a space between the sound absorbing material 16 and the outer cylinder 4 is hollow. It is characterized by

[0013]

In the present invention, as shown in FIG. 1, the duct unit 1 is provided by the axial blower 15 built in the hanging type ventilation device.
The wind blows in the order of the casing 2 and the duct 3 of the axial blower 15. At this time, the noise generated from the axial blower 15 propagates from the casing 2 to the duct portion 1 and the duct portion 3, respectively. Airflow noise is also generated in all internal flow paths due to the flow of wind. The synthesized sound of those noises is duct 1,
3 propagates from the outer end portion to the outside.

The noise is transmitted through the inner tube 10 of the porous plate while propagating through the inner flow path 9, and is absorbed and reduced by the sound absorbing material 16 filled between the inner tube and the outer tube. The sound absorbing material 16 is suitable for reducing noise of a relatively high frequency such as air flow noise, but the conventional circular silencer does not muffle noise of a relatively low frequency such as the ZN frequency of the blower to the outside. Propagate (see curve 6-4 in FIG. 6).

As shown in FIG. 3, in the silencer of the invention described in claim 1, a thick portion (long axis of an ellipse) of the sound absorbing material 16 is formed, and a sound wave is incident on the sound absorbing material 16 and again the sound absorbing material is external. Propagation distance to go out becomes longer, friction resistance increases, and sound absorption effect at low frequency increases compared to the conventional case. Therefore Z
The amount of noise reduction at low frequencies such as N frequencies also increases, and the synthesized sound propagating to the outside is also reduced (curve 6-1 in FIG. 6).
reference). This muffler with an elliptical cross section has more sound absorbing material, but it is at the same height as the conventional type, so it is convenient to install inside the tunnel.

In the muffler according to the second aspect of the present invention, as shown in FIG. 4, since the cavity 17 between the outer cylinder 4 and the inner cylinder 10 constitutes a resonance muffler, the ZN frequency It is suitable for sound reduction of a specific frequency as described above, and at a low frequency, a larger volume reduction can be obtained than that of the sound absorbing silencer of FIG. 3 (FIG. 6).
Curve 6-2).

In the muffler of the invention described in claim 3, as shown in FIG. 5, the sound absorbing material 16 is attached around the inner cylinder 10 of the porous plate with an appropriate thickness to enhance the muffling effect at high frequencies. By providing the cavity 17 between the sound absorbing material 16 and the outer cylinder 4, it is possible to construct a silencer that enhances the low-frequency sound deadening effect and simultaneously reduces low-frequency sound and high-frequency noise (FIG. 6).
Curve 6-3).

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a vertical sectional view of a hanging type ventilation device of the present invention, and FIG. 2 shows a sectional view taken along the line AA. As shown in the figure, the hanging type ventilation device of the present invention comprises an axial blower 15, a casing 2 around it, and ducts 1 and 3 for an air inlet and an air outlet. The ventilation device is suspended and fixed on the ceiling of the tunnel by an appropriate suspension means (not shown). Here, the silencer refers to the casing portion 2 around the axial blower 15 of the hanging type ventilation device and the duct portions 1 and 3 attached before and after the casing, and has a three-part structure.

The casing 2 of the axial blower 15 is an inner cylinder 11
The outer cylinder 5 has a double structure, and the outer cylinder 5 is a cylinder having an elliptical cross section. The inner cylinder 11 is a cylinder made of a porous plate having a circular cross section, and an axial blower 15 is installed in the center.
Similarly, the duct portions 1 and 3 also have a double structure of inner cylinders 10 and 12 made of a porous plate having a circular cross-sectional shape and outer cylinders 4 and 6 having an elliptical cross-sectional shape, and a casing 2 of the axial blower 15. Are connected to each other via partition plates 13 and 14, and both ends are end plates 7,
It is fixed at 8.

[Embodiment 1] FIG. 3 is a cross-sectional view of the muffler portion of the present invention (the invention according to claim 1) (a sectional view taken along the line BB of FIG. 1). As shown, the space between the outer cylinder 4 of the duct 1 and the inner cylinder 10 of the porous plate is filled with the sound absorbing material 16. In operation, as shown in FIG. 1, the axial blower 1
The direction of the wind flows as shown by the arrow by 5. Although not shown, the space between the outer cylinder 5 and the inner cylinder 11 of the casing 2 of the axial blower 15 and the space between the outer cylinder 6 and the inner cylinder 12 of the duct 3 are filled with the sound absorbing material 16. There is.

[Embodiment 2] FIG. 4 is a cross-sectional view of the muffler portion of the present invention (the invention according to claim 2) (a sectional view taken along the line BB in FIG. 1). This muffler does not use the sound absorbing material 16 of the first embodiment, but hollows the space between the inner cylinder 10 and the outer cylinder 4, and the cavity 17 constitutes a resonance muffler. Although not shown, the space between the outer cylinder 5 and the inner cylinder 11 of the casing 2 of the axial blower 15 and the space between the inner circumference of the outer cylinder 6 and the outer circumference of the inner cylinder 12 of the duct 3 are also cavities 17. There is.

FIG. 5 shows a cross-sectional view of the silencer portion of the present invention (the invention according to claim 3). This silencer is a sound absorbing material 16
Is attached to the outer circumference of the inner cylinder 10 made of a porous plate with an appropriate thickness, and the space between the outer circumference of the sound absorbing material 16 and the inner circumference of the outer cylinder 4 is a cavity 17. Although not shown, the sound absorbing material 16 is attached to the outer circumference of the inner cylinder 11 of the casing 2 of the axial blower 15 and the outer circumference of the inner cylinder 12 of the duct 3 with an appropriate thickness.
The space between the outer periphery of the sound absorbing material 16 and the inner periphery of the outer cylinders 5 and 6 is hollow. Further, glass fiber, rock fiber or the like is used for the sound absorbing material 16.

In the muffler shown in the first, second, and third embodiments, as shown in FIG. 1, the casing 2 for the duct 1 and the axial blower 15 is provided by the axial blower 15 incorporated in the hanging type ventilation device. , The duct 3 in that order. At this time,
The noise generated from the axial blower 15 propagates through the ducts 1 and 3, respectively. Airflow noise is also generated in all internal flow paths due to the flow of wind. These synthetic sounds propagate to the outside from the outer end openings of the ducts 1 and 3.

FIG. 6 is a diagram showing the frequency characteristics of the volume reduction of the above-mentioned first, second, third and conventional silencers. The curve 6-1 is the first embodiment, the curve 6-2 is the second embodiment, the curve 6 is shown. -3 is the third embodiment, and curve 6-41 is the frequency characteristic of the volume reduction of the conventional silencer.

In Example 1 shown in FIG. 3, a thick portion (long axis of the ellipse) of the sound absorbing material was formed, and the sound absorbing effect at a low frequency was increased as compared with the conventional case. Therefore, as shown by the curve 6-1 in FIG. 6, the noise reduction amount at a low frequency such as the ZN frequency is also increased, and the synthetic sound propagating to the outside is also reduced.

In the second embodiment shown in FIG. 4, the sound absorbing material of the first embodiment is not used, but a hollow is formed between the inner cylinders 10, 11, 12 and the outer cylinders 4, 5, 6 and the cavity 17 resonates. Type muffler, which is suitable for reducing the sound of a specific frequency such as the ZN frequency as shown by the curve 6-1 in FIG.
It is possible to obtain a larger volume reduction than that of the sound absorbing type silencer.

[Embodiment 3] In Embodiment 3 shown in FIG. 5, the sound absorbing material 16 is attached around the inner cylinder 10 of the porous plate with an appropriate thickness to enhance the sound deadening effect at high frequency and at the same time, the sound absorbing material 16 is provided. Since the cavity 17 is provided between the outer cylinder 4 and the outer cylinder 4, the low-frequency sound deadening effect and the high-frequency noise can be simultaneously reduced as shown by the curve 6-3 in FIG. .

[0028]

As described in detail above, according to the present invention, the following excellent effects are expected. (1) It is effective in reducing low-frequency noise that cannot be reduced by the conventional silencer, and also has a high-frequency reducing effect, and noise can be reduced in a wide frequency range.

(2) Since the hanging type ventilation device of the present invention can be made to have the same height as the conventional product, it can be attached to a tunnel or the like in the same manner as the conventional product.

(3) The noise reduction effect can be enhanced while minimizing the increase in cost.

(4) The hanging type ventilation device according to claim 2 is
Since no sound absorbing material is used, cleaning work such as washing with water can be done without removing the soot when it adheres to the equipment, so there is no need to remove it, which simplifies work and reduces maintenance costs. Also disappears.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a hanging type ventilation device of the present invention.

FIG. 2 is a cross-sectional view of the hanging type ventilation device of the present invention.

FIG. 3 is a cross-sectional view of the silencer of the first embodiment.

FIG. 4 is a cross-sectional view of a muffler according to a second embodiment.

FIG. 5 is a cross-sectional view of a muffler according to a third embodiment.

FIG. 6 is a diagram showing frequency characteristics of the volume reduction of the muffler.

[Explanation of symbols]

 1 Duct Part 2 Casing of Axial Blower 3 Duct Part 4 Outer Cylinder 5 Outer Cylinder 6 Outer Cylinder 7 End Plate 8 End Plate 9 Internal Flow Path 10 Inner Cylinder 11 Inner Cylinder 12 Inner Cylinder 13 Partition Plate 14 Partition Plate 15 Shaft Air blower 16 Sound absorbing material 17 Cavity

Claims (3)

[Claims] 1. A hanging type ventilation device equipped with a silencer comprising a casing around an axial blower and ducts for an air inlet and an air outlet, wherein the silencer is an inner cylinder and an outer cylinder. The inner cylinder is a cylinder having a circular cross-sectional shape and is made of a porous material, and the outer cylinder is a cylinder having an elliptical cross-sectional shape, between the inner cylinder and the outer cylinder. A suspended ventilation device having a structure in which the space is filled with a sound absorbing material. 2. A hanging type ventilator equipped with a silencer comprising a casing around an axial blower and ducts for an air inlet and an air outlet, wherein the silencer is an inner cylinder and an outer cylinder. The inner cylinder is a cylinder having a circular cross-sectional shape and is made of a porous material, and the outer cylinder is a cylinder having an elliptical cross-sectional shape, between the inner cylinder and the outer cylinder. A suspended ventilator with a hollow space. 3. A hanging type ventilation device having a silencer, which comprises a casing around an axial blower and ducts for an air inlet and an air outlet, wherein the silencer is an inner cylinder and an outer cylinder. The inner cylinder is formed of a porous material with a circular cross-section, and the outer cylinder is formed of an elliptical cross-section, and the inner cylinder has an appropriate thickness. A hanging-type ventilation device having a structure in which a sound absorbing material is installed and a space between the sound absorbing material and the outer cylinder is hollow.