Control method and system for protecting clutch friction elements of automatic transmission and automatic transmission vehicle including same system

A system for controlling clutch friction elements of an automatic transmission, the system comprising:

• a data storage unit configured to store information about shift clutches;
• a data collection unit configured to collect information required to predict a temperature of a friction element for each shift clutch;
• and
• a transmission control unit (TCU) configured to perform transmission control utilizing the information about the shift clutches and the information required to predict the friction element temperature, the TCU comprising:
• a plurality of processors programmed to predict overheating of the friction element for each shift clutch through the prediction of the temperature of the friction element for each shift clutch utilizing the information about the shift clutches and the information required to predict the temperature of the friction element, and to control shifting while avoiding a shift clutch that is predicted to be overheated, wherein the plurality of processors comprises:
• a predicted temperature deriving part configured to derive a predicted temperature value of the friction element for each shift clutch by using the information about the shift clutches and the information required to predict the temperature of the friction element;
• an overheating determination part configured to predict whether or not overheating occurs for each shift clutch by comparing the derived predicted temperature value of the friction element for each shift clutch with an allowable temperature set for each shift clutch;
• a protection logic operation part having an avoidance shift logic configured to recognize the shift clutch that is predicted to be overheated as an overheating clutch and determine a shift stage while avoiding the shift clutch recognized as the overheating clutch;
• and
• a hydraulic pressure control part configured to derive a final target hydraulic pressure for shifting to a target shift stage and perform transmission control on the basis of the derived final target hydraulic pressure,
• wherein the predicted temperature deriving part derives the predicted temperature value of the friction element for each shift clutch by:
• determining a rotation speed and relative speed of a clutch hub and a clutch drum for each shift clutch corresponding to a current turbine rotation speed from a clutch speed map set by a relationship between a rotation speed of a turbine and the clutch hub and the clutch drum for each shift clutch;
• determining a current rotation speed of an oil pump or the turbine rotation speed and an oil temperature, and an oil supply flow rate for each shift clutch corresponding to a current shift stage using an oil flow rate map;
• determining an estimated transmission torque for each shift clutch using a clutch torque map, which uses a piston acting pressure derived from a target hydraulic pressure for each shift clutch and a rotational inertia of the friction element as factors, and deriving a heating value of the friction element for each shift clutch using a heating value map set by a relationship between the estimated transmission torque for each shift clutch and the relative speed between the clutch hub and the clutch drum;
• and
• finally determining the predicted temperature value of the friction element for each shift clutch corresponding to the oil supply flow rate for each shift clutch and the heating value of the friction element for each shift clutch using a friction element temperature map set by a relationship between the heating value of the friction element for each shift clutch and the oil supply flow rate for each shift clutch.