Transfer Case: Description and Operation

POWER FLOW MECHANISM





^ Normal driving situation: 2WD base driving
^ 4WD driving in driving situations (rapid activation, cornering etc.)
^ Input the information from each sensor in vehicle
- Input torque (Throttle position sensor)
- Cornering situation (Steering angle sensor)
- Vehicle speed and different wheel speed front & rear (Wheel speed sensor)
- Braking situation (Brake signal and ABS signal)
^ Distributed the required driving force after 4WD ECU operates. EMC (Electric Magnetic Clutch) operates the primary clutch.





^ Control the cam's opening gap by operation of primary clutch.





^ Control the slip of inner & outer plate. Control variably the driving force distribution to optimize front & rear driving force.





SYSTEM SCHEMATICS

ITM CONTROLLER





1. NON-ABS controller





2. ABS/TCS controller





3. ESP controller

LOCK MODE DESCRIPTION





^ Based on a driver request for lock mode, the system will supply a fixed torque to the ITM-1 clutch.
^ When the vehicle exceeds 30KPH the system will begin to disable lock mode by ramping down the ITM clutch torque. When the vehicle exceeds 40 KPH the ITM clutch is reduced to its minimum torque value. Lock mode is re-enabled following the same speed-to-torque map.
^ Lock mode is activated based on part number.
^ Lock mode will override all other system requests except for during an ABS event. During an ABS event the ITM clutch is turned off.
^ If there is a speed sensor signal fault, the speeds are no longer considered reliable and lock mode will be disabled.

CONTROL ALGORITHM FLOW CHART





The base control algorithm of the ITM ECM is defined by the flow chart.