ACTIVE TORQUE CONTROL 4WD SYSTEM GENERAL


  1. OUTLINE


    1. This a compact, lightweight, and high performance active torque control 4WD system that optimally controls torque distribution to the front and rear wheels using an electromagnetic control coupling in the rear differential.

  2. MAIN FEATURES


    1. Active Torque Control 4WD


      1. Based on information provided by various sensors, the 4WD ECU assembly controls the amperage applied to the electromagnetic control coupling in order to transmit an appropriate amount of drive torque to the rear wheels when needed. The following describes the features and benefits of the active torque control 4WD:

        Traction performance Realizes stable start-off and acceleration performance.
        Driving stability performance Realizes stable cornering performance.
        Fuel economy Realizes better fuel economy by transmitting an appropriate amount of drive torque to the rear wheels when needed.

      2. An AWD lock switch has been provided. This enables the driver to select between the AUTO and LOCK modes by operating the switch. The system optimally controls the torque distribution to the front and rear wheels in the respective modes

        Mode AWD Lock Switch and Indicator Light Outline
        AUTO Off

        • Optimally distributes drive torque to the front and rear wheels.

        • Ensures optimal start-off performance during a start-off, based on information provided by various sensors.

        • Suppresses the tight corner braking phenomenon* during low-speed cornering.

        • Reduces the amount of torque distribution to the rear wheels and improves fuel economy when the system judges that the vehicle is traveling steadily.

        • Minimizes torque distribution to the rear wheels during braking deceleration.
        LOCK On

        • Distributes the maximum torque limit to the rear wheels.

        • Distributes the maximum torque limit to the rear wheels during start-off.

        • Distributes optimal torque during low-speed cornering.

        • Minimizes torque distribution to the rear wheels during braking deceleration.

        • Disengages the LOCK mode and transfers to the AUTO mode when the vehicle speed exceeds 25 mph (40 km/h).

        *: Tight corner braking phenomenon: a phenomenon in which a AWD vehicle may lurch and decelerate due to a rotational speed difference between the front and rear wheels, such as during low-speed cornering in AWD mode.

      3. The 4WD ECU assembly performs cooperative control with the skid control ECU, in order to control the drive torque distribution to the front and rear wheels in accordance with information received from the skid control ECU. These controls ensure a smooth acceleration and driving stability.

    2. Auto Mode


      1. Starting Off

        - The system ensures start-off performance by optimally distributing engine drive torque to the front and rear wheels.

        - To prevent the tight corner braking phenomenon from occurring during low-speed cornering, the system reduces the amount of torque distributed to the rear wheels.

        A019Q5WE01

      2. Normal Driving

        - During normal driving, when the system judges that the vehicle is traveling steadily, it reduces the amount of torque distribution to the rear wheels. This allows the vehicle to operate in conditions similar to front-wheel-drive, improving fuel economy.

        - The system optimizes torque distribution to the rear wheels to ensure both excellent straightline acceleration performance and excellent driving stability while cornering.

        A019PMRE01

    3. Lock Mode


      1. When the vehicle is being driven in gravel or sand, and more traction is required, the driver can select LOCK mode by operating the AWD lock switch. Thus, this mode achieves optimal control in accordance with the driving conditions and transmits as much drive torque as possible to the rear wheels, in a mode that is similar to the locked AWD mode.