VARIABLEELENGTH EXHAUST PIPE FOR TWOOCYCLE ENGINE

摘要

PURPOSE:To apply reflective pulsation to an exhaust port at appropriate time in high and low speed revolution, prevent blowing-through and improve the performance of an engine, by altering the length of an exhaust pipe depending on the revolution speed of the engine. CONSTITUTION:A rotor d is rotated manually or automatically by a mechanism such as a governor depending on the revolution speed of an engine A. Setting is effected so that the communication passages d1, d2 of the rotor d correspond to communication holes c1, c2, c1', c2' in slow revolution. In that case, the ends of an exhaust pipe b1 connected to a switching chamber communicate with an accessory passage pipe 4 through the communication holes d1, d2 so that the exhaust pipe becomes a long exhaust passage extending from an exhaust port 1 to an expansion pipe b2. The return of reflective pulsation to the exhaust port 1 through the exhaust passage is decelerated so that the reflective pulsation acts to the exhaust port 1 at appropriate time, namely, synchronously with blowing-through. In rapid revolution, the rotor d is rotated in reverse by 180 deg. to define a short exhaust passage to cause action inverse to that described above.