JPH02302552A - Muffler for air-conditioning - Google Patents

Abstract

PURPOSE:To reduce a sound in a low-frequency band and to make an apparatus compact by sticking a perforated plate on the surface of a curved part of an entrance and a sound insulation plate on the surface of a curved part of an exit and by making the outside diameter of a sound-absorbing structure element identical with the dimension of a connection duct. CONSTITUTION:A muffler (shaped in reverse T) for air-conditioning has a perforated plate 5 and a sound-absorbing material 7 on the opposite two sides of an air passage 4 and also an air layer 9 having partition plates 8 outside them, and a curved part of an entrance 2 of the air passage 4 is narrowed down in the shape of a smooth curve and communicates with the air passage. In the curved part of the entrance, a perforated plate 5' is stuck on the surface of the sound-absorbing material, while in a curved part of the exit of the air passage, a sound insulation plate 6 is stuck on the surface of the sound absorbing material. By making the dimension of the outside diameter of the muffler 1 identical with that of a duct, an effect produced by reducing the width of the air passage 4 and the air layer 9 is diminished as much as possible. On the other two sides of the opposite two sides constituting a sound-absorbing structure element, the sound-absorbing material is not provided. In order to increase an effect in medium- and high-frequency bands, otherwise, the air layer is not provided, but only the sound-absorbing material 7 is provided or the surface of the element is left only with the perforated plate stuck. In every case, an apparatus is made compact.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a silencer for air conditioning, and more specifically to a silencer for air conditioning.
This invention relates to an air conditioner silencer that is an improved version of No. 2-297469.

[Conventional technology]

Air conditioning silencers include ducts lined with sound-absorbing material, mufflers and elbows, cell types with partition plates in the ventilation passages, and mufflers with built-in splitters. In addition, we have made some changes in the length and outer diameter of the muffler itself, as well as the thickness of the sound-absorbing material inside, including the expansion type muffler with sound-absorbing material lined inside and the type with a splitter attached to its ventilation path. There are many different types of silencers.

Muffling targets frequencies from 63 to 8000Hz, but especially from 63 to 8000Hz.
There is a demand for muffling over a wide range of frequencies, mainly in the low frequency range of 250 Hz, and from the standpoint of energy conservation, it has been desired that the muffler itself has as little pressure loss as possible.

As a result of research to meet this demand, the present inventor proposed in Japanese Patent Application No. 62-297469 a sound absorbing structure with only two opposing sides, a curved entrance and exit, a perforated plate for the curved part of the entrance, and a curved part of the exit. We proposed a silencer for air conditioning that has a structure with a sound insulating plate and a splitter installed in the ventilation path.

[Problem to be solved by the invention]

The silencer for air conditioning disclosed in Japanese Patent Application No. 62-297469 has a small outer diameter and is compact, and can be used as part of a duct. Since the air layer has a width greater than the minimum limit, the outer diameter becomes larger than the duct size, and there are cases where installation of a silencer larger than the duct size is restricted due to construction.

[Means for solving the problem 1 Therefore, the present inventor basically proposed
Sound-absorbing structure on only two opposing sides and curved entrance/exit,
In addition, although the structure follows the structure of installing a splitter in the ventilation duct, the outer diameter of the silencer is made the same as the duct size, and the silencer is designed to minimize the effect of reducing the width of the ventilation duct and air layer. We decided to make some changes to its structure.

In other words, the pressure loss is minimized by changing the width of the air layer from wide to narrow and the width of the ventilation path from narrow to wide while keeping the outer diameter of the silencer as the connecting duct, but at the cost of slightly sacrificing the volume reduction. Depending on the purpose of use and the conditions of the place of use, it can be adapted to various types, ranging from types that reduce volume as much as possible but have slightly increased pressure loss.

The present invention will be explained below with reference to the drawings.

FIG. 1 shows an embodiment of the invention according to claim (1), in which (a) is a plan sectional view, and (b) and (c) are front sectional views. The air conditioning silencer I of the present invention has a ventilation passage 4
On two opposing sides (left and right sides in Figure 1), there is a perforated plate 5, a sound absorbing material 7, and an air layer 9 having one or more partition plates 8 (two in Figure 1) on the outside thereof, These constitute the sound absorbing structure. The curved portion of the entrance 2 of the ventilation passage 4 is narrowed into a smooth curve and communicates with the ventilation passage. Here, a perforated plate 5' is attached to the surface of the sound absorbing material at the curved part of the entranceff
L, on the other hand, the outlet of the ventilation path is a curved part similar to the inlet, and a sound insulating plate 6 is attached to the surface of the sound absorbing material.

The curved part of the entrance/exit may have any kind of curve, and the first
It may be a gentler curvature (R is larger) than in the case shown in the figure.

In addition, the other two opposing surfaces (the upper and lower surfaces in Figure 1) that constitute the sound-absorbing structure are not provided with sound-absorbing material, or are not provided with an air layer in order to increase the effect in the medium and high frequency range. The sound absorbing material 7 may be left as it is, or a perforated plate may be attached to its surface (in this case, the height A described later may or may not include the sound absorbing material); in either case, the device The aim is to make it more compact.

Metal plates are used for the perforated plates, sound insulating plates, and partition plates used in the present invention, and inorganic fibers and organic fibers such as glass wool, rock wool, and asbestos can be used as the sound absorbing material, but inorganic fibers are preferable. . The sound absorbing material used preferably has a thickness of 25 to 250 mm and a density of 24 to 48 Kg/m', depending on the diameter of the ventilation passage.

In the present invention, the muffler, which originally has a slightly larger outer diameter than the connecting duct, is matched to the connecting duct. Shows two types. In other words, in (1), the ventilation passage is relatively wide and the air layer is narrowed accordingly, resulting in low pressure loss, so an auxiliary silencer can be used in systems where there is little static pressure margin and a slight lack of sound reduction. Can be used as

The one of (11) can be used as a muffler that can be expected to greatly reduce the sound volume when the designed wind speed in the duct is about several m/s and the pressure loss is somewhat large, but when there is a margin in the static pressure.

Furthermore, (II+) narrows the ventilation passage and maximizes the air space. Although this increases the pressure loss, it can ensure a high volume reduction in the wave number band of all layers, so the design wind speed can be reduced to several m/s.
Best suited for the following cases: Of course, in addition to these three types, it is possible to appropriately select and determine the pressure loss and volume reduction by changing the width of the air layer and ventilation passage.

Next, a silencer according to claim (2) having a splitter will be explained with reference to FIG. FIG. 3 shows one embodiment of the silencer, (
(a) is a plan sectional view, and (b) and (c) are front sectional views. The difference from Figure 1 is that there is a splitter 11 in the ventilation passage 4.
(In Figure 3, one splitter with an air layer) is provided with a perforated plate on the outside of the sound absorbing material, which is curved at both ends and linear in the longitudinal direction, and the surface of the curved part of the inlet is A sound insulating board is attached to the perforated board and the exit curved surface, and the central part has an air layer with a sound insulating board in the center in the long horizontal direction and one or more partition plates perpendicular to the sound insulating board. It is. In addition to this, a perforated plate may be attached to the surface of a round bar-shaped or flat-shaped sound absorbing material.

The number of splitters can be one or more depending on the width of the ventilation path. For example, in the silencer shown in FIG. 1, if the width of the ventilation passage becomes 550 mm or more, it is preferable to provide a splitter because the amount of sound reduction decreases in all frequency ranges.

Further, the interval Q between the partition plates (both the sound absorbing structure and the splitter) provided in the air layer is preferably 500 to 700 mm in the low frequency range, which is better than the case where no partition plate is provided.

The sound insulation board at the exit curved part has a sound reduction effect of 20% in the low frequency range of 63 to 500Hz compared to using a perforated board.
~30% larger. The higher the transmission loss of this sound insulating plate, the more preferable it is.

〔Example〕

Example 1 In the air conditioning silencer of the present invention without a splitter shown in FIGS. 2 (+) to (Ill), the width of the air layer is (1
) : (II) : (Ill) =1 : 2 :
3), the height A and the inlet width of the air-conditioning silencer having one splitter of the present invention shown in FIG.

As a comparative example, we measured the relationship between frequency and volume reduction using a conventional silencer (Fig. 7) with a sound absorbing material inside and no splitter (Fig. 7), where both the inlet width and height were set to A, and the silencer of the present invention. It is shown in Figure 4.

The silencer shown in Figure 2 (1) has the same effect in the low frequency range as the conventional one shown in Figure 7, but the silencer shown in Figure 2 (11), (Ill
) is superior to the conventional one, and the effect is particularly large in the low frequency range.

Regarding the silencer of the present invention with one splitter shown in Figure 3, the results of measuring the volume reduction of the silencer corresponding to (II) without a splitter in Figure 2 are shown in Figure 4. Figure 2 (approximately the same effect as +ri was obtained.

Example 2 The one shown in FIG. 2 ([) to (Ill) in Example 1,
FIG. 5 shows the relationship between wind speed and pressure loss for the conventional device shown in FIG. 7. As a result, although the effect in the low frequency range is the same in Fig. 2 (1) as in Fig. 7, the pressure loss is extremely small, and in Fig. 2 (11) compared to the one in Fig. 7. Although the effect in the low frequency range is excellent, the pressure loss is only slightly large. Figure 2, (
Ill) has the largest pressure loss. From this, the second
It can be seen that by properly using the three types of silencers shown in Figures (1) to (Ill) as air-conditioning silencers, it is greatly useful for optimum noise reduction design depending on the conditions of use.

〔Effect of the invention〕

The air conditioner silencer of the present invention enables sound reduction with emphasis on the low frequency range, which is particularly likely to cause problems in air conditioning ducts.
And the equipment can be made more compact.

Therefore, it is possible to more easily perform an optimal design according to the design conditions (required volume reduction, wind speed in the duct, etc.), and it is also possible to comply with installation restrictions (such as making it the same size as the duct).

[Brief explanation of the drawing]

Fig. 1 shows a silencer for air conditioning according to the present invention ((a) is a plan sectional view, (b) and (c) are front sectional views ((C) is a case without upper and lower sound absorbing materials)), and Fig. 2 is another embodiment ((■)~(
Ill)) is a plan sectional view of FIG. FIG. 3 shows an embodiment of the air conditioning silencer of the present invention having one splitter ((a) is a plan sectional view, (b), (c) is a front sectional view ((C) is a first
Similar to the figure)). Figure 4 is a graph of the relationship between frequency and volume reduction, Figure 5 is a graph of the relationship between wind speed and pressure loss,
FIG. 6 is a graph showing the influence of the interval (9) between the partition plates in the air layer on the relationship between frequency and volume reduction. Figure 7 shows (a) a plan sectional view and (b) a conventional air conditioner silencer.
) is a front sectional view. And... Air conditioning silencer 2... Ventilation duct population 3... Ventilation duct outlet 4...
Ventilation passage 5.5'...Perforated plate 6...
Sound insulation board 7...Sound absorbing material 8...
Partition plate 9...Air layer IO...
... Splinter license applicant Akira Ito, agent Ryoko Co., Ltd. Patent attorney Figure 1 (G) (b) (C) Figure 2 (I) (II) (II[) For Figure 4 Liquid & (H2) Fig. 5 Wind speed (m/S) Fig. 6 M Hesei (H2)

Claims (2)

[Claims] (1) In an air conditioning silencer in which a sound absorbing material is lined inside the ventilation passage, two opposing sides of the ventilation passage are made of a perforated plate and a sound absorbing material, and an air layer having one or more partition plates on the outside thereof. The sound absorbing structure is curved from the entrance and exit of the muffler and narrowed to the straight part of the sound absorbing structure to communicate with the ventilation passage, and the surface of the curved part at the entrance is a perforated plate, and the curved part at the exit is a perforated plate. A silencer for air conditioning, characterized in that a sound insulating plate is attached to the surface of each part, and the outer diameter of the sound absorbing structure part is set to the same size as the connecting duct. (2) The silencer for air conditioning according to claim (1), wherein one or more splitters with or without an internal air layer are provided in the ventilation passage in parallel to the sound-deadening structure. Silencer