Abstract: An exhaust manifold for conducting heated exhaust gas from an internal combustion engine to an exhaust system. The exhaust manifold includes a preform and a metal layer enclosing the preform. The preform has an inner layer of silicon carbide, a middle layer of insulating material, and an outer layer to seal the middle layer from molten metal used to form the metal layer.

Abstract: A vibration-damping laminate having a constraining layer secured to a viscoelastic layer. The constraining layer includes a mat of non-thermoplastic fibers. The viscoelastic layer includes a thermoplastic elastomer.

Abstract: A constrained layer damping structure is provided, including a panel to be damped, a constraining layer and a layer of foam vibration damping material sandwiched therebetween. The foam vibration damping material is provided from a composition including 1-20 weight percent elastomeric polymer, 20-60 weight percent thermoplastic polymer, 0.5-18 weight percent tackifier, 4-23 weight percent asphalt filler, 20-50 weight percent inorganic filler and 0.2-7 weight percent blowing agent.

Abstract: A damped heat shield for a high temperature portion of a vehicle exhaust system. The heat shield has inner and outer metal layers of substantially different thicknesses and substantially different resonant frequencies, which causes the shield to damp vibrational energy and reduce radiated sound energy and noise. Between the metal layers is a layer of sound and heat shielding material such as aluminum foil or ceramic fiber paper. The metal layers are preferably stainless steel, cold rolled steel, aluminized steel, aluminum-clad steel, or aluminum. If cold rolled steel is used, the exterior of the shield is preferably coated with a corrosion-resistant coating.

Abstract: A damped heat shield for a vehicle exhaust manifold includes inner and outer thin steel layers. An intermediate aluminum layer is located between the two steel layers. A high temperature corrosion-resistant coating is applied to the exterior surfaces and the edges of the shield. Such coating along the edges prevents the entry of corrosion producing substances into the interior of the shield. The outer steel layer has a thickness greater than the inner steel layer, so that the two layers do not resonate at the same frequency, and therefore, tend to damp vibrational energy more efficiently and reduce radiated sound energy and noise.

Abstract: A method for making a sound-dampened automotive enclosure, such as an oil pan, having a metal constraining layer, a metal housing layer, and a viscoelastic layer sandwiched therebetween. In a preferred embodiment, the constraining layer and viscoelastic layer are between the housing layer and the die while the housing layer is being drawn. This results in a very close and snug fit between the layers, leading to enhanced sound-dampening effectiveness. The article thus produced is also disclosed.

Abstract: A damped heat shield for a vehicle exhaust manifold includes inner and outer thin steel layers. An intermediate aluminum layer is located between the two steel layers. A high temperature corrosion-resistant coating is applied to the exterior surfaces and the edges of the shield. Such coating along the edges prevents the entry of corrosion producing substances into the interior of the shield. The outer steel layer has a thickness greater than the inner steel layer, so that the two layers do not resonate at the same frequency, and therefore, tend to damp vibrational energy more efficiently and reduce radiated sound energy and noise.

Abstract: The invention concerns a method of using constrained layer sound damping. A composition and a laminated structure are provided for the reduction of noise coming from housings such as oil pans for automobiles. The composition comprises a rubbery polyurethane, an olefin polymer, and a filler. The laminated structure comprises the housing, the composition, and a sheet metal liner. The composition contains a blowing agent which is activated to provide a single unitary structure which dampens noise. The polyurethane and olefin polymer are thoroughly intermixed with each other, but maintain their separate identities in the blend.