Sound-insulated flow duct and process for the manufacture thereof
AssigneesDynamit Nobel Aktiengesellschaft, Helmut Rehlen, Jurgen Roellinghoff
InventorsHans-Ulrich Breitscheidel, Cosmas Lorry, Helmut Rehlen, Jurgen Roellinghoff
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Abstract
A sound-insulated flow duct is provided with walls made up of a composite of an elastic thermoplastic, predominantly closed-cell foam material as the outer layer and an open-cell, elastic soft foam material as the inner layer.
Claims19
A sound-insulated flow duct for conveying gas therethrough which comprises a shape-retaining member having walls to define a gas passage and that are formed from a composite comprising an outer molded layer of an elastic thermoplastic, closed-cell foam material and an inner non-molded layer of an open-cell, elastic soft foam material;
- said inner layer having an inner surface exposed to the gas passing through said passage and an outer surface bonded to said outer layer;
- the inner surface of the inner layer being sealed partially with an air permeable-skin so that the inner layer is air-permeable in a controlled manner.
A sound-insulated flow duct for conveying gas therethrough which comprises a shape-retaining member having walls that define a gas passage and that are formed from a composite comprising an outer molded layer of an elastic thermoplastic, closed-cell foam material and an inner non-molded layer of an open-cell, elastic soft foam material;
- said inner layer having an inner surface exposed to the gas passing through said passage and an outer surface bonded to said outer layer;
- the inner surface of the inner layer being uncovered and being provided with a profiled configuration in order to optimize sound absorption in predetermined frequency ranges.
A sound-insulating flow duct for directing the flow of gas therethrough, which comprises a shape-retaining composite member having a preformed configuration and having inner wall surfaces that define a gas passage for the flow of gas;
- said composite member comprising an outer layer of an elastic closed-cell foam of crosslinked polyolefin molded to provide said preformed configuration and an inner layer of an open-cell elastic polyurethane foam;
- said inner layer having inner surfaces providing the inner wall surfaces that define said gas passage and outer surfaces that are bonded to said outer layer to conform to said preformed configuration;
- said inner layer constituting a primary sound absorber that acts as a resonance absorber and the outer layer constituting a secondary sound absorber that absorbs the resonance generated by vibrations of the open-cell foam forming the inner layer;
- the inner surfaces of the inner layer being sealed partially with an air-permeable skin so that the inner layer is air-permeable in a controlled manner.
Dependencies are inferred from the claim text.