JP4799442B2 - duct - Google Patents

Description

  The present invention relates to a duct suitable as an intake duct for an engine in an automobile.

  2. Description of the Related Art Conventionally, in an intake duct of an engine in an automobile, in order to reduce noise generated when air passes through the duct, as shown in FIGS. 9 and 10, a tubular duct body 71 made of a thermoplastic synthetic resin is used. There is a duct 70 in which an opening 73 is formed in the side wall 72 and the opening 73 of the side wall 72 is covered with a nonwoven fabric 75 (for example, Patent Document 1).

  However, in the duct 70, the non-woven fabric 75 covering the opening 73 of the side wall 72 has air permeability, and the entire opening 73 of the side wall 72 is covered with the non-woven fabric 75 and exposed outside the duct 75. Therefore, there is a problem that sound in the duct easily leaks to the outside through the nonwoven fabric 75. Further, since the area of the nonwoven fabric 75 exposed outside the duct is large, hot air in the engine compartment (abbreviation: ENCOPA) of the automobile in which the duct 70 is disposed is sucked into the duct body 71 through the nonwoven fabric 75 and the engine side. This is not preferable in terms of engine function. Further, when hot air in the engine compartment passes through the nonwoven fabric 75 and is sucked into the duct body 71, dust in the engine compartment is trapped by the nonwoven fabric 75 and clogs the nonwoven fabric 75, resulting in a decrease in sound absorption. There is a problem. Furthermore, since the nonwoven fabric 75 has air permeability and a large area exposed outside the duct, turbulent flow is likely to occur in the duct main body 71, and there is a problem in that pressure loss is adversely affected. Furthermore, since the area of the non-woven fabric exposed outside the duct is large, there is a problem that a tool or the like is easily hit when the duct is attached and is easily damaged.

JP 2001-193587 A

  The present invention has been made in view of the above points, and reduces the volume of leakage from the opening of the side wall to the outside, reduces the amount of external air sucked into the duct body from the opening of the side wall, and It is an object of the present invention to provide a duct that makes it difficult to cause clogging of the sound absorbing material, further prevents damage to the sound absorbing material due to contact with a tool, etc., and maintains good sound absorbing performance.

  The invention according to claim 1 is a tubular duct main body having an opening formed in a side wall, and is provided so as to protrude from the outer surface of the side wall of the duct main body so as to cover the opening, and in the duct main body through the opening. A hollow chamber that communicates with the sound absorbing material provided in the hollow chamber, the hollow chamber having a frame-shaped side portion that surrounds the periphery of the opening of the duct body, and a side opposite to the opening. A side wall of the hollow chamber having a double wall structure of an inner wall and an outer wall, the sound absorbing material can be disposed between the inner wall and the outer wall, and an inner wall opening is formed on the inner wall. An outer wall opening is formed on the outer wall so as to be displaced from the inner wall opening along a circumferential direction of the opening of the duct body, and the outer wall is opposed to the non-opening portion of the outer wall. The opening and the non-opening portion of the inner wall face each other. A partition wall is provided at an end of the outer wall on the opening side of the outer wall toward the inner wall, leaving a gap between the inner wall and the sound absorbing material is disposed between the inner wall and the outer wall. And surrounds the periphery of the opening, and is compressed by the partition wall and the inner wall in the vicinity of the outer wall opening side end portion of the outer wall, and between the non-opening portion of the outer wall and the sound absorbing material between the partition walls. The present invention relates to a duct characterized by having a space.

  According to a second aspect of the present invention, in the first aspect, the sound-absorbing material is formed of a porous body that can be compressed and deformed, and is compressed by the partition wall and the inner wall in the vicinity of the end portion on the outer wall opening side of the outer wall. By this, it is characterized by being denser than the portions located in the inner wall opening and the outer wall opening.

  According to the present invention, the sound in the duct main body enters the hollow chamber from the opening formed in the side wall of the duct main body, and further from the inner wall opening formed in the side portion formed of the double wall structure of the hollow chamber. It enters between the inner wall and the outer wall of the part, passes through the sound absorbing material between the inner wall and the outer wall, and is discharged from the opening of the outer wall to the outside of the duct. At that time, the inner wall opening and the outer wall opening are formed with the positions shifted along the circumferential direction of the opening of the duct body, and the non-opening portion of the outer wall is located at a position facing the inner wall opening. Since the non-opening portion of the inner wall is located at a position facing the outer wall opening, the sound that has entered the sound absorbing material from the inner wall opening passes through the outer wall of the sound absorbing material along the periphery of the opening of the duct body. Since the sound travels to the position of the opening and the traveling distance of the sound in the sound absorbing material becomes longer, the sound reduction is increased and the leakage sound from the outer wall opening can be reduced. Also, when hot air in the engine compartment enters the sound absorbing material from the outer wall opening on the side of the hollow chamber and advances through the sound absorbing material and then sucked into the duct main body through the inner wall opening and the opening of the duct main body. Since the traveling distance of hot air in the sound absorbing material is increased, the ventilation resistance in the sound absorbing material is increased, and the amount of hot air sucked can be reduced.

  Moreover, according to the present invention, the sound absorbing material is compressed and densely compressed by the partition wall and the non-opening portion of the inner wall in the vicinity of the outer wall opening side end portion of the non-opening portion of the outer wall. As a result, the sound volume can be increased, the leakage sound from the opening of the outer wall can be reduced, and the amount of hot air sucked can be reduced.

  Furthermore, according to the present invention, since the compression of the sound absorbing material is released at the inner wall opening portion, the sound absorbing material is rougher at the inner wall opening portion than at the portion compressed by the partition wall and the inner wall, and Since there is a space between the non-opening part of the outer wall between the partition walls and the sound absorbing material in the non-opening part of the outer wall facing the inner wall opening, the sound in the duct easily enters the sound absorbing material from the inner wall opening, Sound absorption by the sound absorbing material is performed more efficiently.

  Moreover, according to the present invention, the hollow chamber covering the opening of the duct body is closed by the end surface on the side opposite to the opening of the duct body, so that the opening portion where sound is likely to leak in the hollow chamber, The side opening of the hollow chamber (inner wall opening, outer wall opening) can be made smaller than the opening of the duct body, and the orientation of the opening of the duct body and the opening of the side of the hollow chamber is not parallel. Because of the crossing direction, when sound leaks out of the duct from the opening of the duct body through the inner wall opening and outer wall opening on the side of the hollow chamber, or when hot air in the engine compartment is exposed to the outer wall opening on the side of the hollow chamber and When air is sucked into the duct body from the opening of the inner wall through the opening of the duct body, it is necessary for the sound and air to collide with the sides and end faces of the hollow chamber and change the direction. Sounds and ho It is possible to reduce the amount of intake Toea.

  In addition, according to the present invention, the opening of the duct main body, which is easily hit by a tool or the like when the duct is mounted, is covered with the end face of the hollow chamber, and the sound absorption is performed by the outer wall opening on the side of the hollow chamber where the tool or the like is hard to hit. Since the material is in an exposed state, even if a tool or the like hits the duct, the sound absorbing material is hardly hit by the tool, and the sound absorbing material can be hardly damaged. Moreover, since the area of the outer wall opening on the side of the hollow chamber can be smaller than that of the end surface, the area of the sound absorbing material exposed at the outer wall opening on the side can be reduced, thereby making it difficult for the sound absorbing material to hit the tool. Can do.

  Hereinafter, embodiments of the present invention will be described in detail. 1 is a perspective view showing a duct according to an embodiment of the present invention, FIG. 2 is a plan view in which a side portion is cut in parallel with the end face portion of the hollow chamber in FIG. 1, and FIG. 4 is a sectional view taken along the line 4-4 in FIG. 2, FIG. 5 is a sectional view taken along the line 5-5 in FIG. 2, FIG. 6 is a diagram showing a method for measuring the leakage reduction and the volume reduction, and FIG. FIG. 8 is a graph showing the sound reduction measurement result.

  A duct 10 according to an embodiment of the present invention shown in FIGS. 1 to 5 is an automobile duct suitable as an intake duct for an engine in an automobile, and includes a duct body 11, a hollow chamber 21, and a sound absorbing material 31. Is connected to the air cleaner directly or via a bellows or the like, and the other end is used as an air suction port.

  The duct body 11 is made of a thermoplastic synthetic resin blow-molded product and is tubular. In the example shown in the figure, the tube has a substantially square cross section, but may be a tube according to the installation location of the duct, such as another rectangle, a circle, or an ellipse. In addition, the cross-sectional shape of the said tubular shape may change in the middle between the both ends in the said duct main body 11. FIG. Moreover, it does not specifically limit as a thermoplastic synthetic resin which comprises the said duct main body 11, A polypropylene, polyethylene, polyamide, polyester, a polystyrene etc. can be mentioned.

  An opening 13 is formed in a predetermined position between both ends of the duct body 11 on the side wall 12 of the duct body 11. In the example shown in the figure, the opening 13 is a quadrangle, but may be another polygon, a circle, an ellipse, or the like. The size of the opening 13 is set to an appropriate size in consideration of the strength of the duct body 11 and the like. The position of the opening 13 is preferably a position where the sound pressure is maximum in the duct body 11.

  The hollow chamber 21 is provided on the outer surface of the side wall 12 of the duct body 11 so as to cover the opening 13. The hollow chamber 21 is defined (partitioned) by a frame-shaped side portion 22 that surrounds the periphery of the opening 13 of the duct body 11 and an end surface portion 28 that closes the opposite side of the opening 13. The duct body 11 is formed of a synthetic resin case having an opening on the opening 13 side. The synthetic resin constituting the hollow chamber 21 is not particularly limited, and examples thereof include polypropylene, polyethylene, polyamide, polyester, and polystyrene. The synthetic resin case constituting the hollow chamber 21 of the present embodiment is made of an injection-molded product, and is fixed to the outer surface of the side wall 12 of the duct main body 11 with an adhesive or adhesive.

  The side portion 22 of the hollow chamber 21 has a double wall structure of an inner wall 23 and an outer wall 25. The inner wall 23 and the outer wall 25 are provided approximately parallel to each other with a predetermined distance, and the sound absorbing material 31 can be disposed between the inner wall 23 and the outer wall 25. In the inner wall 23 and the outer wall 25, an inner wall opening 24 and an outer wall opening 26 are formed with their positions shifted along the circumferential direction X of the opening 13 of the duct body 11. That is, the non-opening portion 25a of the outer wall 25 is located at a position facing the inner wall opening 24, while the non-opening portion 23a of the inner wall 23 is located at a position facing the outer wall opening 26, The position is completely shifted from the outer wall opening 26 without partially overlapping the position. In the present embodiment, a plurality of inner wall openings 24 and outer wall openings 26 are formed.

  The inner wall opening in the non-opening portion 23a of the inner wall 23 is located at the end of the non-opening portion 25a of the outer wall 25 on the outer wall opening 26 side (the end of the non-opening portion 25a along the circumferential direction X of the opening 13). A partition wall 25b faces an end portion 23b on the inner wall opening side of the non-opening portion 23a of the inner wall 23 toward an end portion 24b (end portion of the non-opening portion 23a along the circumferential direction X of the opening portion 13) 23b. Is provided with a gap (d shown in FIG. 3). The tip of the partition wall 25b faces the end portion 23b on the inner wall opening side of the non-opening portion 23a of the inner wall 23.

  The sound absorbing material 31 is made of a porous material, and in particular, a porous material that can be compressed and deformed, such as a nonwoven fabric or a flexible polyurethane foam, is preferable. The sound absorbing material 31 is disposed between the inner wall 23 and the outer wall 25 in the side portion 22 of the hollow chamber 21 and surrounds the periphery of the opening portion 13 of the duct body 11.

  In the present embodiment, the sound absorbing material 31 has a partition wall 25b of the outer wall 25 and an end portion 23b on the inner wall opening side of the non-opening portion 23a of the inner wall 23 in the vicinity of the boundary between the inner wall opening 24 and the outer wall opening 26. It is compressed with. Reference numeral 31 b denotes a compression portion of the sound absorbing material 31. Due to the compression, the sound absorbing material 31 has a portion 31 b located near the boundary between the inner wall opening 24 and the outer wall opening 26, that is, the compressed portion 31 b from the portion 31 a located at the outer wall opening 26 and the inner wall opening 24. The portion 31a located in the outer wall opening 26 and the inner wall opening 24 is relatively rough. Further, a space 27 is formed between the non-opening portion 25a of the outer wall 25 and the sound absorbing material 31 between the partition walls 25b and 25b inside the non-opening portion 25a of the outer wall 25 facing the inner wall opening 24. ing.

  In the present embodiment, the space 27 is formed as follows. The sound absorbing material 31 is made of a compressible and deformable porous body, such as a nonwoven fabric or a flexible polyurethane foam, and the thickness of the sound absorbing material 31 is the distance between the inner wall 23 and the outer wall 25, that is, the portion where the partition wall 25b does not exist. The distance between the inner wall 23 and the outer wall 25 (the distance in the direction perpendicular to the circumferential direction of the opening 13) is preferably less than the distance between the inner wall 23 and the outer wall 25, and the partition wall 25b. The interval (gap d) between the end portion 23b on the inner wall opening side of the non-opening portion 23a of the inner wall 23 is set larger. The sound absorbing material 31 having the thickness is disposed between the inner wall 23 and the outer wall 25, and sandwiched and compressed between the partition wall 25b and the end portion 23b on the inner wall opening 24 side in the non-opening portion 23a of the inner wall 23, A space 27 is formed between the sound absorbing material 31 and the non-opening portion 25a of the outer wall 25 between the partition walls 25b and 25b. When the thickness of the sound absorbing material 31 is equal to the distance between the inner wall 23 and the outer wall 25, that is, the distance between the inner wall 23 and the outer wall 25 in a portion where the partition wall 25 b does not exist, the sound absorbing material 31. Is compressed to the inner wall 23 side by the partition wall 25b, the surface of the sound absorbing material 31 is pulled to the inner wall opening 24 side between the partition walls 25b and 25b, whereby the sound absorbing material 31 and the outer wall 25 are not separated. The space 27 is formed between the opening portion 25a.

  In the duct 10 configured as described above, noise generated by the passage of air through the duct main body 11 enters the hollow chamber 21 through the opening 13 formed in the side wall 12 of the duct main body 11, and further to the hollow chamber 21 side. The sound enters the sound absorbing material 31 between the inner wall 23 and the outer wall 25 of the side portion 22 from the inner wall opening 24 formed in the portion 22. The sound that has entered the sound absorbing material 31 is reduced (sound absorption) while proceeding through the sound absorbing material 31 to the position of the outer wall opening 26 along the periphery of the opening 13 of the duct body 11, and then the outer wall opening. 26 is discharged to the outside. At this time, since the inner wall opening 24 and the outer wall opening 26 are formed so as to be shifted in the circumferential direction of the opening portion 13, the traveling distance of the sound in the sound absorbing material 31 is increased and the volume reduction is increased. . Furthermore, since the sound absorbing material 31 is compressed and densely compressed by the partition wall 25b and the end portion 23b on the inner wall opening side of the non-opening portion 23a of the inner wall 23, sound permeability and air permeability are reduced. As a result, the sound volume can be increased, the leakage sound from the outer wall opening 26 can be reduced, and the amount of hot air sucked can be reduced. Moreover, since the inner wall opening 24 and the outer wall opening 26 of the side part 22 can be made smaller than the opening part 13 of the duct body 11, the leakage sound from the outer wall opening 26 of the side part 22 can also be reduced.

Specific examples are shown below. The duct body 11 is made of a material HDPE (polyethylene) as a rectangular tube of W80 mm × H70 mm × L600 mm × side wall thickness 2.5 mm, and the center position of the opening 13 is 100 mm from one end of the duct body 11. An opening 13 made of a square of 70 mm × 30 mm was formed on the side wall 12 of the duct body 11. The hollow chamber 21 has an outer dimension of 90 mm × 48 mm × 12 mm, a thickness of 2.0 mm between the inner wall 23 and the outer wall 25 and the end face portion 28, a distance of 5 mm between the inner wall 23 and the outer wall 25, and a protruding amount 2 mm toward the inner wall side of the partition wall 25b (ie, A case body made of a material PP (polypropylene) is formed as a case body having a gap d between the partition wall 25b and the end 23b on the inner wall opening side (3 mm), and the side wall 12 of the duct body 11 is covered with the opening 13 so as to cover the opening 13. The outer surface was fixed with an adhesive. The inner wall opening 24 of the hollow chamber 21 is provided with four dimensions 17 mm × 10 mm and four 10 mm × 10 mm, and the outer wall opening 26 is provided with eight dimensions 8 mm × 8 mm. As the sound absorbing material 31, a nonwoven fabric made of polypropylene fiber having a thickness of 5 mm and a basis weight of 400 g / m ² was disposed between the inner wall 23 and the outer wall 25.

  As shown in FIG. 6, the speaker S, the first microphone M1, the second microphone M2, and the third microphone M3 are arranged with respect to the duct 10 of the embodiment, and the sound from the speaker S passes through the duct 10. , And the leakage reduction volume by passing through the hollow chamber 21 of the duct 10 were measured. The speaker S is installed on one end side of the duct main body 11 to generate sound at a predetermined volume. On the other hand, the first microphone M1 is inserted into the duct main body 11 by making a hole in the side wall 12 near the speaker. The two microphones M2 were positioned at the end of the duct body 11 opposite to the speaker S, and the third microphone M3 was positioned outside the hollow chamber 21, and the volume was measured with each microphone. The volume reduction was a value of [measurement volume of the first microphone M1−measurement volume of the second microphone M2], and the leakage reduction volume was a value of [measurement volume of the first microphone M1−measurement volume of the third microphone M3]. The volume measuring apparatus used is a product name: DYNAMIC SIGNAL ANALYZER 35670A and a manufacturer: HEWLETT PACKARD.

  For comparison, the duct of Comparative Example 1 (duct made of only a tubular body) that is made only of the duct main body 11 and is not formed with the opening 13 and the opening 13 are made of the sound absorbing material 31 of the embodiment. The duct of Comparative Example 2 in which the cover hollow chamber 21 is not provided (the duct is covered with a sound absorbing material and has no hollow chamber) and the partition wall 25b are eliminated, and the distance between the inner wall 23 and the outer wall 25 is set to 3 mm. The volume reduction and leakage volume reduction were measured in the same manner for the duct of Comparative Example 3 having no space 27. At that time, the distance from the end of the duct body to each microphone was the same as that of the duct of the example.

  FIG. 7 shows the measurement result of the leakage reduction volume, and FIG. 8 shows the measurement result of the volume reduction. Compared with the duct of the comparative example 2 (opening is covered with a sound absorbing material and having no hollow chamber) and the duct of the comparative example 3 (duct without a partition wall and having no space), the duct of the example has a leak sound. On the other hand, the sound reduction is equal to or greater than that of Comparative Example 2 and Comparative Example 3, and it can be seen that a good sound reduction effect (sound absorption effect) is exhibited. In particular, in the embodiment, the partition wall 25b and the space 27 are provided, so that there is less leakage sound (leakage reduction volume is large) and the sound reduction is better than the comparative example 3 without the partition wall 25b and the space 27. You can see that In addition, the ducts of Example, Comparative Example 2, and Comparative Example 3 have larger leakage noise in a part of the frequency range than the duct of Comparative Example 1 (duct made of only a tubular body having no opening). However, the sound reduction (sound absorption) is larger than that of the duct of Comparative Example 1 over almost the entire range of the measurement frequency, and it can be seen that the sound absorption performance is good.

  In the embodiment, the partition wall 25b of the outer wall 25 and the end portion 23b on the inner wall opening side of the inner wall 23 are opposed to each other. However, in the present invention, the position of the partition wall 25b is the position of the embodiment. It is not limited to this position, and any position where the sound absorbing material 31 can be compressed between the partition wall 25b and the inner wall 23 may be used. Accordingly, the partition wall 25b may be formed to face the inner wall 23 at a position away from the end 23b on the inner wall opening side of the inner wall 23.

  As described above, the duct of the embodiment has an effect of reducing leakage sound and improving sound absorption. In addition, the duct of the embodiment is covered with a hollow chamber in which the opening of the side wall is defined by the side portion and the end surface portion, and the opening formed in the side portion of the hollow chamber is closed with the sound absorbing material. When hot air in the compartment is sucked into the duct body through the opening of the side of the hollow chamber and through the opening of the duct body, the sound or air once collides with the side or end surface of the hollow chamber. Therefore, the amount of hot air sucked in can be reduced, and the sound absorbing material can be hardly clogged. Furthermore, since the sound absorbing material is exposed only at the opening of the side of the hollow chamber where it is difficult for tools to hit when installing the duct, etc., even if a tool hits the duct, It is difficult for the tool to hit and damage to the sound absorbing material can be prevented. In addition, since the opening of the side portion of the hollow chamber can have a smaller area than the end surface portion and the opening portion of the duct body, this also reduces the amount of hot air inhaled in the engine compartment and is exposed at the opening portion of the side portion. It is possible to make it difficult for the sound absorbing material to hit the tool.

It is a perspective view which shows the duct which concerns on one Example of this invention. It is the top view which cut | disconnected the side part in parallel with the end surface part of a hollow chamber in FIG. FIG. 3 is a sectional view taken along line 3-3 in FIG. 2. FIG. 4 is a cross-sectional view taken along 4-4 in FIG. 2. FIG. 5 is a sectional view taken along line 5-5 in FIG. It is a figure which shows the measuring method of leakage volume reduction and volume reduction. It is a graph which shows a leakage reduction sound volume measurement result. It is a graph which shows a sound reduction measurement result. It is a perspective view which shows the conventional duct. FIG. 10 is a sectional view taken along the line 10-10 in FIG. 9;

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Duct 11 Duct main body 12 Side wall of duct main body 13 Opening part of duct main body 21 Hollow chamber 22 Side part of hollow chamber 23 Inner wall of side part 23a Non-opening part of inner wall 23b End part of inner wall opening side in non-opening part of inner wall 24 Inner wall opening 25 Side outer wall 25a Non-opening part of outer wall 25b Partition wall 26 Outer wall opening 27 Space 28 End face part of hollow chamber 31 Sound absorbing material 31a Part located at inner wall opening and outer wall opening 31b Compression part of sound absorbing material

Claims (2)

A tubular duct body (11) having an opening (13) formed in a side wall (12);
A hollow chamber (21) which covers the opening (13) and protrudes from the outer surface of the side wall (12) of the duct body and communicates with the inside of the duct body (11) via the opening (13);
A sound absorbing material (31) provided in the hollow chamber (21),
The hollow chamber (21) includes a frame-shaped side portion (22) surrounding the periphery of the opening (13) of the duct body, and an end surface portion (28) closing the opposite side of the opening (13). Defined by
The side (22) of the hollow chamber has a double wall structure of an inner wall (23) and an outer wall (25), and the sound absorbing material (31) can be disposed between the inner wall (23) and the outer wall (25). And
An inner wall opening (24) is formed in the inner wall (23), and the inner wall opening (24) is positioned along the circumferential direction (X) of the opening (13) of the duct body on the outer wall (25). The outer wall opening (26) is formed by shifting the inner wall opening (24) and the non-opening portion (25a) of the outer wall (25), and the outer wall opening (26) and the inner wall (23) are not opened. The part (23a) is configured to face each other,
At the end of the outer wall (25) on the outer wall opening (26) side, a partition wall (25b) projects toward the inner wall (23) leaving a gap (d) between the inner wall (23). Established,
The sound absorbing material (31) is disposed between the inner wall (23) and the outer wall (25) so as to surround the opening (13), and on the outer wall (25) side of the outer wall opening (26). In the vicinity of the end portion, the partition wall (25b) and the inner wall (23) are compressed,
A duct having a space (27) between a non-opening portion (25a) of the outer wall between the partition walls (25b) and the sound absorbing material (31). The sound absorbing material (31) is composed of a porous body that can be compressed and deformed. In the vicinity of the outer wall opening (26) side end portion of the outer wall (25), the partition wall (25b) and the inner wall (23) 2. The duct according to claim 1, wherein the duct is made denser than a portion located in the inner wall opening (24) and the outer wall opening (26) by being compressed.

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