Variable Gear Ratio Steering System -- System Description |
| GENERAL DESCRIPTION |
The VGRS (Variable Gear Ratio Steering) system controls the steering angle in accordance with vehicle speed. The system is controlled by the steering control ECU which operates the steering actuator mounted on the steering intermediate shaft. The operating angle of the steering actuator is added to the steering angle of the intermediate shaft in order to vary the turning angle of the front wheels in accordance with vehicle speed.
When the VGRS system is operating normally, the steering wheel can be turned approximately 2.7 turns from lock to lock, with the engine running and the vehicle stopped.
If a malfunction occurs in the VGRS system, steering actuator operation will immediately stop and the input and output shafts will be directly connected to enable the conventional steering mechanism to operate, maintaining steering function (fail-safe). At the same time, the master warning light (VGRS) will come on to inform the driver of the malfunction.
| FUNCTIONS OF COMPONENTS |
Functions of VGRS system components
Component Function Steering Control ECU Calculates the steering gear ratio based on tire angle signals and vehicle speed signals. Drives the steering actuator based on calculation results of steering cooperative control received from the skid control ECU, and of steering gear ratio control. Steering Actuator Drives the motor using the output current from the steering control ECU to change the output shaft angle. Rotation Angle Sensor Outputs the motor rotation angle to the steering control ECU. Steering Angle Sensor Outputs the steering wheel angle to the steering control ECU. Master Warning Light Located on the combination meter ECU. Comes on or blinks in accordance with system conditions to inform the driver of system malfunctions. Multi-information Display Located on the combination meter ECU. Displays a warning message to inform the driver of system malfunctions.