US Patent 9074522 Four-way exhaust gas valve

A four-way exhaust gas valve has a permanent inlet, a permanent outlet, a selectable inlet, a selectable outlet and a pivotable valve flap. The pivotable valve flap is arranged for switching between a first mode of operation, in which exhaust gas entering through the permanent inlet is guided directly to the permanent outlet, and a second mode of operation, in which exhaust gas entering through the permanent inlet is discharged through the selectable outlet and exhaust gas re-entering through the selectable inlet is discharged through the permanent outlet.