Driving force control system for vehicle

摘要

A driving force control system for a vehicle having a mechanism for changing an engine speed continuously. The driving force control system basically controls said mechanism in a manner such that the engine speed is adjusted to optimize fuel economy. The driving force control system is configured to determine an index representing a demand to enhance agility of behavior of the vehicle based on an actual behavior of the vehicle or an amount of operation carried out by a driver to cause said behavior. An upper limit value of the engine speed of the case in which a drive demand is increased is determined on the basis of the index, and the upper limit value is set to the higher value with an increase in the index representing the demand to enhance agility of behavior of the vehicle.

主权项

1. A driving force control system for a vehicle having a transmission mechanism for changing an engine speed continuously in accordance with a vehicle speed, comprising a control unit configured to:
control a speed ratio of the speed of the transmission mechanism on the basis of a vehicle speed and an opening degree of an accelerator; determine an index representing a demand to enhance agility of behavior of the vehicle based on an acceleration of the vehicle; change the index promptly in the direction to enhance the agility of the vehicle but relatively slower in the direction to moderate the behavior of the vehicle; select a sporty mode if the index is larger than a threshold value; and restrict the engine speed to an upper limit value that is lower than that to be achieved by a current speed ratio of the transmission when the acceleration is demanded, carry out an upshifting when the engine speed reaches the upper limit value of the current speed ratio, and set the upper limit value to a higher value with an increase in the index, in a case that the sporty mode is selected, wherein the upper limit value is set in each stage of the speed ratio based on a maximum demanded acceleration rate which is a ratio of a demanded acceleration to a maximum possible acceleration of the vehicle that is calculated based on the index, and wherein the upper limit value is set to a higher value with a reduction in the speed ratio.