Transfer Case: Description and Operation

MF1A TRANSFER / 4WD / AWD: ACTIVE TORQUE CONTROL 4WD SYSTEM: SYSTEM DIAGRAM









SYSTEM DESCRIPTION

1. GENERAL DESCRIPTION

(a) The active torque control 4WD system detects the driving conditions based on signals from each ECU, each switch, the steering angle sensor, the wheel speed sensor, and the yaw rate sensor. The system controls the electronic current passing through the linear solenoid of the electromagnetic control coupling, and performs electronic control to distribute the optimum torque to the rear wheels.





(b) Main components and their functions.





2. DRIVING FUNCTION





3. OPERATION

(a) AWD Mode

(1) The drive force is transmitted from the propeller shaft to the front housing.

(2) The 4WD ECU assembly judges whether it is necessary to send drive torque to the rear wheels based on input from various sensors. When it is necessary to send drive torque to the rear wheels, the electromagnetic solenoid is operated.

(3) The electromagnetic solenoid attracts the armature to the control clutch side. This causes the control clutch to engage and the cam to rotate.

(4) The rotational movement of the cam causes the piston to push on the main clutch, causing the main clutch to engage.





(5) The amount of drive force that is transmitted to the rear wheels is controlled steplessly by controlling the amperage that is applied to the electromagnetic solenoid.

(6) Accordingly, drive force from the propeller shaft is transmitted to the rear wheels.