JP2006276778A - Air intake duct - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress noise outside a vehicle and to control suction noise heard in a vehicle compartment to a desirable tone. <P>SOLUTION: The air intake duct has a suction pipe 1 constituting an air intake path, a branch pipe 2 which is branched from a branching part 11 of the suction pipe 1 and extends toward the inside of the vehicle compartment, a sound source 3 for uttering toward the inside of the branch pipe 2 is provided at a part of the branch pipe 2, and a partition 13 consisting of a perforated porous member is provided between the branching part 11 and the sound source 3. The suction noise is reduced by the partition 13 and the noise in the vehicle compartment is controlled to the desirable tone by the sound source 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an intake duct as a passage for supplying air to an engine. More specifically, the present invention relates to an intake duct that can reduce a noise during intake and can generate a preferable sound in a passenger compartment.

  In the intake system of an automobile engine, there is a problem that noise is generated during intake. This intake noise is particularly disturbing when the engine rotates at a low speed. Therefore, conventionally, a side branch and / or a resonator is provided in the intake duct to reduce noise of a specific frequency calculated based on Helmholtz resonance theory or the like.

  However, the side branch has a length of about 30 cm when it is long, and it has a size of 14 liters when the volume of the resonator is large. For this reason, the space occupied in the engine room of these silencers increases, resulting in a problem that the degree of freedom of mounting other components is reduced.

  Accordingly, various proposals have been made. For example, in Japanese Patent Application Laid-Open No. 2001-336457, an intake duct in which a long opening in the longitudinal direction of the pipe wall is formed in a part of the intake pipe and the opening is covered with a breathable porous member. Has been proposed. According to this intake duct, although the reason is unknown, intake noise can be greatly reduced. In addition, by forming the opening so as to overlap the antinode position of the generated resonance wave, it is possible to effectively reduce the primary resonance sound and the secondary resonance sound that are particularly loud.

  However, in the air intake duct, if the air permeability of the porous member is too high, there is a problem in that the noise outside the vehicle increases due to the transmitted sound transmitted through the porous member.

  As another means for reducing the intake noise, it has been proposed to weaken the intake sound by producing a sound having a phase opposite to that of the intake sound from a speaker. Since the intake noise is mainly regarded as a pressure wave caused by pressure pulsation associated with opening and closing of the intake valve, both waves interfere with each other by adding an antiphase pressure wave at the same frequency to cancel the pressure wave. Can cancel each other out and reduce the amplitude of the sound of the intake sound, that is, the sound pressure.

  For example, in Japanese Patent Application Laid-Open No. 05-106524, a speaker unit having an enclosure that constitutes a back chamber is attached in the middle of an intake pipe, and a resonance pipe that communicates the back room and the intake pipe is provided. It has been proposed that the resonance frequency is substantially matched in a predetermined low frequency range. Japanese Patent Application Laid-Open No. 07-036468 discloses that a loudspeaker is disposed in a vehicle interior and that a murmur generated in the vehicle interior is canceled by a control sound emitted from the loudspeaker.

  However, when a speaker is disposed in the middle of the intake pipe, a large speaker is required in order to reduce the intake sound particularly in the low frequency range, and noise outside the vehicle increases due to sound leaking from the intake port. Further, since the distance to the passenger compartment is long, the propagation loss is large, and the evaluation in the passenger compartment is not preferable.

On the other hand, in the passenger compartment, it is preferable to hear an intake sound corresponding to the driving situation. That is, when the accelerator is depressed, a loud intake sound can be heard, and a small intake sound can be heard during idling or the like, so that the driving situation matches the intake sound, and a favorable driving feeling can be obtained. However, in the conventional technology in which a loudspeaker is arranged in the vehicle interior, the purpose is only to cancel the intake sound, and the driving feeling is not taken into consideration.
JP 2001-336457 JP 05-106524 A JP 07-036468

  This invention is made | formed in view of the said situation, and makes it the subject which should be solved to enable it to control the outside noise from a vehicle and to control the intake sound heard in a vehicle interior to a preferable thing.

  A feature of the intake duct of the present invention that solves the above problems is an intake duct disposed between an outside air intake port of an automobile and an intake manifold of an engine, the intake pipe constituting the intake passage, and a branch of the intake pipe A branch pipe that branches from the section and extends toward the vehicle interior, and a part of the branch pipe has a sound source that utters into the branch pipe, and a breathable porous member is provided between the branch section and the sound source. Is provided with a partition wall.

  It is desirable that the branch pipe is further provided with a silencer. It is desirable to further include a control device that utters a sound source with a sound pressure corresponding to the engine speed.

Noise generated during intake is mainly due to standing waves of sound waves generated inside the intake duct, and the frequency of the standing wave is determined by the intake duct length, intake duct diameter, intake duct material, and the like. Therefore, in the present invention, a partition made of a breathable porous member is disposed between the branch portion of the intake pipe and the sound source. As a result, the following three actions are performed, and intake noise is reduced.
(1) The air-permeable porous member is often an elastic body, and the generation of sound waves due to vibration of the tube wall is suppressed by the damping action of the partition walls.
(2) The sound wave that has entered a large number of gaps in the porous member is weakened due to the viscosity of the gap and the effect of heat conduction, and the sound energy is attenuated due to resonance of the porous member itself due to fluctuations in the sound pressure. .
(3) Since the partition wall has a certain degree of air permeability, a part of the sound wave passes through the tube wall, thereby suppressing the occurrence of standing waves.

  Furthermore, by arranging the sound source on the branch pipe that branches off from the intake pipe and extends toward the vehicle interior, the sound from the sound source can be added to the sound wave that leaks through the partition wall from the branch section and is perceived in the vehicle interior. Sound can be controlled arbitrarily. That is, if a sound having the same frequency as the sound wave that leaks through the partition wall from the branching part is uttered from the sound source, the noise in the passenger compartment can be greatly reduced. In addition, when the sound source is uttered with a sound pressure corresponding to the engine speed, the driving situation and the perceived sound in the passenger compartment coincide with each other, and a favorable driving feeling can be obtained. And since the distance to a vehicle interior is short, a propagation loss becomes small and since a sufficient effect is acquired with a small sound source, a mounting space can be reduced.

  And in this invention, since the branch pipe is extended toward the vehicle interior, the sound from a sound source cannot leak easily out of a vehicle. In addition, the sound leaking from the branch portion through the partition wall is transmitted only to the vehicle interior side via the branch pipe. Therefore, there is a great advantage that the noise outside the vehicle is suppressed while the driving feeling of the occupant is improved by the sound of the sound source.

  The intake duct of the present invention includes an intake pipe, a branch pipe branched from a branch part of the intake pipe, a sound source arranged in the branch pipe, and a partition wall arranged in the branch pipe between the branch part and the sound source. It is configured.

  The intake pipe constitutes an intake passage between the outside air intake and the intake manifold of the engine. In general, an air filter device is disposed in the intake passage, but the branch portion may be provided on either the upstream side or the downstream side of the air filter device. Moreover, a branch part can also be provided in an air filter apparatus.

  The branch pipe branches off from a branch portion formed in the intake pipe and communicates with the intake pipe. Therefore, an opening communicating with the branch pipe is formed in the branch portion of the intake pipe. The partition wall made of a breathable porous member may be disposed so as to cover the opening, or may be disposed in the branch pipe so as to partition the branch pipe. There is no restriction on the position of the partition wall as long as it is between the branching portion and the sound source.

  When the partition wall is arranged so as to cover the opening of the branching section, it is desirable that the opening of the branching section formed in the intake pipe has a long shape, and the width in the short direction of the opening is the circumference of the pipe wall. It is preferable to set it to 1/20 or more. By covering such a slit-shaped opening with a partition made of a porous member, the intake noise can be greatly reduced although the reason is unknown. If the width in the short direction of the opening is smaller than 1/20 of the circumference of the tube wall, it is difficult to obtain the effect of arranging the partition walls, and intake noise increases. The upper limit of the width in the short direction of the opening is not particularly limited, but even if the width is increased, the effect of reducing the intake noise hardly changes, and there is a problem that the cost increases due to the increase in the size of the partition wall. . Accordingly, the practical opening width considering the molding process or the porous member joining process in addition to the cost problem is preferably about 1/20 or more and 1/4 or less of the circumference of the tube wall. .

  In addition, the longer the length of the opening in the longitudinal direction, the more the intake noise can be reduced. However, since the amount of the porous member increases, the problem of increasing the cost also increases. In consideration of the balance, the length of the opening only needs to be larger than the above-described width, and is preferably set to 1/4 or less of the entire length of the tube wall. This length is a value that is appropriately adjusted depending on the required intake amount of the engine, the diameter of the intake pipe or the ventilation resistance.

  The center in the longitudinal direction of the opening is preferably at a position that is ¼ of the total length of the pipe wall from the end of the intake pipe. By doing so, intake noise can be further reduced. In the intake pipe, there is a primary resonant sound having the same wavelength as twice the length of the intake pipe, a secondary resonant sound having the same wavelength as the length of the intake pipe, and a tertiary resonant sound having a wavelength that is 2/3 of the length of the intake pipe. These are generated and become intake noise. In order to reduce the resonance noise, it is preferable to provide an opening by removing the position corresponding to the node of each sound wave. That is, it is desirable to set the position in the longitudinal direction of the opening so as to overlap the antinode position of the generated resonance wave. For example, if the center in the longitudinal direction of the opening is set to a position that is 1/4 of the total length of the pipe wall from the end of the intake pipe, the primary resonance sound and the secondary resonance sound that are particularly loud can be effectively reduced. it can.

  As the porous member constituting the partition wall, those formed from fibers of various materials, paper, foam, or the like can be used, but nonwoven fabrics, woven fabrics, knitted fabrics, etc. formed from thermoplastic fibers are particularly desirable. If a nonwoven fabric made of thermoplastic resin fibers or the like is used, it can be easily shaped by hot press molding or the like in accordance with the opening shape of the branch portion and the cross-sectional shape of the branch pipe. Moreover, since it can join to a pipe wall by welding, a man-hour can be reduced. The thermoplastic resin fiber may constitute a part of a nonwoven fabric or the like, or the whole may be composed of thermoplastic resin fibers. In addition, even a cloth in which a non-thermoplastic fiber is impregnated with a thermoplastic resin binder can be shaped by hot press molding or the like in the same manner as a cloth formed from a thermoplastic resin fiber.

If the air permeability of the partition wall is too high, the sound from the intake pipe passes through the partition wall, causing a problem that the noise in the passenger compartment increases. Therefore, it is desirable that the degree of air permeability is 6000 m ³ / h or less per 1 m ² of air flow when the pressure difference is 98 Pa. The air flow rate means the amount of air per unit time passing through the unit area of the test specimen when the pressure difference between the two chambers partitioned by the test specimen is set to 98 Pa. Of course, the limitation of 6000 m ³ / h or less per unit area is a limitation in the case of air with a pressure difference of 98 Pa, and it goes without saying that the limit value of the air flow rate is different if the pressure of intake air is different.

When the air flow rate per 1 m ² of air at a pressure difference of 98 Pa exceeds 6000 m ³ / h, the sound wave passing through the partition increases and the transmitted sound increases. If the airflow is zero, the noise suppression effect in the low frequency range of 200 Hz or less is reduced, but the noise can be suppressed as compared with the conventional intake duct. In order to obtain a porous member having zero ventilation, a film-like skin layer may be formed on the outer surface of the porous member. Even if a skin layer is formed on the inner surface, the air flow rate can be reduced to zero, but it is not preferable because it is difficult to reduce noise due to the reason (2) described above. Note aeration amount of air when the pressure difference 98Pa in the porous member is preferably larger 4200m less than ³ / h than zero, 0 <particularly preferred range of the air permeability of <3000 m ³ / h.

  In addition, the thickness and characteristics of the nonwoven fabric change due to aging, moisture intrusion, etc. May change.

  Therefore, it is desirable that the partition wall has 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, and the functional layer can be easily formed by using a porous member in which fibers having respective functions are mixed. Moreover, you may use the film which has each function laminated | stacked on a porous member.

  The branch pipe is branched at the branch portion of the intake pipe and extends toward the vehicle interior. The branch pipe may be opened in the vehicle interior or may not be opened in the vehicle interior but may be blocked by the body panel or the like. Good. If it is configured to open in the passenger compartment, the direct sound from the branch pipe is perceived, so the sound source can often be made smaller. The branch pipe is preferably branched so as to cover the entire opening of the branch portion, but a part of the opening may protrude outward from the branch pipe.

  As a sound source, a speaker that utters by cone vibration caused by electromagnetic force is typically exemplified. It is desirable to use a speaker device that has an enclosure behind it and that excels in low-frequency sound output due to resonance. In this case, the enclosure may be a sealed type or a bus reflex type.

  This sound source is arranged in a part of the branch pipe so as to speak into the branch pipe. By doing so, the utterance from the sound source is efficiently perceived by the passenger in the vehicle compartment through the branch pipe.

  The sound source can control utterance according to the sound leaking through the partition wall from the opening of the branch portion. For example, when the air permeability of the partition wall is high and the leaked intake sound is large, a sound with the same amplitude and opposite phase as that of the intake sound is uttered. Thereby, the intake sound leaking from the partition wall is canceled out, and the quietness in the passenger compartment is improved.

  Furthermore, it is also preferable to utter a sound source with a sound pressure corresponding to the engine speed. For example, the sound source is uttered so that the volume gradually increases during acceleration, and the sound source is uttered so that the volume gradually decreases during deceleration. By doing so, the driving situation and the perceived sound coincide with each other, and a preferable driving feeling can be obtained. Further, if the tone of the utterance of the sound source is made a tone close to the engine sound or the intake sound, a more comfortable tone can be enjoyed.

  In order to utter a sound source with a sound pressure corresponding to the engine speed, a control device that uses a sensor capable of detecting a physical quantity corresponding to the engine speed and drives the sound source by the signal can be used. The physical quantity corresponding to the engine speed includes the engine speed itself, intake negative pressure, accelerator pedal depression angle, and the like.

  Further, it is preferable that the branch pipe is further provided with a silencer such as a side branch or a resonator. This makes it possible to mute unwanted sounds such as the intake sound leaking from the branching portion and the noise from the sound source. The position of the silencer is not particularly limited, but it is desirable to provide the silencer downstream from the sound source, that is, at a position close to the passenger compartment, in order to mute the sound leaking from the branch portion and the sound from the sound source.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

Example 1
FIG. 1 shows an intake duct of this embodiment. This intake duct is welded and branched to a peripheral portion of a high-density polyethylene intake pipe 1 having an air cleaner case 10 connected to the downstream side and a window opening 12 formed on a pipe wall of the branch part 11 of the intake pipe 1. A branch pipe 2 made of high-density polyethylene that communicates with the passenger compartment, a speaker device 3 disposed in a part of the branch pipe 2, and a control device 4 that drives the speaker device 3.

The window opening 12 is formed in a substantially rectangular shape having a length in the circumferential direction, which is a width in the short direction, of 50 mm, which is a quarter of the general circumferential length of the intake pipe 1, and a length of 200 mm. The window opening 11 is covered with a partition wall 13 made of a nonwoven fabric (weight per unit area: 1000 g / m ² , thickness: 3.5 mm, air permeability: 1680 m ³ / h · m ² ) made of PET (polyethylene terephthalate) fiber. Note that the partition wall 13 is integrated with the intake pipe 1 by thermally welding the peripheral edge portion to the peripheral edge portion of the window opening 12.

  The branch pipe 2 is welded to the peripheral edge portion of the window opening 12 by a flange portion 20 having a diameter slightly larger than the partition wall 13 covering the window opening 12, branches from there and extends toward the vehicle interior, and the tip of the branch pipe 2 extends to the vehicle body panel 5. It is fixed to. The vehicle body panel 5 is formed with a through hole 50 that communicates with the outside of the vehicle interior, and the tip of the branch pipe 2 is fixed so as to cover the through hole 50.

  The speaker device 3 includes a speaker unit 30 and a speaker box 31 that holds the speaker unit 30, and a sealed enclosure is formed behind the speaker unit 30. The speaker box 31 is fixed to the branch pipe 2 so that the cone portion of the speaker unit 30 is exposed inside the branch pipe 2.

  As shown in FIG. 2, the control device 4 includes an I / O unit 40, a calculation unit 41, and a ROM 42. An automobile equipped with this intake duct is provided with a sensor (not shown) for sending a signal corresponding to the depression angle of the accelerator pedal. An output signal from the sensor is first processed by the I / O unit 40 and input to the calculation unit 41. The calculation unit 41 determines the driving situation from the depression angle of the accelerator pedal at that time, and calculates a drive voltage substantially proportional to the engine speed at that time. Further, the calculation unit 41 reads the timbre to be uttered by referring to the ROM 42 at the same time. Then, the calculation unit 41 drives the speaker unit 30 via the I / O unit 40 based on the determined tone color and drive voltage.

  Therefore, according to the intake duct of the present embodiment, the window opening 12 is formed in the intake pipe 1 and the window opening 12 is covered with the partition wall 13 made of nonwoven fabric, so that intake noise is suppressed, and vehicle interior noise and vehicle exterior noise. Both are suppressed. Further, since the sound transmitted through the partition wall 13 is directly transmitted to the vehicle interior through the branch pipe 2, noise outside the vehicle is further suppressed.

  The speaker device 3 utters at a sound pressure substantially proportional to the engine speed, and the utterance is emitted into the vehicle compartment through the branch pipe 2. Accordingly, by setting the speaker unit 30 to be driven with a tone that simulates the intake sound or the engine sound, a preferable simulated sound according to the driving situation can be heard by the occupant, so that the driving feeling is good. In addition, the transmitted sound that has passed through the partition wall 13 from the window opening 12 often has a sound pressure proportional to the engine speed, so the drive voltage of the speaker device 3 only needs to be added to the sound pressure of the transmitted sound. Therefore, the speaker device 3 can be reduced in size, which is advantageous in terms of space, and the simulated sound uttered from the speaker device 3 is emitted from the branch pipe 2 into the vehicle interior, and thus may be noise outside the vehicle. Absent.

(Example 2)
FIG. 3 shows the intake duct of this embodiment. The present embodiment is the same as the first embodiment except that the end of the branch pipe 2 is not opened in the vehicle compartment and the end surface is abutted against the vehicle body panel 5.

  In the present embodiment, since the sound from the branch pipe 2 is indirectly perceived through the vehicle body panel 5 in the vehicle interior, the sound becomes close to the actual intake sound or engine sound, and the driving feeling is further improved. There is.

(Example 3)
FIG. 4 shows the intake duct of this embodiment. The present embodiment is the same as the first embodiment except that the silencer 6 is further provided in the branch pipe 2 on the downstream side of the speaker device 3 and the partition wall 13 is joined to the branch pipe 2 side.

  In the present embodiment, the transmitted sound transmitted through the partition wall 13 from the window opening 12 or a part of the simulated sound uttered by the speaker device 3 can be silenced by resonance of the silencer 6. Therefore, only a particularly preferable sound can be supplied into the vehicle interior, and the driving feeling is further improved.

Example 4
FIG. 5 shows the intake duct of this embodiment. In the present embodiment, the branch cylinder part 14 is projected from the middle of the intake pipe 1, and the branch cylinder part 14 is inserted into and joined to the end of the branch pipe 2 to form the branch part 11. Further, a partition wall 13 made of a nonwoven fabric similar to that of the first embodiment is disposed between the branching portion 11 and the speaker device 3, and the branch pipe 2 is partitioned by the partition wall 13.

  The intake duct of the present embodiment also has the same effects as the other embodiments.

It is typical sectional drawing which shows the structure of the sound absorption duct of one Example of this invention. It is a block diagram of the control apparatus used for the sound absorption duct of one Example of this invention. It is typical sectional drawing which shows the structure of the sound absorption duct of 2nd Example of this invention. It is typical sectional drawing which shows the structure of the sound absorption duct of 3rd Example of this invention. It is typical sectional drawing which shows the structure of the sound absorption duct of 4th Example of this invention.

Explanation of symbols

1: Intake pipe 2: Branch pipe 3: Speaker device (sound source)
4: Control device 5: Body panel 11: Window opening
13: Bulkhead

Claims (3)

An intake duct disposed between an outside air intake of an automobile and an intake manifold of the engine, an intake pipe constituting an intake passage, and a branch pipe branched from a branch portion of the intake pipe and extending toward the vehicle interior With
An air intake duct characterized in that a part of the branch pipe has a sound source that utters into the branch pipe, and a partition wall made of a breathable porous member is provided between the branch portion and the sound source.   The intake duct according to claim 1, wherein the branch pipe is further provided with a silencer.   The intake duct according to claim 1, further comprising a control device that utters the sound source with a sound pressure corresponding to an engine speed.

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