JP2003076373A - Lightweight acoustical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lightweight acoustic system. SOLUTION: An improved acoustical system for inhibiting noise in a motor vehicle comprises an impermeable layer and an underlayment adjacent to the impermeable layer. The underlayment includes a first fibrous layer and a second fibrous layer. The underlayment has an airflow resistance between about 2,000 and about 5,000 mks Rayls.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an acoustic device.

[0002]

The use of water-permeable decorative fabrics or films to improve their low frequency response on acoustic absorbers has been demonstrated in the technical literature and in many commercial applications primarily in the construction and construction fields. It was Recently, this concept has been applied to automobile interior acoustic products.

[0003]

Although these devices may exhibit improved sound transmission loss in the intermediate frequency range as compared to double-walled devices, they are also generally in the higher frequency range. It shows a reduction in sound transmission loss. In addition, porous surfaces can cause some practical problems. When used on the floor of an automobile, acoustic absorbers with water-permeable facings allow the ingress of water, which can cause mold and odor formation in the underpad, and sometimes floor pans. It may rust.

[0004]

The present invention provides an improved acoustic device including a water impermeable layer and an underlayment. The underlay is
Adjacent to the impermeable layer is a first fiber layer and a second fiber layer. The first fibrous layer has a density less than that of the second fibrous layer, and the underlayment has about 2000 and about 5000 mks R
Has airflow resistance between ayls. That is, it is an object of the present invention to provide an improved acoustic device that works well over a wide frequency range. Another object of the present invention is to provide an improved acoustic barrier that does not allow water ingress. These and other objects, features and advantages of the present invention will become readily apparent when the following detailed description of the best mode for carrying out the invention is considered in conjunction with the accompanying drawings.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an apparatus 10 for suppressing vehicle noise. The device 10 includes a relatively light water impermeable layer 12 and an underlay 14. Underlay 14 is
Located immediately adjacent to the impermeable layer 12 and includes a first or bulky fiber layer 16 and a second or compressed fiber layer 18. In a preferred embodiment, both layers 16 and 18 include recycled nonwoven fibers that are fluffed and carded to create a non-directional matrix or core. Both layers 16 and 18 preferably have a surface density of between about 500 grams / square meter and about 1400 grams / square meter.

A semipermeable layer 20 comprising a soluble plastic film using thermosetting adhesive or a cellulose filter scrim is preferably placed between layers 16 and 18 to provide additional airflow resistance and bond the layers together. To help. For scrims, the material preferably has a surface density in the range of about 44 grams / square meter. Also, a decorative layer 2 such as a carpet or a decorative cloth
2 may be provided adjacent to the impermeable layer 12.

To make the acoustic device 10, it is preferred that layers 16 and 18 of approximately the same thickness be first heat cured through a furnace. One of the layers 16 or 18 is then bonded to the semi-transmissive layer 20 and the bond is bonded to the other of the layers 18 or 16. The obtained laminated body is about 40
Heat to 0-450 ° F for about 30-40 seconds and then place in a cooled mold. When the mold is closed, layers 16 and 18 undergo different compression. First 2
Decorative material 22 coated with an impermeable layer 12 of polyethylene of from 0 to 500 grams / square meter to a thickness of less than 1 millimeter, more preferably about 0.1 millimeters, is then coated with the impermeable layer. It is bonded to the underlayment 14 by heating it to near its melting point and then transferring the impermeable layer to a cooled mold in which the underlayment has already been placed.

In the finished product, the underlay 14
Has a total thickness of 10 to 25 millimeters (mm), and the second or compression layer 18 occupies about 3 millimeters of its thickness, resulting in a higher molding than the first or bulky layer 16. It preferably has a density. In this form, the underlayment is about 2000 and about 5000 mks Ray.
ls, preferably about 2500 and 4500 mk
s Rayls with a specific airflow resistance. The device 10 can be placed on a sheet metal 24 of a motor vehicle such that the lofted layer 16 is immediately adjacent to the sheet metal and the compression layer 18 is immediately adjacent to the impermeable layer 12.

The present invention is an improvement over the prior art. The present invention modifies the structure to improve performance over a wide frequency range and eliminates physical imperfections. The acoustic transmission loss of this device is significantly improved over a common heavy barrier device at an intermediate region frequency of about 200 to 1000 Hertz, and is almost comparable to a heavy barrier device at a high frequency region. These results were unexpected from previous lightweight device experience. All other lightweight devices show a significant reduction in transmission loss at higher frequencies. Further, the device 10 is preferably formed entirely of thermoplastic for complete reusability.
Although the invention is particularly applicable to automotive floor equipment, it may have other vehicle or architectural noise reduction applications. In some of these applications, such as automotive shock isolation, carpets are unnecessary. The design of the impermeable layer allows the acoustic properties of the structure to be tuned for transmission loss and / or acoustic absorption over a particular frequency range.

While the embodiments of the invention shown and described above constitute preferred embodiments of the invention, they are not intended to represent all possible forms of the invention. Similarly, the words used are words of description rather than of limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosed invention.

[Brief description of drawings]

1 is a cross-sectional view of an acoustic device according to the present invention.

[Explanation of symbols]

10 audio equipment 12 Impermeable layer 14 Underlay 16 First fiber layer 18 Second fiber layer 20 Semi-transmissive layer 22 Cosmetic materials 24 Sheet metal

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Liangyu Fang, the inventor             48083, Michigan, United States             Roy Langford Drive 1719 (72) Inventor Gordon Ebitt             48104, Michigan, United States             Arbor Brookwood Place               848 (72) Inventor Barry Weyerman             48374 No, Michigan, United States             Viwillingham drive 45859 (72) Inventor David Boyles             United States Pennsylvania             17013 Carlisle Nesbitt Dry             Ve 821 F-term (reference) 3B088 FA01 FB03 FC01                 3B120 AA14 AB11 BA04 BA15 CA01                       CA11 EA10 EB07                 5D061 AA23 GG06

Claims (16)

[Claims] 1. An underlay comprising a water impermeable layer, a second fiber layer adjacent to the water impermeable layer, and a first fiber layer having a density lower than that of the second fiber layer. Including, the underlay is about 2000 and about 5000 mks Ray.
An acoustic device comprising a semi-transmissive layer disposed between the first and second fibrous layers, the acoustic device having a specific airflow resistance between 1s and 1s. 2. The acoustic device according to claim 1, wherein the semi-transmissive layer includes a film. 3. The acoustic device of claim 1, wherein the first fiber layer has a surface density of between about 500 grams / square meter and about 1400 grams / square meter. 4. The acoustic device of claim 1, wherein the second fiber layer has a surface density of between about 500 grams / square meter and about 1400 grams / square meter. 5. The acoustic device according to claim 1, wherein the second fiber layer is adjacent to the impermeable layer. 6. The acoustic device according to claim 1, wherein the second fiber layer is a composite material. 7. The acoustic device according to claim 1, wherein the underlay is located between the impermeable layer and the noise source. 8. The acoustic device of claim 1, further comprising a decorative layer located adjacent to the impermeable layer. 9. A carpet having noise suppressing properties for use in an automobile, comprising: a water impermeable layer; and a density of the second fiber layer and the second fiber layer adjacent to the water impermeable layer. Including a first fiber layer having a lower density, the underlay comprising about 2000 and about 5000 mks Ray.
A carpet having a specific air flow resistance of between 1 and ls, wherein the first and second fiber layers have a surface density of between about 500 grams / square meter and about 1400 grams / square meter. 10. The carpet of claim 9, further comprising a semi-permeable layer disposed between the first fiber layer and the second fiber layer. 11. The carpet of claim 10, wherein the semi-transmissive layer comprises a film. 12. The carpet of claim 9, wherein the second fiber layer is adjacent to the impermeable layer. 13. The carpet of claim 9, wherein the second fiber layer is a composite. 14. The carpet according to claim 9, wherein the underlay is located between the impermeable layer and the noise source. 15. The carpet of claim 9, wherein the first layer is located between the second layer and a noise source. 16. An impermeable layer and a first fibrous layer having a surface density of between about 500 grams / square meter and about 1400 grams / square meter, between about 500 grams / square meter and about 1400 grams / square meter. An underlay comprising a second fiber layer having a surface density and a semi-permeable layer, the underlay being adjacent to the impermeable layer;
The underlay includes about 2000 and about 5000 mks Ray.
A device for suppressing vehicle noise, characterized in that it has a specific airflow resistance between ls.