FIELD: mechanical engineering; internal combustion engines. SUBSTANCE: proposed muffler has cylindrical housing with end face walls in which inlet, outlet and several additional chambers are formed by cross partitions, inlet and outlet branch pipes arranged coaxially with housing cylinder and intermediate branch pipes whose spaces are connected to spaces of corresponding chambers by means of open cuts and through perforated sections. Muffler has also preliminary expansion chamber with inlet branch pipe adjoining muffler inlet chamber whose geometric parameters provide more effective noise damping in medium frequency sound range. Inlet branch pipe of preliminary expansion chamber of muffler is mounted in its side wall so that dynamic cut of inlet branch pipe is located at equal distances from end face wall and cross partition of preliminary expansion chamber at angle to axis of housing cylinder so that imaginary extension of section of inlet branch pipe along its axis does not intersect wall of housing inlet branch pipe and outlet dynamic cut of inlet branch pipe is located in node zone of minimum values of sound pressure levels of second radial natural resonance waveforms of sound pressure of volume of gas enclosed in space of muffler preliminary expansion chamber. Section of outlet branch pipe is arranged along axis of preliminary expansion chamber over its entire length and is provided with through perforation holes whose summary passage area is not less than 1.4 F where F is area of section of outlet cut of inlet branch pipe. EFFECT: improved acoustic efficiency of muffler. 9 dwg
