Patent ID: 8700280
Filing Date: 2014-04-15
Classification: B60K,B60W

Abstract:
1. A four-wheel-drive vehicle comprising: a drive source configured to generate a driving force; a driving force transmitting device; left and right main drive wheels to which the driving force is always transmitted when the driving force of the drive source is transmitted; left and right auxiliary drive wheels to which the driving force is transmitted by the driving force transmitting device depending on a traveling state of the vehicle; a steering device configured to steer the left and right main drive wheels depending on an operation of a steering wheel; a steering angle sensor configured to detect a steering angle of the steering wheel; a control device configured to obtain the driving force to be transmitted to the auxiliary drive wheels, the control device comprising: a first straight travel determination unit configured to determine whether or not the vehicle travels straight based on a rotational speed difference between the left and right auxiliary drive wheels; a second straight travel determination unit configured to determine whether or not the vehicle travels straight based on the steering angle detected by the steering sensor; a selection unit configured to select one of determination results of the first straight travel determination unit and the second straight travel determination unit for determining whether or not the vehicle travels straight; a frictional coefficient estimation unit configured to estimate a frictional coefficient of a road surface on which the vehicle travels when the selected determination result indicates that the vehicle travels straight; and a driving force calculation unit configured to calculate the driving force to be transmitted to the auxiliary drive wheels based on the frictional coefficient estimated by the frictional coefficient estimation unit; and the driving force transmitting device configured to transmit the driving force to the auxiliary drive wheels in an amount equal to the calculated driving force.