JP4713326B2 - Sound quality transmission structure - Google Patents

Description

  The present invention relates to a sound quality transmission structure for an internal combustion engine.

  In an intake system or exhaust system of an automobile engine, a resonance tube or a resonance box is used to lower the sound pressure level of sound waves other than the target frequency, and to relatively increase the sound pressure level of sound waves of the target frequency. A technique for adjusting the sound pressure of sound and exhaust sound is known.

  However, when the sound pressure level of a sound wave having a target frequency is lowered, there is a problem that various resonance tubes and resonance boxes are required because the frequency range to be lowered is wide.

In Patent Document 1, there is provided an intake device that can provide a powerful intake sound by providing a resonance tube or a resonance box that resonates at a predetermined frequency in a dust side duct connected to an air cleaner, and amplifying a sound wave having a target frequency. It is disclosed.
JP 2003-113748 A

  However, in Patent Document 1, in order to amplify a sound wave having a predetermined frequency in the intake sound, it is necessary to fix the length, diameter, and volume of the resonance tube and the resonance box to a certain value. For this reason, the arrangement of the resonance tube and the like is restricted, and it is difficult to arrange the resonance pipe at a position in the engine room where the increased intake sound is difficult to attenuate. As a result, the increased intake sound is attenuated before being guided into the vehicle interior, which makes it difficult to hear the intake sound in the vehicle interior.

  Therefore, an object of the present invention is to provide a sound quality transmission structure that can guide a sound wave having a predetermined frequency amplified by a resonance tube into a vehicle interior without being attenuated.

The present invention relates to a transmission pipe that is connected to an intake system of an internal combustion engine and transmits intake pulsation in the intake system, a vibration body that is provided at one end of the transmission pipe and vibrates due to the intake pulsation, and a transmission pipe via the vibration body while being connected with, among the sound waves generated by the vibration of the vibrating body, and a resonance tube that amplifies the sound waves in a predetermined frequency band, a larger diameter than the diameter of the resonance tube, be a tubular member having opposite open ends A waveguide disposed at a predetermined position in the engine room so that an opening on one end side is connected to the resonance tube and an amplified sound wave is transmitted to the vehicle interior in the opening on the other end side. It is characterized by.

  According to the present invention, a waveguide having a diameter larger than that of the resonance tube is provided concentrically at the resonance port of the resonance tube of the resonator. In addition, the open end of the waveguide is disposed opposite to the driver's seat at a position in the engine room where sound insulation is difficult. Thereby, it becomes possible to guide into the vehicle interior with almost no change in the frequency of the sound wave in the predetermined frequency band amplified by the resonance tube. Further, attenuation of the amplified sound wave can be suppressed, and a powerful intake sound can be obtained in the passenger compartment.

  Hereinafter, the present embodiment will be described with reference to the drawings.

  FIG. 1 is a schematic view showing an engine room 1 of a vehicle viewed from above the vehicle. The front shows the front of the vehicle.

  The engine room 1 is defined by a side panel 2 and a dash panel 3. The engine room 1 houses a 6-cylinder engine 4.

  The engine 4 includes an intake system 5 for supplying air to the engine 4. The intake system 5 includes an air cleaner 51, a throttle valve 52, and an intake collector 53. The intake system 5 opens an intake port 54 for taking air into the front of the vehicle. The intake port 54 communicates with the air cleaner 51 that purifies the intake air (hereinafter referred to as “intake air”) through the dust side duct 55.

  The air cleaner 51 is separated into a dust side 51b and a clean side 51c by a filter element 51a. One end of the clean side duct 56 communicates with the clean side 51c of the air cleaner 51. The other end of the clean side duct 56 communicates with the intake collector 53 via a throttle valve 52 for adjusting the intake air amount.

  A plurality of branch pipes 57 are connected to the intake collector 53. The branch pipe 57 communicates with a combustion chamber of each cylinder (not shown) of the engine 4.

  In such an intake system 5, the intake air purified by the air cleaner 51 is adjusted by the throttle valve 52 according to the driving condition of the vehicle. The intake air is guided into the combustion chamber by the intake negative pressure of the engine 4. Then, intake pulsation occurs in the intake system 5 due to the operation of transmitting intake air to the engine 4 and the reciprocating motion of a piston or intake valve (not shown).

  In the present embodiment, a sound wave in a predetermined frequency band is amplified by the resonator 20 using the intake pulsation as an excitation source. The resonator 20 is provided in a clean side duct 56 between the clean side 51 c of the air cleaner 51 and the throttle valve 52.

  FIG. 2 is a schematic diagram showing the configuration of the resonator 20.

  As shown in FIG. 2A, the resonator 20 includes a transmission tube 21 that transmits the intake pulsation generated in the intake system 5 and a resonance tube 22 that amplifies a sound wave in a predetermined frequency band. One end of the transmission tube 21 communicates with the clean side duct 56. The other end of the transmission tube 21 is connected to one end of the resonance tube 22. The other end of the resonance tube 22 is opened to the outside (resonance port 22a), and a sound wave having a predetermined frequency band is emitted from the resonance port 22a. A waveguide 23 described later is concentrically fixed to the resonance port 22 a of the resonance tube 22 by a bolt 24.

  As shown in FIG. 2B, a disc-shaped diaphragm 25 that vibrates using the transmitted intake pulsation as an excitation source is concentrically interposed between the transmission tube 21 and the resonance tube 22. For the diaphragm 25, rubber, resin, cone paper, or the like that vibrates due to intake pulsation is used.

  In the resonator 20, the diaphragm 25 vibrates using the intake pulsation generated in the intake system 5 as an excitation source. Among the sound waves generated by the vibration of the diaphragm 25, the sound wave of a predetermined frequency band is amplified by the resonance tube 22 by so-called air column resonance. Since the sound wave based on the intake pulsation that fluctuates in conjunction with the accelerator opening is amplified by the resonator 20, it is possible to obtain a sound pressure characteristic that changes linearly with an increase in the engine rotation speed.

  In such a resonator 20, the axial length and the inner diameter of the resonance tube 22 of the resonator 20 determine the frequency band of the sound wave to be amplified and the amount of increase in sound pressure of the sound wave. In other words, the shape (axial length and inner diameter) of the resonance tube 22 is determined by the frequency band of the target sound wave. Therefore, the arrangement of the resonance tube 22 is restricted in the engine room 1, and it is difficult to arrange the resonance tube 22 at a position where the amplified sound wave of a predetermined frequency band is difficult to attenuate. As a result, there is a problem that the amplified sound wave is attenuated in the engine room 1 and is difficult to hear in the passenger compartment. Therefore, in the present embodiment, the waveguide 23 is attached in the vicinity of the resonance port 22 a of the resonance tube 22.

  FIG. 3 is a schematic diagram showing the configuration of the waveguide 23. As shown in FIG. 3A, the waveguide 23 has a cylindrical shape with both ends open. The diameter of the waveguide 23 is larger than the diameter of the resonance tube 22. One end of the waveguide 23 is concentrically connected by a bolt 24 via a sleeve 26 in the vicinity of the resonance port 22 a of the resonance tube 22. The open end 23a of the waveguide 23 is disposed at a predetermined position in the engine room 1 where the sound wave in the target frequency band is easily heard so that the sound wave in the target frequency band can be easily heard in the passenger compartment. Further, as shown in FIG. 3B showing a BB cross section of the waveguide 23, the waveguide 23, the resonance tube 22 and the diaphragm 25 are arranged concentrically.

  The length of the waveguide 23 is set so that the open end 23a of the waveguide 23 can be disposed at a predetermined position in the engine room 1 where sound insulation is difficult. The diameter of the waveguide 23 is set larger than the diameter of the resonance tube 22. For this reason, the waveguide 23 can be guided into the vehicle interior with almost no change in the predetermined frequency band of the sound wave amplified by the resonance tube 22.

  FIG. 4 is a schematic view showing the arrangement position of the open end 23 a of the waveguide 23 in the engine room 1. As in FIG. 1, the front side indicates the front of the vehicle. The arrangement position shown in FIG. 4 is a position that is considered to be less likely to be sound-insulated based on the configuration of the engine room 1 and has been selected in advance.

  A indicates a position immediately before the dash panel 3 in the center of the engine room 1. B indicates the rear position of the engine 4 in the center of the engine room 1. C indicates the position immediately before the dash panel 3 behind the clean side duct 56. D indicates the rear position of the clean side duct 56. E indicates the rear position of the right strut tower 6. F indicates the left position of the right strut tower 6. In the arrangement positions A to F, the open end 23a of the waveguide 23 is arranged so as to face the vehicle interior.

  FIG. 5 is a characteristic diagram showing a transfer function with respect to the frequency of the sound wave transmitted into the vehicle interior when the open end 23a of the waveguide 23 is arranged at each arrangement position. The horizontal axis indicates the frequency of the amplified sound wave. The vertical axis shows the transfer function at that time. The larger the transfer function, the easier it is to hear the sound wave of a predetermined frequency amplified by the resonator 20 in the passenger compartment.

  As shown in FIG. 5, at the rear position E of the right strut tower 6, the transfer function is greatest particularly in the low frequency range, and the transfer function is large even in the average of all frequency ranges. Therefore, when the open end 23a of the waveguide 23 is disposed at the rear position E of the right strut tower 6, the attenuation of the sound wave amplified by the resonator 20 is suppressed most.

  FIG. 6 is an engine rotation speed-sound pressure level characteristic diagram when a sound wave having a predetermined frequency is transmitted into the vehicle interior when the open end 23a of the waveguide 23 is disposed at the position E.

  The resonator 20 emits sound waves in the frequency band of the order determined by the number of cylinders of the engine from the open end 23 a of the waveguide 23. That is, when the resonator 20 is applied to a 6-cylinder engine as in the present embodiment, the third-order and sixth-order sound waves are dominant.

  FIG. 6A is an engine rotation speed-sound pressure level characteristic diagram of the third-order sound wave. The horizontal axis represents the engine speed. The vertical axis represents the sound pressure level of the sound wave guided into the passenger compartment. Note that there is a correlation between the engine speed and the frequency, and they are related by the following mathematical formula.

(1) as shown by the formula, the engine rotational speed N _e is the frequency f is also increased greatly.

  Here, the solid line in FIG. 6A indicates the sound pressure level when the waveguide 23 is applied. A broken line indicates a sound pressure level when the waveguide 23 is not applied. When the waveguide 23 is used, the open end 23a of the waveguide can be disposed at a position where sound insulation is difficult. For this reason, the sound pressure level is increased in the frequency band above the middle rotational speed by the action of the waveguide 23. Therefore, compared with the case where the waveguide 23 is not used, it is easier to hear the amplified sound wave having a predetermined frequency in the passenger compartment.

  FIG. 6B is an engine rotation speed-sound pressure level characteristic diagram of sixth-order sound waves. The horizontal axis represents the engine speed. The vertical axis represents the sound pressure level of the sound wave guided into the passenger compartment. The relationship between the engine speed and the frequency is related in the equation (1) as described above.

  The solid line indicates the sound pressure level when the waveguide 23 is applied. A broken line indicates a sound pressure level when the waveguide 23 is not applied. When the waveguide 23 is used, the open end 23a of the waveguide can be disposed at a position where sound insulation is difficult. Therefore, due to the action of the waveguide 23, the sound pressure level is increased in a part of the low rotation speed region and in a frequency band higher than the medium rotation speed region. Therefore, compared with the case where the waveguide 23 is not used, it is easier to hear the amplified sound wave having a predetermined frequency in the passenger compartment.

  As described above, the present embodiment can obtain the following effects.

  In the present embodiment, a waveguide 23 having a diameter larger than that of the resonance tube 22 is provided concentrically near the resonance port 22 a of the resonance tube 22 of the resonator 20. Further, the open end 23 a of the waveguide 23 is disposed at a position in the engine room 1 where sound insulation is difficult. Thereby, it becomes possible to guide into the vehicle interior with almost no change in the frequency of the sound wave in the predetermined frequency band amplified by the resonance tube 22. Further, attenuation of the amplified sound wave can be suppressed, and a powerful intake sound can be obtained in the passenger compartment.

  The sound wave emitted from the resonance port 22 a of the resonance tube 22 is added based on the intake pulsation generated from the intake system 5. Therefore, it is possible to obtain a sound pressure characteristic of the intake sound that linearly changes as the engine speed increases, and to experience an acceleration sound that changes linearly as the acceleration increases.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  For example, a soundproofing material may be disposed on the inner peripheral wall or outer peripheral wall of the waveguide 23 to remove sound waves emitted from the resonance tube 22 or high-frequency noise sounds included in the external environment. The resonator 20 may be provided in a part of the dust side duct 55 between the air inlet 54 and the dust side 51 b of the air cleaner 51. Further, the resonator 20 may utilize so-called cavity resonance (Helmholtz resonance) based on vibrations of the resonator.

It is the schematic which showed the engine room of the vehicle seen from the vehicle upper direction. It is a block diagram of a resonator. It is a block diagram of the waveguide attached to the resonance tube of the resonator. It is the schematic which shows the arrangement position of the waveguide in an engine room. It is a figure which shows the sound insulation degree when a waveguide is arrange | positioned in each arrangement position. It is an engine rotation speed-sound pressure level characteristic diagram of the sound wave guided into the passenger compartment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine room 4 Engine 5 Intake system 6 Strut tower 51 Air cleaner 55 Dust side duct 56 Clean side duct 20 Resonator 21 Transmission pipe 22 Resonance pipe 22a Resonance port 23 Waveguide 23a Open end 25 Diaphragm (vibration body)

Claims (4)

A transmission pipe connected to the intake system of the internal combustion engine to transmit the intake pulsation in the intake system;
A vibrating body that is provided at one end of the transmission pipe and vibrates by the intake pulsation;
A resonance tube that is connected to the transmission tube via the vibrating body and amplifies a sound wave of a predetermined frequency band among sound waves generated by the vibration of the vibrating body;
A larger diameter than the diameter of the resonance tube, a cylindrical member both ends of which are open, is connected the opening of the one end in the resonance tube, the other end of the opening the amplified sound waves cabin A waveguide disposed at a predetermined position in the engine room to transmit to
A sound quality transmission structure for an internal combustion engine, comprising:   The sound quality transmission structure for an internal combustion engine according to claim 1, wherein the waveguide is disposed concentrically with the resonance tube.   The sound quality transmission structure for an internal combustion engine according to claim 1 or 2, wherein the predetermined position in the engine room is a position where the sound wave amplified by the resonance tube is not easily insulated.   The sound quality transmission structure for an internal combustion engine according to claim 3, wherein the position where the sound is hardly insulated is behind the strut tower.

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