| TUCSON(LM) >2011 > G 2.0 DOHC > 4 Wheel Drive (4WD) System > Coupling Assembly > Direct Electro Hydraulic Actuator Coupling (2010-12-01~)>Description and Operation |

Description
4WD ECU processes signals from various sensors and determines the current road and driving conditions. The ECU then utilizes this information to implement precision control over the 4WD coupling's multi-plate clutch and variably adjust the amount of torque delivered tothe rear wheels. Four Wheel Drive (4WD) transfer mode selection
1. | AUTO MODE:
A. | When driving in 4WD AUTO mode, the vehicle operates similar to conventional 2WD vehicles under normal operating conditions. However, if the system determines that there is a need for the 4WD mode, the engine’s driving power is distributedto all four wheels automatically without driver intervention.
B. | When driving on normal roads and pavement, the vehicle moves similar to conventional 2WD vehicles.
2. | LOCK MODE:
A. | This mode is used for climbing or descending sharp grades, off-road driving, driving on sandy and muddy roads, etc., to maximize traction.
B. | This mode automatically begins to deactivate at speeds above 30 km/h (19 mph) and is shifted to 4WD AUTO mode at speed above 40 km/h (25 mph). If the vehicle speed decelerates to below 30 km/h (19 mph), however, the transfermode is shifted into 4WD LOCK mode again.
Electronic Coupling - 4WD Control (By Driving Condition)
1. | Cruising (Auto Mode) - Power is delivered mostly to the front wheels.
2. | Cornering (Auto Mode) - Adjusts the amount of power to the rear wheels based on the turning radius and cornering speed.
3. | Wheel Slip (Auto Mode) - If one or both of the front wheels lose traction, the system transfers an appropriate amount of power to the rear wheels based on the slip amount at the front wheels.
4. | Lock Mode - Maximizes rough terrain performance (active only at speeds below 40 km/h).
Operation
Electronic Coupling
[Inactive] [Active]
Operation Order
1. | 4WD ECU receives CAN signals from the vehicle's sensors.
2. | 4WD ECU calculates the necessary amount of rear-wheel torque and sends the corresponding driving current to the actuator (electronic motor and hydraulic pump).
3. | Hydraulic pressure generated by the actuator moves the piston.
4. | Friction from the piston's movement engages the clutch.
5. | Power is delivered to the rear wheels.