JP2015034508A - Air intake duct - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air intake duct which can attenuate a broadband standing wave and in which excellent sound absorption performance is developed in a specific frequency region in which sound needs to be reduced in particular.SOLUTION: An air intake duct 1 comprises by two half-split bodies made of a fiber mold body being combined includes a cylindrical part 3 and a muffler part 5 provided by branching from the cylindrical part 3. Also, air permeability of a molding wall of the cylindrical part 3 measured by the JIS L1096 A method is 1.0-5.0 cc/cm/sec, and air permeability of a molding wall of the muffler part 5 measured by the JIS L1096 A method is 0.5 cc/cm/sec or less. Furthermore, it is preferable that, when the whole length of the cylindrical part 3 is defined as L, a first high ventilation part having air permeability of 10 cc/cm/sec or more is provided at a position 1/4 of L from one end on a side where air from the cylindrical part 3 flows in, and a second high ventilation part having air permeability of 10 cc/cm/sec or more is provided at a position 3/4 of L.

Description

  The present invention relates to an intake duct. More specifically, the present invention relates to an intake duct that can attenuate a wide-band standing wave and that exhibits excellent sound absorption performance particularly in a specific frequency region where it is desired to reduce sound.

  Conventionally, an attempt has been made to reduce noise generated from an intake duct in a vehicle such as an automobile. That is, the pulsation sound caused by the intake of the engine is a noise in the vehicle interior and the exterior of the vehicle interior. As a countermeasure for reducing the intake pulsation sound, a method of providing a silencer or a throttle in the intake duct is known. For example, an intake duct for an internal combustion engine in which a sound absorbing material is installed in a region corresponding to a quarter wavelength, preferably a half wavelength, of a specific range of frequencies of a cylindrical portion is known (see, for example, Patent Document 1). .) Moreover, the manufacturing method of the air intake duct which heat-molds a nonwoven fabric sheet is also known (for example, refer patent document 2).

JP-A-8-200170 JP-A-11-343938

  However, the air intake duct described in Patent Document 1 is such that a sound absorbing material made of fiber is arranged in a specific region of a cylindrical portion made of a resin material such as polypropylene, and its structure is complicated. It has been difficult to produce the nonwoven fabric sheet by a method of heat compression molding or ordinary press molding.

  The present invention has been made in view of the above-described conventional situation, is easy to manufacture, can attenuate a broadband standing wave, and has excellent sound absorption particularly in a specific frequency region where it is desired to reduce sound. An object of the present invention is to provide an air intake duct that exhibits its performance.

The present invention is as follows.
1. An air intake duct formed by combining two halves made of a fiber molded body,
A tubular portion, and a silencer portion provided by branching from the tubular portion,
The air permeability measured by the JIS L1096 A method of the molding wall of the cylindrical part is 1.0 to 5.0 cc / cm ² / sec,
An air intake duct characterized in that the air permeability measured by the JIS L1096 A method of the molding wall of the silencer part is 0.5 cc / cm ² / sec or less.
2. When the overall length of the tubular part is L, the first highly ventilated part having the air permeability of 10 cc / cm ² / sec or more at a position 1/4 L from one end of the tubular part on the air inflow side. 1 is provided. The intake duct described in 1.
3. When the overall length of the tubular portion is L, the second highly ventilated portion having the air permeability of 10 cc / cm ² / sec or more at a position 3 / 4L from one end of the tubular portion on the air inflow side. 1 is provided. Or 2. The intake duct described in 1.

In the intake duct of the present invention, not only the cylindrical portion but also the silencer portion branched from the cylindrical portion is formed integrally by combining two halves made of a fiber molded body. Moreover, the air permeability of the molding wall of the cylindrical part is within a specific numerical range, and the air permeability of the molding wall of the silencer part is not more than a specific numerical value.
With such a configuration, since the cylindrical portion has air permeability, a broadband standing wave can be sufficiently attenuated. Further, since the silencer portion has low air permeability to the extent that it can resonate, it is possible to sufficiently reduce sound particularly in a specific frequency region where it is desired to absorb sound. Furthermore, the fiber cylindrical portion and the fiber silencer portion can be integrally formed at the same time, and the intake duct can be efficiently manufactured by a simple process.
In the intake duct according to the ^{second aspect} , the first high ventilation portion having air permeability of 10 cc / cm ² / sec or more is provided at a position 1/4 L from one end of the cylindrical portion on the air inflow side.
If it is set as such a structure, the 1-3rd resonance judged to be the dominant mode of intake noise can be reduced efficiently, and a standing wave can be attenuated more efficiently.
In the intake duct according to the third aspect, a second high ventilation portion having air permeability of 10 cc / cm ² / sec or more is provided at a position 3/4 L from one end of the cylindrical portion on the air inflow side.
If it is set as such a structure, the effect similar to when the above-mentioned 1st high ventilation part is provided will be show | played. Moreover, if the 2nd high ventilation part is provided together with the 1st high ventilation part, the 1st-3rd order resonance can be reduced more efficiently and a standing wave can be attenuated especially greatly.
Even in a conventional resin-made air intake duct, a wide-band standing wave can be attenuated by providing a plurality of resin-made silencers. However, the process becomes complicated and the cost increases, and the weight of the intake duct increases. In addition, a high ventilation portion may be provided at a position 1/2 L from one end of the cylindrical portion on the air inflow side, but at a position 1/2 L [refer to the position of FIG. 4B]. The primary and tertiary resonances are antinode positions, but the secondary resonance is a node position, and the standing wave cannot be attenuated efficiently.

It is a perspective view of a half body. It is a perspective view of the air intake duct of the present invention. It is explanatory drawing which shows the progress of a standing wave while it is the cross section which looked at the intake duct of this invention from the side surface. It is explanatory drawing which shows the position where the high ventilation part of the length direction of a cylindrical part is provided. It is explanatory drawing which shows the progress of the standing wave in resin-made cylindrical parts. It is explanatory drawing which shows advancing of the standing wave in the air intake duct by which the resin-made silencer part was provided in the cylindrical part made from a fiber. It is explanatory drawing which shows the progress of the standing wave in resin-made cylindrical parts. It is a graph which shows the correlation of the volume reduction and frequency in various intake ducts.

  The items shown here are for illustrative purposes and exemplary embodiments of the present invention, and are the most effective and easy-to-understand explanations of the principles and conceptual features of the present invention. It is stated for the purpose of providing what seems to be. In this respect, it is not intended to illustrate the structural details of the present invention beyond what is necessary for a fundamental understanding of the present invention. It will be clear to those skilled in the art how it is actually implemented.

The intake duct of the present invention will be described below with reference to the drawings.
The air intake duct (1) of the present invention is an air intake duct (1) formed by combining two halves (1a) and (1b) (see FIG. 1) made of a fiber molded body, and has a cylindrical portion (3). ) And a silencer part (5) provided by branching from the cylindrical part (3) (see FIG. 2). Moreover, the air permeability measured by JIS L1096 A method (fragile type method) of the molding wall of the cylindrical part (3) is 1.0 to 5.0 cc / cm ² / sec, and the muffler part (5) is molded. The air permeability of the wall measured by the JIS L1096 A method (Fragile type method) is 0.5 cc / cm ² / sec or less.

  The two halves (1a) and (1b) are made of fiber molded bodies. The fiber molded body is formed of inorganic fibers and a thermoplastic resin that binds the inorganic fibers. The material and dimensions of the inorganic fiber are not particularly limited, and various inorganic fibers can be used. Examples of the inorganic fiber include glass fiber and carbon fiber, and glass fiber is often used. The fiber diameter of the inorganic fiber is preferably 5 to 10 μm. Moreover, content of the inorganic fiber in a fiber molded object is not specifically limited. When the total of the inorganic fiber and the thermoplastic resin is 100% by mass, the inorganic fiber is preferably 30 to 70% by mass, particularly 40 to 60% by mass.

  The form of the inorganic fiber contained in the two halves (1a) and (1b) is not particularly limited. For example, a form in which a plurality of inorganic fibers are regularly arranged in the length direction, a form in which the plurality of inorganic fibers are regularly arranged to draw a mesh pattern, and a plurality of inorganic fibers are It can be a randomly arranged form or the like. In addition, a plurality of inorganic fiber sheets in which a plurality of inorganic fibers are aligned in the length direction are laminated, and the inorganic fibers contained in the inorganic fiber sheets adjacent vertically may intersect with each other. it can. Such a configuration is preferable because the intake duct (1) having excellent mechanical characteristics can be obtained.

  Furthermore, when using an inorganic fiber sheet, the number of layers is not particularly limited. For example, it can be 2-50 layers. Moreover, it is preferable to laminate | stack so that the orientation direction of the inorganic fiber contained in the inorganic fiber sheet adjacent up and down may differ as mentioned above. In this case, the angle formed by the orientation direction of each inorganic fiber is preferably 30 to 90 °. Furthermore, the inorganic fiber sheets adjacent in the vertical direction are more preferably laminated so that the orientation directions of the inorganic fibers contained in each sheet are substantially orthogonal. If it is such a form, it can be set as the intake duct (1) which has the outstanding mechanical characteristic in any direction of a length direction, a radial direction, and the diagonal direction.

  Moreover, it can be set as the intake duct (1) which has the outstanding mechanical characteristic because each inorganic fiber contained in the inorganic fiber sheet adjacent to the upper and lower sides is bound by the thermoplastic resin. Furthermore, by setting the cylindrical portion (3) to a thickness having a predetermined air permeability, a wide-band standing wave can be sufficiently attenuated, and an intake duct (1) having a more excellent sound reduction effect is obtained. be able to. In order to obtain an intake duct (1) having a more excellent sound reduction effect, it is particularly preferable to use a cylindrical portion (3) having a thickness corresponding to ¼ of the noise wavelength λ. With the cylindrical part (3) having such a thickness, noise in a longer wavelength region can be sufficiently reduced.

  The thermoplastic resin for binding the inorganic fibers is not particularly limited. For example, polyolefin resin, polystyrene resin, acrylic resin and the like can be mentioned. The thermoplastic resin is preferably a polyolefin resin that can bind inorganic fibers and can be easily molded. The polyolefin resin may be an olefin homopolymer, a copolymer of two or more olefins, or a copolymer of an olefin and another monomer.

  Examples of the olefin homopolymer include polyethylene and polypropylene. Examples of the copolymer of two or more olefins include ethylene-propylene copolymer, linear low-density polyethylene that is a copolymer of ethylene and 1-butene, 4-methyl-pentene-1, 1-octene, and the like. Is mentioned. Examples of the copolymer of olefin and another monomer include ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, and the like. These polyolefin resins may be used alone or in combination of two or more.

  Moreover, various additives are normally mix | blended with a thermoplastic resin. For example, fillers, antioxidants, ultraviolet absorbers, anti-aging agents, flame retardants, lubricants, stabilizers, weathering agents, antistatic agents and the like are blended. Furthermore, a plasticizer, a water repellent, an oil repellent, an antibacterial agent, an antiseptic, a colorant, and the like may be blended as necessary.

  The intake duct (1) formed by combining two halves (1a) and (1b) includes a cylindrical part (3) and a silencer part (5) (see FIG. 2). Moreover, a cylindrical part (3) has air permeability. The cylindrical portion (3) is composed of a plurality of inorganic fibers and a thermoplastic resin that binds these inorganic fibers. And the minute space | gap is formed between the adjacent inorganic fibers and between the binding parts which consist of an inorganic fiber and a thermoplastic resin. The void communicates from the inner surface to the outer surface of the molding wall of the cylindrical portion (3), and the cylindrical portion (3) has air permeability.

The air permeability of the tubular portion (3) measured by JIS L1096 A method (Fragile method) is 1.0 to 5.0 cc / cm ² / sec, and 1.5 to 3.0 cc / cm ² / It is preferable that it is sec. If the air permeability of the cylindrical portion (3) is 1.0 to 5.0 cc / cm ² / sec, a broadband standing wave can be sufficiently attenuated. If only the attenuation of the standing wave is considered, the higher the air permeability, the better, but the radiated sound deteriorates. Therefore, the air permeability of the cylindrical portion (3) is calculated in consideration of the tradeoff between the attenuation of the standing wave (reduction of the inlet sound) and the radiated sound, and 1.0 to 5.0 cc / cm ² / sec. Was set.

  Furthermore, the air passage of the cylindrical portion (3) is formed by intricately communicating minute gaps. In addition, thermoplastic resins, particularly polyolefin resins, are highly hydrophobic. Therefore, although the cylindrical part (3) has air permeability, water does not permeate.

Further, when the total length of the cylindrical portion (3) is (L), the JIS L1096 A method (fragile type method) is placed at a position 1/4 L from one end of the cylindrical portion (3) on the air inflow side. It is preferable that a first highly ventilated portion (a) (see FIG. 4) having an air permeability measured by the above of 10 cc / cm ² / sec or more is provided. The air permeability in the first highly ventilated part (a) is more preferably 20 cc / cm ² / sec or more (usually 50 cc / cm ² / sec or less).

Furthermore, when the total length of the cylindrical portion (3) is (L), the JIS L1096 A method (fragile type method) is positioned at 3 / 4L from one end of the cylindrical portion (3) on the air inflow side. It is preferable that a second highly ventilated portion (c) (see FIG. 4) having an air permeability measured by the above of 10 cc / cm ² / sec or more is provided. The air permeability in the second highly ventilated part (c) is more preferably 20 cc / cm ² / sec or more (usually 50 cc / cm ² / sec or less).

  By providing the first high ventilation part (a) and the second high ventilation part (c), in addition to the attenuation of the standing wave in other parts of the cylindrical part (3), the dominant mode of the inlet sound and It is possible to efficiently reduce the determined first to third order resonances. Moreover, although both a 1st high ventilation part (a) and a 2nd high ventilation part (c) may be provided and only one may be provided, it is preferable to provide both. Furthermore, the dimension in the length direction of the cylindrical part (3) of each of the first high ventilation part (a) and the second high ventilation part (c) is not particularly limited. The dimension of the 1st high ventilation part (a) and the 2nd high ventilation part (c) can be made into L / 3-L / 5 of the full length (L) of a cylindrical part (3), respectively, L / 4 Most preferably.

  Moreover, the through-hole which penetrates a cylindrical part (3) can also be provided in a cylindrical part (3). As described above, the cylindrical portion (3) has a communication hole in which voids formed between inorganic fibers and the like are formed in a complex and continuous manner. In addition to the hole, a through hole penetrating the cylindrical portion (3) may be provided. By providing such a through hole, the air permeability of the cylindrical portion (3) is adjusted, and noise can be further reduced. The air permeability of the cylindrical portion (3) provided with the through hole can be in the same numerical range as the air permeability of the cylindrical portion (3) described above.

  The silencer part (5) provided by branching from the cylindrical part (3) is provided in order to efficiently reduce noise in a frequency region particularly desired to be reduced. For example, it can be provided in order to efficiently reduce annoying noise in the frequency range of 180 to 200 Hz among noises generated by inhalation. The specific frequency region in which noise is to be reduced efficiently is the length of the connecting pipe part (5c) from the opening to the silencer body (5d) where the silencer part (5) branches off from the cylindrical part (3). (D), the diameter (d) of the connecting pipe portion (5c), and the volume v of the silencer body (5d) can be set (see FIG. 3). As described above, the specific frequency region in which noise is efficiently reduced and reduced is determined by the configuration of the silencer unit (5). Therefore, the position where the silencer part (5) is provided is not particularly limited, and may be provided at any position of the tubular part (3).

Moreover, in order to make a silencer part (5) function effectively, it is preferable that a silencer part (5) does not have air permeability. However, since the muffler part (5) is made of a fiber molded body, it is not easy to make the muffler part (5) having no air permeability, and a slight air permeability is allowed. JIS L1096 A method of forming the wall of the silencer unit (5) breathability measured by (Frazier method) is less than 0.5cc ^/ cm 2 ^/ sec, or less 0.1cc ^/ cm 2 ^/ sec Is preferred. In addition, the lower limit value of the air permeability can be set to 0.005 cc / cm ² / sec, and can also be set lower than the measurement limit value. That is, it is preferable that the silencer part (5) has substantially no air permeability.

The manufacturing method of the intake duct (1) of the present invention is not particularly limited. For example, it can be produced by the following method.
Inorganic fibers such as glass fibers and thermoplastic resin fibers are defibrated as necessary, and are fed onto a belt conveyor or the like while being blended to form a nonwoven fabric. Then, this nonwoven fabric is heated, then impregnated and compression-molded, and then cooled to produce a sheet-like base material for forming the half body (1a) and the half body (1b). The impregnation compression molding impregnates the molten thermoplastic resin between the inorganic fiber fibers, and the inorganic fiber fibers are bound by the thermoplastic resin solidified by the subsequent cooling. The heating temperature can be set according to the melting point of the thermoplastic resin used for forming the thermoplastic resin fiber. The heating temperature before the impregnation compression molding is preferably 30 to 90 ° C. higher than the melting point of the thermoplastic resin. The heating time can be 2 to 3 minutes. Furthermore, it is preferable that the heating temperature at the time of impregnation compression molding is a temperature that exceeds the melting point of the thermoplastic resin by 20 to 80 ° C. The pressure can be 10 to 20 MPa, and the pressurization time can be 3 to 10 seconds. Furthermore, although the cooling conditions are not particularly limited, the cooling is performed to a temperature range of 80 to 150 ° C. by primary cooling, and then cooled to room temperature, for example, 10 to 30 ° C. by secondary cooling, and then cooled by tertiary cooling. By blowing cold air, the entire substrate can be uniformly and sufficiently cooled. Then, the base material is cut into a predetermined size according to the dimensions of the half body (1a) and the half body (1b), and loaded on the mounting table to form the half body (1a) and the half body (1b). To pay.

  The halved body (1a) and the halved body (1b) heat the above-mentioned base material, and then convert the base material made of the inorganic fiber and the molten thermoplastic resin fiber into the half body (1a) and the half body (1a). Place the mold on the lower mold of the mold at room temperature (for example, 20-30 ° C.) of the press molding machine in which the cavities of the respective shapes of the halves (1b) are formed. It can be produced by a cold compression molding method in which the mold is lowered and pressed. In this case, the thermoplastic resin fibers are melted and pressure-molded with the molten thermoplastic resin interposed between the inorganic fibers. Therefore, the surface of the half body (1a) and the half body (1b) becomes denser, and it can be set as the air intake duct (1) in which the invasion of water is more reliably prevented while ensuring the air permeability. . A plurality of thin nonwoven fabrics may be laminated to form a base material having a predetermined thickness, or a base material made of a single layer of nonwoven fabric having a predetermined thickness.

The heating temperature of a base material can be set with the melting | fusing point of the thermoplastic resin used for formation of a thermoplastic resin fiber. The molding temperature is preferably 30 to 90 ° C. above the melting point of the thermoplastic resin. The heating time can be 45 to 60 seconds. Further, the pressure at the time of cold compression is taken into account the molding temperature, and the air permeability measured by the above-described method of the cylindrical portion (3) of the intake duct (1) is 1.0 to 5.0 cc / cm. ² / sec, especially 1.5 to 3.0 cc / cm ² / sec. Moreover, the thickness of the shaping | molding wall of a cylindrical part (3) will also be determined by compression-molding so that it may become predetermined | prescribed air permeability. The time for cold compression can usually be 5 to 10 seconds.

The air permeability of the cylindrical portion (3) can be set by the molding temperature and the molding pressure as described above. On the other hand, the air permeability measured in the same manner of the silencer part (5) can be adjusted by a cavity formed so that the molding wall becomes thinner than the cylindrical part 3 under the molding temperature and pressure. Since the molding wall is thinner than the cylindrical part (3), that is, is more compressed, the silencer part (5) has very few voids between the inorganic fibers compared to the cylindrical part (3). Thus, the air permeability is greatly reduced as compared with the cylindrical portion (3). Thereby, the air permeability measured by the above-mentioned method of the silencer part (5) is 0.5 cc / cm ² / sec or less.

  Further, the halves 1a and 1b are formed by laminating a plurality of inorganic fiber sheets in which a plurality of inorganic fibers are aligned in the length direction, and the inorganic fibers contained in adjacent inorganic fiber sheets intersect each other. It can produce using the laminated sheet made into the form to do. If it does in this way, the binding point of the inorganic fibers by the molten resin which the thermoplastic resin fiber etc. which are contained in an inorganic fiber sheet | seat fuse | melt will increase. Thereby, delamination of an inorganic fiber sheet is prevented and it can be set as the intake duct (1) which has the outstanding mechanical characteristic. Moreover, it is more preferable to laminate | stack the inorganic fiber sheet | seat adjoining up and down so that the orientation direction of the inorganic fiber contained in each sheet | seat may be substantially orthogonal. If it does in this way, it can be set as the air intake duct (1) which has the outstanding mechanical characteristic in any direction of a length direction, a radial direction, and the diagonal direction. The half halves 1a and 1b are prepared using a sheet in which the fibers of a single inorganic fiber sheet having a predetermined thickness are bound by a molten resin, and the intake duct is formed using the halves 1a and 1b. (1) can also be manufactured.

  The halves (1a) and halves (1b) may be produced using separate molds, and the halves (1a) and (1b) are simultaneously molded with the same mold, You may divide | segment into a half body (1a) and a half body (1b). The produced halves (1a) and (1b) are preferably trimmed and shaped with a Thomson blade or the like as necessary. In addition, the end faces of the half body (1a) and the half body (1b) are combined, and the end faces can be heat-sealed to produce the intake duct (1). Specifically, the end surfaces of the half cylinder part (3a) of the half body (1a) and the half cylinder part (3b) of the half body (1b) are brought into contact with each other, and the half body (1a) The respective end surfaces of the silencer molding part (5a) and the silencer molding part (5b) of the half body (1b) are brought into contact with each other. Thereafter, the abutted portion is fused by various methods such as hot plate welding, ultrasonic welding, vibration welding, infrared laser welding, etc., and the air intake duct (1) can be manufactured (see FIG. 2). ).

  As described above, the end faces of the halves (1a) and (1b) are fused, and the cylindrical part (3) and the silencer part 5 are integrally formed at the same time to produce the intake duct (1). can do. At this time, not only the end faces of the halves (1a) and (1b) are fused, but as shown in FIG. 1, flanges ( It is preferable to provide f) and to fuse the surfaces of the flange portions (f) by a method such as ultrasonic welding. If it does in this way, a half body (1a) and a half body (1b) can be fused more firmly.

  Further, as described above, the intake duct (1) can be manufactured using inorganic fibers and thermoplastic resin fibers, but instead of thermoplastic resin fibers, thermoplastic resin particles or thermoplastic resin powders are used. It can also be used. Further, the thermoplastic resin particles and the thermoplastic resin powder may be used in combination. When using particles and / or powder in this way, the thermoplastic resin particles and / or thermoplastic resin powder are supplied onto the belt conveyor and deposited together with the inorganic fibers in the same manner as when using the thermoplastic resin fibers. A sheet | seat is formed, a base material is formed similarly after that, A half body (1a) and a half body (1b) can be produced using this base material.

Hereinafter, the present invention will be described specifically by way of examples.
(1) Configuration of intake duct Example 1
The tubular portion 1 having a length of 600 mm, an outer diameter of 70 mm, an inner diameter of 55 mm, and a molding wall thickness of 7.5 mm, and a position branched from the tubular portion 1 at a position 150 mm from the end surface on the intake side of the tubular portion 1 are provided. An intake duct 1 having a silencer portion 5 was manufactured.

The position of 150 mm from the end surface on the intake side of the tubular portion 1 provided with the silencer portion 5 is the center point in the radial direction of the end surface on the intake side of the tubular portion 1 and the connecting pipe portion 5c of the silencer portion 5. It means that the dimension between is 150 mm. Moreover, the silencer part 5 has the connecting pipe part 5c having a cylindrical shape, the silencer body 5d is a rectangular parallelepiped, and the molding wall thickness is 1.5 mm. Further, the length D of the connecting pipe portion 5c from the opening to the silencer body 5d at a location branched from the cylindrical portion 3 is 30 mm, the diameter d of the connecting pipe portion 5c is 14 mm, and the volume v of the silencer body 5d is 1000 cm ³ .

The intake duct 1 was manufactured as follows.
A plurality of glass fiber sheets were overlapped so that the orientation directions of the glass fibers contained in adjacent sheets were substantially orthogonal to each other to form a laminated sheet having a thickness of about 5 mm. Each glass fiber sheet was formed such that polypropylene fibers having a fiber diameter of 7.5 to 8.2 dtex were sandwiched between the aligned glass fibers. The basis weight of the laminated sheet was 820 g / m ² . When the laminated sheet was 100% by mass, the glass fiber was 40% by mass and the resin fiber was 60% by mass.

  Thereafter, the laminated sheet was heated in a heating furnace at a temperature of 210 ° C. for 2 minutes and 30 seconds, and then heated and pressurized at a temperature of 200 ° C. and a pressure of 14.8 MPa for 5 seconds between flat hot plates of a compression molding machine, impregnation. Compression molded. In this way, the polypropylene fiber is melted, and then the set temperature of the hot plate is lowered to 100 to 130 ° C. to perform primary cooling, and then 18 ° C. cold water is circulated through the flow path provided in the hot plate. Second cooling, then mold opening, blown cold air to the molded body and tertiary cooling, the entire molded body is sufficiently solidified, and the thickness of the glass fibers bonded by this solidified resin A 5 mm sheet-like substrate was formed. Thereafter, the substrate is heated in a heating furnace at a temperature of 210 ° C. for 45 to 60 seconds. It mounted on the lower mold | type of the compression molding machine which has a cavity equivalent to each shape of the flange part f connected with each of the parts 3a and 3b and the muffler molding parts 5a and 5b. Thereafter, the upper mold was lowered and cold-compressed to integrally manufacture a molded body in a state where the halves 1a and 1b (see FIG. 1) having the flange portion f were connected. Subsequently, the molded body was cut at an intermediate portion between the semicylindrical portions 3a and 3b to obtain half-split bodies 1a and 1b. Then, the periphery of each halved body 1a, 1b was trimmed with a Thomson blade and shaped. In the halves 1a and 1b thus manufactured, the thickness of each of the semi-cylindrical portions 3a and 3b (the thickness of the cylindrical portion 3) was 7.5 mm. The thickness of each of the muffler molding parts 5a and 5b (the thickness of the muffler part 5) was 1.5 mm.

  Then, the flange part f which the half cylinder part 3a of the half body 1a has, and the flange part f which the half cylinder part 3b of the half body 1b contact | abutted were made to contact | abut. Moreover, the flange part f which the molded part 5a for silencers of the half body 1a has, and the flange part f which the molded part 5b for silencers of the half body 1b contact | abutted were made to contact | abut. Thereafter, the flange portions f that were in contact with each other were welded by an ultrasonic welding method to manufacture the intake duct 1 (see FIG. 2).

A test piece for air permeability evaluation was cut out from each of the cylindrical part 3 and the silencer part 5 manufactured as described above. Then, air permeability was evaluated by JIS L1096 A method (fragile type method) using these test pieces. As a result, the air permeability of the cylindrical portion 3 was 3.0 cc / cm ² / sec. On the other hand, the air permeability of the silencer part 5 was 0.01 cc / cm ² / sec. Thus, the cylindrical part 3 had air permeability suitable for attenuating a broadband standing wave. Further, the air permeability of the silencer unit 5 was an extremely low value that effectively functions as a silencer.

Comparative Example 1
An intake duct 9 composed of a cylindrical portion 11 made of acrylic resin having the same shape and the same dimensions as in Example 1 was used (see FIG. 5). The intake duct 9 was not provided with a silencer. The air permeability of the cylindrical part 11 measured in the same manner as in Example 1 was less than the measurement lower limit [in Table 1, expressed as (0 cc / cm ² / sec)].

Comparative Example 2
An intake duct 15 having an acrylic resin cylindrical portion 11 and a silencer portion 13 having the same shape and the same dimensions as in Example 1 was used (see FIG. 6). The air permeability measured in the same manner as in Example 1 was less than the measurement lower limit for both the cylindrical part 11 and the silencer part 13 [indicated as (0 cc / cm ² / sec) in Table 1].

Comparative Example 3
Two half halves similar to those of the first embodiment except that the air intake duct 17 composed of the fiber-shaped cylindrical portion 3 having the same material, the same shape and the same dimensions as those of the first embodiment is not provided. Was used in the same manner as in Example 1 (see FIG. 7). The air permeability of the cylindrical part 3 measured in the same manner as in Example 1 was 3.0 cc / cm ² / sec.

Comparative Example 4
Using the same halves as in Example 1, except that the cylindrical part made of fiber having the same material, shape and dimensions as in Example 1 does not have a muffler molding part. 1 was prepared. Then, the silencer part made from the acrylic resin of the same shape and the same dimension as Example 1 was provided in the same position of the cylindrical part, and the air intake duct was manufactured. The air permeability of the cylindrical portion measured in the same manner as in Example 1 was 3.0 cc / cm ² / sec. Further, the air permeability of the silencer portion was less than the measurement lower limit [indicated as (0 cc / cm ² / sec) in Table 1].

Comparative Example 5
The intake duct consisting of a cylindrical part made of fiber of the same material, the same shape and the same dimensions as in Example 1 and a silencer part is used in the same manner as in Example 1 using the same two halves as in Example 1. Manufactured. However, the molding wall of the silencer part was thickened to have air permeability. The air permeability of the cylindrical portion measured in the same manner as in Example 1 was 3.0 cc / cm ² / sec. Moreover, the air permeability of the silencer part was 40.0 cc / cm ² / sec.
The air permeability of each of the cylindrical portion and the silencer portion of Example 1 and Comparative Examples 1 to 5 is described in Table 1 above. In addition, the volume reduction in the following (2) evaluation of sound absorption is listed in Table 1.

(2) Evaluation of sound absorption property A tester in which a speaker was connected to one end of the cylindrical portion of each intake duct of Example 1 and Comparative Examples 1 to 5 was produced. Thereafter, this tester was placed in an anechoic chamber, and a microphone (microphone 1) connected to the FFT analyzer was fixed immediately before the opening at the other end of the cylindrical portion. Further, another microphone (microphone 2) was disposed in the vicinity of the other end of the cylindrical portion of each intake duct. In this state, white noise was oscillated from the speaker, and its A-characteristic sound pressure level was measured (see speaker excitation method). FIG. 8 shows the result of measurement immediately before the opening at the other end of the cylindrical portion, with the frequency as the horizontal axis and the volume reduction based on the value of the measured A characteristic sound pressure level based on the speaker sound pressure [dB ] (Sound pressure in microphone 1−Sound pressure in microphone 2) is a graph representing their correlation with the vertical axis.

(3) Action of intake duct According to Table 1, in the intake duct 1 of Example 1, the air permeability of the tubular portion 3 made of fiber is 3.0 cc / cm ² / sec, which is within an appropriate range. . Moreover, the air permeability of the silencer part 5 is 0.01 cc / cm ² / sec, and has substantially no air permeability. As a result, according to Table 1 and FIG. 8, in the intake duct 1 of Example 1, the volume reduction at a frequency of 190 Hz, which is annoying noise during inhalation, is 57.789 dB, and the annoying noise is sufficiently reduced. I understand that. Furthermore, the volume reduction at a frequency of 525 Hz is 32.386 dB, and it can be seen that the noise due to the standing wave in a wide band is sufficiently reduced (see the attenuation wave 7a in which the standing wave 7 in FIG. 3 is attenuated).

  On the other hand, in the intake duct 9 (see FIG. 5) of the comparative example 1 having only the resin-made cylindrical portion 11, the volume reduction at a frequency of 190 Hz is smaller than that of the first embodiment, and the volume reduction is extremely small at a frequency of 525 Hz. Thus, it can be seen that the standing wave in the wide band is hardly attenuated (see FIG. 5 where the standing wave 7 is not attenuated at all). Further, in the intake duct 15 (see FIG. 6) of the comparative example 2 including the resin-made cylindrical portion 11 and the resin-made silencer portion 13, sound reduction at a frequency of 190 Hz is sufficiently performed by the silencer portion 13. However, it can be seen that the attenuation of the standing wave in a wide band is not sufficient as compared with the first embodiment (see the attenuation wave 7a in which the standing wave 7 in FIG. 6 is attenuated).

Furthermore, in the intake duct 17 of Comparative Example 3 including only the fiber-made cylindrical portion 3, although the standing wave is attenuated in a wide band (see the attenuation wave 7a in which the standing wave 7 is attenuated in FIG. 7), Since there is no muffler part, sound reduction at a frequency of 190 Hz is insufficient. Moreover, in the comparative example 4 provided with the fiber-shaped cylindrical part and the resin-made silencer part, the sound reduction effect is equivalent to the example, but the manufacturing process is complicated and it is extremely disadvantageous in terms of cost. Furthermore, although the fiber-shaped cylindrical portion and the silencer portion are provided, in the comparative example 5 in which the air permeability of the silencer portion is as high as 40.0 cc / cm ² / sec, the standing wave is sufficiently attenuated in a wide band. However, it can be seen that the volume reduction at 190 Hz is small and inferior.

It should be noted that the present invention is not limited to the above-described specific examples, and can be variously modified examples within the scope of the present invention according to the purpose, application and the like. For example, in the embodiment, by making the molding wall of the silencer part 5 sufficiently thin, that is, by compressing and molding, the air permeability is extremely low as 0.01 cc / cm ² / sec. If it is / cm ² / sec or less, even if the air permeability in the silencer unit 5 is a little high, the sound can be sufficiently reduced at a frequency of 190 Hz, which is an annoying noise during intake.

  The foregoing examples are for illustrative purposes only and are not to be construed as limiting the invention. Although the invention has been described with reference to exemplary embodiments, it is to be understood that the language used in the description and illustration of the invention is illustrative and exemplary rather than limiting. As detailed herein, changes may be made in its form within the scope of the appended claims without departing from the scope or spirit of the invention. Although specific structures, materials and examples have been referred to in the detailed description of the invention herein, it is not intended to limit the invention to the disclosures presented herein, but rather, the invention is claimed. It covers all functionally equivalent structures, methods and uses within the scope of

  The present invention can be used in the technical field of an intake duct for supplying air to a vehicle air cleaner.

  1; intake duct, 1a, 1b; halved body, 3; cylindrical portion, 3a, 3b; semi-cylindrical portion, 5; silencer portion, 5a, 5b; muffler molding portion, 5c; connection pipe portion, 5d; Silencer body, a: first high ventilation part, c: second high ventilation part.

Claims (3)

An air intake duct formed by combining two halves made of a fiber molded body,
A tubular portion, and a silencer portion provided by branching from the tubular portion,
The air permeability measured by the JIS L1096 A method of the molding wall of the cylindrical part is 1.0 to 5.0 cc / cm ² / sec,
An air intake duct characterized in that the air permeability measured by the JIS L1096 A method of the molding wall of the silencer part is 0.5 cc / cm ² / sec or less. When the overall length of the tubular part is L, the first highly ventilated part having the air permeability of 10 cc / cm ² / sec or more at a position 1/4 L from one end of the tubular part on the air inflow side. The air intake duct according to claim 1, wherein: When the overall length of the tubular portion is L, the second highly ventilated portion having the air permeability of 10 cc / cm ² / sec or more at a position 3 / 4L from one end of the tubular portion on the air inflow side. The air intake duct according to claim 1, wherein the air intake duct is provided.

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