Control system for all-wheel drive vehicles

Abstract

To provide a control device of a whole wheel drive vehicle which can optimize a minimum transmission torque of a transfer clutch with respect to individual variation and aged deterioration or the like, can suppress the deterioration of fuel consumption and the deterioration of drivability by suppressing that a main drive wheel having a quicker rotation speed becomes minus torque excessively (more than necessary) in such a travel state that longitudinal difference is produced upon driving and a relation of "input torque<driven wheel transmission torque" holds (the travel state in which the main drive wheel having a quicker rotation speed can become a minus torque).SOLUTION: A TCU70, when predetermined learning conditions hold, gradually reduces an engagement force of a transfer clutch 41, gradually reduces a torque to be transmitted to rear wheels 10RL, 10RR (driven wheels), acquires a rear wheel transmission torque when the torque to be transmitted to front wheels 10FL, 10FR (main driving wheels) is changed from negative to positive as a learning value and corrects a minimum transmission torque of the transfer clutch 41 by using the learning value.SELECTED DRAWING: Figure 1

Claims

1. A transfer clutch adjusts the torque transmitted to the driven wheels according to the fastening force, The system includes a control unit that controls the engagement force of the transfer clutch based on the vehicle's operating conditions to adjust the torque transmitted to the driven wheels, The control unit is characterized in that, when predetermined learning conditions are met, it gradually reduces the torque transmitted to the driven wheels, acquires the torque transmitted to the driven wheels when the torque transmitted to the main drive wheels changes from negative to positive as a learned value, and uses the learned value to correct the minimum transmission torque of the transfer clutch.

2. The control unit for an all-wheel drive vehicle according to claim 1 is characterized in that it determines that the predetermined learning conditions have been met when the accelerator opening is greater than or equal to a predetermined opening, the change in vehicle speed is within a predetermined range, and the steering angle of the steering wheel is within a predetermined range.

3. The control device for an all-wheel drive vehicle according to claim 1 or 2, characterized in that the control unit stops acquiring the learned value if the torque transmitted to the primary drive wheel does not change from negative to positive even when the torque transmitted to the secondary drive wheel is reduced to a predetermined lower limit.

4. The control unit for an all-wheel drive vehicle according to any one of claims 1 to 3 is characterized in that it periodically performs learning and periodically acquires the learned values.

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