METHOD OF CALCULATING SLIP RPM IN AUTOMATIC TRANSMISSION

摘要

PURPOSE: A method of calculating slip rpm(revolutions per minute) in an automatic transmission is provided to prevent an error of learning by improving calculation of slip rpm and applying the slip rpm to a control logic. CONSTITUTION: A method of calculating slip rpm in an automatic transmission comprises steps of initializing variables related to slip rpm(S200); calculating turbine rpm(Nt) by the current vehicle speed(No) and the gear ratio of a desired speed range(S210); deciding whether turbine the rpm exceeds desired turbine rpm(Ntt), to calculate over run rpm(S220); deciding whether the current slip rpm is under a difference between the turbine rpm and the desired turbine rpm if the turbine rpm exceeds the desired turbine rpm(S230); adding a count value if the current slip rpm is under the difference between the turbine rpm and the desired turbine rpm(S240); setting up the current slip rpm to the maximum slip rpm if the count value is under a predetermined value(S260); and applying the maximum slip rpm to a low-speed power-on downshift learning control logic(S270).