1. Field of the Invention
The present invention relates to a shift control system for an electric vehicle, for controlling the shifting of a transmission interposed between an electric motor and a driven wheel based on a shift map compiled with at least the accelerator opening degree and the vehicle speed used as parameters.
2. Description of the Prior Art
In an electric vehicle using an electric motor connected to a battery as a traveling drive source, a technique is conventionally known in which a regenerative braking force is exhibited by the electric motor to convert kinetic energy of the moving vehicle into electric energy, and the electric energy is recovered in the battery (for example, see Japanese Patent Application Laid-open No. 191904/93).
In the technique described in Japanese Patent Application Laid-open No. 191904/93, in order to exhibit a regenerative braking force corresponding to an engine brake in an engine-mounted vehicle when the accelerator opening degree is smaller than a reference accelerator opening degree, the regenerative braking force at the reference accelerator opening degree is set at zero, and when the accelerator opening degree is at a value such that an accelerator pedal is in a fully closed state, a maximum regenerative braking force is set. The regenerative braking force is varied linearly between zero and the maximum regenerative braking force value.
In the known technique, however, if the vehicle speed is increased, the maximum regenerative braking force is decreased in a hyperbolic curve. For this reason, if the vehicle speed is increased, for example, when the vehicle travels down a downward slope, a speed-reducing force is abruptly weakened to produce an inconsistency of braking feeling.