Exhaust system for IC engine with two pre=silencer exhaust pipes

摘要

An engine that generates noise whose harmonic waves H of the order N equal to half the engines frequency of rotation F: Hx = 0.5*N*F (N=1,2,3...) and is fitted with two exhaust pipes (1,3) with different lengths, being united before going into the silencer (4), can be dimensioned in a way that harmonic waves will silence each other by interference. For that purpose the longer pipe (3) has to have a bigger cross-section than the shorter pipe (1). The ratio of the cross-section S3/S1 equals the ratio of the lengths L3/L1. A resonance chamber (7) can be fitted to the shorter exhaust pipe. In case the cross-sections of both exhaust pipes are equal, the distance L2 of the entry into the resonance chamber from the point (2) where both pipes unite equals the product of the cross-section S1, the volume of the resonance chamber V and half the difference of the squares of pipe lengths: L2=S1*V*(L3 power 2 - L1 power 2)/2.