JP2000073895A - Intake pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the intake noise in the low-speed rotation of an engine and supply sufficient air in the high-speed rotation thereof by forming a part of the pipe wall of an intake pipe arranged between the outside air inlet port of a motor vehicle and the intake manifold of the engine from a molded body consisting of nonwoven fabric. SOLUTION: This intake duct 6 is formed of two split bodies divided in a part having a small curvature radius, which are connected and integrated together. The split bodies are formed of halved upper member 60 and lower member 61, and they are welded together. The nonwoven fabric is formed of PET fiber, which contains a binder fiber consisting of low-melting point PET fiber, and the upper member 60 and lower member 61 are formed by thermal press molding it. Accordingly, the intake noise in low-speed rotation of an engine can be reduced with a simple and inexpensive structure, and since no throttle is used, sufficient air can be supplied in high-speed rotation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an intake pipe as a passage for supplying air to an engine, and more particularly to an intake pipe in which noise during intake is reduced.

[0002]

2. Description of the Related Art In an intake system of an automobile engine, there is a problem that noise is generated in an intake pipe such as an air cleaner hose or an intake duct during intake. This intake noise is particularly harsh when the engine is running at a low speed. Therefore, conventionally, as shown in FIG. 18, a side branch 101 and / or a resonator 102 are provided in the intake duct 100 to reduce noise of a specific frequency calculated based on Helmholtz's resonance theory or the like. .

However, the side branch 101 has a length of about 30 cm when it is long, and has a volume of 14 liters when the volume of the resonator 102 is large. As a result, the space occupied by the sound absorbing devices in the engine room becomes large, and the degree of freedom in mounting other components is reduced. Thus, Japanese Utility Model Laid-Open Publication No. 64-22866 discloses that an orifice is arranged in an intake duct, and intake air is reduced at the position of the orifice to reduce intake noise. By narrowing the intake passage in this way, the acoustic mass increases, and the intake sound in a low-frequency range can be reduced.

In Japanese Utility Model Laid-Open Publication No. 3-43576, two intake pipes connected in parallel to an air cleaner case, branch pipes branched from the two intake pipes, and branch pipes are connected together. An intake noise reduction device is disclosed that has a common resonator and an open / close valve that is selectively opened in accordance with an operation state on the upstream side of a connection portion of a branch pipe in one intake pipe.

According to the apparatus disclosed in Japanese Utility Model Laid-Open Publication No. 3-43576, the on-off valve is controlled in accordance with the engine speed to switch the intake pipe to one or two pipes, whereby the engine is controlled in accordance with the engine speed. The intake air amount can be controlled, and the intake noise can be reduced.

[0006]

However, the above-described method of narrowing the intake passage has a disadvantage that the amount of intake air is insufficient at the time of high-speed rotation of the engine and the output is reduced. The apparatus disclosed in Japanese Utility Model Laid-Open Publication No. 3-43576 is not preferable in terms of cost because an electronic control circuit, an electromagnetic on-off valve, a diaphragm actuator, and the like are used to drive the on-off valve. Further, since an electronic control circuit and an electromagnetic on-off valve are required, the apparatus becomes complicated and expensive, and also requires a large number of maintenance steps.

The present invention has been made in view of the above circumstances, and has a simple and inexpensive configuration at the time of low-speed rotation of an engine without restricting the intake passage, without using an electronic control circuit, an electromagnetic switching valve, or the like. It is an object of the present invention to reduce intake noise and supply a sufficient amount of air during high-speed rotation.

[0008]

According to a first aspect of the present invention, there is provided an intake pipe comprising a non-woven fabric in an intake pipe disposed between an outside air intake of an automobile and an intake manifold of an engine. That is, at least a part of the tube wall is formed from the molded body. According to a second aspect of the present invention, in the intake pipe according to the first aspect, the air flow rate per m ² of the molded body is 6000 m ³ / h or less when the pressure difference is 98 Pa. It is in.

According to a third aspect of the present invention, in the intake pipe according to the first aspect, the entire pipe wall is formed of a molded body, and the non-woven fabric is made of a high melting point fiber made of a high melting point thermoplastic resin and a high melting point. And a low-melting fiber made of a low-melting thermoplastic resin having a melting point lower than that of the fiber, and the ratio of the low-melting fiber in the nonwoven fabric is larger than that of the high-melting fiber. A feature of the intake pipe according to claim 4 is that, in the intake pipe according to claim 1, the entire pipe wall is formed of a molded body, and the nonwoven fabric is coated on a core material made of a high melting point thermoplastic resin and the surface of the core material. It comprises thermoplastic fibers comprising a coating layer made of a low melting point thermoplastic resin having a lower melting point than the core material, and the volume of the coating layer is larger than the volume of the core material.

[0010] The features of the intake pipe according to claim 5 are as follows.
In the intake pipe according to the first aspect, the molded body is formed of a nonwoven fabric having a functional layer provided with a predetermined function, and the characteristic of the intake pipe according to the sixth aspect is that of the intake pipe according to the fifth aspect. In the intake pipe, the functional layer is a water-repellent layer. Further, the intake pipe according to claim 7 is characterized in that, in the intake pipe arranged between the outside air intake of the automobile and the intake manifold of the engine, a first divided body made of a synthetic resin molded body and a nonwoven fabric made of a non-woven fabric are formed. The first divided body and the second divided body are formed into a cylindrical shape by being integrally combined with each other.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The inventors of the present invention have conducted intensive studies on the relationship between the material of an intake pipe and the noise generated, and as a result, have formed a pipe wall from a breathable material having a predetermined permeability. It has been found that waves are unlikely to occur and intake noise is significantly reduced. The present invention has been made based on such a finding.

The noise generated during intake is mainly caused by a standing wave of a sound wave generated inside the intake pipe, and the frequency of the standing wave is determined by the intake pipe length, the intake pipe diameter, the material of the intake pipe, and the like. Therefore, in the present invention, at least a part of the pipe wall of the intake pipe is formed from a molded body made of a nonwoven fabric. The details of the reason why the suction noise is reduced by forming the tube wall from the nonwoven fabric molding are unknown, but the following three reasons are considered. (1) Since the nonwoven fabric is an elastic body, it has a vibration damping action, and generation of sound waves due to vibration of the tube wall is suppressed. (2) The energy of the sound wave that has entered the many gaps between the fibers of the nonwoven fabric is weakened by the action of the viscosity and heat conduction of the gaps, and the fibers themselves resonate due to the fluctuation of the sound pressure, and the sound energy is attenuated. (3) Since at least a part of the tube wall has a certain degree of air permeability, a part of a sound wave passes through the tube wall, thereby suppressing generation of a standing wave.

It is considered that the intake noise is reduced by these synergistic effects. However, if the air permeability of the nonwoven fabric molding is too high, the sound waves in the suction pipe penetrate through the pipe wall and leak to the outside, so that there is a problem that noise increases. Therefore, the degree of air permeability is as follows.
It is desirable to be 6000 m ³ / h or less per m ² . In addition, the ventilation amount referred to in the present invention refers to an amount of air per unit time passing through a unit area of a test body when a pressure difference between two chambers defined by the test body is set to 98 Pa. The limitation of 6000 m ³ / h or less per unit area is, of course, a pressure difference of 98
This is a limitation in the case of air of Pa. Needless to say, if the pressure of the intake air differs, the limited numerical value of the ventilation amount also differs.

When the air flow rate per m ² of air at a pressure difference of 98 Pa exceeds 6000 m ³ / h, sound waves passing through the pipe wall of the intake pipe increase, and transmitted sound increases. If the ventilation rate is zero, the effect of suppressing noise in the low frequency range of 200 Hz or less is reduced, but the noise is smaller than that of the conventional intake pipe. In order to obtain a nonwoven fabric having a zero air permeability, a film-like skin layer may be formed on the outer surface of the nonwoven fabric. Even if a skin layer is formed on the inner surface, the air permeability can be reduced to zero, but it is not preferable because it is difficult to reduce noise due to the reason (2) described above. The air flow rate at a pressure difference of 98 Pa in the nonwoven fabric molded article is 4200 m ³ / h at zero or more.
Is preferably less than 0, and particularly preferably in the range of 0 <airflow <3000 m ³ / h.

The intake pipe of the present invention has at least a part thereof formed of a nonwoven fabric. This nonwoven fabric is preferably formed from thermoplastic fibers. If a nonwoven fabric made of a thermoplastic resin fiber is used, even an intake pipe having a complicated shape can be easily shaped and molded by hot press molding or the like. In this case, the thermoplastic resin fiber may constitute a part of the nonwoven fabric, or the entire nonwoven fabric may be composed of the thermoplastic resin fiber. Non-thermoplastic fibers impregnated with a binder made of thermoplastic resin can be shaped by hot press molding, etc., like nonwoven fabrics made of thermoplastic resin fibers, reducing intake noise as well. can do.

A molded article made of a nonwoven fabric has a certain effect in reducing intake noise if it is present on at least a part of the pipe wall of the intake pipe. However, a molded article made of a non-permeable material other than the nonwoven fabric is often used. Since a standing wave is more likely to be generated, it is preferable to form the entire intake pipe from a molded body made of a nonwoven fabric. However, when the entire intake pipe is formed from a molded article made of non-woven fabric, if hot press molding is performed into a shape that has a deep drawn part or a bent part with a small radius of curvature, problems such as cracks on the wall surface will occur and the intake noise will be reduced. May leak. To prevent such inconvenience, a method of dividing the formed body into a plurality of parts and joining them to form a predetermined shape can be considered, but the number of man-hours increases and the productivity decreases and the cost also increases. There is a problem of doing.

Therefore, as described in claim 3, the entire tube wall is formed from a molded body, and the nonwoven fabric includes a high melting point fiber and a low melting point fiber having a lower melting point than the high melting point fiber. Desirably, the ratio is higher than that of the high melting point fiber. If hot press molding is performed using the nonwoven fabric configured as described above, the low melting point fiber is softened and melted preferentially, the high melting point fiber is plastically or elastically deformed, and the softened low melting point fiber is finally solidified by cooling. By doing so, it is shaped into a predetermined shape. Therefore, since the degree of freedom of movement of the fiber during molding is large, it is possible to easily form a shape having a deep drawn portion or a bent portion having a small radius of curvature. Even if a crack is generated on the wall surface, the crack is filled with a sufficiently existing low-melting-point fiber and welded, so that the above-mentioned problem is prevented.

It is sufficient that the low melting point fiber is higher than the high melting point fiber, but it is preferable that the ratio of the low melting point fiber in the nonwoven fabric is 20 to 50%. If it is less than 20%, the above-mentioned effects are hardly exhibited,
If it exceeds 50%, the heat resistance of the molded product becomes insufficient.
The low melting point fiber preferably has a melting point in the range of 150 to 170 ° C, and the high melting point fiber preferably has a melting point in the range of 220 to 260 ° C.

The nonwoven fabric may contain fibers other than the high-melting fiber and the low-melting fiber. Other fibers are not particularly limited, but it is also preferable to use fibers having a special function such as water-repellent fibers. Further, as described in claim 4, the nonwoven fabric comprises a thermoplastic material comprising a core material made of a high-melting-point thermoplastic resin and a coating layer made of a low-melting-point thermoplastic resin having a lower melting point than the core material and coated on the surface of the core material. It is also desirable to include the coating layer so that the volume of the coating layer is larger than the volume of the core material.

With such a configuration, the coating layer is preferentially softened and melted during hot press molding, the core material is plastically or elastically deformed, and finally the softened coating layer is cooled and solidified to a predetermined shape. It is shaped into Therefore, since the degree of freedom of movement of the fiber during molding is large, it is possible to easily form a shape having a deep drawn portion or a bent portion having a small radius of curvature. Even if a crack occurs on the wall surface, the crack is filled with a sufficiently existing molten coating layer and welded, so that the above-mentioned problem is prevented.

The volume of the coating layer may be larger than the volume of the core material, but the ratio of the thermoplastic fibers in the nonwoven fabric is preferably 20 to 50%. If it is less than 20%, the above-mentioned effects are hardly exhibited, and if it exceeds 50%, the heat resistance of the molded article becomes insufficient. The coating layer preferably has a melting point in the range of 150 to 170 ° C, and the core material preferably has a melting point in the range of 220 to 260 ° C.

When a nonwoven fabric partially containing the above-described two-layered thermoplastic fiber is used, it is desirable to use a nonwoven fabric containing at least 20 to 50% by volume of the thermoplastic fiber. If the content of the thermoplastic fiber is less than 20% by volume, the above-mentioned effect is not exerted well, and cracks may remain in the molded article.
In addition, in the intake pipe of the present invention, the thickness and characteristics of the molded body change due to aging, infiltration of moisture, and the like, and the balance between the transmitted sound transmitted through the molded body and the exit sound radiated from the intake port at the tip of the intake duct is lost. Therefore, the performance of suppressing intake noise may change.

Therefore, as described in claim 5, the molded article is desirably formed of a nonwoven fabric having a functional layer provided with a predetermined function. Examples of the functional layer include a water-repellent layer, a clogging prevention layer, and the like. The functional layer can be easily formed by using a nonwoven fabric in which fibers having the respective functions are mixed in the portion. Further, films having respective functions may be laminated on a nonwoven fabric and used.

The position of the functional layer can be appropriately set in the thickness direction of the molded body. For example, when a water-repellent layer is used, it is desirable to provide it on the surface layer or intermediate layer of the molded article. As a result, infiltration of moisture is prevented, and a change in the characteristics of the molded body is prevented, so that the intake noise reduction effect can be maintained for a long time. In addition, since infiltration of water into the air cleaner is also suppressed, engine malfunction due to impaired air permeability of the air cleaner element can also be suppressed.

Further, as described in claim 7, it is preferable that the first and second divided bodies are formed, one of which is formed of a resin molded body, and the other is formed of a nonwoven fabric molded body. Since the first divided body made of the resin molded body has high rigidity, a bracket portion and a fitting portion for fixing to the air cleaner can be integrally formed, and productivity is improved by reducing the number of parts. Also, the assemblability and reliability are improved.

In order to integrally connect the first divided body and the second divided body, they may be connected by a separate clip or the like, but there is a problem that the number of parts is increased. Therefore, it is desirable to couple only the first divided body and the second divided body. For example, a method of mechanically coupling by a coupling means such as an engagement claw formed in the first divided body, or a method of coupling by welding, or the like. No. Since the first divided body is made of resin, the first divided body has a sufficient strength, and the connecting means such as the engagement claws can be integrally formed.

[0027]

The present invention will be specifically described below with reference to Test Examples and Examples. (Test Example) Using the test apparatus shown in FIG. 1, the sound absorption characteristics of tubes made of various materials were investigated. The following three types of materials were used, each of which was formed into a straight pipe having an inner diameter of 60 mm and a length of 400 mm.

Sample A: Acrylic resin Sample B: Nonwoven fabric made of PET (polyethylene terephthalate) fiber (weight per unit area: 700 g / m ² , thickness: 1.5 mm, air permeability: 3,500 m ³ / h
・ M2) Sample C: Two nonwoven fabrics made of PET fiber of Sample B (airflow: 1750 m ³ / h ・ m ² ) In this test apparatus, one end of Sample 1 is made of an acrylic resin pipe penetrating through sound insulation wall 3. 2 (inner diameter 66 mm) is connected to one end of the sample 1. The sample 1 is entirely placed in the soundproof room. A speaker 4 is disposed at the other end of the pipe 2, at a position 10 mm away from the opening of the other end of the sample 1 and at a distance of 100 mm from the tube wall of the sample 1.
Microphones 5 are arranged at positions separated by mm.

Then, the speaker 4 emits white noise, and the microphone 5 measures the frequency characteristics (frequency-sound pressure) of the exit sound exiting from the opening of the sample 1 and the transmitted sound transmitted through the tube wall of the sample 1, respectively. Are shown in FIG. 2 and FIG.
2 and 3 that the sound pressure of the standing wave is lower in the samples B and C formed of the nonwoven fabric than in the sample A formed of the acrylic resin, and the generation of the standing wave is suppressed. Understand. Further, it can be seen that the sound pressure of the standing wave of the exit sound of sample C is higher than that of sample B, but the sound pressure of the standing wave of the transmitted sound is lower than that of sample B. The reason for this is that the sample C has a smaller amount of air per 1 m ² than the sample B, so that the transmission of sound waves is further suppressed. Therefore, it can be understood that the balance between the exit sound and the transmitted sound can be adjusted by adjusting the ventilation amount per 1 m ² .

Although the sample A has no air permeability, the transmitted sound is higher than the samples B and C as shown in FIG. This is for picking up the exit sound coming from the horizontal microphone 5. (Embodiment 1) FIG. 4 is a perspective view of the intake duct 6 of the present embodiment, and FIG. This intake duct 6
In the above, two divided bodies divided at a portion having a small radius of curvature are joined and integrated. Each of the divided bodies is formed by welding a half-shaped upper member 60 and a lower member 61. Hereinafter, a method of manufacturing the intake duct 6 will be described, and the detailed description of the configuration will be substituted.

First, it is formed from PET fiber and has a thickness of about 35 mm.
Was prepared. This nonwoven fabric contains 30% by volume of binder fiber made of low melting point PET fiber, and has a basis weight of 7%.
00 g / m ² . Next, the nonwoven fabric was placed in a press mold, and hot press-molded to a thickness of 3 mm while heating to the melting point of the binder fiber, thereby forming an upper member 60 and a lower member 61.

Next, the upper member 60 and the lower member 61 are joined so as to form a tube, and they are integrally joined by ultrasonic welding to form an intake duct 6 (pipe length: 700 mm, inner diameter: 66 mm).
I got The air permeability in the thickness direction per 1 m ² of the pipe wall of the intake duct 6 is 3900 m ³ / h when the pressure difference is 98 Pa. (Example 2) A kitchen wrap made of polyethylene was wound around the entire outer peripheral surface of the intake duct 6 of Example 1 to a thickness of 10 µm to obtain an intake duct of Example 2. Air permeability of the tube wall 1 m ² per intake duct, the pressure difference 98
It is zero when Pa.

(Comparative Example 1) A conventional intake duct shown in FIG.
100 was set as Comparative Example 1. This intake duct 100 is blow molded from high-density polyethylene and has a pipe length of 700 mm and an inner diameter of
The air permeability in the thickness direction of the tube wall is zero when the pressure difference is 98 Pa. (Test / Evaluation) Each of the above intake ducts was placed in the same test apparatus as in the test example, and the frequency characteristics of intake noise were measured in the same manner. The intake noise is composed of two sounds: an exit sound from the inlet of the intake duct and a transmitted sound from the pipe wall.
The types were measured, and the result of the exit sound is shown in FIG. 6, and the result of the transmitted sound is shown in FIG.

FIG. 6 shows that the air intake ducts of Examples 1 and 2 have a significantly reduced exit sound as compared with the conventional air intake duct of Comparative Example 1. It is clear that this is the effect of using the body to form the intake duct. FIG. 7 also shows that the intake ducts of the first and second embodiments have a higher transmitted sound than the first comparative example.

Since the intake noise is composed of both the exit sound and the transmitted sound, the evaluation of FIG. 6 and FIG. 7 shows that the comparative example 1 having the extremely large exit sound is the worst in intake noise. I understand. Also, from FIG.
The intake duct of the first embodiment has a lower sound pressure level in a low frequency range than the second embodiment having no ventilation. Therefore, regarding the exit sound, it is understood that the air flow rate is preferably larger than zero.

Example 3 High melting point P having a melting point of 220 to 260 ° C.
Non-woven fabric containing 70% by volume of ET fiber and 30% by volume of low-melting point PET fiber having a melting point of 160 ° C. (weight per unit area: 1400 g / m ² , thickness: 3
mm) was prepared. This non-woven fabric is placed in a press mold,
Heat-press forming to a thickness of 3 mm while heating to the melting point of the low-melting PET fiber, and halving the upper and lower members of the intake duct half the same shape as in FIG. Each was formed in the same manner as in Example 1.

Then, the upper member and the lower member are formed into a tubular shape, and the flange portions on both sides are integrally joined by ultrasonic welding to obtain an intake duct (tube length: 700 mm, inner diameter: 66 mm) of this embodiment. Was. The air permeability in the thickness direction per 1 m ² of the pipe wall of this intake duct is 1000 when the pressure difference is 98 Pa.
m ³ / h. The obtained intake duct was excellent in shape accuracy and no cracks were observed, although there was a portion having a small radius of curvature. As for the intake noise (exit sound and transmitted sound), an intermediate characteristic between Example 1 and Example 2 was obtained.

Example 4 As shown in FIG.
Core material of high-melting point PET with a diameter of approx.
And a coating layer 11 of low-melting point PET having a melting point of 160 ° C. and having a thickness of about 12 μm coated around the core material 10.
Using a non-woven fabric formed from 10 denier PET fiber,
An intake duct was manufactured in the same manner as in Example 3. The air permeability in the thickness direction per 1 m ² of the pipe wall of the intake duct is 900 m ³ / h when the pressure difference is 98 Pa. The coating layer 11
Is about 18 times as large as the volume of the core material 10.

The obtained intake duct was excellent in shape accuracy and no cracks were observed, although there was a portion having a small radius of curvature. The intake noise showed almost the same characteristics as in Example 3. (Reference Example) As shown in FIG.
And a coating layer 11 made of low melting point PET having a melting point of 160 ° C. and having a thickness of about 4 μm coated around the core material 10, using a nonwoven fabric formed entirely of 2 denier PET fibers,
An intake duct was manufactured in the same manner as in Example 3. The air permeability in the thickness direction per 1 m ² of the pipe wall of the intake duct is 3000 m ³ / h when the pressure difference is 98 Pa. The coating layer 11
Is about three times the volume of the core material 10.

In the intake duct of this reference example, cracks occurred on the pipe wall in the portion having a small radius of curvature during hot press molding, so that there was leakage of intake noise. (Embodiment 5) FIG. 10 is a perspective view of a main part of an intake duct of this embodiment. This intake duct is the same as that of the third embodiment except that the flange portions 14 and 15 of the half-shaped upper member 12 and the lower member 13 are joined by sewing. In addition, you may join with a stapler instead of sewing.

By joining by sewing or stapling in this way, a large-scale apparatus such as welding is not required, and is most suitable for small-scale production of other products. (Embodiment 6) FIG. 11 is a sectional view of an intake duct of this embodiment. This intake duct is divided into an upper member 12 and a lower member
The third embodiment is the same as the third embodiment except that a water-repellent layer 16 is formed on the surface of each of the substrates 13.

This air intake duct was manufactured in the same manner as in Example 3 by using a nonwoven fabric 21 in which a water-repellent fiber 20 formed by coating a surface of a PET fiber 17 with a silicon resin layer 18 was disposed on the surface layer. According to this intake duct, since the water-repellent layer 16 is formed on the surface, permeation of moisture into the pipe wall is suppressed. Therefore, a change in thickness due to intrusion of moisture is suppressed, and the balance between the transmitted sound passing through the molded body and the outlet sound emitted from the intake port at the tip of the intake duct can be stably maintained. In addition, intrusion of water into the air cleaner device is suppressed.

The position of the water-repellent layer 16 is most preferably on the outer peripheral surface of the intake duct, but is not limited thereto.
It may be provided at any position of the outer peripheral surface, the inner peripheral surface, and the intermediate layer, or may be provided at a plurality of positions. Furthermore, a nonwoven fabric in which the water-repellent fibers 20 are uniformly dispersed may be used, and the whole may be used as a water-repellent layer. In the present embodiment, the water-repellent layer 16 is formed by using a nonwoven fabric including the water-repellent fiber 20, but the water-repellent layer can be formed by laminating a silicon resin film, a fluororesin film, or the like on the nonwoven fabric. . Also in this case, the position of the water-repellent layer may be any of the outer surface, the inner surface, and the intermediate layer, or may be provided at a plurality of positions.

(Embodiment 7) FIG. 12 is a sectional view of an intake duct of this embodiment. The intake duct includes a first divided body 30 and a second divided body 40. The first divided body 30 is formed by injection molding from polypropylene, and has flange portions 31 on both left and right sides. A plurality of engaging projections 32 are integrally arranged on the flange portion 31 at intervals. A bracket 33 is formed integrally with a part of the flange portion 31.

The second divided body 40 is formed from a nonwoven fabric made of PET fiber by hot press molding in the same manner as in the first embodiment, and has flange portions 41 on both left and right sides. Flange 41
, A plurality of through-holes 42 are arranged in a row at intervals. The through-hole 42 is formed at the same time in a step of punching unnecessary portions around the flange portion 41 performed after the formation of the second divided body 40.

The intake duct of this embodiment is provided with an engagement projection.
The first divided body 30 and the second divided body 40 are integrally connected by the engagement of the 32 with the through hole 42. Therefore, in this intake duct, since the rigidity of the first divided body 30 is large, the first divided body 30 can be connected to the mating member via the bracket 33, and another component such as a mounting bracket is not required. In addition, since the rigidity of the engagement protrusion 32 is large, sufficient bonding strength can be secured. The second divided body 40 is made of non-woven fabric and has a slight air permeability, and the intake noise (exit sound and transmitted sound) of the intake duct of the present embodiment has intermediate characteristics between those of the first and second embodiments. .

In this embodiment, the first divided body 30 and the second divided body 40 are connected by a mechanical connecting means using the engaging projections 32 and the through holes 42. However, as shown in FIG. After inserting the protrusion 34 protruding from the flange portion 31 of the divided body 30 into the through hole 42, a heat caulking may be used in which the tip is melted and engaged. Further, as shown in FIG. 14, the second divided body 40 is disposed in a mold, and an engagement portion 35 which is integrally formed with the second divided body 40 through the through hole 42 by injection molding is formed. Thereafter, the first divided body 30 and the second divided body 40 can be integrated via the engaging part 35 by overlapping the first divided body 30 and vibration-welding the engaging part 35.

Although not shown, both flange portions 31,
By forming through holes that communicate with each other when integrated with 41, it is also possible to integrate the through holes by inserting a clip or the like. Further, it is also preferable to adopt a coupling structure as shown in FIG. In this coupling structure, as shown in FIG. 15, a plurality of half-shaped flexible pin bosses 36 protruding from the flange portion 31 of the first divided body 30 are formed at intervals, and the front end portion of the flange portion 31 is formed. Is formed with a ridge 37 and an engagement hole 38. A hinge 39 is formed between the pin boss 36 and the engagement hole 38. And pin boss 36 through hole
After being inserted through 42, the distal end of the flange portion 31 is bent 180 degrees outward by the hinge portion 39, and the engaging hole 38 is engaged with the pin boss 36. Thereby, the flange portion 41 of the second divided body 40 is sandwiched between the flange portions 31 of the first divided body 30, and the first divided body 30 and the second divided body 40 are integrated.

According to this coupling structure, the action of the projection 37 pressing the flange portion 41 against the flange portion 31 is exerted, so that the adhesion is improved, and the flange portion 31 is further joined to the flange portion 41 of the second divided body 40. Can be covered over the entire circumference, so that intrusion of water from the boundary between the first divided body 30 and the second divided body 40 can be reliably prevented. In the case where a part of the duct is formed of a non-woven fabric molded body as in this embodiment, the area occupied by the non-woven fabric molded body in the entire duct is at least 1/4 of the duct length, and It is desirable to make it 1/4 or more. In addition, the area may be provided at a plurality of locations, in which case the duct is composed of a first divided body and a plurality of second divided bodies, and the duct of each area occupied by the plurality of second divided bodies. What is necessary is just to make each total of a longitudinal direction and a circumferential direction satisfy | fill the said conditions.

(Embodiment 8) Although the intake pipe of the present invention effectively suppresses air column resonance, it suppresses noise in a low frequency range of 80 to 100 Hz caused by factors other than air column resonance such as the engine speed. Hard to control. In order to suppress such noise, it is effective to reduce the diameter of the opening of the intake pipe on the air inlet side and make the diameter gradually increase toward the air outlet side opening. However, there is a case where it is necessary to make the opening diameter on the air inlet side extremely small. In such a case, there is a problem that the output of the engine is reduced in a high rotation range where a large amount of air is required.

Therefore, in this embodiment, as shown in FIG.
Inlet duct 7 in which the diameter of the air inlet side opening is small and the diameter gradually increases from the air inlet side opening to the air outlet side opening
Is formed in the same manner as in the first embodiment, and the outlet side opening 70 is connected to the first air inlet 80 of the air cleaner 8. on the other hand,
The air cleaner 8 has a second air inlet 81 having a larger diameter than the first air inlet 80. Further, a valve 82 driven by driving means (not shown) is swingably provided at the second air inlet 81.

According to such an intake device, when the engine is running at a low speed, the valve 82 is closed and the intake air is supplied to the intake duct 7.
From the air cleaner 8. The intake noise in the middle and high frequency ranges is reduced by the characteristics of the intake duct 7 made of nonwoven fabric. The intake noise in the low frequency range is reduced by the shape of the intake duct 7 (the opening on the air inlet side is reduced in diameter).

When the engine speed rises to a predetermined value, the valve 82 is driven by a driving means (not shown), and the second air inlet 81 is opened. Therefore, the air cleaner 8
Since the intake air flows from both the first air inlet 80 and the second air inlet 81, the required amount of air at the time of high rotation can be secured.

[0054]

According to the intake pipe of the present invention, it is possible to reduce intake noise when the engine is rotating at a low speed with a simple and inexpensive configuration. Also, since no aperture is used,
At the time of high-speed rotation, a sufficient amount of air can be supplied.
Furthermore, if the entire intake pipe is formed from a nonwoven fabric by hot press molding, a complicated three-dimensional shape can be manufactured in a single molding step, and an inexpensive and lightweight intake pipe with high outer diameter dimensional accuracy can be obtained. Further, since the inner peripheral surface can be formed by the mold, the surface roughness of the inner peripheral surface can be reduced, and there is no problem that the ventilation resistance increases.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a configuration of an apparatus used for measuring a frequency characteristic in a test example of the present invention.

FIG. 2 is a graph showing the relationship between the exit sound frequency and the sound pressure in a test example.

FIG. 3 is a graph showing the relationship between the frequency of transmitted sound and sound pressure in a test example.

FIG. 4 is a perspective view of an intake duct according to one embodiment of the present invention.

FIG. 5 is a sectional view of an intake duct according to an embodiment of the present invention.

FIG. 6 is a graph showing the relationship between the frequency and the sound pressure of the intake sound generated in the intake ducts of Examples 1 and 2 and Comparative Example 1.

FIG. 7 is a graph showing the relationship between the frequency and the sound pressure of the transmitted sound generated in the intake ducts of Examples 1 and 2 and Comparative Example 1.

FIG. 8 is a cross-sectional view of PET fibers used in an intake duct of Example 4.

FIG. 9 is a cross-sectional view of a PET fiber used for an intake duct of Comparative Example 2.

FIG. 10 is a perspective view of a main part of an intake duct according to a fifth embodiment, which is shown in a partial cross section.

FIG. 11 is a cross-sectional view of an intake duct according to a sixth embodiment and an enlarged view of a main part thereof.

FIG. 12 is a sectional view of an intake duct according to a seventh embodiment.

FIG. 13 is a cross-sectional view of a principal part showing another aspect of the intake duct of the seventh embodiment.

FIG. 14 is a cross-sectional view illustrating a main part of another embodiment of the intake duct of the seventh embodiment.

FIG. 15 is a cross-sectional view of a main part of another state of the intake duct according to the seventh embodiment in a state before the first divided body and the second divided body are combined.

FIG. 16 is a cross-sectional view of a principal part showing another aspect of the intake duct of the seventh embodiment.

FIG. 17 is a cross-sectional view illustrating an intake duct of Embodiment 8 together with an air cleaner.

FIG. 18 is a perspective view of a conventional intake duct.

[Explanation of symbols]

1: Sample 2: Pipe 3:
Sound insulation wall 4: Speaker 5: Microphone

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Zenichi Yasuda 1 Ochiai Ogata, Kasuga-cho, Nishi-Kasugai-gun, Aichi Prefecture Inside Toyoda Gosei Co., Ltd. Address Toyoda Gosei Co., Ltd. (72) Inventor Kazuo Fujiwara Kaichi, Nishi-Kasugai-gun, Aichi Prefecture Ochiai, Nagahata 1 Address Toyoda Gosei Co., Ltd. 1 No. 1 Toyoda Gosei Co., Ltd. (72) Inventor Yoshikazu Hirose 1 Aichi Ochiai, Nagasaki, Nishikasugai-gun, Aichi Prefecture No. 1 Toyoda Gosei Co., Ltd. Address: Toyoda Gosei Co., Ltd. (72) Inventor: Hidetoshi Ishihara Hata 1 Toyoda Gosei Co., Ltd.

Claims (7)

[Claims] 1. An intake pipe disposed between an outside air intake of an automobile and an intake manifold of an engine, wherein at least a part of a pipe wall is formed from a molded body made of a nonwoven fabric. ^2. The air flow rate per 1 m ^{2 of the} molded body is as follows:
2. The intake pipe according to claim 1, wherein the pressure is 6000 m ³ / h or less in the case of air having a pressure difference of 98 Pa. 3. The non-woven fabric is made of a high melting point fiber made of a high melting point thermoplastic resin and a low melting point fiber made of a low melting point thermoplastic resin having a lower melting point than the high melting point fiber. The intake pipe according to claim 1, wherein the ratio of the low-melting fiber in the nonwoven fabric is larger than that of the high-melting fiber. 4. The whole tube wall is formed of the molded body, and the nonwoven fabric is made of a high melting point thermoplastic resin core material and a low melting point thermoplastic resin having a lower melting point than the core material and coated on the surface of the core material. 2. The intake pipe according to claim 1, wherein a volume of the coating layer is larger than a volume of the core material. 5. The intake pipe according to claim 1, wherein the molded body is formed of a nonwoven fabric having a functional layer provided with a predetermined function. 6. The intake pipe according to claim 5, wherein the functional layer is a water-repellent layer. 7. An intake pipe arranged between an outside air intake of an automobile and an intake manifold of an engine, wherein a first divided body made of a synthetic resin molded body and a second divided body made of a nonwoven fabric molded body are provided. Wherein the first divided body and the second divided body are integrally joined to form a cylindrical shape.