Transfer Case: Description and Operation

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










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

1. GENERAL DESCRIPTION

(a) The Active Torque Control 4WD system detects the driving conditions based on signals from each ECU and the wheel speed 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. REFERENCE MECHANISM

(a) Electromagnetic control coupling

(1) The outer part of the main clutch is attached together with the front housing. The inner part of the main clutch is attached together with the shaft. The control clutch is attached together with the control cam. The activation energy from the transfer is transferred from the propeller shaft to the front housing. However, when the linear solenoid is not operating, the main clutch and control clutch are in a free state, and the activation energy from the transfer is not transferred to the rear wheels.





(2) If current is applied to the linear solenoid, the solenoid magnetizes, and the electromagnet pull force causes the armature to attach to the control clutch side. Or, if there is a difference between the rotation speed of the front and rear wheels and the control clutch attaches, a difference occurs in the rotation of the main cam attached to the shaft and the control cam attached to the front housing. As a result, each ball pushes its cam, and the main clutch attaches. The activation energy from the front housing passes through main clutch to the shaft, and then to the rear differential. Then the activation energy is transferred to the rear wheels.





(3) Depending on the rotation difference between the front and rear wheels, the system controls the current flowing to the linear solenoid. Then the activation energy applied to the rear wheels is smoothly controlled. Depending on the amount of current, the restraint energy of the outer and inner side of the main clutch changes, and the activation energy from the propeller shaft is smoothly controlled from a limited condition to condition that is nearly a direct-link 4WD condition.