Transmission shift control device

A transmission shift control device for control of transmission of a vehicle having an internal combustion engine with an intake system, said control comprising:

• throttle sensor means for generating an actual throttle signal representing the present throttle opening of the engine intake system;
• engine speed sensor means for generating an actual engine speed signal representing the present engine rotational speed;
• shift position sensor means for generating an actual shift position signal designating the present shift position of said transmission;
• upshifting memory means, which stores upshifting limits for various values of one of said throttle signal and said engine speed signal corresponding to various shift positions of said transmission, for providing one of said stored upshifting limits as an upshift limit signal in accordance with (1) the other of said throttle signal and said engine speed signal and (2) said shift position signal;
• downshifting memory means, which stores downshifting limits for various values of said one of said throttle signal and said engine speed signal corresponding to various shift positions of said transmission, for providing one of said stored downshifting values as a downshift limit signal in accordance with (1) said other of said throttle signal and said engine speed signal and (2) said shift position signal;
• first comparator means, which receives said upshift limit signal from said upshifting memory means and said one of said throttle signal and said engine speed signal for comparing these two received signals with each other, and for generating an upshift demand signal when said one of said throttle signal and said engine speed signal is smaller than said upshift limit signal;
• second comparator means, which receives said downshift limit signal from said downshifting memory means and said one of said throttle signal and said engine speed signal, for comparing these two received signals with each other and for generating a downshift demand signal when said one of said throttle signal and said engine speed signal is larger than said downshift limit signal;
• and
• switching circuit means, which receives said upshift demand signal from said first comparator and said downshift demand signal from said second comparator, for determining shifting of said transmission in accordance with receipt of one of said upshift demand and downshift demand signals.