JP2009264316A - Muffler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide sufficient reduction effect for both of intake noise and penetrating noise, regardless of the engine speed, in a muffler 1 which reduces the intake noise by the vibration of a thin film 9. <P>SOLUTION: In this muffler 1, ECU 11 closes a capacity chamber 4 with respect to the outside air by closing an on-off valve 10, when the engine speed is lower than a prescribed threshold, and opens the capacity chamber 4 to the outside air by opening the on-off valve 10, when the engine speed is higher than the threshold. As a result, an engine speed range which reduces the intake noise and penetrating noise by the resonance of the thin film 9 and the range of engine speed which reduces the intake noise by the vibration of the thin film 9 and reducing penetrating noise by the capacity chamber 4 and a communication passage between the capacity chamber 4 and the outside air are freely selected, and sufficient reduction effect for both of intake noise and penetrating noise can be provided, regardless of the engine speed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a silencer that reduces intake noise generated in an intake duct accompanying intake air into an engine.

  Conventionally, in order to reduce intake noise, various silencers have been considered and applied to intake ducts (hereinafter simply referred to as ducts). One of these silencers is a thin film tube. Some are part of the duct. According to this silencer, due to the vibration of the thin film, the sound waves generated in the duct due to the intake pulsation and the air column resonance of the intake air are attenuated and partially transmitted outside the duct to reduce the intake sound (for example, , See Patent Document 1).

  By the way, the sound wave transmitted from the thin film becomes a transmitted sound and constitutes noise separately from the intake sound. Therefore, in order to reduce the transmitted sound, a transmitted sound reducing means is required in addition to the intake sound reducing means, and various transmitted sound reducing means have been considered.

  For example, according to the silencer of Patent Document 1, a sound absorbing material is arranged on the outer peripheral side of the thin film, and the transmitted sound is reduced by the sound absorbing material. However, the lower the engine speed and the lower the frequency of the sound wave, the more difficult it is to block the transmission of the sound wave, and the lower the frequency, the lower the sound-absorbing effect.

  Further, a silencer is also considered in which a highly rigid wall portion is disposed on the outer peripheral side of the thin film, and a closed volume chamber is formed between the thin film and the wall portion (see, for example, Patent Document 2). According to the silencer of Patent Document 2, it is intended to reduce transmitted sound by attenuating a sound wave transmitted from a thin film by a highly rigid wall.

However, the closed structure of the volume chamber as in Patent Document 2 acts as rigidity against vibration of the thin film, and causes a resonance phenomenon of the thin film only in a specific frequency band having a relatively low frequency. For this reason, the thin film can sufficiently vibrate by resonance only in a specific frequency band, and may not vibrate sufficiently in a frequency region higher than the specific frequency band. As a result, when the engine speed increases, the sound wave in the duct cannot be sufficiently attenuated or transmitted, and there is a possibility that sufficient intake noise and transmitted sound reduction effects cannot be obtained.
JP 2004-346750 A Japanese Patent Laid-Open No. 2003-322062

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a silencer that reduces intake noise by vibration of a thin film, regardless of the engine speed. It is to obtain a sufficient reduction effect for both of the above.

[Means of Claim 1]
The silencer according to claim 1 includes an inner peripheral pipe that forms a part of an intake duct that communicates with the engine, an outer peripheral pipe that forms a volume chamber on the outer peripheral side of the inner peripheral pipe, and an open / close that opens and closes the volume chamber with respect to the outside air. And a control means for controlling the on-off valve. Further, the inner peripheral pipe is made of a thin film that is thinner than the other part of the intake duct, and the intake sound generated in the intake duct is attenuated and transmitted to the outside of the intake duct due to the vibration of the thin film. The control means closes the open / close valve to close the volume chamber against the outside air when the engine speed is lower than a predetermined threshold value, and opens and closes when the engine speed is higher than the threshold value. The valve is opened to open the volume chamber to the outside air.

  As a result, when the engine speed is lower than the threshold value, the volume chamber is sealed and rigidity against vibration of the thin film is increased, so that an effect of reducing intake sound and transmitted sound due to resonance of the thin film can be obtained. Further, when the engine speed is higher than the threshold value, the volume chamber is not sealed, but is substantially expanded and the rigidity is lowered, so that the thin film can freely vibrate. For this reason, the intake sound is sufficiently attenuated and transmitted to the outside of the duct to reduce the intake sound, and the transmitted sound is attenuated according to the size of the volume chamber or the communication path between the volume chamber and the outside air.

  As described above, by setting the threshold value according to the permissible range of the transmitted sound, it is possible to obtain a sufficient reduction effect for both the intake sound and the transmitted sound regardless of the engine speed. In other words, the engine rotation speed range that reduces both the intake and transmitted sound due to the resonance of the thin film, the intake sound is reduced mainly due to the vibration of the thin film, and the transmitted sound is transmitted through the volume chamber and the communication path between the volume chamber and the outside air. By freely selecting the range of the engine speed for reducing the engine speed, it is possible to obtain a sufficient reduction effect for both the intake sound and the transmitted sound regardless of the magnitude of the engine speed.

[Means of claim 2]
According to a second aspect of the present invention, there is provided a silencer comprising: an inner peripheral pipe that forms a part of an intake duct that communicates with the engine; an outer peripheral pipe that forms a volume chamber on the outer peripheral side of the inner peripheral pipe; And an on / off valve for controlling the on / off valve. Further, the inner peripheral pipe is made of a thin film that is thinner than the other part of the intake duct, and the intake sound generated in the intake duct is attenuated and transmitted to the outside of the intake duct due to the vibration of the thin film. The control means closes the open / close valve to close the volume chamber with respect to the intake duct when the engine speed is lower than a predetermined threshold value, and when the engine speed is higher than the threshold value. Then, the open / close valve is opened to open the volume chamber with respect to the intake duct.
Thereby, the same effect as that of the means of claim 1 can be obtained.

  The silencer of the best mode 1 includes an inner peripheral pipe that forms a part of an intake duct leading to an engine, an outer peripheral pipe that forms a volume chamber on the outer peripheral side of the inner peripheral pipe, and an on-off valve that opens and closes the volume chamber with respect to the outside air And control means for controlling the on-off valve. Further, the inner peripheral pipe is made of a thin film that is thinner than the other part of the intake duct, and the intake sound generated in the intake duct is attenuated and transmitted to the outside of the intake duct due to the vibration of the thin film. The control means closes the open / close valve to close the volume chamber against the outside air when the engine speed is lower than a predetermined threshold value, and opens and closes when the engine speed is higher than the threshold value. The valve is opened to open the volume chamber to the outside air.

  Further, according to the silencer of the best mode 2, the on-off valve opens and closes the volume chamber with respect to the inside of the intake duct. The control means closes the open / close valve to close the volume chamber with respect to the intake duct when the engine speed is lower than a predetermined threshold value, and when the engine speed is higher than the threshold value. Then, the open / close valve is opened to open the volume chamber to the intake duct.

[Configuration of Example 1]
The structure of the silencer 1 of Example 1 is demonstrated using FIG. 1 and FIG.
The silencer 1 reduces intake noise generated in an intake duct (hereinafter referred to as a duct 2) in accordance with intake air to an engine (not shown). And the silencer 6 which consists of the outer periphery pipe | tube 5 which forms the volume chamber 4 in the outer peripheral side of the inner periphery pipe | tube 3 is provided, and the silencer 6 is distribute | arranged between the air cleaner and the throttle apparatus, for example.

The inner peripheral pipe 3 is made of a thin film 9 thinner than the other part of the duct 2 and is provided, for example, by blow molding a polyester resin such as polyethylene naphthalate (PEN) or polyethylene terephthalate (PET).
The outer peripheral tube 5 is thicker than the thin film 9 and is provided with high rigidity, and is disposed on the outer peripheral side of the inner peripheral tube 3 to partition the volume chamber 4 from the outside air.

  The intake sound generated in the duct 2 is attenuated by the vibration of the thin film 9 and partially penetrates into the volume chamber 4 to be transmitted sound. That is, the thin film 9 vibrates in response to the input of sound waves accompanying inspiration such as inspiration pulsation and air column resonance, thereby attenuating the sound waves accompanying inspiration and removing some of the sound waves accompanying inspiration outside the duct 2. Permeate to reduce intake noise.

  Further, the silencer 1 includes an on-off valve 10 that opens and closes the volume chamber 4 with respect to the outside air, and an electronic control device (hereinafter referred to as ECU 11) as a control unit that controls the on-off valve 10.

  The on-off valve 10 is a valve device that opens or closes its own valve body by a known actuator such as an electromagnetic solenoid, and opens the volume chamber 4 to the outside air by opening the valve. By doing so, the volume chamber 4 is closed with respect to external air. That is, an input side pipe 13 leading to the volume chamber 4 is connected to the input port of the on-off valve 10, and an output side pipe 14 leading to the outside air is connected to the output port, and the input side and output side pipes 13, 14 are connected. The internal flow path, together with the internal flow path of the on-off valve 10, forms a communication path between the volume chamber 4 and the outside air. And the on-off valve 10 opens and closes its valve body by opening and closing the communication passage by its own valve body, thereby opening and closing the volume chamber 4 with respect to the outside air.

  The ECU 11 controls the on-off valve 10 by giving a command to the actuator of the on-off valve 10 to operate the valve body. And ECU11 acquires the detected value of engine speed, and performs control of on-off valve 10 according to engine speed.

  That is, the ECU 11 stores a threshold value for the detected value of the engine speed, and when the engine speed is lower than the threshold value, the ECU 11 closes the open / close valve 10 and closes the volume chamber 4 with respect to the outside air. When the engine speed is higher than the threshold, the on-off valve 10 is opened to open the volume chamber 4 to the outside air. The threshold value is stored, for example, as a numerical value larger than a specific frequency band in which the thin film 9 resonates when the on-off valve 10 is closed (hereinafter referred to as a resonance frequency band).

  The ECU 11 includes a CPU that performs control processing and arithmetic processing, a memory such as ROM and RAM, a microcomputer that includes an input / output device, and a drive that receives an input of a command signal from the microcomputer and energizes an actuator. An electronic circuit element such as a circuit is mounted, and the control of the on-off valve 10 is executed by the function of these electronic circuit elements. The ECU 11 may be set to perform control of the throttle device, engine ignition control, injection control, and the like.

[Effects of Example 1]
According to the silencer 1 of the first embodiment, the silencer 6 includes a thin film 9 that forms a part of the duct 2 and an outer peripheral tube 5 that forms a volume chamber 4 on the outer peripheral side of the inner peripheral tube 3. The volume chamber 4 is changed in communication with the outside air by the on-off valve 10. The on-off valve 10 is controlled by the ECU 11, and the ECU 11 closes the volume chamber 4 with respect to the outside air by closing the on-off valve 10 when the engine speed is lower than a predetermined threshold value. When higher than the threshold value, the on-off valve 10 is opened to open the volume chamber 4 to the outside air.

  Thereby, when the engine speed is lower than the threshold value, the volume chamber 4 is sealed and the rigidity against vibration of the thin film 9 is increased, so that an effect of reducing intake sound and transmitted sound due to resonance of the thin film 9 is obtained. Further, when the engine speed is higher than the threshold value, the volume chamber 4 is not sealed and is substantially expanded to reduce the rigidity, so that the thin film 9 can freely vibrate. For this reason, the intake sound is sufficiently attenuated and transmitted to the outside of the duct 2 to reduce the intake sound, and the transmitted sound is attenuated according to the dimensions of the volume chamber 4 and the communication path between the volume chamber 4 and the outside air. .

  As described above, it is possible to obtain a sufficient reduction effect for both the intake sound and the transmitted sound regardless of the engine speed.

[Example 2]
According to the silencer 1 of the second embodiment, as shown in FIG. 2, the on-off valve 10 opens and closes the volume chamber 4 with respect to the inside of the duct 2. That is, the output side pipe 14 connected to the output port of the on-off valve 10 communicates with the inside of the duct 2, and the internal flow paths of the input side and output side pipes 13 and 14 together with the internal flow path of the on-off valve 10 have a volume. A communication path between the chamber 4 and the duct 2 is formed.

  The on-off valve 10 opens or closes the valve chamber with respect to the inside of the duct 2 by opening or closing the communication passage with its own valve body. Further, the ECU 11 closes the open / close valve 10 to close the volume chamber 4 with respect to the inside of the duct 2 when the engine speed is lower than the threshold value, and closes the open / close valve when the engine speed is higher than the threshold value. 10 is opened to open the volume chamber 4 to the inside of the duct 2.

  As described above, the silencer 1 of the second embodiment can obtain the same effects as the silencer 1 of the first embodiment.

[Modification]
According to the silencer 1 of the embodiment, the silencer 6 is disposed between the air cleaner and the throttle device, but the silencer 6 may be disposed upstream of the air cleaner.
Further, according to the silencer 1 of the embodiment, the threshold value is stored as a numerical value larger than the resonance frequency band of the thin film 9, but the threshold value may be set according to the permissible range of the transmitted sound, and is not necessarily the thin film. It is not necessary to set a numerical value larger than the 9 resonance frequency band. Therefore, if the transmitted sound is sufficiently attenuated in the volume chamber 4 or the communication path between the volume chamber 4 and the outside air while the on-off valve 10 is open, the numerical value included in the resonance frequency band is set as a threshold value. May be.

It is explanatory drawing of a silencer (Example 1). (Example 2) which is explanatory drawing of a silencer.

Explanation of symbols

1 Silencer 2 Duct (intake duct)
3 inner peripheral tube 4 volume chamber 5 outer peripheral tube 9 thin film 10 on-off valve 11 ECU (control means)

Claims (2)

An inner peripheral pipe that forms part of an intake duct that communicates with the engine, an outer peripheral pipe that forms a volume chamber on the outer peripheral side of the inner peripheral pipe, an on-off valve that opens and closes the volume chamber with respect to outside air, and controls the on-off valve Control means for
The inner peripheral pipe is made of a thin film that is thinner than the other part of the intake duct,
By the vibration of the thin film, the intake sound generated in the intake duct is attenuated and transmitted outside the intake duct.
The control means closes the open / close valve to close the volume chamber against the outside air when the engine speed is lower than a predetermined threshold value, and the engine speed is higher than the threshold value. In some cases, the silencer is characterized in that the open / close valve is opened to open the volume chamber to the outside air. An inner peripheral pipe that forms part of an intake duct that communicates with the engine, an outer peripheral pipe that forms a volume chamber on the outer peripheral side of the inner peripheral pipe, an on-off valve that opens and closes the volume chamber with respect to the intake duct, Control means for controlling the valve,
The inner peripheral pipe is made of a thin film that is thinner than the other part of the intake duct,
By the vibration of the thin film, the intake sound generated in the intake duct is attenuated and transmitted outside the intake duct.
When the engine speed is lower than a predetermined threshold value, the control means closes the open / close valve to close the volume chamber with respect to the intake duct, and the engine speed is set to the threshold value. When it is higher, the silencer is characterized in that the open / close valve is opened to open the volume chamber with respect to the intake duct.

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