JPH0421486Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a sound-absorbing sheet for a vehicle that is capable of reducing noise in a vehicle interior.

(Prior Art) Conventionally, various sound absorbing means have been installed in the cabin forming part or the cabin space in order to reduce the noise generated in the cabin of a vehicle. As shown in the publication, a Helmholtz-type resonator is installed in the vehicle interior forming part or in a region where the sound pressure level of noise in the vehicle interior space is high, such as the front seat back or the rear package tray. Sound absorption mechanisms have been proposed that attempt to reduce vehicle interior noise, particularly low frequency noise, through resonance effects.

In this way, low-frequency noise in particular is targeted for reduction because, in general, in vehicles, the vertical axis shown in Figure 4 represents the noise level (dB), and the horizontal axis represents the frequency (Hz). This is because, as seen in the characteristic diagram shown below, during steady running, a relatively high level of noise (muffled sound) is generated due to engine operation etc. in the low frequency band of about 80 to 120 Hz.

(Problems to be solved by the invention) However, as mentioned above, a sound absorption mechanism for a vehicle is adopted in which a resonator is installed in a region where the sound pressure level of noise in the vehicle interior forming part or the vehicle interior space is high. In this case, a considerable sound absorption effect can be obtained in the vicinity of the part of the vehicle interior space where the resonance hole of the resonator opens, but a sufficient sound absorption effect cannot be obtained in the part away from the part where the resonance hole opens. ,
There is a problem that noise is not reduced.

In order to solve this problem, it would be sufficient to install a large number of resonators in the vehicle interior forming part or in each part of the vehicle interior space so that the desired sound absorption effect can be obtained in various parts of the vehicle interior space. A resonator that can effectively absorb frequency noise requires a resonance chamber with a relatively large volume, and as a result, installation locations are limited and it is difficult to install it in the vehicle interior forming part or in various parts of the vehicle interior space. It is. For this reason, even if conventional vehicle sound absorption mechanisms have been adopted in which a resonator is installed in the cabin forming part or the cabin space, low-frequency noise for occupants seated in the cabin cannot be sufficiently reduced. has not been obtained.

In view of this, the present invention is based on the idea of effectively utilizing the seats arranged in the vehicle interior space to reduce the noise inside the vehicle interior. Without causing the inconvenience of unduly narrowing the space and impairing the comfort of the vehicle, noise to the occupants inside the vehicle, in particular,
An object of the present invention is to provide a sound-absorbing sheet for a vehicle that can sufficiently reduce low-frequency noise.

(Means for Solving the Problems) In the present invention, the following matters are used as the basis for solving the above problems.

In other words, by absorbing only low-frequency noise having a frequency of about 80 to 120 Hz, which is shown at a particularly high level in the characteristic diagram shown in FIG. It is possible to effectively reduce noise for occupants seated in the vehicle.

In order to form a sound absorbing means for sounds in a relatively narrow frequency band centered on a specific frequency with a relatively small occupied volume, a sound absorbing wavelength tube such as a quarter wavelength tube may be used. thing.

When using sound absorbing means to reduce noise for occupants seated in the vehicle interior, it is effective to place the sound absorbing section of the sound absorbing means near the ears of the occupants. It is most desirable that the sheet provided has a sound absorbing effect.

In view of the above, the present invention provides a sound-absorbing seat that can solve the above-mentioned problems. A seat back frame is formed, the ends of which are closed, and a resonant opening is provided to function as a sound absorbing wavelength tube. A sound permeable member is disposed in a portion of the cushion member of the seat bag that corresponds to the resonance opening provided in the seat back frame.

(Function) In the sound-absorbing seat for a vehicle according to the present invention as described above, the sound-absorbing wavelength tube embedded in the seat back portion, for example, the seat back frame functioning as a quarter-wave tube, allows the sound absorbing seat to absorb sound according to its length. Noise existing in a frequency band centered on a specific frequency set by the seatback is absorbed in the upper part of the seatback part where the resonance opening provided in the seatback frame that functions as a sound-absorbing wavelength tube is located, Reduced. The frequency band centered on this specific frequency can be determined by selecting the effective length of the seatback frame that functions as a sound-absorbing wavelength tube, for example, the frequency of low-frequency noise having a frequency of about 80 to 120 Hz as described above. It is assumed that it matches the band.

Therefore, the sound absorbing sheet for a vehicle according to the present invention is as follows:
This makes it possible to sufficiently reduce noise, particularly low-frequency noise, for occupants inside the vehicle interior without causing the inconvenience of unduly confining the vehicle interior space and impairing comfort.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a partially cutaway example of a sound-absorbing sheet for a vehicle according to the present invention, and FIG. 2 shows a cross-sectional structure of a portion thereof.

In this example, a seat frame 10 is provided, a cushion spring 12 is stretched over the seat frame 10, and a cushion seat 14 serving as a seating portion is attached to the cushion spring 12. seat frame 10
A seat back 20 is tiltably connected to the seat back 20 via a reclining mechanism 16, only a portion of which is shown.

As shown in FIG. 3, the seat bag 20 has a frame formed by bending a pipe having a predetermined opening cross-sectional area into a U-shape, and its lower end is connected to the reclining mechanism 16 by welding. It is formed by two left and right seat back frames 22A and 22B. For each of these seat back frames 22A and 22B,
Left and right seat back brackets 23 (only the one on the 22A side is shown in FIG. 1) are attached. A cushion spring 24 is stretched between the left and right seat back brackets 23, and these seat back brackets 22A
and 22B, the seat back bracket 23, and the cushion spring 24 are covered by a cushion member 26 comprising a pad 26a and a skin 26b forming the exterior of the seat back 20.

Further, as shown in FIG. 1, a headrest 28 is connected to the upper part of the seatback frames 22A and 22B by a connecting member 30. As shown in FIG. 2, the connecting member 30 includes a support member 32 having a U-shaped cross section, and crank-shaped connecting plates 34 fixed to the upper and lower ends of the support member 32. Member 32
The upper ends of each of the seat back frames 22A and 22B are inserted between the seat back frames 22A and 22B and the connecting plate 34.

Then, as described above, the seat back 20
Seat back frame 2, which is buried in
2A and 22B, as clearly shown in FIG.
8B and are provided with resonance openings 22a and 22b that open upward, and function as a sound-absorbing wavelength tube, for example, a quarter wavelength tube, embedded in the seat back 20. It's like that. In this case, the effective length of each of the seat back frames 22A and 22B as a quarter wavelength tube is, for example, approximately 80 to 120 Hz as described above.
The wavelength is selected to be 1/4 of the wavelength of a signal having a frequency approximately at the center of the frequency band of low frequency noise having a frequency of . That is, each of the seat back frames 22A and 22B has a resonant frequency approximately at the center of the frequency band of low frequency noise having a frequency of approximately 80 to 120 Hz, and therefore has a resonance frequency of approximately 80 to 120 Hz.
A quarter-wavelength tube is formed which has a sound absorbing effect on low-frequency noise having a frequency of .

In addition, the resonance opening 22a of the support member 32
Through holes 32a and 32b corresponding to the resonance openings 22a and 22b are formed in a portion directly above the pads 26a and 22b.
and 26b, a sound-permeable felt 27 is provided in a portion directly above the through holes 32a and 32b, respectively.
and a breathable sheet 29 are disposed so that sound outside the seat bag 20 is propagated through the felt 27 and the breathable sheet 29 to the resonance openings 22a and 22b.

In the case of the vehicle seat configured as described above, when placed in the interior space of the vehicle, the low frequency noise having a frequency of about 80 to 120 Hz in the vehicle interior is absorbed by the seat 1 buried in the seat back 20. Resonance openings 22a and 2 of seatback frames 22A and 22B that function as /4 wavelength tubes
2b and is absorbed by its resonance effect. For such a sound absorption effect, the resonance opening 22
a and 22b are positioned above the seat bag 20, so that the seat bag frame 2
The sound absorption effect of 2A and 22B is highest near the ears of the occupant, and low frequency noise for the occupant is effectively reduced.

According to the experimental results, the resonance openings 22a and 22
Each length of b・L=L ₁ +L ₂ +L ₃ (Figure 3) is approximately 80
cm, and the pipe diameter is 50 mm, approximately 80~
It was confirmed that the level of low frequency noise having a frequency of 120 Hz was reduced from the level shown by the solid line in the characteristic diagram of FIG. 4 to the level shown by the broken line.

Note that in the above example, the seat bag frames 22A and 22B forming the frame of the seat bag 20 are
Since a sound-absorbing wavelength tube, for example, a quarter-wavelength tube, is formed by using the above-described method, it has the advantage that the sound-absorbing sheet has a simple structure and can be produced at low cost.

(Effects of the invention) As is clear from the above explanation, the sound-absorbing seat for a vehicle according to the present invention has a seat back frame embedded therein which effectively utilizes the seat back portion and functions as a sound-absorbing wavelength tube, thereby achieving the following effects: With a simple configuration that does not require a separate space for a sound absorbing member in the seat back, it is possible to obtain a sound absorbing effect on noise in the vehicle interior, such as low frequency noise, and also functions as a sound absorbing wavelength tube. Since the resonance opening provided in the seatback frame is positioned above the seatback part, there is no possibility that it will be placed in the interior space of the vehicle, unduly narrowing the interior space and impairing the comfort of the vehicle. To absorb low-frequency noise near the ears of a passenger without causing the inconvenience of noise, and to effectively reduce noise, especially low-frequency noise, to the passenger inside the vehicle.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view showing an example of a sound absorbing sheet for a vehicle according to the present invention, FIGS. 2 and 3 are partial detailed views of the example shown in FIG. 1, and FIG. 4 1 is a characteristic diagram used to explain the noise state in a vehicle and the operation of the example shown in FIG. 1. FIG. In the figure, 10 is a seat frame, 20 is a seat back, 22A and 22B are seat back frames, 22a and 22b are resonance openings, and 28 is a headrest.

Claims (1)

[Scope of utility model registration request] A seat back frame, which is formed of a pipe member and whose end is closed and is provided with a resonance opening and functions as a sound-absorbing wavelength tube, is located in the seatback portion above the resonance opening. A sound-absorbing seat for a vehicle, wherein a sound-permeable member is embedded in a cushion member of the seat back portion at a portion corresponding to the resonance opening.