JP2006057491A - Silencer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To materialize high silencing performance of a silencer attached to a duct without relying on general solution method for increasing silencing performance such as thickening sound absorbing material. <P>SOLUTION: The silencer 1 is provided with a tubular housing 2 forming an annular space 8 between an inner tube part 6 and an outer tube part 5. A sound introduction opening 6a communicating to an annular space 8 is formed in the inner tube part 6. The sound absorbing material 3 of thickness to be stored with keeping an annular gap 9 is provided inside of the annular space 8. Consequently, external noise transmitting a duct enters the annular space 8 through the sound introduction opening 6a of the tubular housing 2 and is greatly silenced by the sound absorbing material 3 and the annular gap 9. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a silencer that is connected to a duct of a building and silences transmission of external noise to the room.

A silencer is attached to the duct so as to prevent external noise coming from the outdoor opening end of the duct from being transmitted to the room as much as possible. As a silencer, what has various characteristics for silencing the noise is known (patent documents 1 and 2).
JP 2002-147831 A JP 2003-130410 A

  By the way, in order to improve the sound deadening performance, it is common to approach from a solution method such as using a thick sound absorbing material as much as possible or expanding the contact area between the sound absorbing material and air. However, the silencer attached to the duct is usually installed between the outer wall and the inner wall of the building or structure, depends on the shape of the duct, particularly the outer diameter size, and further, the duct is installed as much as possible. It is a given premise that consideration is required not to reduce the pressure loss of the circulating air. For this reason, there is a problem that the above-described general solution for improving the silencing performance cannot be simply applied to the silencer attached to the duct.

  For example, in the solution method using the thick sound absorbing material as described above, there is a problem that the pressure loss of the air flowing through the duct is greatly reduced, and it is also possible to enlarge the duct diameter so as not to impair the pressure loss. There are limitations from the viewpoint of the structure of things. Further, as a solution method for expanding the contact area between the sound absorbing material and air, it is conceivable to attach the sound absorbing material along the length of the duct, but it is short enough that the duct penetrates the outer wall and the inner wall. Since the length is customary, it is not so effective.

  It is an object of the present invention to provide a silencer having a high silencing performance while satisfying the constraint condition of being attached to a duct.

  The invention according to claim 1, which solves the above problem, is provided with a cylindrical housing that forms an annular space between an inner cylinder and an outer cylinder, both ends of which are closed with respect to the silencer connected to the duct. The shape housing is provided with a sound introduction port communicating with the annular space along the circumferential direction in the inner cylinder, and an annular sound absorber having a thickness accommodated in the annular space leaving an annular gap.

  According to the first aspect of the present invention, the external noise transmitted through the duct enters the annular space through the sound guide port of the cylindrical housing, and can be largely silenced by the annular sound absorber and the annular gap. Further, in the silencer having such a structure, the opening width of the sound guide opening along the cylinder axis direction of the cylindrical housing, the thickness of the annular sound absorber, that is, the size of the annular gap in the inner and outer directions (radial direction), etc. By changing the configuration, it is possible to easily control the silencing performance so that it mainly matches the sound of the frequency that is the silencing target.

  According to the second aspect of the present invention, an annular sound absorber is attached to the outer cylinder so that an annular gap is formed on the inner cylinder side.

  According to the second aspect of the present invention, since the sound introduction port is not blocked by the annular sound absorber and the annular gap can be utilized for silencing, high sound deadening performance can be exhibited by both the annular gap and the annular sound absorber.

  The invention described in claim 3 is obtained by coating an annular sound absorber with a resin film.

  According to the third aspect of the invention, it is possible to exhibit a silencing performance different from the case where the resin film is not covered. That is, the silencing performance can be controlled. In addition, it is possible to suppress a decrease in sound absorption and deterioration of the material due to adsorption of moisture such as condensed water.

  According to a fourth aspect of the present invention, the sound guide port is formed at the center position in the cylinder axis direction of the inner cylinder, and the half housing is formed by combining the cylindrical housing at the center position in the cylinder axis direction.

  According to the fourth aspect of the present invention, the sound guide port is formed at the center position in the cylinder axis direction of the inner cylinder, and the half housing is formed by combining the cylindrical housing at the center position in the cylinder axis direction. Since a cylindrical housing can be formed by combining the two, it can be manufactured with one molding die.

  According to the silencer of the present invention, it is possible to exhibit excellent silencing performance while satisfying the constraints for mounting on the duct. Further, since the silencing performance can be easily controlled by a slight change in the configuration, it is possible to obtain the silencing performance suitable for the frequency band to be the silencing target. Therefore, there is little transmission of external noise to the room, and a better living environment is realized.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment and an example of a silencer of the invention will be described with reference to the drawings.

  The silencer 1 according to the present embodiment is attached by being inserted into the duct D (see FIG. 3), and includes a cylindrical housing 2 and a sound absorber 3. The cylindrical housing 2 is configured by combining two halved housings 4 having the same shape made of a hard resin molded body.

  In the structure of the cylindrical housing 2, an inner / outer double outer cylinder part 5 and an inner cylinder part 6 are formed, and the corresponding end parts are closed by an annular closing part 7.

  Among them, the outer cylindrical portion 5 of each half housing 4 is provided with an engaging piece 5a protruding in the cylinder axis direction, and an engaging groove 5b in which the engaging piece 5a of the other half housing 4 is latched is recessed. Has been.

  The inner cylinder portion 6 is formed with a sound guide port 6a along the circumferential direction at a central position along the cylinder axis direction. External noise that passes through the inside of the inner cylinder portion 6 passes therethrough and is guided to the annular space 8 defined by the outer cylinder portion 5, the inner cylinder portion 6, and the annular closing portion 7. The opening width d1 (FIG. 3) of the sound guide port 6a in the cylinder axis direction is sufficiently small with respect to the length of the inner cylinder portion 6 along the cylinder axis direction. A specific opening width d1 is set to 5 mm to 80 mm, preferably within a range of 15 mm to 30 mm.

  The above-described sound absorber 3 is accommodated in the annular space 8. The sound absorber 3 includes a sound absorbing material 3a and a resin film 3b covering the entire outer surface. The sound absorber 3 is in the form of a single flexible plate. Therefore, the sound absorber 3 is bent in an annular shape when accommodated, and is attached along the inner side surface of the outer cylinder portion 5. At the time of attachment, the sound absorber 3 may be completely fixed to the inner side surface of the outer cylinder portion 5 with an adhesive or a tape, but a special fixing means is used in consideration of ease of replacement. Instead, the curved sound-absorbing material 3a itself may be accommodated as it is by utilizing the tension (elastic restoring force) of the curved sound-absorbing material 3a itself. The sound absorbing material 3a is formed of a porous body or foam having a silencing effect, and for example, a urethane resin or a melamine resin is used as the specific material. On the other hand, as the resin film 3b, for example, a fluororesin material is used.

  Further, as the sound absorber 3 as described above, as shown in FIG. 4, a sound absorber 3 having a thickness t1 thinner than a width d2 along the radial direction of the annular space 8 is used. By making the sound absorber 3 thin in this way, an annular space 8 having a width d3 along the radial direction is formed in the annular space 8 in which the sound absorber 3 is accommodated. It can exhibit a silencing effect due to resonance absorption. The thickness t1 of the sound absorbing material 3a is set within a range of 10 mm to 30 mm according to the diameters of the inner cylinder portion 6 and the outer cylinder portion 5. The width d3 of the annular gap 9 is also set within a range of 5 mm to 25 mm according to the diameters of the inner cylinder portion 6 and the outer cylinder portion 5 and the thickness t1 of the sound absorbing material 3a. The cylindrical housing 2 has, for example, an inner cylindrical portion 6 having an inner diameter of 50 mm and an outer cylindrical portion 5 having an outer diameter of 97 mm, and an inner cylindrical portion 6 having an inner diameter of 82 mm and an outer cylindrical portion 5 having an outer diameter of 148 mm. Composed.

  Next, the operation and effect of the silencer 1 according to the present embodiment will be described.

  According to the silencer 1, the external noise transmitted through the duct D enters the annular space 8 through the sound guide port 6 a of the cylindrical housing 2, and is due to the silencing effect by the sound absorber 3 and resonance absorption in the annular gap 9. By exhibiting the silencing effect in a superimposed manner, excellent silencing performance can be exhibited.

  In addition, the silencer 1 having the above-described configuration is suitable for sound in a frequency band mainly used as a silencer target by changing the opening width d1 of the sound guide port 6a and the thickness t1 of the sound absorbing material 3a, that is, the width d3 of the annular gap 9. It is also possible to easily control the silencing performance.

  The silencer 1 has a sound absorber 3 attached to the outer cylinder 5 side so that an annular gap 9 is formed on the inner cylinder 6 side. For this reason, the sound guide port 6a is not blocked by the sound absorber 3, and the annular gap 9 can be utilized for noise reduction by resonance absorption, and both the annular gap 9 and the sound absorber 3 can exhibit high noise reduction performance.

  Since the sound absorbing body 3 of the silencer 1 is obtained by covering the sound absorbing material 3a with the resin film 3b, the sound absorbing performance different from that when not covering with the resin film 3b can be exhibited. That is, the silencing performance can be controlled. Moreover, the sound absorbing material 3a can suppress a decrease in sound absorbing property and deterioration of the material due to absorption of moisture such as condensed water.

  The cylindrical housing 2 is configured by a combination of the half-shaped housing 4 having the same shape in which the sound guide port 6a is formed at the central position of the inner cylinder portion 6 in the cylinder axis direction. For this reason, it becomes possible to manufacture with one molding die, productivity can be improved, and cost can be reduced.

  The silencer 1 according to the above embodiment can be modified within a range that does not impair the basic functions and effects of the present invention. For example, the half housing 4 is formed with an engagement piece 5a and an engagement groove 5b, but the engagement piece 5a has a claw and an engagement groove 5b at the tip, and has a claw at the tip. It is good also as a structure which inserts and combines a piece into the other half housing 4 inside. Further, the outer peripheral surface of the cylindrical housing 2 may be configured as a fastening piece that is in elastic contact with the duct D.

  Hereinafter, the superiority of the silencer according to the above embodiment will be further described based on examples.

  In this example, a confirmation test of the silencer performance of the silencer and a confirmation test that the silencer performance can be controlled by changing the configuration were performed. There were four concrete tests, and each test was performed under the following conditions.

  As shown in FIG. 5, the reverberation room and the anechoic room were connected by a duct, and the silencer (test body) according to the example was attached in the duct. In the reverberation room, five microphones (MI-421 manufactured by Ono Sokki Co., Ltd.) and speakers were installed. On the other hand, an SI measurement probe (manufactured by MI-6410) was installed at the open end of the duct in the anechoic chamber. The microphone was connected to the front end unit (DS-9100 manufactured by the company), and the SI measurement probe was connected to the front end unit via a microphone amplifier (CF-0610 manufactured by the company). The speaker was also connected to the front end unit via an audio amplifier. The front-end unit was connected to a personal computer that executed a sound transmission loss measurement program (manufactured by the same company).

  Using the above equipment, in the reverberation room, the average sound thickness of the sound output from the speaker is measured through a microphone, and in the anechoic room, the sound power transmitted through the duct is measured through the SI measurement probe to determine the sound transmission loss. A test was conducted to confirm the silencing performance. The sound power was calculated from the measured sound intensity. The purpose of each test, the test specimen used, and the test results are as follows.

Test 1 ; This test was performed to confirm the silencing performance of the silencer (1) according to the mounting position of the sound absorber (3). The cylindrical housings (2) of the prepared test bodies 1 and 2 are hard resin molded bodies having the same shape as that of the above embodiment, and the inner cylinder part (6) has an inner diameter of 82 mm and the outer cylinder part (5). The outer diameter 148 mm, the width (d2) along the radial direction of the annular space (8) is 27 mm, the length along the cylinder axis direction of the annular space (8) is 96 mm, and the opening width (d1) of the sound guide port (6a) is A 15 mm one was used. For the sound absorber (3), a melamine resin-based porous material was used as the sound-absorbing material (3a), and a fluororesin-based resin film (3b) with a thickness of about 21 μm was used. Further, the sound absorbing material (3a) having a thickness (t1) of 15 mm was used. And in the test body 1, the sound absorber (3) was wound around the inner cylinder part (6) and attached, and in the test body 2, the sound absorber (3) was attached along the outer cylinder part (5). The test results are as shown in FIGS.

  According to this test result, the transmission loss coefficient is larger in the test body 1 in which the sound absorbing body is attached to the inner cylinder portion on the lower frequency side than around 450 Hz, and on the higher frequency side, the sound absorbing body is placed in the outer cylinder portion. The specimen 2 having an annular gap attached to the plate has a significantly larger transmission loss coefficient. That is, it can be seen that it is preferable to adopt the structure of the test body 1 to mute the sound on the low frequency side near 450 Hz, and the structure of the test body 2 to mute the sound on the higher frequency side. In particular, it can be confirmed that a sound absorber mounting structure having an annular gap like the test body 2 is preferable in order to mute the sound in the frequency band of 500 Hz to 1000 Hz, which is particularly disturbing as traffic noise.

Test 2 ; This test was performed to confirm the silencing performance of the silencer (1) due to the change in the opening width (d1) of the sound guide port (6a). The prepared test bodies 4 to 6 are the same as the above-described test body 2 except for the difference in the opening width (d1) of the sound guide port (6a). Regarding the different opening widths (d1), the test body 4 was set to 20 mm, the test body 5 was set to 25 mm, and the test body 6 was set to 30 mm. Moreover, the test body 3 identical to the test body 2 has an opening width (d1) of 15 mm. The test results are as shown in FIGS.

  According to this test result, for sound in the frequency band of 315 Hz to 3150 Hz, the transmission loss coefficient on the low frequency side is larger and the opening width is larger as the opening width of the sound guide opening is smaller between 630 Hz and 800 Hz. The transmission loss coefficient on the high frequency side is larger. In other words, when the silencer on the lower frequency side is required depending on the surrounding living environment where the silencer is installed, the sound inlet has a smaller opening width, and when the silencer on the higher frequency side is required, the sound inlet It can be seen that the silencing characteristics can be controlled by using a large opening width.

Test 3 : This test was performed to confirm the silencing performance of the silencer (1) by changing the thickness (t1) of the sound absorbing material (3a) without the resin film (3b). The prepared test bodies 7 to 10 are the same as the above-described test body 2 except that there is no resin film (3b) and the thickness (t1) of the sound absorbing material (3a). Regarding the thickness (t1) of the sound absorbing material (3a), the test body 7 was set to 10 mm, the test body 8 was set to 15 mm, the test body 9 was set to 20 mm, and the test body 10 was set to 25 mm. The test results are as shown in FIGS.

  According to this test result, for sound in the frequency band of 315 Hz to 3150 Hz, the transmission loss coefficient on the low frequency side is larger as the sound absorbing material is thicker (the smaller the annular gap is) with 800 Hz as the boundary, and the sound absorbing material is thinner. The transmission loss coefficient on the high frequency side is larger (as the annular gap is larger). Therefore, when the noise reduction on the low frequency side is required according to the surrounding living environment where the silencer is installed, the sound absorption material is thick (the annular gap is small), and when the noise reduction on the high frequency side is required It can be seen that the silencing characteristics can be controlled by using a thin sound absorbing material (large annular gap).

Test 4 : This test was performed to confirm the silencing performance of the silencer (1) by changing the thickness (t1) of the sound absorbing material (3a) with a resin film. The prepared test bodies 11 to 14 are the same as the above-described test body 2 except for the difference in the thickness (t1) of the sound absorbing material (3a). The specimen 11 has a thickness (t1) of 10 mm. Similarly, the specimen 12 is 15 mm, the specimen 13 is 20 mm, and the specimen 14 is 25 mm. The test results are as shown in FIGS.

  According to this test result, the test bodies 11 to 13 with a resin film have a large transmission loss coefficient on the low frequency side and a high silencing effect when compared with the result of the test 3 without the resin film described above. It can be seen that the transmission loss coefficient is small and the silencing effect is reduced, so that the silencing characteristic is generally smoothed. Further, for example, when the sound absorbing material is thicker like the test body 10 and the test body 14 than the thin sound absorbing material like the test body 7 and the test body 11, the change in the transmission loss coefficient due to the presence or absence of the resin film becomes larger. I understand that.

  Note that the test results 2, 3 and 12 are completely identical, but the test results are different because it was performed under different weather conditions. The

The exploded view of the silencer by one embodiment. The perspective view which partially cuts and shows the cylindrical housing of the silencer of FIG. SB-SB sectional view taken on the line of FIG. FIG. 4 is a sectional view taken along line SA-SA in FIG. 3. The schematic diagram explaining test facilities, such as an Example. The figure which shows the table | surface of a test result. The graph which shows a test result. The graph which shows a test result. The graph which shows a test result. The graph which shows a test result.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Silencer 2 Cylindrical housing 3 Sound absorber 3a Sound absorbing material 3b Resin film 4 Half housing 5 Outer cylinder part 5a Engagement piece 5b Engagement groove 6 Inner cylinder part 6a Sound introduction port 7 Annular closure part 8 Annular space 9 Annular gap

Claims (4)

In the silencer connected to the duct,
While having a cylindrical housing that forms an annular space between the inner cylinder and the outer cylinder, both ends of which are closed to each other,
A sound guide port communicating with the annular space along the circumferential direction of the inner cylinder;
A silencer comprising: an annular sound absorber having a thickness that is accommodated while leaving an annular gap in the annular space.   The silencer according to claim 1, wherein an annular sound absorber is attached to the outer cylinder so that an annular gap is formed on the inner cylinder side.   The silencer according to claim 1 or 2, wherein the annular sound absorber is covered with a resin film.   The silencer according to any one of claims 1 to 3, wherein the sound guide port is formed at a center position in the cylinder axis direction of the inner cylinder, and a half housing is formed by combining the cylindrical housing at the center position in the cylinder axis direction.

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