Patent ID: 6273034
Filing Date: 2001-08-14
Classification: F01P,F02D,Y02T

Abstract:
A method of controlling an internal combustion engine, the engine including a hydraulically driven variable speed fan wherein hydraulic oil is pumped by a pump to drive a hydraulic fan motor, 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:determining the applied fan request signal value based on at least one engine operating condition;determining a reference hydraulic oil pressure for the fan motor based on the applied fan request signal;monitoring an actual hydraulic oil pressure for the fan motor;determining an error signal by comparing the reference pressure to the actual pressure; anddriving the fan motor based on the error signal such that the actual pressure tracks the reference pressure.