Engine rotational speed control apparatus

An engine rotational speed control apparatus comprising:

• a fuel economy consumption operating point computing section configured to determine a fuel economy consumption operating point based on a combination of an engine rotational speed and an engine torque lying on a fuel economy consumption operation curve that achieves a requested engine output with a scheduled fuel economy consumption;
• a rotational speed suppression operating point computing section configured to determine a rotational speed suppression operating point based on a combination of the engine rotational speed and the engine torque lying on a rotational speed suppressing operation curve that achieves the requested engine output with the engine rotational speed being lower than would be obtained using the fuel economy consumption operating point lying on the fuel economy consumption operation curve;
• a requested engine output change detecting section configured to detect a change in the requested engine output;
• a fuel amount comparing section configured to determine if a fuel efficiency degradation amount is larger than a rotational speed restoration fuel consumption amount upon the requested engine output change detecting section detecting that the requested engine output has increased to an increased requested engine output, with the fuel efficiency degradation fuel increase amount indicating an amount by which a fuel consumption amount that would result if the increased requested engine output was achieved using the rotational speed suppression operating point exceeds a fuel consumption amount that would result if the increased requested engine output was achieved using another fuel economy consumption operating point of the fuel economy consumption operation curve, and the rotational speed restoration fuel consumption amount indicating an amount of fuel that would be consumed by increasing the engine rotational speed to move the rotational speed suppression operating point from the rotational speed suppressing operation curve to the another fuel economy consumption operating point corresponding to the requested engine output;
• and
• a continuously variable transmission control section configured to control the engine rotational speed by controlling the gear ratio of the continuously variable transmission such that the increased requested engine output is achieved using the rotational speed suppression operating point before the fuel amount comparing section determines that the fuel efficiency degradation fuel increase amount is larger than the rotational speed restoration fuel consumption amount, such that the increased requested engine output is achieved using the fuel economy consumption operating point after the fuel amount comparing section determines that the fuel efficiency degradation fuel increase amount is larger than the rotational speed restoration fuel consumption amount, and such that the requested engine output is achieved using the fuel economy consumption operating point when the requested engine output change detecting section detects that the requested engine output has decreased.