Patent Application
20110285178
The present invention generally relates to automotive vehicle headliners, and more particularly relates to a lightweight automotive headliner that provides enhanced acoustic dampening.
Automotive vehicles are commonly equipped with headliners installed underneath the roof within the passenger compartment. Thermoset polyurethane headliners are generally cost-effective and lightweight. Conventional polyurethane headliner construction typically includes blocking layers that prevent liquid thermoset adhesive from bleeding through one or more surfaces or layers of the headliner. Liquid adhesive can leak into the mold during manufacture and can create an unacceptable appearance. The presence of the conventional blocking layers prevents air and other sound waves from passing into and through the headliner and prevents the sound within the interior of the vehicle passenger compartment from being adequately absorbed by the headliner.
It is therefore desirable to provide for a vehicle headliner which is lightweight, cost-effective and provides desirable acoustic dampening.
According to one aspect of the present invention, a vehicle headliner is provided that includes an air permeable foam core, a surface cover, and an adhesive disposed on opposite sides of the foam core. The headliner also includes an air permeable hydrophobic layer that restricts liquid penetration and allows air permeation into the headliner for acoustic dampening.
According to another aspect of the present invention, a vehicle headliner is provided that includes an air permeable foam core, a first adhesive provided on a first side of the foam core, and a surface cover adhered to the first side of the foam core via the first adhesive. The headliner also includes a second adhesive disposed on a second opposite side of the foam core and an air permeable hydrophobic layer adhered to the second side of the foam core via the second adhesive. The air permeable hydrophobic layer restricts liquid penetration and allows air permeation into the headliner for acoustic dampening.
These and other aspects, objects, and features of the present invention will be understood and appreciated by those skilled in the art upon studying the following specification, claims, and appended drawings.
In the drawings:
Referring now to
Referring to
Bonded onto the bottom side of the foam core 22 is a first or bottom adhesive layer 24 and a chopped glass fiber mat 26. The fiberglass mat 26 may be formed with an array of chopped glass fibers that are randomly oriented with numerous spaces between fibers to allow for airflow and sound penetration. The fiberglass mat 26 provides structural rigidity to one side of the foam core 22. A fabric surface cover 28 is adhered to the bottom of the glass fibers 26 and the bottom of the foam core 22 via the adhesive layer 24. The cover 28 forms the visible bottom surface of the headliner 20 which is visible to passengers in the vehicle 10. The cover 28 may include a woven fabric, according to one embodiment. According to another embodiment, the cover 28 includes a non-woven fabric. The fabric may include a flame laminated soft foam that has an open cell polyurethane which is also permeable to air and sound waves. The cover 28 has a substantially open air porosity such that air and sound, such as noise, pass through with little resistance.
Bonded onto the top side of the foam core 22 is a second or top adhesive layer 30 and a chopped glass fiber mat 32. The fiberglass mat 32 may be formed with an array of chopped glass fibers that are randomly oriented with spaces between fibers to allow for air flow and sound penetration. The fiberglass mat 32 provides further structural rigidity to the opposite side of the foam core 22. The headliner 20 includes an air permeable and hydrophobic backing layer 34 adhered to the fiberglass mat 32 and top side of core foam 22 via the top adhesive 30. The air permeable and hydrophobic backing layer 34 may include a felt mat that is formed of non-woven polypropylene fibers that are blended on top of each other and pressed together to form a pressed mat, according to one embodiment. According to other embodiments, the hydrophobic backing layer 34 may include pure polypropylene (PP), polyethylene terephthalate (PET), or polytetrafluoroethylene (PTFE) fibers or blends of two or more of these fibers. Other hydrophobic fibers may also be used, according to further embodiments. The backing layer 34 may be a scrim construction, according to one embodiment. The backing layer 34 is air permeable and hydrophobic in that it allows air and sound waves to pass through, but blocks liquid, particularly the liquid adhesive, from leaking or bleeding through the backing layer 34 in the mold during manufacture. The backing layer 34 may have an airflow resistivity in the range of about 10 to 50 rayls before adhering to the headliner, according to one embodiment.
The various layers of the headliner 20 are formed together in a mold during manufacture. The layers of headliner 20 may be arranged one on top the other in a mold and cured. In doing so, the adhesive layers 24 and 30 are initially provided as a liquid adhesive which is cured during the molding process in the mold to form a solid adhesive that bonds the headliner layers together with the molded shape. The hydrophobic backing layer 34 advantageously prevents the liquid adhesive 30 from passing therethrough, but allows air and sound waves to permeate the hydrophobic backing layer 34.
The resulting headliner 20 advantageously allows air and sound waves to pass through the various layers and to acoustically absorb sound waves, particularly noise. Sound waves may pass from the bottom side upward through the headliner 20 as shown in
The thermoset polyurethane headliner 20 is air and sound permeable and is absorptive and hydrophobic such that air and sound waves are able to permeate through the headliner 20 and provide sound dampening while restricting liquid transmission. The headliner 20 achieves excellent noise, vibration and harshness (NVH) performance with a structure that is lightweight and exhibits sufficient strength characteristics. According to one embodiment, the headliner 20 has an airflow resistivity in the range of 700 to 3,000 rayls, and more preferably in the range of 700 to 2,700 rayls. Airflow resistivity is indicative of how absorptive the material is and is evaluated by determining how much air can pass through the material at a given volumetric flow rate. Air resistivity may be measured according to ASTM test method C522 “Standard Test Methods for Airflow Resistance of Acoustical Materials.”
Referring to
Accordingly, the acoustically absorptive vehicle headliner 20 provides the lightweight and strong structure that advantageously passes and dampens acoustic sound waves, such as noise, and blocks liquid transmission through the headliner 20. The block in liquid transmission prevents the liquid adhesive from leaking or bleeding through one or more layers of headliner 20 which prevents leakage of liquid adhesive in the mold and provides an enhanced appearance. The headliner 20 may be used in any of a number of vehicles to dampen acoustical sound generated within the vehicle and/or from outside the vehicle, such as wind and road noises to provide an aesthetically pleasing and quiet vehicle passenger compartment.
It is to be understood that variations and modifications can be made on the aforementioned structure without departing from the concepts of the present invention, and further it is to be understood that such concepts are intended to be covered by the following claims unless these claims by their language expressly state otherwise.
