Patent ID: 7516006

Claim:
A control method for a four-wheel drive vehicle, comprising the steps of: detecting an unstable condition of said vehicle during turning of said vehicle; switching auxiliary drive wheels from an increasing speed condition to a same speed condition with respect to main drive wheels when said unstable condition of said vehicle is detected; and switching an outer wheel of said auxiliary drive wheels, which is on an outer side of said vehicle relative to a center of turning, from an increasing speed condition to a same speed condition with respect to an inner wheel of said auxiliary drive wheels, which is on an inner side of said vehicle relative to said center of turning, when said unstable condition of said vehicle is detected, wherein said vehicle comprises: said main drive wheels connected to a driving source, said auxiliary drive wheels whose drive torque is adjustable, and a speed increasing mechanism capable of switching between said same speed condition and said increasing speed condition for said auxiliary drive wheels with respect to said main drive wheels and capable of switching between said same speed condition and said increasing speed condition for said outer wheel of said auxiliary drive wheels with respect to said inner wheel of said auxiliary drive wheels.