JPH0417769Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Field of Application] The present invention relates to a silencer for a blower disposed at the discharge port of a Roots blower, a Natsushi pump, etc. that must co-draw air and water in the fields of water treatment, paper manufacturing, chemical industry, etc. [Prior Art] Conventionally, the following two types of silencers are known as this type of silencer. (1) As shown in Figure 2, this is called a single-stage expansion muffler, and the muffler length l is designed with the tonic tone in mind. (2) As shown in Figure 3, a perforated plate is placed on the outside of the muffler, a layer of sound-absorbing material is placed on the outside, and the whole is covered with another container. In addition, in FIGS. 2 and 3 above, 1
1 and 21 are main containers, 12 and 22 are entrances, 1
3 and 23 are outlets, 24 is a perforated plate, and 25 is a sound absorbing material. [Problems to be solved by the invention] (1) In the case of a single-stage expansion muffler, when trying to muffle the lowest pitch frequency of the source as n ₀ (tonic), n ₀ = 1/4 C/l ( C is the speed of sound), the silencing effect for odd multiples of sounds such as 3n ₀ , 5n ₀ , 7n ₀ is extremely good, but 2n ₀ ,
It has no effect on even-numbered sounds such as 4n ₀ and 6n ₀ . This can also be theoretically proven using the following table and FIG.

[Table] By the way, the above-mentioned overtones are unavoidably generated in ordinary mechanical devices once the tonic is determined.Although a muffler can eliminate the tonic, a ``harsh'' sound remains to the human ear. (2) Those with built-in sound-absorbing material interfere with the tonic sound and eliminate overtones with sound-absorbing effect, and from this point of view this is the correct answer, but if the sound-absorbing material gets wet or its physical properties change. While it is predicted that the performance will not be achieved as planned, the sound absorbing material will corrode or slime will occur. In addition, depending on the placement, the sound absorbing material may be biased to one side, which may cause practical problems. It is an object of the present invention to solve the above-mentioned conventional problems and provide a silencer for a blower that has a silencing effect on almost any band of sound and is easy to design. [Means for Solving the Problems] The blower silencer according to the present invention guides the blower discharge pipe into a container having a larger cross-sectional area than that, and uses the sound coherence of the container to muffle the sound. It is a muffler that discharges this to the outside of the system, and if the wavelength of the maximum and lowest sound generated from the blower is λ, then the lengths of the containers are λ/4, λ/4√2, and λ/, respectively. 8, λ/8√2, λ/16, etc. 1/√2 of the length of the front chamber
It is characterized by having compartments stacked one on top of the other with partitions such as perforated plates inserted so that the compartments are stacked one on top of the other. [Function] In order to avoid the conventional troubles mentioned above and to eliminate overtones, it is sufficient to connect a box of length l next to a box of length l/2, as shown in Fig. 5. This leaves the 4th and 6th harmonics. Furthermore, in such a general-purpose blower, even _n0 may deviate by 10% or 20% due to the induction machine and V-belt slip, and the silencing effect varies widely, especially for high-cycle sounds whose wavelengths are close to each other. overtones may remain. According to the present invention, a box of length l is then given a length l/√
By inserting chamber 2, as shown in Figure 6, although the sound in question is not completely muted, either chamber 1 or chamber 1/√2 takes center stage, producing a fairly wide range of sound. Can be erased.
Moreover, since the ratio of 1:/√2 is an irrational number, it is almost impossible for the "indelible wavelengths" to match, so the series of l, l/2 and l/√2, l/2 By combining a small number of stages of the √2 series, sound at almost any frequency can be muted. [Example] Fig. 1 is a diagram showing the configuration of an embodiment of the present invention. In Fig. 1, the container body 1 is connected to the drain separating section 4 and the first chamber A to the fourth chamber D under the following conditions. It is constructed according to the dimensions. The drain separator 4 is sized according to conventional cyclone design to separate moisture contained in the exhaust gas. The first chamber A is determined as l=C/4n ₀ (C is the speed of sound in m/s) for the maximum and lowest frequency n ₀ (c/s) generated from the blower. Next, as shown in FIG. 1, the length of the second chamber B is determined to be 1/√2 of the front chamber. The operation of the embodiment of the present invention described above will be explained. In the first chamber A, as shown in Figure 4,
Sounds with frequencies such as 2n ₀ , 3n ₀ , and 4n ₀ do not disappear, but
Other sounds can be muted, although the effects vary in magnitude. Next, in the second chamber B, it has no effect on sounds that are integral multiples of √2n ₀ , but other sounds can be suppressed, so the combined effect with the first chamber A can consume a considerable amount of band. Next, in the third chamber C alone, 2n ₀
It mainly mutes the sounds of 4n ₀ and 8n ₀ , but these sounds can be muted by the effect of the second chamber, and by adding the fourth chamber D to this, most of the sounds are muted. Ru. [Effect of the invention] According to the invention, the container body of the silencer is
By dividing the room in the manner of √2, l/2, l/2√2, it is possible to achieve a silencing effect on almost any band of sound with a small number of divisions without using conventional sound-absorbing materials. Moreover, excellent effects such as being able to be practically dealt with even if l becomes slightly out of order in terms of design can be achieved.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a silencer as an embodiment of the present invention, Fig. 2 is a sectional view of a conventional single-stage expansion muffler, Fig. 3 is a sectional view of a conventional muffler with sound absorbing material, and Fig. 4 is a sectional view of a conventional muffler with sound absorbing material. A diagram showing the silencing performance of a single-stage muffler, Figure 5 A, B, C, and D are diagrams showing the silencing performance of a 1/2 series two-stage muffler, and Figure 6 shows A, B, and C as 1/√2,
It is a diagram showing a 1/2 series multi-stage muffler. 1...Main container, 2...Perforated plate, 3...Inlet,
4...Drain separation section, 5...Discharge port, A to D...
...1st room to 4th room.

Claims (1)

[Scope of Claim for Utility Model Registration] A silencer that guides a blower discharge pipe into a container with a larger cross-sectional area, uses the sound interference of the container to muffle the sound, and discharges the sound to the outside of the system. hand,
If the maximum and lowest wavelength of sound generated from the blower is λ, then the length of the container is λ/4, λ/4√2, λ/8, λ/8√2, λ/16, etc. A silencer for a blower, characterized in that the compartments are stacked one on top of the other with partitions inserted with perforated plates or the like so that the length of the chamber is 1/√2 times the length of the chamber.