Cooling In A Liquid-To-Air Heat Exchanger

• US 20120061069A1
• Filed: 09/10/2010
• Published: 03/15/2012
• Est. Priority Date: 09/10/2010
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Schwartz, William Samuel
• Granted Patent: US 8,997,847 B2
• Time in Patent Office: Days
• US Class Current: 165/271
• CPC Class Codes: F01P 5/02 Pumping cooling-air; Arrangements of cooling-air pumps, e.g. fans or blowers
• CPC Class Codes: F01P 5/10 Pumping liquid coolant; Arrangements of coolant pumps
• CPC Class Codes: F01P 7/04 by varying pump speed, e.g. by changing pump-drive gear ratio
• CPC Class Codes: F01P 7/042 using fluid couplings couplings or clutches of this type per se F16D35/00
• CPC Class Codes: F01P 7/164 by varying pump speed

Abstract

In an engine coolant circuit with a radiator and an engine, a fan and a coolant pump may be provided. The fan and pump may be electrically driven, driven by a variable speed clutch, hydraulically driven, or driven by some other actively controllable means. When an increase in heat transfer rate is indicated, the fan speed or the coolant pump speed may be increased. According to an embodiment of the disclosure, the choice of increasing the fan speed or increasing the pump speed is determined so that the power consumed is minimized. The broad concept is that dQ/dP, the gradient in heat transfer rate to power, is determined for both the fan and the pump at the present operating condition. The one with the higher gradient is the one that is commanded to increase speed.

Claims

1. A method to control cooling in a liquid-to-air heat exchanger with a fan and a pump forcing convection, the method comprising:

determining a first gradient in heat transfer rate to fan power associated with adjusting fan speed;

determining a second gradient in heat transfer rate to pump power associated with adjusting pump speed; and

adjusting one of fan speed and pump speed based on the gradients.

2. The method of claim 1, further comprising:

determining whether a change in heat transfer is indicated wherein the adjusting one of fan speed and pump speed is further based on such change in heat transfer being indicated.

3. The method of claim 2 wherein:

the fan speed is increased when the first gradient is greater than the second gradient and an increase in heat transfer is indicated;

the pump speed is increased when the second gradient is greater than the first gradient and an increase in heat transfer is indicated;

the fan speed is decreased when the second gradient is greater than the first gradient and a decrease in heat transfer is indicated; and

the pump speed is decreased when the first gradient is greater than the second gradient and a decrease in heat transfer is indicated.

4. The method of claim 1 wherein the liquid is a coolant comprising water and ethylene glycol.

5. The method of claim 1 wherein the liquid is contained within a duct and the air is ducted or unducted.

6. The method of claim 1 wherein the liquid-to-air heat exchanger is called a radiator and the first and second gradients are determined by:

evaluating a radiator performance relationship as a function of liquid coolant and air flows; and

transforming the radiator performance relationship into a heat transfer performance relationship with heat transfer rate as a function of liquid coolant and air flows.

7. The method of claim 6 wherein the flows are expressed in one of:

mass flowrate, volumetric flowrate, and velocity.

8. The method of claim 6 wherein the performance relationships may be expressed as lookup tables, graphs, or empirical formulas.

9. The method of claim 1, further comprising:

determining whether a change in heat transfer is indicated wherein;

the first gradient is determined for increased fan speed and the second gradient is determined for increased pump speed when an increase in heat transfer is indicated; and

the first gradient is determined for decreased fan speed and the second gradient is determined for decreased pump speed when a decrease in heat transfer is indicated.

10. A method to control cooling in a liquid-to-air heat exchanger with a fan and a pump forcing convection, the method comprising:

determining a first gradient in heat transfer to power for increasing fan speed;

determining a second gradient in heat transfer to power for increasing pump speed; and

increasing fan speed when the first gradient is greater than the second gradient.

11. The method of claim 10, further comprising:

increasing pump speed when the second gradient is greater than the first gradient.

12. The method of claim 11, further comprising:

determining whether an increase in heat transfer is desired wherein the one of increasing fan speed and the increasing the pump speed is further based on the determination that an increase in heat transfer is desired.

13. The method of claim 10 wherein the first gradient is determined based on determining a gradient in heat transfer rate to air flow from a map of radiator performance and determining a gradient in air flow to fan power.

14. The method of claim 10 wherein the second gradient is determined based on determining a gradient in heat transfer rate to coolant flow from a map of radiator performance and determining a gradient in coolant flow to fan power.

15. A cooling system for an automotive engine, comprising:

a radiator coupled to an engine cooling circuit in which the engine is disposed;

a fan forcing air past the radiator;

a pump disposed in the cooling circuit; and

an electronic control unit electronically coupled to the fan and the pump, the electronic control unit commanding one of the fan and the pump to change operating speed when an adjustment in heat transfer rate is indicated and the electronic control unit determining which of the fan and the pump to command based on a first gradient of heat transfer rate to power for adjusting fan speed and a second gradient of heat transfer rate to power for adjusting pump speed.

16. The system of claim 15 wherein the fan and pump driven by one of:

an electrical motor, a variable speed clutch, and a hydraulic motor.

17. The system of claim 15, further comprising:

an ambient temperature sensor electronically coupled to the electronic control unit;

an engine coolant sensor electronically coupled to an engine coolant circuit coupled to the engine; and

a vehicle speed sensor electronically coupled to the electronic control unit wherein the first and second gradients are further based on at least one of;

the ambient temperature, an engine coolant temperature, and the vehicle speed.

18. The system of claim 15 wherein the electronic control unit commands:

the fan speed to increase when the first gradient is greater than the second gradient and an increase in heat transfer is indicated;

the pump speed to increase when the second gradient is greater than the first gradient and an increase in heat transfer is indicated;

the fan speed to decrease when the second gradient is greater than the first gradient and a decrease in heat transfer is indicated; and

the pump speed to decrease when the first gradient is greater than the second gradient and a decrease in heat transfer is indicated.

19. The system of claim 15 wherein the amount of an increase or decrease in the fan speed and the amount of an increase or decrease in the pump speed is based on an amount of a change in heat transfer rate that is indicated.

20. The system of claim 15 wherein at some values of the first and second gradients, both the fan and the pump speeds are adjusted.