A vehicle driving force control apparatus is configured for a four-wheel drive
vehicle that switches between a four-wheel drive state and a two-wheel drive state.
The driving force control apparatus improves the response when a vehicle shifts
into a four-wheel drive state while starting to move from a state of rest and,
simultaneously, avoids the occurrence of shock when the clutch is connected. When
the rotational speeds of the motor and the rear wheels reach or fall below their
respective minimum detectable rotational speeds, the controller calculates estimated
times until the motor and the rear wheels will stop based on the rotational speeds
detected up until the minimum detectable rotational speed was reached and begins
counting down from those estimated times. Since the clutch is connected after both
estimated times have reached zero, the clutch is connected while reliably avoiding
the occurrence of shock.
