Method and apparatus for attenuating sound waves in gas streams

Claim 1

A CYLINDRICAL EXHAUST PIPE FOR ATTACHMENT DIRECTLY TO THE EXHAUST MANIFOLD OF A VEHICLE ENGINE: (A) SAID EXHAUST PIPE HAVING A SUBSTANTIALLY UNIFORM DIAMETER FROM FRONT TO REAR AND HAVING A GENERALLY CONTINUOUS AND UNOBSTRUCTED OUTER SURFACE, (B) SAID EXHAUST PIPE BEING OF SUBSTANTIALLY LENGTH, (C) AT LEAST TWO SPACED SOUND ATTENUATING TUBES COAXIALLY WITHIN SAID PIPE, (D) SAID TUBES BEING CYLINDRICAL AND OPEN ENDED AND HAVING A UNIFORM OUTER DIAMETER THROUGHOUT THEIR LENGTH, (E) ONE OR SAID TUBES HAVING A RESTRICTION ON THE INSIDE THEREOF, (F) ANOTHER OF SAID TUBES HAVING A UNIFORM UNRESTRICTED INNER DIAMETER, (G) EACH OF SAID TUBES BEING SUPPORTED ADJACENT THEIR ENDS BY IMPERFORATE ANNULAR RINGS, (H) SAID ANNULAR RINGS, THE OUTER SURFACES OF SAID TUBES BETWEEN SAID RINGS, AND THE INNER SURFACES OF SAID PIPE BETWEEN SAID RINGS FORMING ANNULAR CHAMBERS, (I) SAID TUBES HAVING PERFORATIONS, IN THE OUTER SURFACES OF SAID TUBES BETWEEN SAID RINGS, OPENING INTO SAID CHAMBERS, (J) SAID TUBES BEING STRAIGHT THROUGHOUT THEIR LENGTH, AND (K) SAID PIPE IN THE AREA OF SAID TUBES BEING STRAIGHT.