Intake noise transmission device

Abstract

Intake noise transmission device (20) for transmitting an intake noise of an engine (EG) mounted in a vehicle (1) into a passenger compartment (7), the intake noise transmission device (20) comprising: a branch pipe (21) branching from an intake system of the engine (EG); a sound generating device (30) communicating with the branch pipe (21), the sound generating device (30) having a vibration device (33), the vibration device (33) vibrating with the intake pulsation of the intake noise propagating within the branch pipe (21); and a communication channel (50) communicating with the sound generating device (30) for transmitting a vibration of the vibration device (33) into the passenger compartment (7), wherein the communication channel (50) has a step section (51C, 55D), wherein the sound generating device (30) has an inlet pipe (31A) connected to a passenger compartment end of the branch pipe (21), a housing (35) enclosing the inlet pipe (31A), and a rear opening (35b) formed on the housing (35), wherein the vibration device (33) is arranged at a passenger compartment end of the inlet pipe (31A), wherein the passenger compartment side end of the inlet pipe (31A) is arranged at a predetermined distance opposite the rear opening (35b).

Description

[0001] The present invention relates to an intake noise transmission device for transmitting the intake noise of an engine mounted in a vehicle into a passenger compartment.

[0002] In recent years, intake sound transmission devices have been developed that transmit the intake sound of an engine installed in a vehicle into a passenger compartment for an enhanced sporty feel. For example, a vehicle intake sound transmission device described in JP 2009-30451A (Japanese Patent Application Publication No. 2009-30451) includes a communication pipe, a vibration device, and a resonator pipe (a "resonator" in JP 2009-30451). The communication pipe branches from the intake pipe of the engine.

[0003] The vibration device is arranged inside the communication pipe and vibrates with the intake pulsation of the intake noise propagating in the communication pipe. The resonance pipe is connected to the downstream end of the communication pipe and is designed such that its channel cross-sectional area changes monotonically from the upstream side to the downstream side.

[0004] The intake noise transmission device allows the intake noise to resonate at a desired frequency through the resonance pipe, thereby making the desired noise louder and transmitting the noise into the passenger compartment.

[0005] However, related art intake noise transmission devices are unable to suppress unwanted high-frequency components of intake noise (e.g., engine valve noise or intake noise transmitted at high engine speed). Consequently, unwanted noise components are mixed with the intake noise transmitted into the passenger compartment.

[0006] From DE 197 04 376 A1 an air filter arrangement for an internal combustion engine of a motor vehicle with a filter housing is known.

[0007] From DE 102 23 872 A1 a device for noise design in a motor vehicle is known.

[0008] From US 2006 / 0 283 658 A1 a sound enhancing device with a partition wall between two machine compartments is known.

[0009] From DE 101 16 169 A1 a device for targeted sound transmission from an intake tract of an internal combustion engine is known.

[0010] The present invention was developed in view of the above-mentioned problem, and therefore, it is an object of the present invention to provide an intake noise transmission device capable of reducing unnecessary noise and transmitting a desired noise into the passenger compartment. This object is achieved by the features of the claims.

[0011] Preferred embodiments of an intake noise transmission device will be described below with reference to the drawings. Fig. 1 shows a schematic side view of a first embodiment of an intake noise transmission device; Fig. 2 shows a schematic side view of a modification of the Fig. 1 shown intake noise transmission device; Fig. 3 is an explanatory diagram for explaining the mounting position of a resonator according to the first embodiment; Fig. 4 shows a schematic side view of a second embodiment of an intake noise transmission device; Fig. 5 shows a schematic side view of a modification of the Fig. 4 shown intake noise transmission device; Fig. 6 shows a schematic side view of a third embodiment of an intake noise transmission device (according to the invention); Fig. 7A shows a cross-sectional view of a communication pipe according to the third embodiment; Fig. 7B shows a cross-sectional view of a modification of the communication tube; Fig. 8A is an explanatory diagram showing how low-frequency components of intake noise are transmitted; Fig. 8B is an explanatory diagram showing how high-frequency components of intake noise are transmitted; Fig. 9 shows a schematic side view of a modification of the Fig. 6 shown intake noise transmission device; Fig. 10 shows a schematic side view of a fourth embodiment of an intake noise transmission device (according to the invention); Fig. 11A shows a cross-sectional view of a communication pipe according to the fourth embodiment; Fig. 11B shows a cross-sectional view of a modification of the communication pipe; Fig. 12A is an explanatory diagram showing how low-frequency components of intake noise are transmitted; Fig. 12B is an explanatory diagram showing how high-frequency components of the intake noise are transmitted; and Fig. 13 shows a schematic side view of a modification of the Fig. 10 shown intake noise transmission device.

[0012] As in Fig. 1 (in a schematic view), a first embodiment of an intake noise transmission device 20 is arranged inside an engine compartment 3 of a vehicle 1. In the engine compartment 3, an intake pipe 5 for supplying combustion air to an engine EG is connected to the engine EG via an air cleaner AC. One end of the intake pipe 5 is open at a front end of the engine compartment 3 and is held by the front end of the engine compartment. The other end of the intake pipe 5 is connected to the engine EG. The intake pipe 5 is formed of a synthetic resin or the like in a cylindrical shape. The intake noise transmission device 20 for transmitting an intake noise to a driver in a passenger compartment 7 of the vehicle 1 is connected to a downstream side 5a of the intake pipe 5 located downstream of the air cleaner AC.

[0013] The intake noise transmission device 20 includes a branch pipe 21 branching from the intake pipe 5, a sound generator 30 communicating with the branch pipe 21, a communication pipe 50 enabling communication between the branch pipe 21 and the interior of the passenger compartment 7 via the sound generator 30, and a resonator 60 communicating with the communication pipe 50. The branch pipe 21 is arranged in the engine compartment 3 such that one end of the branch pipe 21 is connected to an opening 5b located on a downstream side 5a of the intake pipe 5, located downstream of the air cleaner AC, and the other end of the branch pipe 21 extends toward the passenger compartment 7. The branch pipe 21 is formed into a cylindrical shape from a synthetic resin or the like.

[0014] The sound generating device 30 includes an intake pipe 31A connected to the passenger compartment end of the branch pipe 21, a vibrator 33 disposed at a passenger compartment end of the intake pipe 31A, and a casing 35 enclosing the intake pipe 31A. The vibrator 33 is a plate-shaped diaphragm made of a synthetic resin or rubber. The vibrator 33 is disposed to block the intake pipe 31A inside the casing 35. The vibrator 33 vibrates with the intake pulsation of the intake noise propagating in the branch pipe 21 and the intake pipe 31A. The casing 35 is box-shaped. A front opening 35a is formed at one end of the casing 35, and a rear opening 35b is formed at the other end of the casing 35.

[0015] The intake pipe-side end of the intake pipe 31A is open at the front opening and held by the front opening. The passenger compartment-side end of the intake pipe 31A is arranged at a predetermined distance opposite the rear opening 35b. The front opening 35a has substantially the same circular shape as the outer shape of the intake pipe 31A, and the intake pipe 31A is inserted into the front opening 35a such that no noise leaks through the front opening 35a. A space 37 enclosed by the casing 35 is defined around the intake pipe 31A. The space 37 has a size that allows multiple frequencies included in the sound vibration generated by the vibration of the vibrator 33 as a sound source to resonate due to their air column vibration. The rear opening 35b has substantially the same size as the vibrator 33 and is cylindrical.The rear opening 35b transmits the intake pulsation generated by the vibrator 33 to the communication pipe 50. The space 37 and the communication pipe 50 used to transmit vibrations from the vibrator 33 to the passenger compartment 7 are hereinafter referred to as the downstream side passage 51A.

[0016] In the downstream duct 51A, the resonator 60 is connected to a portion of the communication pipe 50 located on the passenger compartment side with respect to the vibrator 33. The resonator 60 has a tubular neck 61 and a box-shaped body 63. One end of the neck 61 is connected to the communication pipe 50. The body 63 is connected to the other end of the neck 61 and has a resonance chamber 63a defined inside the body 63. When a specific frequency of the intake noise impinges on the resonator 60, the movement of the intake noise becomes intense at the portion of an opening 61a inside the neck 61, causing friction loss to produce a sound damping effect centered at that frequency. In the first embodiment, the resonator 60 is configured to provide a sound damping effect for unwanted high-frequency components of a noise (e.g.,the valve noise of the engine EG or the intake noise transmitted at high speed).

[0017] In the intake sound transmission device 20 thus configured, when outside air is sucked in through the intake pipe 5 while the engine EG is running, intake pulsation at a frequency corresponding to the rotational speed of the engine EG is generated inside the intake pipe 5. This intake pulsation is transmitted from the intake pipe 5 to the vibrator 33 via the branch pipe 21. Therefore, the vibrator 33 vibrates at a frequency corresponding to the rotational speed of the engine EG. As a result, sound vibration is generated inside the sound generation device 30 with the vibration of the vibrator 33 as a sound source. Then, multiple frequencies included in the sound vibration are resonated due to air column vibration in the casing 35 and transmitted to the communication pipe 50.

[0018] Here, high-frequency components of the sound vibration transmitted to the communication pipe 50 are attenuated by the resonator 60. Consequently, unwanted high-frequency components of the intake noise, such as the valve noise of the engine EG or the intake noise transmitted at high speed, can be reduced. Therefore, the intake noise transmitted from the communication pipe 50 into the passenger compartment 7 does not contain unwanted high-frequency components. This allows a desired intake noise to be transmitted into the passenger compartment 7. Furthermore, although the resonator 60 attenuates unwanted high-frequency components of the noise, the resonator 60 does not affect desired frequency ranges. Therefore, the intensity of desired sound frequencies does not decrease. In addition, the resonator 60 is configured such that the intake pulsation of the intake noise transmitted to the communication pipe 50 is enhanced by the resonance effect.Therefore, the volume of the sound generating device 30 can be reduced and miniaturization can be achieved.

[0019] Although the first embodiment is directed to the case where the resonator 60 is arranged in the portion of the communication pipe 50 connected to the passenger compartment side with respect to the sound generating device 30, the resonator 60 may also be arranged on the outside of the casing 35 of the sound generating device 30, as shown in Fig. 2. The housing 35 is formed in a shape that allows resonance of high-frequency components of the noise Sh within the space 37 of the housing 35. The resonator 60 is arranged on the outside of the portion of the housing 35 located on the passenger compartment side with respect to the vibrator 33 and communicates with the space 37 inside the housing 35.

[0020] The mounting position of the resonator 60 with respect to the housing 35 according to the first embodiment will be described below with reference to Fig. 3 described. In Fig. 3, for example, the horizontal axis L indicates the length of the housing 35 in the sound transmission direction. As in Fig. As shown in Figure 3, the resonator 60 is arranged at a position corresponding to the antinode h of the vibration of the intake noise Sk at resonance. Therefore, the intake noise Sk at resonance can be effectively damped by the resonator 60.

[0021] For this reason, undesirable high-frequency components of the intake noise, such as the valve noise of the engine EG or the intake noise transmitted at a high speed, can be reduced, whereby a desired intake noise can be transmitted to the passenger compartment 7 via the communication pipe 50.

[0022] Although the cross-sectional shapes of the branch pipe 21 and the communication pipe 50 are circular in the first embodiment described above, this configuration should not be construed as limiting. The cross-sectional shapes of these components may be triangular, rectangular, or polygonal. Second embodiment

[0023] As in Fig. 4 (schematic diagram), a second embodiment of an intake noise transmission device 20 is arranged inside an engine compartment 3 of a vehicle 1. In the engine compartment 3, an intake pipe 5 for supplying combustion air to an engine EG is connected to the engine EG via an air cleaner AC. One end of the intake pipe 5 is open at a front end of the engine compartment 3 and is held by the front end of the engine compartment. The other end of the intake pipe 5 is connected to the engine EG. The intake pipe 5 is formed of a synthetic resin or the like in a cylindrical shape. The intake noise transmission device 20 for transmitting an intake noise to the driver in a passenger compartment 7 of the vehicle 1 is connected to a downstream side 5a of the intake pipe 5 located downstream of the air cleaner AC.

[0024] The intake noise transmission device 20 includes a branch pipe 21 branching from the intake pipe 5, a sound generator 30 communicating with the branch pipe 21, a communication pipe 50 providing communication between the branch pipe 21 and the interior of the passenger compartment 7 via the sound generator 30, and a resonator 60 communicating with the branch pipe 21. The branch pipe 21 is arranged in the engine compartment 3 such that one end of the branch pipe 21 is connected to an opening 5b located on the downstream side 5a of the intake pipe 5, located downstream of the air cleaner AC, and the other end of the branch pipe 21 extends toward the passenger compartment 7. The branch pipe 21 is formed into a cylindrical shape from a synthetic resin or the like.

[0025] The sound generating device 30 includes an exhaust pipe 31B connected to the intake-side end of the branch pipe 21, a vibrator 33 disposed at the intake-side end of the exhaust pipe 31B, and a housing 35 enclosing the exhaust pipe 31B. The vibrator 31 is a plate-shaped diaphragm made of a synthetic resin or rubber that vibrates with the intake pulsation of the intake noise propagating through the branch pipe 21. The housing 35 is box-shaped. A front opening 35a is formed at one end of the housing 35, and a rear opening 35b is formed at the other end of the housing 35.

[0026] The passenger compartment-side end of the branch pipe 21 is open at and connected to the front opening 35a. The passenger compartment-side end of the exhaust pipe 31B is open at and supported by the rear opening 35b. The intake system-side end of the exhaust pipe 31B is arranged at a predetermined distance opposite the front opening 35a. The rear opening 35b is formed in substantially the same circular shape as the outer shape of the exhaust pipe 31B, and the exhaust pipe 31B is inserted into the rear opening 35b so that no sound leaks through the rear opening 35b. A space enclosed by the casing 35 is defined around the exhaust pipe 31B. The space 37 has a size that allows multiple frequencies included in the sound vibration generated by the vibration of the vibrator 33 as a sound source to resonate due to air column vibration.The rear opening 35b has substantially the same size as the vibrator 33 and is formed in a cylindrical shape. The rear opening 35b transmits the intake pulsation generated by the vibrator 33 to the communication pipe 50. The branch pipe 21 and the space 37, which form the passage from the intake system to the vibrator 33, are hereinafter collectively referred to as the upstream passage 51B.

[0027] The resonator 60 is connected to a portion of the branch pipe 21 of the upstream-side passage 51B, which is located on the intake system side with respect to the vibration device. The resonator 60 has a tubular throat 61 and a box-shaped body 63. One end of the throat 61 is connected to the branch pipe 21. The body 63 is connected to the other end of the throat 61 and has a resonance chamber 63a defined inside the body 63. When a specific frequency of the intake noise impinges on the resonator 60, the movement of the intake noise becomes intense at the portion of an opening 61a of the throat 61, causing friction losses that produce a sound-damping effect centered at that frequency. In the second embodiment, the resonator 60 is configured to produce a sound-damping effect for unwanted high-frequency components of the noise (e.g.,for valve noise of the engine EG or for intake noise transmitted at high speed).

[0028] In the intake sound transmission device 20 thus configured, when outside air is sucked in through the intake pipe 5 while the engine EG is running, intake pulsation is generated inside the intake pipe 5 at a frequency corresponding to the rotational speed of the engine EG. The intake pulsation is transmitted from the intake pipe 5 to the vibrator 33 via the branch pipe 21 and the space 37. As a result, the vibrator 33 vibrates at a frequency corresponding to the rotational speed of the engine EG. Therefore, sound vibration is generated inside the sound generation device 30, with the vibration of the vibrator 33 serving as a sound source. The multiple frequencies included in the sound vibration resonate due to air column vibration within the casing 35 and are transmitted to the communication pipe 50.

[0029] Here, high-frequency components of the sound vibration transmitted to the communication pipe 50 are attenuated by the resonator 60. As a result, unwanted high-frequency components of the intake noise, such as the valve noise of the engine EG or the intake noise transmitted at high speed, can be eliminated. Therefore, the noise generated by the vibrator 33 of the sound generator 30 does not contain unwanted high-frequency components. Therefore, a desired intake noise can be transmitted to the passenger compartment 7 via the communication pipe 50.

[0030] Because high-frequency components of the sound vibration transmitted to the branch pipe 5 are damped by the resonator 60, the intake noise generated by the vibration generator 33 of the sound generator 30 does not contain high-frequency components. Therefore, the required strength of the casing 35 of the sound generator 30 can be minimized, so that the strength of the casing 35 can be easily designed.

[0031] Although the second embodiment relates to the case where the resonator 60 is arranged in the portion of the branch pipe 21 which is located on the intake system side with respect to the vibration generating device 33, the resonator 60 may also be arranged on the outside of the casing 35 of the sound generating device 30, as shown in Fig. 5. The housing 35 is formed in a shape that allows high-frequency components of the noise to resonate within the space 37. The resonator 60 communicates with a portion of the space 37 inside the housing 35 that is located on the intake system side with respect to the vibration generating device 33.

[0032] The mounting position of the resonator 60 according to the second embodiment will be described below with reference to Fig. 3 described. In Fig. 3, for example, the horizontal axis L represents the length of the housing 35 in the sound transmission direction. As in Fig. As shown in Figure 3, the resonator 60 is arranged at a position corresponding to the antinode h of the vibration of the intake noise Sk at resonance. Therefore, the intake noise Sk at resonance can be effectively absorbed by the resonator 60.

[0033] For this reason, undesirable high-frequency components of the intake noise, e.g., the valve noise of the engine EG or an intake noise transmitted at a high speed, can be reduced, so that a desired intake noise can be transmitted to the passenger compartment 7 via the communication pipe 50.

[0034] Although the cross-sectional shapes of the branch pipe 21 and the communication pipe 50 are circular in the above-mentioned second embodiment, this should not be considered limiting. The cross-sectional shapes of these components may be triangular, rectangular, and polygonal. Third embodiment

[0035] As in Fig. 6 (schematic diagram), a third embodiment of an intake noise transmission device 20 is arranged inside an engine compartment 3 of a vehicle 1. In the engine compartment 3, an intake pipe 5 for supplying combustion air to the engine EG is connected to the engine EG via an air cleaner AC. One end of the intake pipe 5 is open at a front end of the engine compartment 3 and is held by the front end of the engine compartment. The other end of the intake pipe 5 is connected to the engine EG. The intake pipe 5 is formed of a synthetic resin or the like in a cylindrical shape. The intake noise transmission device 20 for transmitting an intake noise to the driver in a passenger compartment 7 of the vehicle 1 is connected to a downstream side 5a of the intake pipe 5 located downstream of the air cleaner AC.

[0036] The intake noise transmission device 20 includes a branch pipe 21 branching from the intake pipe 5, a sound generator 30 communicating with the branch pipe 21, and a communication pipe 50 providing communication between the sound generator 30 and the passenger compartment 7. The branch pipe 21 is arranged in the engine compartment 3 such that one end of the branch pipe 21 is connected to an opening 5b located on the downstream side 5a of the intake pipe 5, located downstream of the air cleaner AC, and the other end of the branch pipe 21 extends toward the passenger compartment 7. The branch pipe 21 is formed into a cylindrical shape from a synthetic resin or the like.

[0037] The sound generating device 30 includes an intake pipe 31A connected to the passenger compartment end of the branch pipe 21, a vibrator 33 disposed at the passenger compartment end of the intake pipe 31A, and a housing 35 enclosing the intake pipe 31A. The vibrator 31 is a plate-shaped diaphragm made of a synthetic resin or rubber that vibrates with the intake pulsation of the intake noise propagating in the branch pipe 21 and the intake pipe 31A. The housing 35 is box-shaped. A front opening 35a is formed at one end of the housing 35, and a rear opening 35b is formed at the other end of the housing 35.

[0038] The intake pipe-side end of the branch pipe 21 is open at the front opening 35a and held by the front opening. The passenger compartment-side end of the intake pipe 31A is arranged at a predetermined distance opposite the rear opening 35b. The front opening 35a is formed in substantially the same circular shape as the outer shape of the intake pipe 31A, and the intake pipe 31A is inserted into the front opening 35a so that no sound leakage occurs through the front opening 35a. A space 37 enclosed by the casing 35 is defined around the intake pipe 31A. The space 37 has a size that allows multiple frequencies included in the sound vibration generated by the vibration of the vibrator 33 as a sound source to resonate due to air column vibration.The rear opening 35b has substantially the same size as the vibrator 33 and is formed in a cylindrical shape. The rear opening 35b transmits the intake pulsation generated by the vibrator 33 to the communication pipe 50.

[0039] As in the Fig. 6 and Fig. As shown in Fig. 7A (cross-sectional view), the communication pipe 50 includes a tubular reduced step portion 51C and a downstream-side tubular communication portion 55C. The reduced step portion 51C serves as a large-diameter communication pipe connected to the rear opening 35b of the casing 35. The downstream-side communication portion 55C is connected to the passenger compartment-side end of the reduced step portion 51C. The inner diameter of the reduced step portion 51C is substantially equal to the inner diameter of the rear opening and communicates with the sound generating device 30. The reduced step portion 51C protrudes outward with respect to the downstream-side communication portion 55C to define a step shape whose inner diameter changes in a discontinuous manner.The reduced step portion 51C extends toward the passenger compartment and communicates with the downstream side communication portion 55C. The reduced step portion 51C communicates with the downstream side portion 55C, and its inner cross-sectional area is larger than the inner cross-sectional area of the downstream side communication portion 55C.

[0040] The downstream-side communication portion 55C communicates with the passenger compartment 7, with its internal cross-sectional area being smaller than the internal cross-sectional area of the reduced step portion 51C. The downstream-side communication portion 55C is arranged substantially coaxially with the reduced step portion 51C. The intake pipe-side end of the downstream-side communication portion 55C is integrally connected to the passenger compartment-side end of the reduced step portion 51C.

[0041] In the thus configured, in Fig. In the intake noise transmission device 20 shown in FIG. 6, when outside air is sucked in through the intake pipe 5 while the engine EG is running, intake pulsation is generated inside the intake pipe 5 at a frequency corresponding to the rotational speed of the engine EG. The intake pulsation is transmitted from the intake pipe 5 to the vibrator 33 of the sound generator 30 via the branch pipe 21. As a result, the vibrator 33 vibrates at a frequency corresponding to the rotational speed of the engine EG. Therefore, sound vibration is generated inside the sound generator 30 with the vibration of the vibrator 33 as a sound source. The multiple frequencies included in the sound vibration resonate due to air column vibration within the casing 35 and are transmitted to the communication pipe 50.

[0042] Then, the intensity of high-frequency components of the intake noise transmitted to the communication pipe 50, such as the valve noise of the engine EG and intake noise transmitted at high speeds, is reduced when transmitted from the reduced step portion 51C of the communication pipe 50 to the downstream side communication portion 55C. As a result, the intensity of undesirable high-frequency components of the intake noise transmitted into the passenger compartment 7 can be reduced, and a desired intake noise can be transmitted into the passenger compartment 7.

[0043] The following are considered as reasons why undesirable high-frequency components of the intake noise can be reduced by the reduced step portion 51C and the downstream communication portion 55C.

[0044] The sound vibration of the intake noise transmitted to the communication pipe 50 is transmitted via the reduced step section 51C to the downstream communication section 55C. Here, as in Fig. 8A, some low-frequency components of the noise Sd included in the sound vibration are reflected by the passenger compartment-side end of the reduced step portion 51C, with the result that only a part of the sound vibration is transmitted to the downstream-side communication portion 55C. This is considered to be the reason why the strength of the low-frequency components of the noise Sd can be reduced.

[0045] As in Fig. As shown in Fig. 8B, similar to the low-frequency components of the noise Sd, some high-frequency components of the noise Sh included in the sound vibration are reflected by the passenger compartment-side end of the reduced step portion 51C, with the result that only a part of the sound vibration is transmitted to the downstream-side communication portion 55C. This is considered to be the reason why the strength of the high-frequency components of the noise Sh can be reduced.

[0046] In the third embodiment described above, the communication pipe 50 has the reduced step portion 51C and the downstream side communication portion 55C formed integrally with each other (see FIG. Fig. 7A). As in Fig. However, as shown in Fig. 7B, a reduced step portion 51C' and a downstream-side communication portion 55C' may be made of a flexible material and formed as separate components, and an intake-pipe-side end of the downstream-side communication portion 55C' may be connected to the passenger compartment-side end of the reduced step portion 51C'. In this case, the downstream-side communication portion 55C' is formed in a tubular shape. The reduced step portion 51C' includes a connecting portion 51C'b formed at the passenger compartment-side end of the reduced step portion 51C', a side wall 51C'c formed at the intake-pipe-side end of the connecting portion 51C'b, and a large tubular body 51C'd formed at the outer edge of the side wall 51C'c.The connecting portion 51C'b is a tubular portion to which the outer periphery of the intake-pipe-side end of the downstream communication portion 55C' can be fitted. The side wall 51C'c is an annular portion protruding outward in the radial direction. The large pipe body 51C'd is a tubular portion extending toward the intake pipe.

[0047] The connecting portion 51C'b is connected to the downstream-side communication portion 55C' and is fittedly engaged with the downstream-side communication portion 55C'. For example, by providing a locking projection on the inner surface of the connecting portion 51C'b and providing an engagement recess for locking engagement with the locking projection on the outer surface of the downstream-side communication portion 55C', the downstream-side communication portion 55C' can be connected to the reduced step portion 51C' through locking engagement between the locking projection and the engagement recess. Alternatively, the downstream-side communication portion 55C' can be connected to the reduced step portion 51C' by welding the connecting portion 51C'b to the downstream-side communication portion 55C'.In this way, by forming the communication pipe 50 by separate components, that is, the reduced step portion 51C' and the downstream side communication portion 55C', and further by forming the reduced step portion 51C' and the downstream side communication portion 55C' by a flexible material, the freedom for placement of the communication pipe 50 within the engine compartment 3 can be improved.

[0048] In the third embodiment described above, the branch pipe 21 and the communication pipe 50 of the intake noise transmission device 20 communicate with each other via the sound generating device 30 (see FIG. Fig. 6). As in Fig. However, as shown in Fig. 9, the vibrator 33 may be disposed inside the passenger compartment side end of the branch pipe 21 to form the sound generating device 30, and the intake pipe side end of the reduced step portion 51C of the communication pipe 50 may be connected to the passenger compartment side end of the branch pipe 21. This configuration simplifies the structure of the intake noise transmission device 20, thereby reducing the cost of the intake noise transmission device 20.

[0049] Although the third embodiment described above relates to the case where the reduced step portion 51C is formed on the intake pipe side of the communication pipe 50, the reduced step portion 51C may also be formed on the intake pipe side of the branch pipe 21, and the reduced step portion 51C may communicate with the intake pipe 21C.

[0050] Although the cross-sectional shapes of the branch pipe 21 and the communication pipe 50 are circular in the third embodiment described above, this should not be considered limiting. The cross-sectional shapes of these components may be triangular, rectangular, and polygonal. Fourth embodiment

[0051] As in Fig. 10 (schematic diagram), a fourth embodiment of an intake noise transmission device 20 is arranged inside an engine compartment 3 of a vehicle 1. In the engine compartment 3, an intake pipe 5 for supplying combustion air to an engine EG is connected to the engine EG via an air cleaner AC. One end of the intake pipe 5 is open at a front end of the engine compartment 3 and is held by the front end of the engine compartment. The other end of the intake pipe 5 is connected to the engine EG. The intake pipe 5 is formed of a synthetic resin or the like in a cylindrical shape. The intake noise transmission device 20 for transmitting an intake noise to the driver in a passenger compartment 7 of the vehicle 1 is connected to a downstream side 5a of the intake pipe 5 located downstream of the air cleaner AC.

[0052] The intake noise transmission device 20 includes a branch pipe 21 branching from the intake pipe 5, a sound generator 30 communicating with the branch pipe 21, and a communication pipe 50 providing communication between the sound generator 30 and the interior of the passenger compartment 7. The branch pipe 21 is arranged in the engine compartment 3 such that one end of the branch pipe 21 is connected to an opening 5b located on the downstream side 5a of the intake pipe 5, located downstream of the air cleaner AC, and the other end of the branch pipe 21 extends toward the passenger compartment 7. The branch pipe 21 is formed into a cylindrical shape from a synthetic resin or the like.

[0053] The sound generating device 30 includes an intake pipe 31A connected to the passenger compartment end of the branch pipe 21, a vibrator 33 disposed at the passenger compartment end of the intake pipe 31A, and a casing 35 enclosing the intake pipe 31A. The vibrator 31 is a plate-shaped diaphragm made of a synthetic resin or rubber that vibrates with the intake pulsation of the intake noise propagating within the branch pipe 21 and the intake pipe 31A. The casing 35 is box-shaped. A front opening 35a is formed at one end of the casing 35, and a rear opening 35b is formed at the other end of the casing 35.

[0054] The intake pipe-side end of the intake pipe 31A is open at the front opening 35a and held by the front opening. The passenger compartment-side end of the intake pipe 31A is disposed opposite the rear opening 35b at a predetermined distance. The front opening 35a is formed in substantially the same circular shape as the outer shape of the intake pipe 31A, and the intake pipe 31AB is inserted into the front opening 35a so that no sound leakage occurs through the front opening 35a. A space 37 enclosed by the casing 35 is defined around the intake pipe 31A. The space 37 has a size that allows multiple frequencies included in the sound vibration generated by the vibration of the vibrator 33 as a sound source to resonate due to air column vibration.The rear opening 35b has substantially the same size as the vibrator 33 and is formed in a cylindrical shape. The rear opening 35b transmits the intake pulsation generated by the vibrator 33 to the communication pipe 50.

[0055] As in the Fig. 10 and Fig. As shown in Fig. 11A (cross-sectional view), the communication pipe 50 includes an upstream-side tubular communication portion 51D and a tubular extended step portion 55D. The upstream-side communication portion 51D is connected to the rear opening 35b of the housing 35. The extended step portion 55D is connected to the passenger compartment-side end of the upstream-side communication portion 51D and protrudes outwardly from the upstream-side communication portion 51D to define a step shape whose inner diameter changes in a discontinuous manner. The extended step portion 55D serves as a large-diameter communication portion extending toward the passenger compartment. The upstream-side communication portion 51D communicates with the extended step portion 55D while its inner diameter is substantially equal to the inner diameter of the rear opening 35b.The upstream side communication portion 51D is formed of a synthetic resin or the like.

[0056] The extended step portion 55D communicates with the passenger compartment 7, with its internal cross-sectional area being larger than the internal cross-sectional area of the upstream-side communication portion 51D. The extended step portion 55D is arranged substantially coaxially with the upstream-side communication portion 51D. The intake pipe-side end of the extended step portion 55D is integrally connected to the passenger compartment-side end of the upstream-side communication portion 51D.

[0057] In the thus configured, in Fig. In the intake noise transmission device 20 shown in FIG. 10, when outside air is sucked in through the intake pipe 5 while the engine EG is running, intake pulsation is generated inside the intake pipe 5 at a frequency corresponding to the rotational speed of the engine EG. The intake pulsation is transmitted from the intake pipe 5 to the vibrator 33 of the sound generator 30 via the branch pipe 21. As a result, the vibrator 33 vibrates at a frequency corresponding to the rotational speed of the engine EG. Therefore, sound vibration is generated inside the sound generator 30 with the vibration of the vibrator 33 as a sound source. The multiple frequencies included in the sound vibration resonate due to air column vibration within the casing 35 and are transmitted to the communication pipe 50.

[0058] Then, the intensity of high-frequency components of the intake noise Sh transmitted to the communication pipe 50, such as the valve noise of the engine EG and intake noise transmitted at high speeds, is reduced by the expanded step portion 55D of the communication pipe 50. This allows removing unwanted high-frequency components from the intake noise Sh transmitted into the passenger compartment 7, so that a desired intake noise can be transmitted into the passenger compartment 7.

[0059] The following are considered as reasons why undesirable high-frequency components of the intake noise Sh can be removed by the extended step portion 55D.

[0060] The sound vibration of the intake noise transmitted to the communication pipe 50 is transmitted to the extended step section 55D via the upstream communication section 51D. Here, as in Fig. As shown in FIG. 12A, the low-frequency components of the noise Sd contained in the sound vibration undergo little refraction when entering the extended step portion 55D and are not easily scattered. Therefore, only a slight decrease in the amount of energy caused by the sound vibration coming into contact with an inner surface 55S of the extended step portion 55D occurs.

[0061] As in Fig. As shown in Figure 12B, high-frequency components Sh contained in the sound vibration are refracted and widely scattered upon entering the extended step portion 55D. As a result, a large decrease in the amount of energy caused by the sound vibration coming into contact with the inner surface 55S of the extended step portion 55D occurs. This is considered to be the reason why the noise intensity can be reduced.

[0062] In the fourth embodiment described above, the communication pipe 50 has the upstream side communication portion 51D and the extended step portion 55D formed integrally with each other (see FIG. Fig. 11A). As in Fig. However, as shown in FIG. 11B, an upstream-side communication portion 51D' and an extended step portion 55D' may be formed of a flexible material and as separate components, and the intake-pipe-side end of the extended step portion 55D' may be connected to the passenger compartment-side end of the upstream-side communication portion 51D'. In this case, the extended step portion 55D' is formed in a tubular shape. The extended step portion 55D' includes a connecting portion 55D'b formed at the intake-pipe-side end of the upstream-side communication portion 51D', a side wall 55D'c formed at the passenger compartment-side end of the connecting portion 55D'b, and a large tubular body 55D'd formed at the outer edge of the side wall 55D'b.The connecting portion 55D'b is a tubular portion with which the outer periphery of the passenger compartment end of the upstream communication portion 51D' mates. The side wall 55D'c is an annular portion protruding outward in the radial direction. The large tubular body 55D'b is a tubular portion extending toward the passenger compartment 7.

[0063] The connecting portion 55D'b is connected to the upstream-side communication portion 51D' and is fittedly engaged with the upstream-side communication portion 51D'. For example, by providing a locking projection on the inner surface of the connecting portion 55D'b and providing an engagement recess for locking engagement with the locking projection on the outer surface of the upstream-side communication portion 51D', the downstream-side communication portion 55C' can be connected to the upstream-side communication portion 51D' through locking engagement between the locking projection and the engagement recess. Alternatively, the downstream-side communication portion 55C' can be connected to the upstream-side communication portion 51D' by welding the connecting portion 55D'b to the upstream-side communication portion 51D'.In this way, by forming the communication pipe 50 by separate components, that is, the upstream side communication portion 51D' and the extended step portion 55D', and further by forming the upstream side communication portion 51D' and the extended step portion 55D' by a flexible material, the freedom for placement of the communication pipe 50 within the engine compartment 3 can be improved.

[0064] In the fourth embodiment described above, the branch pipe 21 and the communication pipe 50 of the intake noise transmission device 20 communicate with each other via the sound generating device 30 (see FIG. Fig. 10). As in Fig.However, as shown in FIG. 13, the vibration device 33 may be disposed inside the passenger compartment side end of the branch pipe 21 to form the sound generating device 30, and the intake pipe side end of the upstream side communication portion 51D' of the communication pipe 50 may be connected to the passenger compartment side end of the branch pipe 21. This configuration simplifies the structure of the intake noise transmission device 20, thereby reducing the cost of the intake noise transmission device 20.

[0065] Although the fourth embodiment described above relates to the case where the extended step portion 55D is formed on the passenger compartment side of the communication pipe 50, the extended step portion 55D may also be formed on the passenger compartment side of the branch pipe 21, and the extended step portion 55D may communicate with the inlet pipe 31A of the sound generating device 30.

[0066] Although the cross-sectional shapes of the branch pipe 21 and the communication pipe 50 are circular in the fourth embodiment described above, this should not be considered limiting. The cross-sectional shapes of these components may be triangular, rectangular, and polygonal.

Claims

[1] Intake noise transmission device (20) for transmitting an intake noise of an engine (EG) mounted in a vehicle (1) into a passenger compartment (7), the intake noise transmission device (20) comprising: a branch pipe (21) branching from an intake system of the engine (EG); a sound generating device (30) communicating with the branch pipe (21), wherein the sound generating device (30) has a vibration device (33), wherein the vibration device (33) vibrates with the intake pulsation of the intake noise propagating within the branch pipe (21); and a communication channel (50) communicating with the sound generating device (30) for transmitting a vibration of the vibration device (33) into the passenger compartment (7), wherein the communication channel (50) has a step section (51C, 55D), wherein the sound generating device (30) has an inlet pipe (31A) connected to a passenger compartment end of the branch pipe (21), a housing (35) enclosing the inlet pipe (31A) and a rear opening (35b) formed on the housing (35), wherein the vibration device (33) is arranged at a passenger compartment end of the inlet pipe (31A), wherein the passenger compartment side end of the inlet pipe (31A) is arranged at a predetermined distance opposite the rear opening (35b). [2] The device according to claim 1, wherein the step portion is a reduced step portion (51C), the reduced step portion (51C) protruding outward with respect to the passenger compartment side portion of the communication duct (50), the inner cross-sectional area of the reduced step portion (51C) being larger than an inner cross-sectional area of the passenger compartment side portion, and the reduced step portion (51C) extending toward the intake system, the reduced step portion (51C) communicating with the sound generating device (30). [3] Device according to claim 2, wherein: the communication channel (50) has the reduced step portion (51C) and a downstream communication portion (55C), wherein the downstream communication portion (55C) is detachably connected to an inner side of a passenger compartment end of the reduced step portion (51C), and wherein the downstream communication portion (55C) has a tubular shape with an outer shape that is smaller than the reduced step portion (51C), and wherein an intake system side end of the downstream side communication portion (55C) is inserted into the passenger compartment side end of the reduced step portion (51C) to connect the downstream side communication portion and the reduced step portion (51C) to each other. [4] The device according to claim 1, wherein the step portion is an extended step portion (55D), the extended step portion (55D) protruding outward with respect to the intake system side portion of the communication passage (50), the inner cross-sectional area of the extended step portion (55D) being larger than an inner cross-sectional area of the intake system side portion, the extended step portion extending toward the passenger compartment, and the extended step portion (55D) communicating with the passenger compartment (7). [5] Device according to claim 4, wherein: the communication channel (50) has the extended step portion (55D) and an upstream-side communication portion (51D), wherein the upstream-side communication portion (51D) is detachably connected to an inside of an intake system-side end of the extended step portion (55D), and wherein the upstream-side communication portion (51D) has a tubular shape with an outer shape that is smaller than the extended step portion (55D), and wherein a passenger compartment side end of the upstream side communication portion (51D) is inserted into the intake system side end of the extended step portion (55D) to connect the upstream side communication portion (51D) and the extended step portion (55D) to each other. [6] The apparatus according to claim 1, wherein a space (37) enclosed by the housing (35) is defined around the inlet pipe (31A), the space (37) having a size that allows a plurality of frequencies included in the sound vibration generated by the vibration of the vibrator (33) as a sound source to resonate due to air column vibration. [7] The device according to claim 1 or 2, wherein the rear opening (35b) has substantially the same size as the vibrating means (33) and is formed in a cylindrical shape.

Images