JP2007321735A - Muffling device for blower and muffling material for blower - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a muffling device having higher muffling effect than a former resistance type muffler without complicating a structure and without complicating assembling. <P>SOLUTION: The muffling device 5 for a blower provided with a cylindrical sound absorbing body 50 in a cylindrical case 50 and used with attached on a delivery port of the blower, is provided with a cavity 51B in the cylindrical sound absorbing body 50. Both actions of a resistance type muffling device and a simple expansion type muffling device are provided by the cylindrical sound absorbing body 50. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a blower silencer using a cylindrical sound absorbing member, and particularly to a silencer and a silencer suitable for a blower equipped with an impeller.

  Blowers include centrifugal blowers and vortex blowers equipped with impellers, and are useful for forcible transfer of gaseous fluids such as air. In some cases, it is equipped with a silencer. As a silencer used at this time, either a resistance type or a reactance type silencer has been conventionally used. In the case of the reactance type, a simple expansion type and a simple expansion type are provided with an insertion tube. Any of the combined methods will be adopted.

  Here, FIG. 4 is an example of a conventional electric blower when a resistance silencer is applied to the vortex blower. The illustrated vortex blower 1 is not shown because its impeller is rotationally driven by the electric motor 2. The function of the blower is demonstrated by sending out the air taken in from the suction port of the blower to the discharge port 3. At this time, a resistance silencer 4 is provided at the discharge port 3 of the blower, and the operation noise is attenuated here. It is made to let you.

  Therefore, the resistance silencer 4 will be described in detail with reference to FIG. 5. This is because, for example, a cylindrical sound absorber made of a metal such as steel is used to form a porous sound absorbing material such as a synthetic resin foam material. A cylindrical sound absorber 41 is provided, one end of the case 40 is connected to the blower outlet 3 as an inlet passage 42, and the other is an outlet passage 43. The vortex blower 1 is operated and the blower discharge When air flows into the inlet passage 42 from the outlet 3, the air passes through the central hole 41A of the cylindrical sound absorber 41 and is discharged from the outlet passage 43. At this time, the cylindrical sound absorber 41 is configured. The porous sound-absorbing material which absorbs the sound wave energy absorbs the sound wave, and as a result, a silencing effect is obtained.

  The attenuation amount of the sound wave by the resistance silencer 4 at this time depends on the length and thickness of the cylindrical sound absorber 41, and the frequency of the sound wave to be silenced is further the sound absorption characteristic of the sound absorbing material constituting the cylindrical sound absorber 41. Also depends on. Therefore, by selecting the length and thickness of the cylindrical sound absorber 41 and the type of the sound absorbing material, a necessary silencing characteristic can be obtained even for sound waves over a relatively wide range of frequencies, and a relatively simple structure is sufficient. Widely used in the past.

  By the way, in recent years, the demand for lowering the noise of equipment has increased, and the blower is no exception. In this case, naturally, it is necessary to equip a silencer, but here, in the case of the conventional resistance silencer 4 described above, In order to further enhance the silencing effect, it is necessary to increase the area where the sound wave contacts the sound absorbing material. For this purpose, the length and diameter of the silencer must be increased. Therefore, the resistance silencer 4 becomes large, and the eddy current blower 1 becomes large.

Therefore, a certain prior art has proposed a resistance silencer in which the area in which sound waves come into contact with the sound absorbing material is increased by combining sound absorbing materials having different cross-sectional shapes of the resistance type silencer (see, for example, Patent Document 1). In other prior arts, a resistance silencer has been proposed in which the area in which sound waves contact the sound absorbing material is increased by changing the cross-sectional area of the sound absorbing material (see, for example, Patent Document 1).
JP-A-5-209600 JP 2005-2897 A

  In the above prior art, it cannot be said that consideration is given to the fact that the noise reduction of the eddy current blower is accompanied by complicated assembly and complicated configuration, and it is difficult to promote further noise reduction. there were. That is, in the above-described certain prior art, a combination of sound absorbing materials having different cross-sectional shapes is required, so that the assembly is complicated. In other conventional technologies, the sound absorbing material needs to have a complicated cross-sectional shape. In both cases, the cost of the blower will eventually increase, and it will be difficult to further reduce noise.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a silencer and a silencer that have a higher silencing effect than conventional resistance silencers without complicating the configuration and complicating assembly.

  The above-described object is achieved by a sound absorbing device having a cylindrical case and a sound absorbing material having a ventilation path attached to a blower that operates to suck or discharge gas. The

  In addition, the above-described object is achieved by a sound absorbing material that is used by being attached to a blower that sucks or discharges gas and has a cylindrical case and a ventilation path, and that the sound absorbing material has a simple expansion silencer shape.

  Similarly, in the silencer device for a blower, which is provided with a cylindrical sound absorbing member in a cylindrical case and attached to the discharge port of the blower, the sound absorbing member is operated as an expansion chamber of a simple expansion silencer. This is achieved by providing a cavity having a necessary shape and providing the operation of both a resistance type silencer and a simple expansion type silencer by the sound absorbing member. At this time, even if the blower is a blower provided with an impeller, and the length and diameter of the cavity are determined according to the number of blades and the rotational speed of the impeller of the blower, the above object is achieved. .

  According to the present invention, a sound absorbing material having a ventilation path is provided in a cylindrical case, and a sound absorbing material having a simple expansion type structure is employed in a silencer that is used by being attached to a blower that sucks or discharges gas. A resistance-type silencer structure is obtained, and as a result, it is possible to provide a silencer that has a higher silencing effect than prior art silencers.

  Hereinafter, the present invention will be described in detail with reference to illustrated embodiments. FIG. 1 shows an embodiment of a silencer for a blower according to the present invention. In this case as well, the eddy current blower 1 shown in FIG. The function of the blower is exhibited by sending the air taken in from the suction port of the blower (not shown) to the discharge port 3 by being driven to rotate. At this time, in this embodiment, the muffler is silenced in the blower discharge port 3. A device 5 is provided to attenuate the operating noise.

  Next, the details of the silencer 5 will be described with reference to FIG. 2. This is a cylindrical sound absorber 51 made of a porous sound absorbing material such as a synthetic resin foam material in a case 50 made of a metal cylindrical member. And a cylindrical member having a diameter smaller than that of the cylindrical member constituting the case 50 is provided at both ends of the case 50, one being an inlet passage 52 and the other being an outlet passage 53. In this respect, it is similar to a general resistance silencer.

  Therefore, in this embodiment, the shape of the cylindrical sound absorber 51 is different from that of a general resistance type, and as shown in the drawing, small diameter portions are provided at both ends of the cylindrical portion. Each end portion is formed to have the same diameter as that of the inlet passage 52 and the outlet passage 53, and the cylindrical portion is formed to have a larger diameter than both end portions. A feature is that a cavity 51B serving as an inflating portion is formed, and it also functions as a simple inflating silencer.

  Therefore, according to this embodiment, the silencing action as a resistance type silencer given by the air passing through the cavity 51B of the cylindrical sound absorber 51 and the cavity 51B formed in the cylindrical sound absorber 51. Both of the silencing action as a simple expansion silencer can be obtained, and as a result, a silencing device having a silencing effect higher than that of a conventional resistance silencer can be achieved without complicating the configuration and complication of assembly. This point will be described below in more detail.

  First, a simple expansion silencer will be described. Here, FIG. 3 shows a general simple expansion silencer 6, which, as shown, is connected to both ends of a case 61 made of a relatively large diameter cylindrical member from a relatively small diameter pipe line. An inlet passage 62 and an outlet passage 63 are provided, and a cavity 61B serving as an expansion pipe is formed inside the case 61. Then, if this is applied to, for example, the vortex blower 1 of FIG. 4 and replaced with the resistance silencer 4, air enters the cavity 61 </ b> B from the inlet passage 62 by driving the vortex blower 1, After expanding here, it comes out of the exit passage 63.

At this time, since the air has expanded in the cavity 61B, reflection and interference of sound waves occur in the cavity 61B and cancel each other, so that a silencing effect can be obtained. This is the origin of the name of the simple expansion type. If the sound transmission loss by the simple expansion silencer at this time is TL, the cross-sectional area of the cavity 61B is S1, and the cross-sectional area of the inlet passage 62 is S2. When the cross-sectional area of the outlet passage 63 is S3, the length of the cavity 61B is L [m], and the wave number of the sound wave is k [rad / m], it is expressed by the following equation.

  Next, assuming that the frequency of the sound wave when the sound transmission loss TL is maximum is f, this is expressed by the following expression, where the sound speed is c [m / s]. Here, n is an integer.

f = c / 4L. (2n + 1) [Hz]

Accordingly, when the wavelength of the sound wave is λ [m], the sound transmission loss TL is maximized when the length L of the cavity 61B is an odd multiple of “λ / 4”. However, when the inner diameter of the cavity 61B is D [m], the inequality “λ> D” is satisfied and the plane wave logic is satisfied. As a result, the simple expansion silencer has a specific frequency. It can be seen that it has a silencing effect particularly on the sound that appears in a peak shape.

  By the way, an air blower equipped with an impeller such as a vortex blower has a noise of an NZ component (frequency is N × Z [Hz] when the rotational frequency is N [Hz] and the number of impeller blades is Z (anonymous number). ]), It is known to generate so-called dominant noise. However, it is difficult to mute the sound because it has a sharp peak shape. However, in this embodiment, in addition to the function as a resistance silencer derived from the presence of the cylindrical sound absorber 51, the function as a simple expansion silencer derived from the shape of the cylindrical sound absorber 51 is also provided. It has come to be obtained.

  Therefore, in the muffler according to this embodiment, the dimension L is set in accordance with the frequency of the NZ component, and then applied to a blower such as a vortex blower. It can be reduced by the function as a silencer, and the prevailing sound can be reduced by the function as a simple expansion silencer. As a result, there is no unpleasant sound and the overall noise level is suppressed. Can be provided.

  In addition, the silencer 5 according to this embodiment has a complicated structure because there is only a difference that the hollow sound absorber 51 is formed in the cylindrical sound absorber 51 when compared with the simple expansion silencer 6 of FIG. Therefore, according to this embodiment, there is no risk of complicated configuration and complicated assembly, and a low-cost and high-performance silencer can be provided. It can contribute to improvement.

  Further, the silencer 5 according to this embodiment is only required to add the case 50 and the cylindrical sound absorber 51 to the simple expansion silencer 6 of FIG. Since the increase is only the addition of the case 50 and the cylindrical sound absorber 51, it does not require much size. Therefore, according to this embodiment, a low-cost and high-performance silencer is provided. Can contribute to the improvement of the low noise performance of the blower.

It is a side view showing an example of an electric blower to which an embodiment of a silencer for a blower according to the present invention is applied. It is a sectional side view which shows one Embodiment of the silencer for blowers by this invention. It is a sectional side view for demonstrating a simple expansion type silencer. It is a side view which shows an example of the electric blower provided with the silencer by a prior art. It is a sectional side view for demonstrating a resistance type silencer.

Explanation of symbols

1: Vortex blower 2: Electric motor 3: Discharge port 5: Silencer 50: Case 51: Cylindrical sound absorber 51B: Cavity (expansion pipe)
52: Entrance passage 53: Exit passage

Claims (4)

In the silencer composed of a sound absorbing material having a cylindrical case and a ventilation path, used by attaching to a blower that sucks or discharges gas,
A silencer, wherein the sound absorbing material has a simple expansion silencer shape. In a sound-absorbing material equipped with a cylindrical case and a ventilation path used by attaching to a blower that sucks or discharges gas,
A muffler having a simple expansion silencer shape. In a silencer for a blower that is equipped with a cylindrical sound absorbing member in a cylindrical case and is used by being attached to a blower outlet,
The sound absorbing member is provided with a cavity having a shape necessary for operation as an expansion chamber of a simple expansion silencer,
A silencer for a blower, characterized in that the sound absorbing member allows the operation of both a resistance silencer and a simple expansion silencer. The blower silencer according to claim 1,
The blower is a blower provided with an impeller;
A blower silencer, wherein the length and diameter of the cavity are determined in accordance with the number of blades and the rotational speed of the blower impeller.

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