JPS5936160B2 - Silencer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a silencing device used to prevent noise from propagating in ducts installed in buildings.

Generally speaking, sound damping devices include those in which sound absorbing material is pasted on the inner wall of the duct, and those in which the duct itself is bent.In particular, for the latter, a sound damping device in which a spiral plate is attached inside the duct has been proposed. .

However, noise attenuation by sound-absorbing materials is large at medium and high temperatures, but is not sufficient at low temperatures, and creating bends in the duct increases air flow resistance, increasing the burden on air conditioners. , the cost of manufacturing the spiral plate was too high.

In addition, conventional noise reduction devices have problems in that they do not provide sufficient noise reduction when the flow velocity of the air carrying the noise is high, and they also cannot sufficiently reduce the energy of pulsating flows such as engine exhaust. .

The present invention has been made in view of the conventional problems as described above, and its purpose is to obtain a good silencing effect throughout the entire low temperature range to high temperature range, and to provide a sufficient sound damping effect regardless of the audible frequency. It is an object of the present invention to propose a sound damping device that is easy to manufacture, which can obtain a good sound pressure attenuation, and further suppresses air flow resistance.

Another object of the present invention is to propose a silencing device that can perform good silencing even when the flow velocity of noise-carrying air is very low, and can sufficiently reduce the energy of pulsating flow.

Hereinafter, the present invention will be explained in detail using drawings showing a preferred embodiment.

FIG. 1 is a partially cutaway perspective view of the silencer 10. As shown in FIG.

Reference numeral 12 denotes an outer cylinder, and although an example is shown here in which it is constructed of a rectangular prism-shaped cylinder, it may be cylindrical or other polygonal cylinders.

14 indicates the inner wall of the outer cylinder.

16 is an inner cylinder that is sufficiently finer than the outer cylinder 12,
The shaft has a rectangular cross section and is located at the axial center of the outer cylinder 12.

As shown in FIG. 2, the structure of the inner cylinder 16 is such that the hollow interior is divided into two in the axial direction by providing a wind shield plate 18 near the middle portion.

Resonance holes 20 are provided in the four sides of the inner cylinder 16 as appropriate.
is bored to communicate between the inside and outside of the inner cylinder 16.

The cavity 22 formed between the inner tube 16 and the outer tube 14 together with the resonance hole 20 constitute a resonator.

The present inventor assumes that the diameter of the resonance hole 20 is 45 mm and the diameter is 250 mm.
Made it possible to obtain low frequency resonance below z.

24 is a guide plate formed using only sound absorbing material,
It is made up of an inclined part 26 and a horizontal part 28 arranged in series at an intersection U.

Here, the inclined part 26 refers to the inclined part 26', 2 da 2 in the figure.
6///,... are the same as the horizontal part 28 (slanted part 28
', 2za7, 281//, . . .

The horizontal portion 28' is in contact with the corner of the inner cylinder 16 and extends between the inner wall of the outer cylinder, and in this example, since both the inner cylinder 16 and the outer cylinder 14 have a square cross section, the horizontal portion 28 is square.

The inclined part 26' is continuous with the horizontal part 28', and is inclined between one side of the inner cylinder 16 and the inner wall of the outer cylinder, but the inner cylinder side and the inner wall of the outer cylinder are It is a right angle.

The horizontal part 2g' is in contact with this inclined part 26'.
It is adjusted so that it is one step lower than 8', and further, following this, an inclined part 26'' is stretched between the next side surface of the inner cylinder 1 and the outer cylinder.

Similarly, horizontal portions 28 and inclined portions 26 are alternately provided clockwise (or counterclockwise) around the inner cylinder 16, and the horizontal portions 28 become lower one by one, so that the guide plate 24 It becomes like a spiral.

The inner edge of the guide plate 24 (the inner edge of the inclined plate 26) is entirely connected to the inner cylinder 1.
The outer edge 32 is securely secured to the inner wall of the outer cylinder 14, and the cavity 22 is formed into a spiral ventilation path by the guide plate 24, and this ventilation path is connected to the silencer 10.
Opens above and below.

It goes without saying that when the silencer 10 is installed horizontally, the horizontal portion 28 becomes vertical.

Next, the operation of this muffling device 10 will be explained.

This muffling device 10 is installed, for example, at a suitable location in an air conditioning duct in a building, and noise carried along with air circulation enters the inside through one opening 1'' of the muffling device 10.

Noise is a mixture of sounds in the mid-high temperature range and low-temperature range, but noise in the low-temperature range has a longer wavelength and is more likely to be a diffracted wave that goes around to the back of an object, so it has a spiral shape. Although it is easy to pass through the cavity 22, it enters and exits the inside and outside of the inner cylinder 16 through the resonance hole 20, and since the inner cylinder 16 and the cavity 22 form a resonator, it is converted into vibration energy, and it also forms a guide plate 24. The adsorbent converts it into thermal energy.

Here, since the inner cylinder 16 has a wind shield plate 18 fixedly installed in the center part, the sound does not escape from one side to the other, and the function of allowing low frequency noise to go in and out of the inner cylinder 16 is enhanced. This contributes to a reduction in sound pressure due to changes in the width of the road and resonance.

In addition, since wide-range and mid-range noises travel straight and have weak diffraction power, the sound that enters the inner cylinder 16 loses most of its energy when it collides with the windshield plate 18 and leaks into the cavity 22, and furthermore, the sound that enters the inner cylinder 16 loses energy when it collides with the wind shield 18 and leaks into the cavity 22. The sound is converted into thermal energy and absorbed by the plate 24.

The medium and high temperatures that have directly entered the cavity 22 serving as the ventilation path are guided by the guide plate 24.
The acoustic energy is significantly attenuated by causing the fine fibers of the sound-absorbing material to resonate and converting the acoustic energy into thermal energy, and by diffraction through the spiral ventilation path.

Further, at the open end of the outer cylinder 12 on the side where the noise flows in, a baffle plate 30 having a conical shape and an aperture ratio of 65 to 80% is provided with its tip facing forward as shown in the figure. .

This baffle plate 30 sufficiently reduces the flow rate of fluid flowing into the muffler 10.

Therefore, even when the flow velocity of the air carrying noise is high, the flow velocity is reduced by the baffle plate 30, so that good noise reduction is achieved.

Note that the baffle play 1-30 can also effectively reduce the energy of pulsating flows such as engine exhaust gas.

As described above, according to the present invention, low-range noise is mainly muffled by the resonator portion formed by the inner cylinder and the cavity, and mid- and high-range noise is muffled by the sound absorbing material when passing through the substantially spiral ventilation path. Therefore, extremely good attenuation effects can be obtained with a single muffler over a wide range from the low range.

In addition, even when the flow velocity of the air carrying noise is high, the flow velocity can be reduced by the baffle plate, which provides sufficient sound-dampening power and also effectively reduces the energy of pulsating flow such as engine exhaust. Can be done.

Furthermore, since the guide plate is made of only sound absorbing material, it is inexpensive and extremely easy to manufacture.

Note that the application of the present invention is not limited to air conditioning devices, but has various applications as a muffling device for internal combustion engines and the like.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially cutaway perspective view of a silencer according to the present invention, FIG. 2 is a longitudinal sectional view, and FIG. 3 is a front view of an inner cylinder. Here, 10...muffler, 12...
Outer cylinder, 16... Inner cylinder, 18... Wind shielding plate, 20... Resonance hole, 22... Cavity, 2
4... Information board, 26... Inclined part, 28
. . . Horizontal portion, 30 . . . Baffle plate.

Claims (1)

[Claims] 1 A quadrangular prism-shaped inner cylinder part installed at an axial position within the outer cylinder part so that a sufficient cavity is formed between the outer cylinder part and the inner wall of the outer cylinder part, and near the middle part. The interior is provided with a wind shield plate that divides the interior into two in the axial direction, and a resonance hole is bored in the axial direction to communicate between the inside and the outside. By having a cylindrical portion, an inclined member and a horizontal member that are connected to each other, and the inclined member and the horizontal member are airtightly fixed between the inner wall of the outer cylindrical portion and the outer wall of the inner cylindrical portion. a guide plate made of a sound-absorbing material that forms a substantially spiral ventilation passage in the cavity;
A muffling device comprising a cone-shaped baffle plate (1) having a plurality of holes throughout the entirety of the baffle plate (1) provided nearby.