Engine compartment casing element with perforated foam layer

An engine compartment casing element for sound absorption, comprising

• a wall element,
• a foamed material element adapted to cooperate with a wall element of the engine compartment, the foamed material element being perforated forming perforations extending completely through said foamed material element from each side thereof to the opposite side thereof, cross sectional dimensions of respective ones of said perforations being greater than or approximately equal to the depths of the respective perforations,
• a continuous air-impermeable foil in continuous contact with and covering each side of said foamed material element and also covering all said perforations which extend through the foamed material element to form a laminate, and
• wherein within said engine compartment, a region of said laminate extends continuously spaced apart from the wall element, and has a rigid curvature providing contact between a periphery of the laminate region and the wall element.

An engine compartment casing element for sound absorption, comprising:

• a foamed material element having perforations, the apertures extending through said foamed material element from each side thereof to the opposite side thereof, the foamed material element being flexible and having an inherent rigidity to be self-supporting, cross sectional dimensions of respective ones of said perforations being greater than or approximately equal to the depths of the respective perforations;
• a continuous air-impermeable foil contiguous to and covering each side of said foamed material element and also covering said perforations which extend through the foamed material element;
• wherein each of said air-impermeable foils is indented into each perforation of said foamed material element and flatly covers residual surface area of the foamed material element to form with said foamed material a laminate;
• and
• a region of said laminate has a curvature adapted to provide contact with an outer wall of said engine compartment along a periphery of said region while maintaining a spacing between said wall and a center of said region.

A method of absorbing sound present within a compartment bounded by a wall, the wall being reflective of sound waves, the method comprising the steps of:

• providing a perforated layer of foamed material, said layer providing step including a step of introducing a curvature to a region of said layer for offsetting said layer region from a corresponding region of said wall, said perforated layer having perforations opening at a first surface of said layer and at a second surface of said layer, said second surface being opposite said first layer, cross sectional dimensions of respective ones of said perforations being greater than or approximately equal to the depths of the respective perforations, a ratio of the total cross sectional areas of said perforations to the area of said foamed material element being approximately 24%;
• laminating a first and a second continuous air-permeable foil contiguous to respectively said first and said second surfaces of said layer to provide a laminate;
• placing said laminate upon a surface of said wall within said compartment, said curvature of said layer preventing contact of said laminate with said wall region except at a periphery of said layer region wherein contact is obtained between said laminate and said wall region, said placing step providing a composite structure of said laminate and said wall for absorption of sound within the compartment.