Auto electric power assisted steering system

The utility model discloses an auto electric power assisted steering system, set up electric motor rotor assembly (6) in motor stator assembly (4), these electric motor rotor assembly (6) are fixed mutually with spin nut (7), wear to locate steering gear casing (2) with spin nut (7) matched with rack spin lead screw (8), in electric motor rotor assembly (6) and the right-hand member lid (5), rack spin lead screw (8) is located to be controlled between two steering linkage (3), the tip of rack spin lead screw (8) is fixed mutually with steering linkage (3) that correspond, the left end of rack spin lead screw (8) is the rack structure, and mesh mutually with the lower extreme of input shaft (1), torque sensor (9) are equipped with on input shaft (1). The utility model discloses a coaxial motor and spin nut pair combine together, make a steering system realize the helping hand performance, and the helping hand bang path is short and direct, and system's rigidity is good, and the assembly is convenient for arrange based on whole car, can guarantee the reliability of system's helping hand and the ability of system's helping hand effectively