Patent ID: 8302393

Claim:
An exhaust system ( 1 ) for an internal combustion engine and comprising: at least one first high acoustic attenuation path (P 1 ) having a first inlet opening ( 2 ) and comprising a muffler ( 8 ); at least one second low acoustic attenuation path (P 2 ) having a second inlet opening ( 3 ) and being free from elements or paths suitable for acoustic muffling; and at least one control valve ( 4 ), which is arranged at the second inlet opening ( 3 ) of the second path (P 2 ) for controlling the flow of the exhaust gases along the second path (P 2 ), wherein the control valve ( 4 ) comprises: a baffle ( 12 ) which forms a wall of an exhaust gas passage pipe when is in a closing position of the second inlet opening ( 3 ); a shaft ( 13 ) which is mounted to rotate about a rotation axis ( 14 ) and supports the baffle ( 12 ) in order to rotate the baffle ( 12 ) itself between the closing position of the second inlet opening ( 3 ) and an opening position of the second inlet opening ( 3 ); and an elastic body ( 15 ), which is mechanically coupled to the shaft ( 13 ) to push the baffle ( 12 ) towards the closing position with an elastic force calibrated according to the area of the baffle ( 12 ) struck by the exhaust gases and to the working pressure of the exhaust gases, so that when the exhaust gas pressure exceeds a predetermined threshold value, the pneumatically originated force generated by the pressure of the exhaust gases on the baffle ( 12 ) is higher than the elastic force generated by the elastic body ( 15 ) and the baffle ( 12 ) moves to the opening position; and wherein the first path (P 1 ) comprises at least one first tail ( 9 ), which originates from the muffler ( 8 ); the second path (P 2 ) comprises at least one second tail ( 11 ), which is arranged by the side of the first tail ( 9 ) and is directly connected to the second inlet opening ( 3 ) by means of a first connecting pipe ( 10 ); the control valve ( 4 ) comprises a chamber ( 5 ) in which the baffle ( 12 ) is accommodated; and an initial end of the first connecting pipe ( 10 ) is arranged inside the chamber ( 5 ) of the control valve ( 4 ) and forms the second inlet opening ( 3 ) of the second path (P 2 ).