F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
F01N1/00—Silencing apparatus characterised by method of silencing
F01N1/08—Silencing apparatus characterised by method of silencing by reducing exhaust energy by throttling or whirling
F01N1/084—Silencing apparatus characterised by method of silencing by reducing exhaust energy by throttling or whirling the exhaust gases flowing through the silencer two or more times longitudinally in opposite directions, e.g. using parallel or concentric tubes