Combination exhaust conduit and muffler

Claim 1

A CONDUIT FOR CONVEYING AND ATTENUATING THE NOISE LEVEL IN GASES COMPRISING: A RIGID IMPERFORATE TUBULAR MEMBER HAVING A GENERALLY UNIFORM OUTSIDE DIAMETER AND AN INTERNAL PASSAGE OF GENERALLY UNIFORM CROSS SECTION THROUGHOUT ITS LENGTH WITH AT LEAST ONE BEND THEREIN, A FLEXIBLE HELICALLY WOUND STRIP OF M ETAL HAVING A WIDTH CONSIDERABLY GREATER THAN ITS THICKNESS POSITIONED IN SAID INTERNAL PASSAGE OF SAID RIGID TUBULAR MEMBER WITH THE WIDTH OF THE STRIP OF METAL FORMING SUCCESSIVE COILS EXTENDING PARALLEL TO THE SIDEWALLS OF SAID RIGID TUBULAR MEMBER, SAID HELICALLY WOUND STRIP BEING SPACED RADIALLY INWARDLY FROM THE WALL OF SAID RIGID TUBULAR MEMBER TO PROVIDE AN ANNULAR SPACE OF APPRECIABLE VOLUME THEREBETWEEN, AND MEANS SUPPORTING SAID HELICALLY WOUND STRIP FROM THE SIDEWALLS OF SAID RIGID TUBULAR MEMBER WITHOUT MATERIALLY REDUCING THE VOLUME OF AIR CAPABLE OF BEING CONTAINED IN SAID ANNULAR SPACE, SAID MEANS RESTRICTING AXIAL FLOW OF GASES THROUGH SAID ANNULAR SPACE, AND SAID COILS OF SAID HELICALLY WOUND STRIP BEING SPACED APART SUFFICIENTLY TO PROVIDE COMMUNICATION FOR GAS FLOW BETWEEN SAID INTERNAL PASSAGE OF SAID HELICALLY WOUND STRIP AND SAID ANNULAR SPACE AND BEING SUFFICIENTLY CLOSE TOGETHER TO PRODUCE A THROTTLING EFFECT FOR SAID GAS FLOW.