Sequential supercharged diesel engine hydraulic device based on waste gas utilization and control method

The invention provides a sequential supercharged diesel engine hydraulic device based on waste gas utilization and a control method. The sequential supercharged diesel engine hydraulic device comprises a fuel feed pump, a hydraulic pump, a speed reducing mechanism, a controlling supercharger, a controlled supercharger, a first hydraulic motor, a second hydraulic motor and a diesel engine. The fuel feed pump communicates with the hydraulic pump; the hydraulic pump and the speed reducing mechanism are connected and then mounted on the controlling supercharger; the first hydraulic motor is disposed on the controlled supercharger; the second hydraulic motor is mounted at the front end of an auxiliary propulsion force crankshaft of the diesel engine; a first bypass valve and a second bypass valve are arranged in the position of the first hydraulic motor and the position of the second hydraulic motor in a parallel connection mode correspondingly; a control unit is further disposed on a fuel pipe between the hydraul