Silencer for an internal combustion engine

Claim 1

A silencer for an internal combustion engine comprising: a tubular main silencer having inlet means at one of its axial ends for connection to an exhaust pipe of said engine, an outlet at the other axial end thereof for the exhaust of combustion gases from said engine, a progressively increasing diameter from the inlet means end to the outlet end for accommodating and silencing the exhaust of gases from said engine when said engine is operating in a high speed range, and an annular conical seat interiorly defined at the inlet end; a tubular secondary silencer entirely positioned interiorly within the main silencer and fixedly supported therein, the secondary silencer having an inlet end and, a substantially constant diameter throughout its length for accommodating and silencing the exhaust of gases from said engine in conjunction said main silencer when said engine is operating in a low speed range; a tubular member slidably supported within a tubular portion of the inlet end of the secondary silencer and axially movable between a first position in which it receives the entire flow of gases from said engine and directs them totally into the secondary silencer and a second position in which said exhaust gases can pass direct by into said main silencer, said tubular element including an annular conical portion at its end adjacent said inlet means of said main silencer which is sealingly received in said conical seat when said tubular member is in said first position; and means for moving said tubular member between said first and second positions to change the exhaust characteristics of said silencer.