Temperature dependent minimum transmission input speed

摘要

A system and method is employed to regulate a minimum transmission input speed based on automatic fluid temperature. The system includes a temperature sensor for sensing a temperature of the automatic transmission fluid and a controller for setting a minimum engine speed of the engine based on the temperature of the automatic transmission fluid. The size of a transmission pump may be reduced while the pump is still able to supply enough automatic transmission fluid to friction elements and gear ratios to provide lubrication and enable friction element actuators to engage and disengage the friction elements in a timely and effective manner. In a preferred form of the invention, when the temperature of the automatic transmission fluid is below 210° F., the minimum engine speed is set to no greater than 900 rpm; and when the temperature of the automatic transmission fluid is above 210° F., the minimum engine speed is set to no less than 1000 rpm.