Method and apparatus for controlling power transmission system in an automotive vehicle

An apparatus for controlling a power transmitting system for an automotive vehicle which includes an engine, the power transmitting system having a continuously variable transmission with a continuously variable speed ratio, and an auxiliary transmission which is connected in series with the continuously variable transmission and which has at least two shift positions for forward driving of the vehicle, said apparatus comprising:

• means for detecting an actual running speed of said vehicle;
• means for detecting an actually required power output of said engine;
• means for detecting an actual speed ratio of said continuously variable transmission;
• and
• control means for determining a timing at which said auxiliary transmission is shifted from one of said at least two shift positions to the other, said control means determining said timing based upon the detected actual running speed of said vehicle, the detected actually required power output of said engine, and the detected actual speed ratio of said continuously variably transmission, and according to a predetermined relation among said actual running speed, said actually required power output, and said actual speed ratio, said control means controlling said auxiliary transmission so as to be shifted at the determined timing.

An apparatus for controlling a power transmitting system for an automotive vehicle which includes an engine, the power transmitting system having a continuously variable transmission with a continuously variable speed ratio, and an auxiliary transmission which is connected in series with the continuously variable transmission and which has at least two shift positions for forward driving of the vehicle, wherein the auxiliary transmission is operated in response to the operation of a shift lever which has at least two operating positions corresponding to said at least two shift positions, said apparatus comprising:

• means for detecting a currently selected operating position of said shift lever;
• means for detecting an actually required power output of said engine;
• means for detecting an actual running speed of said vehicle;
• means for detecting an actual speed ratio of said continuously variable transmission;
• and
• control means for determining a condition which permits said auxiliary transmission to be shifted to one of said at least two shift positions which corresponds to said currently selected operating position of said shift lever, said control means determining said condition based on the detected actually required power output of said engine, the detected actual running speed of said vehicle, and the detected actual speed ratio of said continuously variable transmission, and according to a predetermined relation among said detected actually required power output, said detected actual running speed, and said detected actual speed ratio, said control means controlling said auxiliary transmission so as to be shifted to said one shift position when said condition is satisfied after said currently selected operating position is detected.