Description of 4WD Control System Component Function

1)When driving force of rear wheels is not necessary, no electric current is applied to electromagnetic coil (5) and main clutch (1) and control clutch (2) are not engaged. Thus, front housing (3) and shaft (4) are free from each other and power from transfer is not transmitted to rear differential.

2)When 4WD control module (1) judges necessity of rear wheel driving force based on driving conditions, appropriate electric current (2) is applied to electromagnetic coil (3). The electric current flow in electromagnetic coil creates magnetic field (4) in magnetic path thus armature (5) is pulled to electromagnetic coil side.

3)Control clutch (2) is pressed by armature (1) and control torque (3) is created in control clutch. The control torque is controlled changing electric current flow.

4)Rotating force of front housing (2) is transmitted to control cam (3) and creates control torque (1), and the control torque generates rotational angle difference between control cam and main cam (5) which is combined with shaft (4). This rotational angle difference brings control cam – main cam distance to extend by ball, thereby causing thrust power (6) to create. Due to the created thrust power, control cam – main cam is separated more, therefore main cam moves to the front side (in thrust direction), which creates the main clutch (7) to engage. On the other hand, control cam does not move to the rear side because reaction force of the thrust power (8) is held by thrust bearing (9) and the force is canceled. Thus, control clutch (10) functions to create accurate thrust power in proportion to control torque, electric current supplied from 4WD control module.

5)Main clutch (4) is pressed by thrust power (3) which is converted between control cam (1) and main cam (2), and front driving torque is transmitted to rear differential thus 4WD is set. Further, electric current control for electromagnetic coil (5) optimizes rear wheel driving force.