VARIABLE GEAR RATIO STEERING SYSTEM SYSTEM DESCRIPTION


  1. GENERAL DESCRIPTION


    1. The variable gear ratio steering (VGRS) system controls the steering angle in accordance with vehicle speed. The system is controlled by the VGRS ECU (front steering control ECU) which operates the steering actuator assembly mounted on the No. 2 steering intermediate shaft assembly. The operating angle of the steering actuator assembly is added to the steering angle of the pinion gear in order to vary the turning angle of the front wheels in accordance with vehicle speed.

    2. The VGRS ECU (front steering control ECU) sends rear wheel turning angle control signals to the DRS ECU (rear steering control ECU).

    3. If a malfunction occurs in the VGRS system, steering actuator assembly operation immediately stops and the input and output shafts are directly connected to enable the conventional steering mechanism to operate, maintaining the steering function (fail-safe). At the same time, the master warning light comes on to inform the driver of the malfunction.

  2. FUNCTIONS OF COMPONENTS


    1. Functions of VGRS system components

      Component Function
      Steering actuator assembly Motor Rotates to create the operating angle of the steering actuator assembly upon receiving the signals from the VGRS ECU (front steering control ECU).
      Lock Solenoid Locks the motor shaft so that the motor will not rotate in case of a system malfunction.
      Rotation Angle Sensor Outputs the rotational angle of the motor to the VGRS ECU (front steering control ECU).
      Combination Meter Assembly Multi-information display Displays the warning message to inform the driver of a malfunction in the system.
      Master warning light Illuminates when the warning message is displayed in the multi-information display.
      VGRS ECU (Front Steering Control ECU)

      • Operates the motor by calculating the operating angle of the steering actuator assembly based on the signals from the steering sensor and each ECU.

      • Sends the control signal to the DRS ECU (rear steering control ECU).
      DRS ECU (Rear Steering Control ECU) Drives the DC motor of the rear steering link assembly in accordance with a rear wheel turning angle signal from the VGRS ECU (front steering control ECU).
      Steering sensor Detects the steering direction and angle of the steering wheel.