overheat preventing method for solenoid valves of an auto transmission

摘要

A method for preventing overheat of a solenoid valve of an automatic transmission is provided to cool solenoid valves by increasing flow rates of the solenoid valves positioned at a valve body while an N range or a P range is maintained during a constant time. A condition determination process is performed to determine a cooling condition of a solenoid valve in an N range or a P range. A cooling process is performed to increase control current applied to a DC solenoid valve in order to increase a flow rate of the DC solenoid valve and to shield the control current supplied to the 35R solenoid valve in order to increase a flow rate of a 35R solenoid valve when a cooling process for the solenoid valve is required according to the determined result. A shift possibility determination process is performed to determine shift possibility to another range. A control feedback process is performed to change the flow rate of the DC solenoid value into the previous flow rate and to change the flow rate of the 35R solenoid valve when there is possibility to be shifted to another range.