Muffler controller for use in controllable exhaust system of internal combustion engine

In a controllable exhaust system of an internal combustion engine including an exhaust gas inlet tube extending from said engine, a muffler connected at its inlet side to said exhaust gas inlet tube and having first and second exhaust gas flowing passages defined therein, and first and second exhaust gas outlet tubes respectively connected to said first and second exhaust gas flowing passages and extending from said muffler independently,

• a muffler controller operatively connected to said second exhaust gas outlet tube for varying a flow passage area of said second exhaust gas outlet tube in accordance with a pressure of an exhaust gas entering the muffler from the engine, said muffler controller comprising:
• an actuator operatively connected to said second exhaust gas outlet tube and having a piston rod moving straightly and reciprocatively in accordance with a magnitude of the exhaust pressure in said muffler;
• and
• a valve assembly operatively connected to said second exhaust gas outlet tube and including a valve plate, a pivot shaft through which said valve plate is pivotally installed in said second exhaust gas outlet tube, an operation disc coaxially connected to said pivot shaft to rotate together with said pivot shaft and said valve plate, an elongate slot defined in said operation disc and extending radially with respect to a center of said operation disc, and a roller rotatably connected to said piston rod and slidably received in said elongate slot.