Forward and reverse screw shuttle type free piston engine

The invention discloses a positive and negative screw shuttle type free piston engine which comprises a cylinder body and a rotating shaft, rotating drums are fixedly arranged on the rotating shaft at intervals, spiral grooves are formed in the outer surfaces of the rotating drums, pistons are arranged between the rotating drums and the cylinder body, driving blocks are arranged on the surfaces of inner round holes of the pistons, and the driving blocks are movably embedded into the spiral grooves respectively. Four baffles are arranged on the surface of the outer circle of the piston at intervals, a sealing ring is arranged on the outer circle of each baffle, guide grooves are formed in the upper end and the lower end of an inner round hole of the cylinder body along the axis of the rotating shaft, guide blocks movably matched with the guide grooves are arranged on the baffles along the axis of the rotating shaft, and partition plates staggered with the baffles are arranged on the inner round hole of the cyl