Patent ID: 6453853
Filing Date: 2002-09-24
Classification: F01P,F02D

Abstract:
A method of control an internal combustion engine, the engine including a variable speed fan, the variable speed fan being driven in response to an applied fan request signal having a value between a predetermined maximum fan request value and a predetermined minimum fan request value, the engine being operable over an engine speed range between an idle speed and a full speed, the method comprising:establishing a fan speed limit as a maximum allowable fan speed during operation of the engine at all engine speeds in the engine speed range; determining an initial fan request signal based on engine operating conditions and having a value between the minimum fan request value and the maximum fan request value, wherein the maximum fan request value is sufficiently large to cause the fan speed to approach the fan speed limit as the engine speed approaches an intermediate speed between the idle speed and the full speed; and determining the applied fan request signal by limiting the initial fan request signal based on engine speed such that the fan speed approaches the fan speed limit as the engine speed approaches the intermediate speed and the fan speed remains below the fan speed limit as the engine speed approaches the full speed, while the initial fan request signal value is the maximum fan request value, allowing higher fan speeds at lower engine speeds while avoiding fan overspeed at higher engine speeds.