Method of controlling a variable speed fan
AssigneeDetroit Diesel Corporation
InventorsJeffery Scott Hawkins, Charles C. Blake, Ronald William Mikulik, Steve Miller Weisman
Life of this patent
Estimating the term…
Abstract
Various control strategies and techniques for controlling a variable speed fan in an internal combustion engine are provided. The various control techniques improve fuel economy by operating the fan at a speed sufficient to cool the engine, while avoiding unnecessarily higher speeds that result in poor fuel economy. Further, the fan may be completely disabled at cold start up to avoid over cooling, particularly in an engine using a charge air cooling system.
Claims30
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.
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 maximum fan request value and a 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 hydraulic oil threshold temperature for the hydraulic oil that drives the fan motor;
- monitoring a temperature of the hydraulic oil;
- determining an initial fan request signal having a value between the minimum fan request value and the maximum fan request value;
- and
- determining the applied fan request signal as the initial fan request signal when the oil temperature falls below the oil threshold temperature, and determining the applied fan request signal as a modified fan request signal having a value greater than the initial fan request signal value to compensate for losses due to increased hydraulic oil temperature when the oil temperature exceeds the oil threshold temperature.
A method of controlling an internal combustion engine, the engine being housed in an engine compartment and 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 selectively driven in response to an applied fan request signal based on engine operating conditions having a value between a maximum fan request value and a 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 an engine compartment temperature threshold;
- monitoring a temperature in the engine compartment;
- in the presence of the applied fan request signal, driving the hydraulic fan motor with the pump to drive the fan in accordance with the applied fan request signal;
- and
- in the absence of the applied fan request signal, effectively disabling the fan when the temperature falls below the threshold, and otherwise, driving the hydraulic fan motor with the pump to drive the fan at a predetermined speed.
A method of-controlling an internal combustion engine in a vehicle having a transmission, the engine including a variable speed fan and the transmission including transmission oil, the variable speed fan being driven in response to an applied fan request signal based on engine conditions having a value between a maximum fan request value and a 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 transmission oil threshold temperature for the transmission oil;
- monitoring a temperature of the transmission oil;
- determining a plurality of preliminary initial fan request signals, each request signal having a value based on at least one engine condition, wherein a transmission oil initial fan request signal is based on the transmission oil temperature and the threshold temperature;
- and
- determining the applied fan request signal as the initial fan request signal with the greatest value.
A method of controlling an internal combustion engine in a vehicle having an air conditioning system, the engine including a variable speed fan and the air conditioning system including a condenser for transferring heat from a refrigerant during operation, the variable speed fan being driven in response to an applied fan request signal based on engine conditions and having a value between a maximum fan request value and a 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 condenser threshold pressure;
- monitoring a pressure in the condenser;
- determining a plurality of preliminary initial fan request signals, each request signal having a value based on at least one engine condition, wherein a condenser initial fan request signal is based on the condenser pressure and the threshold pressure;
- and
- determining the applied fan request signal as the initial fan request signal with the greatest value.
A computer readable storage medium having instructions stored thereon that are executable by a controller to perform a method of controlling 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 medium further comprising:
- instructions for 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;
- instructions for 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
- instructions for 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.
A computer readable storage medium having instructions stored thereon that are executable by a controller to perform 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 maximum fan request value and a minimum fan request value, the engine being operable over an engine speed range between an idle speed and a full speed, the medium further comprising:
- instructions for establishing a hydraulic oil threshold temperature for the hydraulic oil that drives the fan motor;
- instructions for monitoring a temperature of the hydraulic oil;
- instructions for determining an initial fan request signal having a value between the minimum fan request value and the maximum fan request value;
- and
- instructions for determining the applied fan request signal as the initial fan request signal when the oil temperature falls below the oil threshold temperature, and determining the applied fan request signal as a modified fan request signal having a value greater than the initial fan request signal value to compensate for losses due to increased hydraulic oil temperature when the oil temperature exceeds the oil threshold temperature.
A computer readable storage medium having instructions stored thereon that are executable by a controller to perform a method of controlling an internal combustion engine, the engine being housed in an engine compartment and 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 selectively driven in response to an applied fan request signal based on engine operating conditions having a value between a maximum fan request value and a minimum fan request value, the engine being operable over an engine speed range between an idle speed and a full speed, the medium further comprising:
- instructions for establishing an engine compartment temperature threshold;
- instructions for monitoring a temperature in the engine compartment;
- instructions for, in the presence of the applied fan request signal, driving the hydraulic fan motor with the pump to drive the fan in accordance with the applied fan request signal;
- and
- instructions for, in the absence of the applied fan request signal, effectively disabling the fan when the temperature falls below the threshold, and otherwise, driving the hydraulic fan motor with the pump to drive the fan at a predetermined speed.
A computer readable storage medium having instructions stored thereon that are executable by a controller to perform a method of controlling an internal combustion engine in a vehicle having a transmission, the engine including a variable speed fan and the transmission including transmission oil, the variable speed fan being driven in response to an applied fan request signal based on engine conditions having a value between a maximum fan request value and a minimum fan request value, the engine being operable over an engine speed range between an idle speed and a full speed, the medium further comprising:
- instructions for establishing a transmission oil threshold temperature for the transmission oil;
- instructions for monitoring a temperature of the transmission oil;
- instructions for determining a plurality of preliminary initial fan request signals, each request signal having a value based on at least one engine condition, wherein a transmission oil initial fan request signal is based on the transmission oil temperature and the threshold temperature;
- and
- instructions for determining the applied fan request signal as the initial fan request signal with the greatest value.
A computer readable storage medium having instructions stored thereon that are executable by a controller to perform a method of controlling an internal combustion engine in a vehicle having an air conditioning system, the engine including a variable speed fan and the air conditioning system including a condenser for transferring heat from a refrigerant during operation, the variable speed fan being driven in response to an applied fan request signal based on engine conditions and having a value between a maximum fan request value and a minimum fan request value, the engine being operable over an engine speed range between an idle speed and a full speed, the medium further comprising:
- instructions for establishing a condenser threshold pressure;
- instructions for monitoring a pressure in the condenser;
- instructions for determining a plurality of preliminary initial fan request signals, each request signal having a value based on at least one engine condition, wherein a condenser initial fan request signal is based on the condenser pressure and the threshold pressure;
- and
- instructions for determining the applied fan request signal as the initial fan request signal with the greatest value.
Dependencies are inferred from the claim text.