Exhaust purification device for internal combustion engine, and exhaust control device and exhaust control method for internal combustion engine

An exhaust purification device for an internal combustion engine, comprising:

• a front catalyst provided in an exhaust passage of an exhaust system of the internal combustion engine that is longitudinally mounted in a vehicle;
• a rear catalyst arranged in series with the front catalyst, provided in the exhaust passage of the exhaust system downstream of the front catalyst;
• and
• a bypass pipe that communicates with the exhaust passage of the exhaust system upstream of the front catalyst, and communicates with the exhaust passage between the front catalyst and the rear catalyst, wherein
• the bypass pipe is arranged at a position that is spaced apart from the exhaust passage in a direction perpendicular to a vibration direction of the exhaust system that vibrates by a vibration of the internal combustion engine,
• the bypass pipe includes a first bypass passage that communicates with the exhaust passage upstream of the front catalyst and is extended in a direction perpendicular to a vibration direction in which vibration of the exhaust system is largest, a second bypass passage that communicates with the exhaust passage between the front catalyst and the rear catalyst and is extended in the direction perpendicular to the direction in which vibration of the exhaust system is largest, and a third bypass passage that connects the first bypass passage with the second bypass passage, and
• a flexible pipe is disposed in the exhaust passage between the first bypass passage and the second bypass passage.