Patent ID: 7537083

Claim:
A silencer with a casing and at least one inlet passage for leading gas into said casing, and at least one outlet opening for leading gas out of said casing, said silencer containing: at least two acoustic chambers contained in the casing; at least one porous body inside at least one of said chambers, said at least one porous body comprising a through-flow filter occupying at least part of the chamber, wherein said at least one porous body is designed to retain particles contained in the gas, or said at least one porous body having interior surface parts which are adapted to be in contact with the gas, the interior surface parts carrying a catalytic material promoting one or more chemical reactions reducing noxious components of said gas; and two or more connecting passages for leading gas from one of the at least two acoustic chambers to another of the at least two acoustic chambers, wherein at least part of at least one of said connecting passages extends along an outer surface of the porous body, so as to lead gas along a helical flow path and cover at least 50% of the surface area of said outer surface area of the porous body, wherein said two or more passages lead gas in two or more parallel flows, and are created by insertion of one or more division members or walls inside an annular spacing.