JP2007056841A - Intake sound control structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce intake noise and provide more preferable intake sound into a cabin. <P>SOLUTION: This structure is provided with a sound leading duct 2 branched and connected to a part of an intake flow passage 1, a volume chamber 3 formed in the sound leading duct 2, and a sound generating body 4 formed on a wall surface of the volume chamber 3 and generating sound by vibration. Intake sound resonates in the volume chamber 3 and the sound generating body 4 resonates by that, and sound generated by that vibration is transmitted into the cabin. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an intake sound control structure provided in an intake passage for supplying air to an engine. More specifically, the present invention relates to an intake sound control structure that can reduce intake noise and at the same time generate a preferable sound in a vehicle interior.

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

  Further, as another means for reducing intake noise, it has been proposed to weaken the intake sound by generating 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 Utility Model Publication No. 63-011379, a microphone and a speaker unit are mounted in the middle of an intake pipe, and a sound pressure signal detected by the microphone and a phase signal from a crank angle sensor are input to a control unit, and calculation is performed. A means for weakening the intake sound by obtaining the amplitude and phase of the sound that is opposite in phase to the intake sound, sending this information to the speaker unit, and uttering a sound wave that has substantially the same amplitude as the intake sound and has the opposite phase. Proposed.

  On the other hand, in the passenger compartment, it is preferable to hear an intake sound corresponding to the driving situation. That is, if the accelerator pedal 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. Therefore, by applying the technology described in the above publication, the sound pressure signal detected by the microphone and the phase signal from the crank angle sensor are input to the control unit, and the amplification degree of the sound transmitted to the vehicle interior can be controlled by calculation. Conceivable.

  However, when a speaker is arranged in the middle of the intake pipe, 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.

  Therefore, JP 2005-139982 A discloses a resonator that vibrates due to intake air pulsation in the intake system, a volume chamber connected to the intake system via the resonator, and a volume that communicates the internal space of the volume chamber to the outside. A resonator having a chamber opening, and the resonance body partitions the space between the internal space of the volume chamber and the inside of the intake system, and the sound pressure of a predetermined frequency band is externally transmitted from the volume chamber opening by the vibration of the resonance body. There has been proposed a sound quality control device in which a resonator is set so as to be emitted into the sound source.

  In this publication, the sound pressure in the frequency band corresponding to the natural frequency of the resonator, the volume of the volume chamber, the shape of the volume chamber opening, etc. is added to the intake sound, so that the accelerator is opened without using a speaker. It is described that the intake sound in the passenger compartment can be controlled following the degree.

However, in the above sound quality control device, the sound corresponding to the natural frequency of the resonant body may not be necessary at a certain engine speed, but since the frequency of the emitted sound depends on the natural frequency of the resonant body, Even in such a case, the emission of resonance sound is inevitable.
Japanese Utility Model Sho 63-011379 JP2005-139982

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to solve the problem of reducing intake noise and simultaneously supplying more preferable intake sound to the vehicle interior.

  The feature of the intake sound control structure of the present invention that solves the above problems is that a sound guide duct that is branched and connected to a part of an intake passage of an automobile, a volume chamber formed in the sound guide duct, and a wall surface of the volume chamber And a sounding body that generates sound by vibration, and the sounding body vibrates by a resonance sound in which the intake sound in the intake passage resonates in the volume chamber, and the sound emitted by the sounding body is transmitted to the vehicle interior And

  It is desirable that the volume chamber is provided with a silencer that silences a sound having a frequency that does not require radiation.

  The volume chambers are preferably composed of a plurality of different volumes, and sound generators are preferably provided in the respective volume chambers. It is also preferable that the volume chamber is provided with an on-off valve capable of controlling on / off of the resonance sound contact with the sounding body.

  According to the intake sound control structure of the present invention, since the intake sound of the natural frequency is silenced by cavity resonance or air column resonance in the volume chamber, intake noise from the intake port perceived from outside the vehicle can be reduced. . Further, the sounding body vibrates by resonating with the sound of the natural frequency in the volume chamber, and the resulting sound is emitted to the outside of the volume chamber. Therefore, by arranging the sounding body in the vicinity of the passenger compartment, the sound of natural frequency can be added to the intake sound and supplied to the passenger compartment. Sound can be controlled to be preferable.

  Since the volume chamber is located on the intake flow path side of the sounding body, even if the natural frequency fluctuates due to deterioration of the sounding body, etc., resonance by the volume chamber is maintained, and at least intake noise perceived outside the vehicle. The reduction effect can be maintained. Furthermore, since a silencer such as a resonator can be formed in the volume chamber, the sound of the natural frequency can be silenced, and the intake sound that can be heard in the passenger compartment can be further improved.

  The intake sound control structure according to the present invention includes a sound guide duct, a volume chamber, and a sound generator in order from the side close to the intake flow path. The sound guide duct is branched and connected to a part of the intake passage. The position is not particularly limited.

  Side branch type or Helmholtz type silencers mute the sound of the natural frequency generated in the intake pipe by resonance. By arranging a sounding body that can vibrate on the wall, the sounding body is resonated by the resonance sound. It is possible to radiate the sound emitted by that. Therefore, in the present invention, a side branch type or Helmholtz type volume chamber is formed in the sound guide duct and used as a silencer and also as a sound generator.

  For example, in the case of a side branch type volume chamber, the natural frequency of the resonant sound depends on the length of the side branch. Therefore, when amplifying low-frequency component sounds, it is necessary to increase the length of the side branch. In this case, it is desirable that part or all of the sound guide duct be a side branch type volume chamber.

  When a Helmholtz type volume chamber is provided, it is preferable that the sound guide duct is a throat chamber and the volume chamber is formed at the tip thereof. In this case, the natural frequency f of the resonance sound is expressed by the following equation.

  In the formula, f represents the natural frequency (resonance frequency), C represents the speed of sound, l represents the length of the throat chamber, V represents the volume of the volume chamber, and S represents the cross-sectional area of the throat chamber. When amplifying low-frequency component sounds, it is necessary to reduce the natural frequency (f). That is, in order to reduce the natural frequency (f), it is necessary to increase l or V with respect to S. However, by increasing the length of the sound guide duct, decreasing the depth of the volume chamber, and increasing the diameter. An increase in the arrangement space of the volume chamber can be suppressed.

  The sounding body formed on the wall surface of the volume chamber has a natural frequency that can be vibrated by the resonance sound of the natural frequency resonated in the volume chamber, and is selected from a metal plate, a resin plate, a rubber plate, etc. It may be formed in a shape having a natural frequency corresponding to the sound. The sounding body may be exposed in the passenger compartment, or may be arranged so as to face a panel that defines the passenger compartment. It is also possible to use the panel itself that defines the passenger compartment as a sounding body.

  It is also preferable to provide one or more silencers in the volume chamber to mute sounds having frequencies that do not require radiation. For example, by forming a resonator or side branch on one wall surface of the volume chamber, it is possible to mute sounds with frequencies other than the resonance frequency corresponding to the natural frequency of the sounding body that do not require radiation from the intake sound that flows into the volume chamber. In addition, since the waveform of the resonance sound in the volume chamber becomes closer to the ideal, the intake sound transmitted to the vehicle interior can be made more preferable.

  It is also preferable that the volume chamber is composed of a plurality of volumes having different volumes, and a sounding body is provided in each volume chamber. In this way, a plurality of resonance sounds having a plurality of natural frequencies can be emitted simultaneously.

  It is also preferable to form an open / close valve in the volume chamber that can control on / off of the contact of the resonance sound to the sounding body. In this way, the control of the intake sound control structure can be turned on / off as necessary. In addition, in the case of having a plurality of volume chambers, it is possible to turn on only the intake sound control structure that generates a necessary natural frequency according to the engine speed by forming an open / close valve in each volume chamber. The intake sound transmitted to the passenger compartment can be further improved.

  The on-off valve can be provided at a branch portion of the sound guide duct with the intake flow path, a boundary portion between the sound guide duct and the volume chamber, or the like, but is preferably provided in the vicinity of the sounding body. In this way, even when the sound generation due to the vibration of the sounding body is turned off, the effect of reducing the intake noise due to the resonance of the volume chamber perceived from outside the vehicle compartment can be maintained.

  The position of the wall surface with the volume chamber sounding body may be the side surface or the bottom surface. The entire wall surface may be a sounding body, or a part of the wall surface may be a sounding body. In order to give directionality to the pronunciation, it is also preferable to cover the sounding body with a container having an opening and to produce sound from the opening.

  Hereinafter, the present invention will be described specifically by way of examples.

Example 1
1 and 2 show the intake sound control structure of this embodiment. A sound guide duct 2 is branched and connected between the air inlet 10 of the intake duct 1 and the air filter case 11, and a cylindrical volume chamber 3 is formed at the tip of the sound guide duct 2. Four through holes 30 are formed at the bottom of the volume chamber 3, and the through holes 30 are made of a resin plate made of PET and covered with a sounding body 4 having a thickness of 0.5 mm. The bottom of the volume chamber 3 faces the panel 100 that partitions the vehicle compartment and the engine room with a slight gap, and the sound generated by the vibration of the sounding body 4 is transmitted to the vehicle interior via the panel 100. It is configured as follows.

  Here, the sound guide duct 2 and the volume chamber 3 constitute a Helmholtz type silencer, and the length (l) of the sound guide duct 2, the cross-sectional area (S) of the sound guide duct 2, and the volume (V) of the volume chamber 3 ), The sound of the natural frequency (f) calculated by Equation 1 can be silenced. Therefore, it is possible to reduce intake noise from the intake port 10 that is perceived from outside the vehicle.

  In this embodiment, the sounding body 4 has a natural frequency that resonates with the sound of the natural frequency (f) calculated by the equation (1). Therefore, the sounding body 4 resonates due to the resonance sound in the volume chamber 3, and the sounding body 4 itself becomes a sound source to generate a sound of the natural frequency (f).

  As shown by the broken line in FIG. 3, it is desirable that the sound pressure rises linearly as the engine speed increases, as indicated by the broken line in FIG. However, for example, the relationship between the sound pressure of the intake sound of the rotation quaternary component that can be heard in the passenger compartment and the engine speed is as shown by the solid line in FIG. 3, and there is a problem that the sound pressure is low in the middle speed range. Therefore, by using the intake sound control structure of the present embodiment, the length (l) of the sound guide duct 2, the cross-sectional area (S) of the sound guide duct 2, and the volume (V) of the volume chamber 3 are appropriately set. 350Hz intake noise can be added to the intake sound heard in the passenger compartment by setting the sound generator 4 to vibrate at 350Hz natural frequency (f). The sound pressure can be heard to increase linearly as the engine speed increases.

(Example 2)
The intake sound control structure of this embodiment shown in FIG. 4 is the same as that of Embodiment 1 except that a Helmholtz type silencer 31 is formed on the wall surface of the volume chamber 3.

  According to the intake sound control structure of this embodiment, a part of the intake sound flowing into the volume chamber 3 can be silenced by the cavity resonance of the silencer 31. Therefore, it is possible to mute the sound of the natural frequency based on the shape of the silencer 31 from the intake air flowing into the volume chamber 3, that is, the sound other than the natural vibration frequency of the sounding body, and the waveform of the resonance sound in the volume chamber becomes more ideal. Since it becomes close, the intake sound transmitted to the passenger compartment can be made more preferable.

(Example 3)
The intake sound control structure according to this embodiment includes a sound guide duct 2 and a volume chamber 3 as in the first embodiment, and the bottom surface of the volume chamber 3 includes a panel 100 as shown in FIG. In other words, the panel 100 also serves as a sound generator, and the panel 100 vibrates with a resonance sound having a natural frequency (f) determined by the shape of the sound guide duct 2 and the volume chamber 3. Therefore, the intake air sound heard in the passenger compartment has the natural frequency (f). Sound can be added.

Example 4
The intake sound control structure according to the present embodiment is composed of a sound guide duct 2, a volume chamber 3, and a sounding body 4 as in the first embodiment. As shown in FIG. The volume chamber 3 and the sounding body 4 are exposed through the vehicle interior. In this case, the sound pressure of the sounding body 4 in the passenger compartment is increased, which may result in a more preferable intake sound.

(Example 5)
As shown in FIG. 7, the intake sound control structure according to this embodiment includes a sound guide duct 2 and a sounding body 4 held at the tip of the sound guide duct 2. The sounding body 4 is opposed to the panel 100 that partitions the vehicle compartment and the engine room with a slight gap.

  In this embodiment, the sound guide duct 2 itself constitutes a side branch type volume chamber, and the sound of the natural frequency (f) corresponding to the length of the sound guide duct 2 can be silenced. Therefore, it is possible to reduce intake noise from the intake port 10 that is perceived from outside the vehicle. The sounding body 4 has a natural frequency that resonates with a sound having a natural frequency (f). Therefore, the sounding body 4 resonates due to the resonance sound in the sound guide duct 2, and the sounding body 4 itself becomes a sound source to generate a sound of the natural frequency (f).

(Example 6)
As shown in FIG. 8, the intake sound control structure according to the present embodiment includes a plurality of sound guide ducts 2 and a sounding body 4 held at the tip of each sound guide duct 2. The sounding body 4 is opposed to the panel 100 that partitions the vehicle compartment and the engine room with a space therebetween.

  In the present embodiment, each sound guide duct 2 itself constitutes a side branch type volume chamber, and sounds of a plurality of natural frequencies corresponding to the length of the sound guide duct 2 can be silenced. Therefore, it is possible to reduce intake noise from the intake port 10 that is perceived from outside the vehicle. Each sounding body 4 has a natural frequency that resonates with a sound having a natural frequency that is silenced by each sound guide duct 2. Therefore, the sounding body 4 resonates due to the resonance sound in the sound guide duct 2, and the sounding body 4 itself serves as a sound source to generate sounds having a plurality of natural frequencies.

(Example 7)
As shown in FIG. 9, the intake sound control structure according to the present embodiment has an on-off valve 20 formed at each branch portion of the plurality of sound guide ducts 2 from the intake duct 1. Example 5 is the same as Example 5 except that the inflow of intake air to the duct 2 can be turned on and off.

  The movement of each on-off valve 20 is controlled by an actuator (not shown), and the actuator is driven by the control device 5. In other words, the control device 5 turns on / off the driving of the actuator according to a map determined in advance according to the value of the engine speed, and controls the opening / closing of the sound guide duct 2 by the respective opening / closing valves 20.

  Therefore, according to the intake sound control structure of this embodiment, the sound guide duct 2 into which intake air flows can be selected according to the value of the engine speed, and the sound generation of the sound generator 4 can be selected from a plurality of types in various combinations. be able to. The on-off valve 20 may be in the middle of the sound guide duct 2.

(Example 8)
As in the first embodiment, the intake sound control structure of the present embodiment is composed of a sound guide duct 2 and a volume chamber 3. As shown in FIG. The area (S) and length (l) are controlled by an actuator (not shown). Therefore, the natural frequency of the resonance sound can be changed as shown in Equation 1.

  The actuator is driven by a control device (not shown). That is, the control device controls the driving of the actuator by a predetermined map according to the value of the engine speed, and the volume (V) of the volume chamber, the cross-sectional area (S) and the length (S) of the sound guide duct 2 ( l) is controlled. It should be noted that one or more of the volume (V) of the volume chamber, the cross-sectional area (S), and the length (l) of the sound guide duct 2 may be variable.

  Therefore, according to the intake sound control structure of this embodiment, the value of the natural frequency can be changed according to the value of the engine speed, and the sound of the necessary frequency can be generated according to the speed. .

It is typical sectional drawing of the intake sound control structure of one Example of this invention. It is a principal part perspective view of the intake sound control structure of one Example of this invention. It is a graph which shows the relationship between an engine speed and a sound pressure. It is typical sectional drawing of the intake sound control structure of 2nd Example of this invention. It is typical sectional drawing of the intake sound control structure of 3rd Example of this invention. It is typical sectional drawing of the intake sound control structure of 4th Example of this invention. It is typical sectional drawing of the intake sound control structure of 5th Example of this invention. It is typical sectional drawing of the intake sound control structure of 6th Example of this invention. It is typical sectional drawing of the intake sound control structure of 7th Example of this invention. It is typical sectional drawing of the intake sound control structure of 8th Example of this invention.

Explanation of symbols

1: Intake duct 2: Sound guide duct 3: Volume chamber 4: Sound generator 5: Control device 20: On-off valve 31: Silencer 100: Panel

Claims (4)

A sound guide duct that is branched and connected to a part of an intake passage of an automobile, a volume chamber formed in the sound guide duct, and a sounding body that is formed on a wall surface of the volume chamber and generates sound by vibration,
An intake sound control structure characterized in that an intake sound in the intake passage vibrates the sounding body by a resonance sound that resonates in the volume chamber, and a sound emitted from the sounding body is transmitted to a vehicle interior.   The intake sound control structure according to claim 1, wherein the volume chamber is provided with a silencer that silences a sound having a frequency that does not require radiation.   The intake sound control structure according to claim 1, wherein the volume chamber includes a plurality of different volumes, and the sounding body is provided in each volume chamber.   4. The intake sound control structure according to claim 1, wherein the volume chamber is provided with an on-off valve capable of on / off control of contact of the resonance sound to the sounding body.

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