JP4328181B2 - Sound quality control device for internal combustion engine - Google Patents

Description

  The present invention relates to a sound quality control device for an automobile internal combustion engine.

  In the intake system of an internal combustion engine, piston diameter can be adjusted by adjusting the diameter of the intake path such as the intake duct, the length of the intake path, the volume of the air cleaner that forms part of the intake system, and adding a resonator to the intake system. It is well known in the prior art to reduce the intake pulsation noise caused by the reciprocating motion of the intake valve.

Further, in Patent Document 1, a plurality of intake ducts having different resonance frequencies are connected to the dust side of an air cleaner, and an intake sound is generated in these intake ducts when the engine is heavily loaded. An intake device that can provide a sensation of intake sound is disclosed.
JP 2000-303925 A

  However, since the former prior art described above is mainly intended to tune the intake sound within a predetermined target sound pressure characteristic set in advance, the sound pressure characteristic of the tuned intake sound is: The sound pressure characteristic does not necessarily change linearly as the engine speed increases, which may cause the driver to feel uncomfortable.

  Further, with respect to the latter prior art, that is, Patent Document 1, the frequency and sound pressure level are substantially reduced as the engine speed increases in the passenger compartment during acceleration using the intake sound generated from the intake duct when the engine is heavily loaded. The linearly rising characteristic can be obtained. However, in the configuration of Patent Document 1, in order to generate a desired intake sound from the intake duct at a high engine load, the length of the intake duct, It is necessary to tune the passage sectional area and the like, and the layout of the intake system may be greatly restricted.

A sound quality control device for an internal combustion engine according to claim 1, wherein a resonance body that vibrates due to intake air pulsation in the intake system, a volume chamber connected to the intake system via the resonance body, and an internal space of the volume chamber to the outside A resonator having a volume chamber opening to be communicated, and the resonance body partitions the space between the interior space of the volume chamber and the inside of the intake system, and the sound pressure in a predetermined frequency band is generated by the vibration of the resonance body. Resonators are set to be discharged from the openings to the outside, and a plurality of the above-described resonators are provided, and each resonator emits sound pressures in frequency bands that are close to each other to the outside from the respective volume chamber openings. The sound pressure emitted from each resonator to the outside is attached to the intake system so as to be emitted to the outside with a predetermined time difference . As a result, the sound pressure characteristic of the intake sound is obtained by adding the sound pressure emitted from the resonator. In addition, sound pressure is emitted from each of the resonators with a time difference from each other, so that so-called rambling noise is generated, and a sense of power and a feeling of dynamism can be increased.

According to a second aspect of the present invention, in the sound quality control device for an internal combustion engine according to the first aspect, the sound pressure released from the resonator is added to the intake sound, whereby the intake air is increased as the engine speed increases. the sound pressure of the sound has been cormorant set'll become larger.

  According to a third aspect of the present invention, in the sound quality control device for an internal combustion engine according to the first or second aspect, the volume chamber opening is at least one of a dash panel or left and right side panels among the panels defining the engine room. Close to one. The sound pressure mode in the engine room forms an antinode of the sound pressure mode in the vicinity of the dash panel and the left and right side panels. As a result, the sound pressure emitted from the resonator is efficiently propagated into the passenger compartment.

  According to a fifth aspect of the present invention, in the sound quality control device for an internal combustion engine according to any one of the first to fourth aspects, (the number of revolutions of the internal combustion engine / 60) × (natural number / The resonator is set so that sound pressure in the frequency band of 2) is emitted from the volume chamber opening.

  According to the present invention, the sound pressure characteristic of the intake sound is obtained by adding the sound pressure emitted from the resonator, so that the sound pressure characteristic of the intake sound is tuned to a desired characteristic using the resonator. Can do.

  In addition, the sound pressure emitted from the resonator is added to the intake sound so that the sound pressure of the intake sound increases as the engine speed increases, so that the intake sound can be increased following the accelerator opening. It does not give the driver a sense of incongruity.

In addition, the volume chamber opening is located close to at least either the dash panel or the left and right side panels among the panels that define the engine room, so that the sound pressure emitted from the resonator is efficiently transmitted to the vehicle interior. since it is possible to, it is possible to achieve a compact resonator.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory view schematically showing a state in which the engine room 1 located on the front body of the vehicle is viewed from above the vehicle. An in-line four-cylinder engine 4 is disposed in the engine room 1 defined by the dash panel 2 and the left and right side panels 3a, 3b. An intake system 5 for introducing intake air is connected to the engine 4. The intake system 5 is arranged such that an intake intake 6 is opened in the front of the vehicle, and air taken from the intake intake 6 is introduced into an intake collector 9 via an air cleaner 7 and a throttle valve 8. After that, the air is supplied from the intake collector 9 to the combustion chamber (not shown) of each cylinder by each branch pipe 10. The clean side duct 11 that connects the clean side 7a of the air cleaner 7 and the throttle valve 8 is caused by intake pulsation in the intake system 5 caused by the reciprocating motion of a piston (not shown) or an intake valve (not shown). Two resonators 12a and 12b that emit sound pressure in a predetermined frequency band are provided adjacent to each other. In addition, 7b in FIG. 1 is a filter element.

  As shown in FIG. 2, the resonator 12 mainly includes a housing made of resin or the like attached to the outer wall of the clean side duct 11. The resonator 12 vibrates due to intake air pulsation in the intake system 5. The volume chamber 14 connected to the clean side duct 11 of the intake system 5 via the resonator 13 and the neck 16 as a volume chamber opening for communicating the internal space 15 of the volume chamber 14 to the outside are roughly constituted. ing. The resonance body 13 closes the through hole 17 provided at the resonator mounting position of the clean side duct 11 and partitions the space 15 between the internal space 15 of the volume chamber 14 and the inside of the intake system 5. It vibrates according to the intake air pulsation in the clean side duct 11.

The structure of the resonator 12 will be described in detail. In the first comparative example , the neck 16 is narrowed with respect to the volume chamber 14 so that so-called cavity resonance (Helmholtz resonance) is obtained based on the vibration of the resonator 13. It has a structure. The neck 16 of the resonator 12 is positioned in the vicinity of the dash panel 2 that defines the engine room 1, and the opening thereof is disposed so as to face the dash panel 2.

In the first comparative example , by adding the sound pressure emitted from the resonators 12a and 12b to the intake sound generated from the intake system 5, the intake sound that changes substantially linearly as the engine speed increases is added. The sound pressure emitted from the resonators 12a and 12b is set to be a sound pressure in a predetermined frequency band so that the sound pressure characteristic can be obtained. In other words, the engine speed is increased by adding the sound pressure from each of the resonators 12a and 12b in a predetermined engine speed range to the intake sound whose sound pressure varies in conjunction with the accelerator opening. Accordingly, the resonators 12a and 12b are set so that the sound pressure characteristic of the intake sound that changes substantially linearly can be obtained. In other words, the sound is emitted from the resonators 12a and 12b into a notch region on the sound pressure characteristic of the intake sound that changes with the engine speed, that is, a region where the sound pressure of the intake sound decreases with an increase in the engine speed. The sound pressure to be applied is set to be added.

  Specifically, these resonators 12a and 12b each have a sound pressure in a frequency band defined by (engine speed / 60) × (number of engine cylinders) in a predetermined engine speed range. , 16 is set to be released. More specifically, when the resonator 12a and the resonator 12b are not provided, as shown by the curve B in FIG. 3, the sound pressure is low in the middle to high range of the target engine speed range. When the sound pressure released from the resonator 12a and the resonator 12b is added to the intake sound generated from the intake system 5, the sound pressure as a whole increases as the engine speed increases as shown by the curve A in FIG. And the sound pressure characteristic of the intake sound that changes substantially linearly as the engine speed increases is set. That is, the resonators 12a and 12b are set so that the sound pressure characteristics substantially follow the target line which is a straight line rising in FIG.

Therefore, in this first comparative example , each of the resonators 12a and 12b is set to emit a sound pressure in a frequency band obtained by multiplying the basic rotational frequency (engine speed / 60) by the number of cylinders of the engine 4. Therefore, it is possible to obtain a sound pressure characteristic that changes substantially linearly as the engine speed increases with respect to the intake sound having a frequency obtained by multiplying the basic rotational frequency by the number of cylinders of the engine 4. In this case, it is possible to experience an acceleration sound that changes substantially linearly as the acceleration increases. In FIG. 3, a curve A indicated by a solid line indicates the sound pressure characteristic of the intake sound in the present comparative example in which the intake system 5 includes the resonator 12, and a curve B indicated by the dotted line indicates a case where the resonator 12 is not provided. It shows the sound pressure characteristics of the intake sound.

  Further, in the above state, that is, in a state where the sound pressure emitted from each of the resonators 12a and 12b is set in a frequency band obtained by multiplying the basic rotational frequency by the number of cylinders of the engine, the basic rotational frequency (the number of engine cylinders / 2) As shown in FIG. 4, the intake sound having the doubled frequency is totally inhaled as shown by curve A in FIG. 4 as compared to the case without the resonator 12 (curve B in FIG. 4). The sound pressure level of the vehicle can be suppressed, and the noise outside the vehicle can be suppressed. This is because part of the energy (sound pressure) of the intake pulsation is consumed when the resonator 13 vibrates.

  The respective neck portions 16 and 16 of the resonators 12a and 12b are located in the vicinity of the dash panel 2 and the openings thereof are disposed so as to face the dash panel 2, whereby the resonator 12 is provided. It is possible to relatively reduce the sound pressure level emitted from the resonator 12 and to make the resonator 12 compact. This is because the sound pressure mode of the intake sound in the engine room 1 tends to form a sound pressure mode antinode (steady wave antinode) in the vicinity of the dash panel 2 and the left and right side panels 3a, 3b. Therefore, the sound pressure emitted from the resonator 12 can be relatively reduced. That is, as shown in FIG. 5, the neck portion of the resonator is disposed in the region A in the vicinity of the dash panel 2 and the left and right side panels 3a, 3b in the engine room 1, and the dash panel 2 or the left and right side panels 3a, If the opening of the neck portion 16 is opposed to any of 3b, the sound pressure can be effectively applied to the intake sound while reducing the sound pressure emitted from the resonator 12.

6 and 7 are explanatory views showing the sound pressure characteristics of the intake sound when the resonator 12 of the first comparative example described above is applied to a V-type 6-cylinder engine. Each resonator 12a, 12b emits sound pressure in a frequency band defined by (engine speed / 60) × (number of engine cylinders) from the neck in a predetermined engine speed range, and the sound to be emitted. When the pressure is added to the intake sound generated from the intake system 5, the sound pressure characteristic of the intake sound that changes substantially linearly as the engine speed increases is set (FIG. 6).

  Therefore, the driver can experience an acceleration sound that changes substantially linearly as the acceleration increases during acceleration. Further, in this case, that is, in a state where the sound pressure emitted from the resonator 12 is set to a frequency band obtained by multiplying the basic rotational frequency by the number of cylinders of the engine, the basic rotational frequency is set to (the number of engine cylinders / 2). As shown in FIG. 7, the intake sound of the intake system 5 in the doubled frequency band is the whole as shown by the curve A in FIG. 7 compared to the case where the resonator 12 is not provided (curve B in FIG. 7). The sound pressure level can be suppressed, and the noise outside the vehicle can be suppressed. This is because part of the energy (sound pressure) of the intake pulsation is consumed when the resonator 13 vibrates.

FIGS. 8 and 9 are explanatory views showing sound pressure characteristics when the resonator 12 of the first comparative example is applied to a V-type 8-cylinder engine. Each resonator 12a, 12b emits sound pressure in the frequency band of (engine speed / 60) × (number of engine cylinders / 2) from the neck 16 in a predetermined engine speed range, and the sound to be emitted. When the pressure is added to the intake sound generated from the intake system 5, the sound pressure characteristic of the intake sound that changes substantially linearly as the engine speed increases is set (FIG. 8).

  Therefore, the driver can experience an acceleration sound that changes substantially linearly as the acceleration increases during acceleration. Further, in a state where the sound pressure emitted from the resonator 12 is set to a frequency band obtained by multiplying the basic rotation frequency by (the number of engine cylinders / 2), intake air having a frequency obtained by multiplying the basic rotation frequency by the number of engine cylinders. As shown by the curve A in FIG. 9, the sound can suppress the overall sound pressure level compared to the case where the resonator 12 is not provided (curve b in FIG. 9), and can suppress the outside noise. Can be planned. This is because part of the energy (sound pressure) of the intake pulsation is consumed when the resonator 13 vibrates.

Further, the resonator 12 of the first comparative example described above can be configured as shown in FIGS.

  A resonator 30 shown in FIGS. 10 and 11 includes a tubular base 31 connected to an intake system 34, a tubular main body 32 having a larger diameter than the base 31, and an internal space of the main body 32 outside. And a neck portion 33 as a volume chamber opening communicated with the main body. The internal space of the main body 32 is partitioned by a rubber resonator 35, and an intake system side volume chamber 36 communicating with the intake system 34 and a volume chamber 37 opened to the outside through the neck 33 are defined. It is made. Further, the neck 33 has a structure constricted with respect to the volume chamber 37.

  Further, the resonator 40 shown in FIGS. 12 and 13 is generally configured by a tubular main body 41 and a rubber resonance body 42 disposed inside the main body 41. One end of the main body 41 is connected to the intake system 43, and the other end of the main body 41 is open to the outside. In the main body 41, an intake system communication space 44 that communicates with the intake system 43 by the resonance body 42 and an external communication space 45 as a volume chamber that communicates with the outside without communicating with the intake system 43. Is defined. The resonator 40 emits sound pressure in a predetermined frequency band from the other end of the main body 41 by so-called air column resonance, when the resonator 42 vibrates according to the intake pulsation generated in the intake system 43. In the resonator 40, the other end of the main body 41 corresponds to a volume chamber opening. Further, the resonator 40 tunes the frequency band of the sound pressure released to the outside and the magnitude of the sound pressure by appropriately setting the axial length of the main body 41, the inner diameter of the main body 41, and the like. Can do.

Next, a second comparative example of the present invention will be described. In the second comparative example , as shown in FIG. 14, a resonator 50 that generates sound pressure in accordance with intake air pulsation of the intake system is integrated with an air cleaner 51.

  The air cleaner 51 is composed of an air cleaner upper part 51a to which an intake duct 52 is connected and an air cleaner lower part 51b integrated with the intake manifold 53. A filter element (not shown) is provided, and the intake downstream side of the air cleaner lower part 51b is mainly the clean side.

  The air cleaner lower part 51 b is integrally formed with a volume chamber base 54 constituting a part of the volume chamber of the resonator 50, and a neck as a volume chamber opening communicating with the inside of the volume chamber base 54. 55 is formed to project outward. The volume chamber base portion 54 is partitioned by a partition wall 56 to define two volume chambers. Each neck 55, 55 is formed so as to communicate with the corresponding volume chamber. The volume chamber base 54 has a structure in which two volume chambers are defined inside the air cleaner lower portion 51b by assembling a volume chamber lid portion separate from the volume chamber base 54. Two holes 58 and 58 corresponding to the respective volume chambers are formed through the volume chamber lid portion 57. In these holes 58 and 58, substantially disk-shaped and rubber-made resonance bodies 59 and 59 are attached by ring members 60 and 60, respectively. Further, the neck portions 55 and 55 are structured so as to be narrowed with respect to the volume chamber.

  In FIG. 14, 61 is an intake intake port located on the upstream side of the air cleaner 51, and 62 is a throttle valve located on the downstream side of the air cleaner 61 and attached to the intake manifold 53.

Also in the second comparative example , since the resonance body 59 can be vibrated by the intake pulsation generated in the intake system, the same effect as the first comparative example described above can be obtained. That is, according to the number of cylinders of the engine, the frequency band of the sound pressure released from the resonator 50 is set to the basic rotation frequency × (the number of engine cylinders) when the engine is four or six cylinders, and the engine is eight. In the case of cylinders, by tuning to basic rotation frequency x (number of engine cylinders / 2), the driver can experience an acceleration sound that changes substantially linearly as the acceleration increases during acceleration. It becomes. Moreover, since the resonator 50 is formed integrally with the air cleaner, the manufacturing cost can be reduced.

  2, 10, and 14 using cavity resonance, the frequency band of sound pressure emitted from the resonator includes the volume of the neck, the volume of the volume chamber, and the resonator. The sound pressure in a desired frequency band can be released to the outside by appropriately setting the mass of.

Next, a first embodiment of the present invention will be described. As shown in FIG. 15, a V-type 6-cylinder engine 73 is disposed in an engine room 72 defined by a dash panel 70, left and right side panels 71a, 71b, and the like. An intake system 74 for introducing intake air is connected to the engine 73. The intake system 74 is arranged such that an intake intake port 75 is opened on the front surface of the vehicle. Air taken in from the intake intake port 75 is introduced into an intake collector 78 through an air cleaner 76 and a throttle valve 77. After that, the air is supplied from the intake collector 78 to the combustion chambers of the cylinders by the branch pipes 79. The clean side duct 80 that connects the clean side 76a of the air cleaner 76 and the throttle valve 77 has an intake pulsation in the intake system 74 that is generated by a reciprocating motion of a piston (not shown) or an intake valve (not shown). Two resonators 81a and 81b are provided that emit sound pressures in a predetermined frequency band similar to each other. These two resonators 81 a and 81 b are arranged at a predetermined interval along the intake air flow direction of the clean side duct 80.

Each of the resonators 81a and 81b has the same configuration as the resonator in the first comparative example described above (see FIG. 2). The resonator 13 vibrates due to the intake pulsation in the intake system, and the resonator 13 is interposed. The volume chamber 14 is connected to the clean side duct 80 of the intake system 74 and the neck portion 16 as a volume chamber opening for communicating the internal space 15 of the volume chamber 14 to the outside. The resonator 13 closes a through hole provided at the resonator mounting position of the clean side duct 80, partitions the interior space 15 of the volume chamber 14 and the inside of the intake system 74, and intake air in the intake system 74. It vibrates according to the pulsation.

In the first embodiment, the sound pressure emitted from each of the resonators 81a and 81b has a frequency band defined by (engine speed / 60) × (number of engine cylinders) as shown in FIG. When the sound pressure is released from the neck 16 and the released sound pressure is added to the intake sound generated from the intake system 74, the sound pressure characteristic of the intake sound that changes substantially linearly as the engine speed increases is obtained. Is set to be able to.

Here, in the first embodiment, the sound pressure is released from the resonator 81a by disposing the resonators 81a and 81 at a predetermined interval along the intake air flow direction of the clean side duct 80. The timing is positively generated and the timing at which the sound pressure is released from the resonator 81b is positively generated.

  Referring to FIG. 17 in detail, the sound pressure mode of the intake pulsation in the clean side duct 80 can be regarded as the open position because the connection position with the throttle valve 77 and the connection position with the air cleaner 76 can be regarded as open ends. A mode clause will be formed. The resonators 81a and 81b emit sound pressure using the same intake pulsation as a sound source, but the resonators 81a and 81b are arranged at predetermined intervals along the intake flow direction of the clean side duct 80. Therefore, when attention is paid to one intake pulsation, a time difference occurs between the time when the intake pulsation reaches the resonator 81a and the time when it reaches the resonator 81b. There is a time difference between the timing at which the pressure is released and the timing at which the resonator 81b releases the sound pressure. Further, since the magnitude of the sound pressure mode at the position of the resonator 81a is different from the magnitude of the sound pressure mode at the position of the resonator 81b, the magnitude of the sound pressure emitted by the resonator 81a and the magnitude of the sound pressure mode emitted by the resonator 81b are different. The sound pressure level to be performed is different from each other.

Therefore, in this first embodiment, so-called rambling noise can be generated by emitting sound pressures having different time and different magnitudes from the resonators 81a and 81b. The tone of the intake sound can be set according to the driver's preference. Here, the rambling noise specifically emphasizes an intake sound having a frequency of (the number of engine cylinders / 2) × {((2 × natural number) −1) / 2)}. In the first embodiment, as shown in FIGS. 18 and 19, the intake sound (FIG. 18) and the basic rotational frequency × (the number of engine cylinders × 3 / the basic rotational frequency × (the number of engine cylinders / 4)). The sound pressure level of the inspiratory sound having the frequency 4) (FIG. 19) is emphasized (increased) compared to the case where the resonator 81 is not provided.

  Further, during acceleration, the driver can experience an acceleration sound that changes substantially linearly with an increase in acceleration, and, as shown in FIG. 20, the basic rotational frequency (the number of cylinders of the engine / 2) The intake sound of the intake system 74 in the doubled frequency band can also suppress the overall sound pressure level compared to the case where the resonator 12 is not provided (curve B in FIG. 20), and the suppression of outside noise. Can be achieved.

In the first embodiment and the first and second comparative examples described above, when the number of cylinders of the applied engine is a four-cylinder or six-cylinder engine, the frequency band of the sound pressure emitted from the resonator is When the sound pressure released from the resonator is added to the intake sound in this frequency band, the basic rotation frequency x (number of engine cylinders / 2) changes approximately linearly as the engine speed increases. If it is set so that the sound pressure characteristic to be obtained can be obtained, the driver can experience a powerful intake sound.

In the first and second comparative examples described above, the number of resonators is not limited to two, and finer tuning becomes possible by increasing the number of resonators. It is possible to further improve the followability of the intake sound with respect to the target line in FIG.

In the first embodiment and the first and second comparative examples described above, the resonator of the resonator is not limited to rubber, but may be, for example, resin or cone paper as long as it is configured to vibrate due to intake pulsation. Etc.

Further, in the first embodiment and the first comparative example described above, the closer the attachment position of the resonator to the intake system is to the engine, the greater the energy of the intake pulsation that acts on the resonator's resonator, which is released from the resonator. The sound pressure applied can be relatively increased. That is, even if the resonators have the same size, those arranged closer to the engine emit a larger sound pressure. Therefore, the resonator can be made compact and the degree of freedom in design can be improved.

Explanatory drawing which shows typically schematic structure of the sound quality control apparatus which concerns on the 1st comparative example of this invention. Explanatory drawing of the principal part of the sound quality control apparatus which concerns on a 1st comparative example . Explanatory drawing which shows the sound pressure characteristic of intake sound. Explanatory drawing which shows the sound pressure characteristic of intake sound. Explanatory drawing which showed typically the position where the antinode of the sound pressure mode of an intake sound is formed in an engine room. Explanatory drawing which shows the sound pressure characteristic of intake sound. Explanatory drawing which shows the sound pressure characteristic of intake sound. Explanatory drawing which shows the sound pressure characteristic of intake sound. Explanatory drawing which shows the sound pressure characteristic of intake sound. Explanatory drawing which shows the other comparative example of a resonator. Explanatory drawing which shows the other comparative example of a resonator. Explanatory drawing which shows the other comparative example of a resonator. Explanatory view showing another comparative example of the resonator. Explanatory drawing which shows typically schematic structure of the sound quality control apparatus which concerns on the 2nd comparative example of this invention. BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows typically schematic structure of the sound quality control apparatus which concerns on 1st Embodiment of this invention. Explanatory drawing which shows the sound pressure characteristic of intake sound. Explanatory drawing which shows typically the relationship between the sound pressure mode of the intake sound in the clean side duct in FIG. 15, and a resonator. Explanatory drawing which shows the sound pressure characteristic of intake sound. Explanatory drawing which shows the sound pressure characteristic of intake sound. Explanatory drawing which shows the sound pressure characteristic of intake sound.

Explanation of symbols

5 ... Intake system 12 ... Resonator 13 ... Resonant body 14 ... Volume chamber 15 ... Internal space 16 ... Neck

Claims (4)

A resonator having 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 chamber opening that communicates the internal space of the volume chamber to the outside. The resonator sets the resonator so that the internal space of the volume chamber and the inside of the intake system are partitioned by the resonator, and the sound pressure in a predetermined frequency band is released to the outside by the vibration of the resonator. A plurality of the above resonators, each resonator being set to discharge sound pressures in frequency bands similar to each other from the respective volume chamber openings, and discharged from each resonator to the outside. A sound quality control device for an internal combustion engine, wherein the sound pressure is attached to the intake system so that the sound pressures are discharged to the outside with a predetermined time difference . By the sound pressure emitted from the resonator is added to the intake sound, to claim 1, she characterized in that the sound pressure of the intake air sound with an increase in engine speed is earthenware pots set by increased The sound quality control device for an internal combustion engine as described.   3. The sound quality control of the internal combustion engine according to claim 1, wherein the volume chamber opening is close to at least one of the dash panel and the left and right side panels among the panels defining the engine room. apparatus. The resonance body is set so that sound pressure in a frequency band of (the number of revolutions of the internal combustion engine / 60) × (natural number / 2) is emitted from the opening of the volume chamber in a predetermined revolution number range of the internal combustion engine. The sound quality control device for an internal combustion engine according to any one of claims 1 to 3 .

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