Steering angle ratio control system and method

摘要

A steering angle ratio control system is provided which includes a steering angle ratio varying mechanism (3; 3') capable of varying a steering angle ratio by an electric drive unit (9), and a controller (13) for controlling the steering angle ratio varying mechanism (3; 3') based on a steering angle ratio determined by a steering angle ratio determining section. The controller (13) includes an electric drive unit overheat protecting section (S8, S9, S10) that determines, when the temperature (TM) of the electric drive unit (9) rises beyond a predetermined temperature (T1), a smaller steering angle ratio as compared with a steering angle ratio determined thereby when the temperature (TM) of the electric drive unit (9) is lower than the predetermined temperature (T1). A steering angle ratio control method is also provided.