Sound absorbing component

Details Sound absorbing component Sound absorbing component

1996-11-12

1999-11-09

MacMillan, Keith D.

Stock material or miscellaneous articles

Structurally defined web or sheet

Including components having same physical characteristic in...

428220, 4283179, 4282971, B32B 518

Patent

active

059810467

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a sound absorbing component.


BACKGROUND ART

Sound absorbing materials have been used heretofore in many fields and are often used typically for walls and ceilings of anechoic room.
A specific example of such sound absorbing materials generally used is a combination of plate-shaped sound absorbing components in which woven cloth covers a porous material such as glass wool. These components are suitably applicable to applications in a relatively large scale such as the anechoic room, but are not suitable for sound absorbing components for automobile such as components in an automobile engine room including an automobile engine cover. Requirements for sound absorbing components for automobile are capability of being used in a limited space and capability of exhibiting a sufficient sound absorbing effect. The conventional sound absorbing materials as described above, however, has a lot of problems; for example, it was not easy to freely shape them so as to be compatible with the space, their sound absorbing performance was degraded by absorption of oil or water, an increase of the weight due to the absorption of oil or water made retention of the shape difficult, and so on.
Also known are sound absorbing materials using a foamed body having isolated cells, i.e., cells not communicating with each other. They had, however, problems that the mechanical strength was poor and that a sufficient sound absorbing effect was not attained especially in the high-frequency region.
Further, the sound absorbing components for automobile, such as those for automobile engine and its surroundings, must have not only excellent sound absorbing performance, but also be light in weight. In addition, since they are used in a narrow limited space, the sound absorbing components themselves are required to be compact and thin. Therefore, the sound absorbing components for automobile are excellent in the sound absorbing performance even if being thin and to be readily producible even if being compact. However, the sound absorbing components conventionally known are inadequate in these respects.
An object of the present invention is to provide a sound absorbing component which can be readily produced not only in a relatively large scale, but also in the form of a compact sound absorbing component, which is excellent in the sound absorbing performance even if lightweight and compact, and which can effectively absorb the sound, especially, in the frequency region 500 to 3000 Hz of exterior noise considered to be problematic in automobiles.


DISCLOSURE OF THE INVENTION

A first sound absorbing component of the present invention is a sound absorbing component comprising a fiber-reinforced thermoplastic resin expanded body having a percentage of voids being not less than 50 vol %, and a resin molded body, in which an air layer is provided between the fiber-reinforced thermoplastic resin expanded body and the resin molded body. Since, in the first sound absorbing component of the present invention having such a structure, the air layer shifts to the lower frequency side the wavelength region of the sound effectively absorbed by the fiber-reinforced thermoplastic resin expanded body, the sound can be effectively absorbed in the frequency region of 500 to 3000 Hz even if the fiber-reinforced thermoplastic resin expanded body is thin. Accordingly, the first sound absorbing component of the present invention has excellent sound absorbing performance even if it is lightweight and thin and, in addition, the first sound absorbing component of the present invention is press-formable, thus being readily producible either on a large scale or on a small scale.
Further, a second sound absorbing component of the present invention is a sound absorbing component comprising a fiber-reinforced thermoplastic resin expanded body having a percentage of voids being not less than 50 vol %, and a thermoplastic resin foamed body, in which the thermoplastic resin foamed body is placed on a part of the fiber-reinfor

REFERENCES:
patent: 4190697 (1980-02-01), Ahrens
patent: 4476183 (1984-10-01), Holtrop et al.
patent: 4798756 (1989-01-01), Fukushima et al.
patent: 4925615 (1990-05-01), Willis et al.
patent: 5149574 (1992-09-01), Gross et al.
patent: 5438171 (1995-08-01), Schmanski
patent: 5532440 (1996-07-01), Fujisawa

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