Muffler apparatus

Claim 1

A MUFFLER FOR AN INTERNAL COMBUSTION ENGINE HAVING EXHAUST MEANS, WHICH ENGINE IS OPERABLE IN A RANGE OF SPEEDS AND VIBRATES DURING OPERATION AT A FREQUENCY PROPORTIONAL TO ENGINE OPERATING SPEED, SAID MUFFLER COMPRISING WALL STRUCTURE DEFINING AN EXPANSION CHAMBER, INLET MEANS CONNECTABLE TO SAID ENGINE EXHAUST MEANS FOR ADMITTING EXHAUST GAS FROM SAID ENGINE EXHAUST MEANS TO SAID CHAMBER, A PLURALITY OF OUTLET MEANS FOR GAS BEING DISCHARGED FROM SAID CHAMBER, A FIRST VALVE OPERATIVELY ASSOCIATED WITH ONE OF SAID OUTLET MEANS, A SECOND VALVE OPERATIVELY ASSOCIATED WITH THE OTHER OF SAID OUTLET MEANS, EACH OF SAID VALVES BEING RESILIENTLY MOUNTED ON RIGID STRUCTURE AND BEING VIBRATORILY MOVABLE BETWEEN OPEN AND CLOSED POSITIONS WITH RESPECT TO ITS ASSOCIATED OUTLET MEANS WHEN VIBRATORILY EXCITED, THE NATURAL FREQUENCIES OF VIBRATION OF SAID FIRST AND SECOND VALVES BEING APPRECIABLY DIFFERENT WHEREBY SAID FIRST VALVE IS VIBRATORILY EXCITABLE IN ONE FREQUENCY RANGE AND SAID SECOND VALVE IS VIBRATORILY EXCITABLE IN ANOTHER FREQUENCY RANGE, AND MEANS FOR TRANSMITTING VIBRATIONS OF SAID ENGINE FROM SAID ENGINE THROUGH THE RIGID STRUCTURE ON WHICH SAID VALVES ARE SUPPORTED TO SAID VALVES, SAID FIRST VALVE BEING OPERABLE BY THE VIBRATIONS OF SAID ENGINE IN ONE PORTION OF THE ENGINE SPEED RANGE AND SAID SECOND VALVE BEING OPERABLE BY THE VIBRATIONS OF SAID ENGINE IN ANOTHER PORTION OF THE ENGINE SPEED RANGE.