Pneumatic fuel oil hybrid power system for recycling waste heat of internal-combustion engine

The utility model relates to a pneumatic fuel oil hybrid power system and provides a pneumatic fuel oil hybrid power system for recycling waste heat of an internal-combustion engine. The system comprises fuel oil cylinders and a pneumatic cylinder. Two fuel oil cylinders and one pneumatic cylinder are used as a power unit of the system, wherein exhaust valves of the fuel oil cylinders are both connected to an inlet valve of the pneumatic cylinder through an exhaust pipe and the two fuel oil cylinders have reverse stroke directions. The utility model directly guides the exhausted gas of the fuel oil cylinder into the pneumatic cylinder so as to swell secondarily, directly uses the heat energy and pressure of the exhausted gas, and solves the problem of low energy grade by using other methods to recycle the waste heat. An air valve is added on the pneumatic cylinder which can supply pressure when the exhausting pressure of the fuel oil cylinder is over-low, so as to avoid the compressing negative work for low-pressure exhaustion in the process of secondarily swelling. The inlet and outlet valves are electronically controlled, therefore the phase precision is matched and the overall efficiency is extremely optimized.