JP5614437B2 - In-vehicle acoustic device - Google Patents

Description

  The present invention relates to an in-vehicle acoustic device that introduces sound generated in an engine room into a passenger compartment.

  With respect to vehicles, it is required to reduce leakage of engine sound to the outside. On the other hand, there is also a driver's request to enjoy comfortable engine sound in the vehicle. For this reason, various in-vehicle acoustic devices have been proposed for transmitting inspiratory noise generated in the engine room to the driver in the passenger compartment. For example, in the in-vehicle acoustic device disclosed in Patent Document 1, a skeleton of a vehicle is configured by a pipe-like frame having a space inside, and an air intake port of an intake duct for sending air to an engine is used as the pipe. Open in the space of the frame. According to this configuration, the intake sound when air flows through the intake duct is transmitted to the driver's ear through the pipe-shaped frame. Further, in the in-vehicle acoustic device disclosed in Patent Document 2, an intake pipe that introduces air into the engine and an outside air introduction pipe that extends from the air conditioner are arranged close to each other. According to this configuration, the intake sound generated in the intake pipe is transmitted to the vehicle interior via the outside air introduction pipe and the air outlet of the air conditioner. Moreover, in the vehicle interior acoustic device disclosed in Patent Document 3, an outside air duct for introducing outside air into the engine is branched into two, and an opening of one of the outside air ducts is a boundary wall between the engine room and the vehicle compartment of the vehicle. It is arrange | positioned in the dash panel vicinity which is (refer especially FIG. 10 of patent document 3). According to this structure, the intake sound when air flows through the outside air duct is transmitted to the vehicle interior via the one of the two outside air ducts and the dash panel.

JP 2006-307770 A Japanese Patent Laid-Open No. 2006-77693 JP 2006-83787 A

  Incidentally, the in-vehicle acoustic device disclosed in Patent Document 1 needs to draw the air intake port of the intake duct of the vehicle into the space of the pipe-shaped frame. Further, the in-vehicle acoustic device disclosed in Patent Document 2 needs to lay out the intake pipe and the outside air introduction pipe so that the intake pipe that introduces air into the engine and the outside air introduction pipe extending from the air conditioner are close to each other. Further, in the in-vehicle acoustic device disclosed in Patent Document 3, the outside air duct must be bifurcated, and the opening of one of the outside air ducts must be disposed near the dash panel. As described above, the in-vehicle acoustic devices disclosed in Patent Documents 1 to 3 have a problem that a large change must be made to the structure of an existing vehicle in order to realize them. In addition, the in-vehicle acoustic devices disclosed in Patent Documents 1 to 3 have a problem that the degree of freedom in design of the structure of the intake sound transmission path is low, and the adjustment range of the sound quality of the intake sound introduced into the vehicle interior is narrow. there were. In addition, when the in-vehicle acoustic device disclosed in Patent Documents 1 to 3 is adopted, the structure of the intake system of the engine is changed, which affects the suction pressure of the intake system of the engine. For this reason, there is a problem that the sound quality of the intake sound cannot be adjusted independently of the adjustment of the engine characteristics.

  The present invention has been made in view of the circumstances described above, and there are few changes to the structure of an existing vehicle, the adjustment range of the quality of the intake sound introduced into the passenger compartment can be widened, and the engine An object of the present invention is to provide an in-vehicle acoustic device that can be realized in a vehicle without changing an intake system.

According to the present invention, a hole is provided in a boundary wall separating the engine room and the vehicle compartment, and sound radiated from the surface of the surge tank is transmitted between the surge tank in the engine room and the boundary wall. Provided is an in-vehicle acoustic device characterized in that a sound collecting device is provided in the vicinity of a hole.
According to this invention, it is possible to realize the in-vehicle acoustic device in the vehicle without changing the existing vehicle structure as much as possible and without changing the intake system of the engine. Further, since this in-vehicle acoustic device has a high degree of design freedom, the sound quality of the sound introduced into the passenger compartment can be adjusted over a wide range.

1 is a side sectional view of a front portion of a vehicle to which an in-vehicle acoustic device according to an embodiment of the present invention is applied. It is the top view which saw through the front part of the vehicle from the upper part. FIG. 3 is a perspective view showing the configuration of the vicinity of the boundary between the engine room 1 and the vehicle compartment 2 in which the resonators 41 and 42 and the resonance tubes 51 and 52 are arranged in the same embodiment. It is the figure which looked at the boundary vicinity part from upper direction. It is a figure which shows the sound absorption part 33 provided before the hole 31 of the dash panel 3 in the same embodiment. It is a figure which shows the effect which provided the hole 31 in the dash panel 3 in the same embodiment. It is a figure which shows the effect which provided the resonance tubes 51 and 52 in the same embodiment. It is a figure which shows the effect which plugged the hole 31 with the thin film in the same embodiment according to the material of the thin film. It is a figure which shows the effect which provided the sound-absorption part 33 in the same embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a side sectional view of a front portion of a vehicle to which an in-vehicle acoustic device according to an embodiment of the present invention is applied, and FIG. 2 is a plan view of the front portion of the vehicle seen through from above. Similar to a general vehicle, the illustrated vehicle has a dash panel 3. The dash panel 3 forms a boundary wall that separates the engine room 1 and the vehicle compartment 2. A cowl 5 that supports the windshield 50 is provided on the upper portion of the dash panel 3. In the engine room 1, there is an engine body 6, and a surge tank 7 is provided above the engine body 6. As is well known, the surge tank 7 is an air reservoir provided in an intake system for guiding outside air to the engine body 6. When intake air is supplied to the engine body 6, intake sound is radiated from the surface of the surge tank 7. The in-vehicle acoustic device according to the present embodiment introduces the intake sound generated in the engine room 1 into the vehicle compartment 2, but the surge tank 7 is selected as a sound source for obtaining the intake sound. There is one feature.

  Between the surge tank 7 and the dash panel 3, there is provided a sound collector 10 that collects intake sound radiated from the surface of the surge tank 7 and introduces it into the vehicle compartment 2 through the dash panel 3. . The sound collecting device 10 has a wall 11 that forms a closed space between the surge tank 7 and the dash panel 3. The intake sound radiated from the surface of the surge tank 7 propagates to the dash panel 3 in the space surrounded by the wall 11 from above, below, left and right. In order to introduce a sufficient level of intake sound into the vehicle compartment 2, it is preferable to expose a region having as large an area as possible on the surface of the surge tank 7 in an inner space surrounded by the wall 11. The wall 11 is made of a sound insulating material. This is to prevent mechanical sound generated in the engine room 1 from propagating into the space inside the wall 11. Further, a cushion 12 made of, for example, rubber packing is interposed between the end of the wall 11 and the surface of the surge tank 7. This is to prevent noise from being generated due to collision or rubbing between the end portion of the wall 11 and the surface of the surge tank 7 due to shaking during travel of the vehicle.

  In the dash panel 3, a plurality of holes 31 arranged in the horizontal direction are provided at substantially the center of the inner region surrounded by the wall 11 of the sound collector 10. In the present embodiment, the number of the holes 31 is three, and each has a diameter of 40 mm. These holes 31 serve to introduce the intake sound that has propagated through the sound collecting device 10 and reached the dash panel 3 into the vehicle compartment 2. Providing a plurality of relatively small holes 31 instead of providing the large holes 31 reduces the amount of processing on the vehicle as much as possible, and efficiently collects the intake sound collected by the sound collecting device 10 toward the compartment 2 side. This is to introduce.

  In the present embodiment, each hole 31 is closed by a thin film (not shown). This is due to the following reason. First, in order to introduce a large level of intake sound into the passenger compartment 2, it is preferable that the hole 31 is completely opened without providing anything that closes the hole 31. However, in such a configuration, the odor in the engine room 1 leaks into the vehicle compartment 2 through the hole 31. Therefore, in the present embodiment, the hole 31 is covered with a thin film to prevent the odor in the engine room 1 from leaking into the vehicle compartment 2 and introduce the intake sound into the vehicle compartment 2 with as little attenuation as possible. -ing

  Resonators 41 and 42 are provided at positions near the dash panel 3 in the space surrounded by the wall 11 of the sound collector 10. Further, in the cowl 5, resonance tubes 51 and 52 extending in the left-right direction when viewed from the driver are provided. These play a role of adjusting the sound quality of the intake sound introduced into the vehicle compartment 2.

  FIG. 3 is a perspective view showing the configuration of the vicinity of the boundary between the engine room 1 and the vehicle compartment 2 where the resonators 41 and 42 and the resonance tubes 51 and 52 are arranged, and FIG. 4 is a view of the same part as viewed from above. . 3 and 4, the cowl 5 is not shown in order to prevent the drawings from becoming complicated.

  As shown in FIGS. 3 and 4, the resonators 41 and 42 are hollow box-like structures having sound holes 41 a and 42 a that are sound entrances and exits. The resonators 41 and 42 are fixed to the dash panel 3 with a sound propagation path from the surge tank 7 to the hole 31 of the dash panel 3 being sandwiched therebetween and the sound holes 41a and 42a facing each other. The intake sound radiated from the surge tank 7 enters the resonators 41 and 42 through the sound holes 41a and 42a before the dash panel 3. Then, the intake sound whose sound quality has been adjusted by the resonators 41 and 42 is output from the sound holes 41a and 42a, and is mixed in front of the dash panel 3, and is directed from the hole 31 of the dash panel 3 toward the driver in the passenger compartment 2. Is emitted. In a preferred embodiment, the resonance frequencies of the resonators 41 and 42 are about 150 to 200 Hz. This is because the resonators 41 and 42 are caused to resonate with the explosion primary (rotary tertiary) component of the intake sound when the 6-cylinder engine is rotating at a rotational speed of 3000 to 4000 rpm. The resonance frequencies of the resonators 41 and 42 may be the same or different.

  The resonance tubes 51 and 52 are hollow tubes having a length of about 30 cm. In the acoustic propagation path from the surge tank 7 to the hole 31 of the dash panel 3, the dash panel 3 is positioned in front of the dash panel 3 with the open ends that are the entrances of the sounds spaced apart and opposed to each other. It is housed in a cowl 5 above the panel 3. A hole (not shown) is provided on the lower surface of the cowl 5 so as to look down between the resonators 41 and 42. The intake sound radiated from the surge tank 7 and propagated to the front of the dash panel 3 enters the resonance tubes 51 and 52 in the cowl 5 through this hole. Holes 51a and 52a opened to the passenger compartment 2 side are provided in a portion near the end of the resonance tube 51 on the left side as viewed from the driver and a portion near the end of the resonance tube 52 on the right side as viewed from the driver. ing. The cowl 5 is also provided with holes 53 and 54 communicating with the holes 51a and 52a, respectively (see FIGS. 1 and 2). The holes 53 and 54 of the cowl 5 are also closed with a thin film, like the hole 31 of the dash panel 3 described above. The intake sound whose sound quality is adjusted in the resonance tubes 51 and 52 is radiated toward the driver in the passenger compartment 2 through these holes and the thin film. In a preferred embodiment, each resonance frequency of the resonance tubes 51 and 52 is about 500 Hz.

  In a preferred aspect, a sound absorbing part for attenuating mechanical noise is provided in the propagation path of the intake sound up to the vehicle compartment 2. FIG. 5A shows a configuration of the sound absorbing portion 33 as an example viewed from the engine room 1 side, and FIG. 5B is a cross-sectional view of the sound absorbing portion 33 taken along the line I-I ′. The sound absorbing portion 33 is made of a porous material. As shown in the drawing, the sound absorbing portion 33 includes a plurality of passages 34 extending from the engine room 1 side to a plurality of holes 31 (three holes 31 in this example) of the dash panel 3. Have. In the intake sound radiated from the surge tank 7, the high frequency component is attenuated in the process of passing through the passage 34 and moving toward the hole 31. Further, holes 35 are provided in the left and right side walls of the sound absorbing portion 33, respectively. The intake sound that has entered the rightmost and leftmost passages 34 in the sound absorbing portion 33 is guided to the resonators 41 and 42 through these holes 35. The high frequency component of the intake sound guided to the resonators 41 and 42 is also attenuated by the sound absorbing unit 33. A sound absorbing portion similar to the sound absorbing portion 33 may be provided in the sound propagation path to the resonance tubes 51 and 52.

Next, the effect of this embodiment will be described.
FIG. 6 is a view showing the effect of providing the hole 31 in the dash panel 3 and the effect of providing the holes 53 and 54 in the cowl 5. In FIG. 6, the horizontal axis represents the center frequency of the engine sound of 1/3 octave band, and the vertical axis represents the intake sound of the engine at that time (radiated sound of the surge tank 7 in this embodiment). This is the amount of increase in the sound pressure level in the passenger compartment 2. The same applies to FIGS. 7 to 9 referred to later.

  In FIG. 6, a graph A <b> 1 shows the amount of increase in sound pressure level at the driver's seat when the holes 53 and 54 of the cowl 5 are closed with a 2 mm thick rubber plate and the hole 31 of the dash panel 3 is opened. Graph A2 shows the amount of increase in the sound pressure level at the driver's seat when the holes 53 and 54 of the cowl 5 are opened and the hole 31 of the dash panel 3 is closed with a rubber plate having a thickness of 2 mm. Graph A3 shows the amount of increase in the sound pressure level at the driver's seat when the holes 53 and 54 of the cowl 5 are opened and the hole 31 of the dash panel 3 is also opened. From these graphs, it can be seen that a sound pressure increase of about 15 to 20 dB can be obtained by providing the hole 31 in the dash panel 3 in particular.

  FIG. 7 is a diagram showing the effect of the resonance tubes 51 and 52. In FIG. 7, the graph B1 indicates the sound pressure level increase observed near the hole 31 of the dash panel 3, and the graph B2 indicates the sound pressure level increase observed near one of the holes 53 or 54 of the cowl 5. That is, it shows an increase in sound pressure level due to the sound that has passed through the resonance tube 51 or 52 being radiated. Comparing the graphs B1 and B2, it can be seen that in the radiated sound through the hole 53 or 54, 500 Hz that is the resonance frequency of the resonance tubes 51 and 52 and the harmonic frequency component thereof are emphasized.

  Although not shown, since the sound output through the hole 31 of the dash panel 3 is subjected to sound quality adjustment by the resonators 41 and 42, the resonance frequency of the resonators 41 and 42 and the harmonic frequency components thereof are emphasized. It will be.

  FIG. 8 shows the effect of closing the hole 31 of the dash panel 3 with a thin film according to the material of the thin film. In FIG. 8, the graph C0 shows the amount of increase in sound pressure level in the vicinity of the hole 31 when the hole 31 is opened without being blocked by a thin film, and the graph C1 shows the hole 31 when the hole 31 is closed with a heat-resistant resin film. A graph C2 shows an increase in sound pressure level near the hole 31 when the hole 31 is closed with an aluminum film having a thickness of 100 μm, and a graph C3 shows a rubber pressure having a thickness of 1 mm. The amount of increase in sound pressure level in the vicinity of the hole 31 when closed by a film is shown. As shown in FIG. 8, the amount of increase in the sound pressure level in the passenger compartment 2 due to the introduction of the intake sound through the hole 31 and the frequency characteristic thereof vary depending on the material of the membrane that closes the hole 31. Therefore, the material of the membrane that closes the hole 31 may be selected according to the required amount of increase in sound pressure level and its frequency characteristics.

  FIG. 9 is a diagram showing the effect of arranging the above-described sound absorbing portion 33 in front of the hole 31 of the dash panel 3. In FIG. 9, the graph C0 ′ shows the increase in sound pressure level in the vicinity of the hole 31 when the hole 31 is opened without being blocked by a thin film, and the graph C2 ′ shows the hole 31 closed by an aluminum film having a thickness of 100 μm. The graph C3 ′ shows the amount of increase in the sound pressure level near the hole 31 when the hole 31 is closed with a rubber film having a thickness of 1 mm. Comparing FIG. 9 with FIG. 8 described above, by providing the sound absorbing portion 33, the sound introduced into the passenger compartment 2 is a component in which a band component of 2 kHz or higher is greatly attenuated. Therefore, it is possible to effectively prevent mechanical noise generated in the engine room 1 from being introduced into the vehicle compartment 2.

  As described above, according to the present embodiment, the intake sound radiated from the surge tank 7 is collected by the sound collecting device 10 and introduced into the passenger compartment 2 without affecting the characteristics of the intake system of the engine. The intake sound can be efficiently introduced into the passenger compartment 2. In addition, according to the present embodiment, the degree of freedom in designing the acoustic propagation path from collecting the intake sound by the sound collecting device 10 and introducing it into the passenger compartment 2 is high, so that changes to the existing vehicle structure are minimized. Thus, there is an advantage that the adjustment range of the quality of the intake sound can be widened.

  Although one embodiment of the present invention has been described above, other embodiments are conceivable for the present invention. For example:

(1) The sound collector 10 and the resonators 41 and 42 having various characteristics, or various units in which the sound absorbing part 33 is integrated in addition to these are prepared, and the user selects a desired unit as the surge tank 7 and the dash. You may comprise so that it can mount | wear between the panels 3, or can be removed from there.

(2) Although the hole 31 of the dash panel 3 and the holes 53 and 54 of the cowl 5 may be always closed by the thin film, the following thin film replacement may be possible. That is, for example, various filters in which various thin films are stretched in a ring-shaped frame are prepared, while the filter frame is received around the hole 31 of the dash panel 3 and the holes 53 and 54 of the cowl 5, for example. Thus, a mechanism for fixing the filter in a state where the hole is closed is provided. According to this aspect, the user can select a filter having a desired characteristic and use it to close the hole 31 and the like, and introduce an intake sound having a desired sound quality into the vehicle compartment 2. Can do.

(3) The sound collecting device 10 may have a shape in which the cross-sectional area decreases from the surge tank 7 toward the hole 31 of the dash panel 3 in order to enhance the sound collecting effect.

(4) The cushion 12 may not be provided at the end of the wall 11 of the sound collector 10, and instead, the end of the wall 11 and the surface of the surge tank 7 may face each other with a certain gap therebetween.

DESCRIPTION OF SYMBOLS 1 ... Engine room, 2 ... Car compartment, 3 ... Dash panel, 5 ... Cowl, 6 ... Engine body, 7 ... Surge tank, 10 ... Sound collector, 11 ... Wall, 12 ... Cushion, 41, 42 ... Resonator, 51, 52 ... Resonant tube, 31, 53, 54, 35 ... Hole, 33 ... Sound absorbing part, 41a, 42a ... Sound hole, 34 ... Passage.

Claims (9)

A hole is provided in a boundary wall that separates the engine room and the vehicle compartment, and a wall that forms a closed space between the surface of the surge tank in the engine room and the boundary wall is provided from the surface of the surge tank. A sound collecting device that collects sound emitted toward the space in the vicinity of the hole in the boundary wall;
The first and second resonators are formed in a hollow box shape having sound holes that serve as sound entrances and exits, and the first and second resonators pass through the holes in the boundary wall from the surge tank. An in-vehicle acoustic device characterized in that an acoustic propagation path leading to is sandwiched between each other and the sound holes are arranged to face each other.   A resonance tube for adjusting the sound quality is housed in a cowl above the vehicle, and the sound collected near the hole in the boundary wall in the sound collecting device is guided to the resonance tube, and the sound quality is adjusted by the resonance tube. The in-vehicle acoustic device according to claim 1, wherein the sound is introduced into the passenger compartment through a hole provided in the cowl. First and second resonance tubes, the first resonance tube and the second resonance tube each sandwiching an acoustic propagation path from the surge tank to the hole in the boundary wall, and each The in-vehicle acoustic device according to claim 2 , wherein opening ends that are sound entrances are arranged so as to face each other.   The boundary wall is a dash panel of a vehicle, and a sound quality of sound introduced into a hole of the dash panel in the sound collector is adjusted by the first resonator and the second resonator. The in-vehicle acoustic device according to any one of 1 to 3.   5. The in-vehicle acoustic device according to claim 1, wherein the first resonator, the second resonator, and the sound collector are integrated and configured as a replaceable unit. 6. .   The in-vehicle acoustic device according to any one of claims 1 to 5, wherein a hole for introducing sound into the vehicle interior is closed with a thin film.   The in-vehicle acoustic device according to claim 6, wherein the thin film is replaceable.   The in-vehicle acoustic device according to any one of claims 1 to 7, wherein a sound absorbing portion for attenuating a high frequency component is provided in a sound path introduced into the vehicle interior. As a unit that can be replaced by integrating a sound absorbing section that is provided in a sound path introduced into the passenger compartment and attenuates a high frequency component of the sound, the sound collector, and the first and second resonators. The in-vehicle acoustic device according to claim 1, which is configured.

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