Vehicle drive force control device

A driving force control system for a vehicle having a starting clutch between an electric motor and drive wheels in which a driving force may be controlled by a transfer torque capacity of the starting clutch when the vehicle is in a motor wet start clutch mode, and a first clutch disposed between the engine and the electric motor, comprising an integrated controller configured to:

• calculate a target driving force of the vehicle based on a vehicle speed and an accelerator opening;
• detect a road surface gradient during travel of the vehicle from a road gradient sensor;
• calculate a gradient load exerted on the vehicle by the road surface gradient;
• and
• perform rotation speed control of the electric motor, suppressing heat generation of the starting clutch, by:
• comparing the gradient load and the target driving force;
• when the target driving force exceeds the gradient load, setting a lower limit of a target input side rotation speed of the starting clutch higher than a slip detection enabling limit, at which a slip rotation indicating a difference over an output side rotation speed is detectable, to provide a driving force to the electric motor to overcome the gradient load;
• and
• when the target driving force is equal to or less than the gradient load, setting an upper limit of the target input side rotation speed of the starting clutch below the slip detection enabling limit to avoid excessive current to the electric motor.