ENGINE COOLING SYSTEM CONTROL

• US 20130255599A1
• Filed: 03/30/2012
• Published: 10/03/2013
• Est. Priority Date: 03/30/2012
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Jentz, Robert Roy, Pursifull, Ross Dykstra
• Granted Patent: US 9,341,105 B2
• Time in Patent Office: Days
• US Class Current: 123/41.1
• CPC Class Codes: F01P 11/14 Indicating devices; Other safety devices
• CPC Class Codes: F01P 2060/045 for transmissions
• CPC Class Codes: F01P 2060/18 Heater
• CPC Class Codes: F01P 3/20 Cooling circuits not specific to a single part of engine or machine F01P3/22 takes precedence

Abstract

Methods and systems are provided for expediting engine system heating by stagnating coolant in one of a plurality of loops in an engine cooling system. Degradation of the various valves and thermostats of the cooling system can be diagnosed by adjusting the valve and monitoring changes in one or more of coolant temperature, transmission temperature and cabin temperature. Based on engine operating conditions, the various valves may be adjusted to vary coolant temperature in different regions of the cooling system, thereby providing fuel economy benefits.

Claims

1. A method for an engine cooling system, comprising:

responsive to an engine operating condition, adjusting each of a bypass shut-off valve and a heater shut-off valve of the cooling system to stagnate a first amount of coolant at an engine block while circulating a second amount of coolant at a thermostat.

2. The method of claim 1, wherein the first amount of coolant is stagnated in a first loop of the cooling system, and wherein the second amount of coolant is circulated in a second loop of the cooling system, the second loop including a heater core upstream of the thermostat.

3. The method of claim 2, wherein the engine operating condition includes an engine cold-start condition.

4. The method of claim 3, wherein the adjusting includes, during an engine cold-start condition, closing the bypass shut-off valve and opening the heater shut-off valve to increase the first amount of coolant stagnated at the engine block relative to the second amount of coolant circulated at the thermostat.

5. The method of claim 4, wherein the adjusting is performed for a duration to raise a first coolant temperature of the first amount of stagnated coolant above a threshold temperature, a second coolant temperature of the second amount of coolant remaining below the threshold temperature over the duration.

6. The method of claim 5, wherein the duration is based on an engine speed, a torque demand, and a vehicle cabin heating request.

7. The method of claim 5, wherein while the bypass shut-off valve is closed, the second coolant temperature is estimated by a temperature sensor at the thermostat, and the first coolant temperature is estimated based on each of a radiator fan speed, a vehicle speed, an ambient air temperature and the second coolant temperature.

8. The method of claim 7, further comprising, after the duration has elapsed, opening the bypass shut-off valve while maintaining the heater shut-off valve open so that the first amount of coolant is also circulated at the thermostat.

9. A method for an engine cooling system, comprising:

during an engine cold-start condition,

closing each of a first valve in a first coolant loop and a second valve in a second coolant loop between an engine and a thermostat to stagnate warmer coolant at the engine while circulating cooler coolant at the thermostat.

10. The method of claim 9, wherein stagnating warmer coolant at the engine while circulating cooler coolant at the thermostat includes disabling coolant flow at a radiator.

11. The method of claim 10, wherein the adjusting is performed for a duration to raise a first coolant temperature of coolant stagnating at the engine above a threshold temperature while maintaining a second coolant temperature of coolant circulating at the thermostat below the threshold temperature, the duration based on each of an ambient air temperature, an engine speed, and a vehicle cabin heating request.

12. The method of claim 11, further comprising, while stagnating coolant at the engine for the duration, intermittently opening the first valve in response to a pressure in the first coolant loop rising above a threshold pressure.

13. The method of claim 12, further comprising, after the duration has elapsed, opening the first valve so that coolant stagnating in the first loop is circulated at the thermostat.

14. The method of claim 13, further comprising, in response to a cabin heating request, opening the second valve so that coolant stagnating in the second loop is circulated at the thermostat.

15. The method of claim 14, wherein circulating coolant stagnating in the second loop and/or first loop at the thermostat includes enabling coolant flow at the radiator.

16. A vehicle system, comprising:

an engine block;

an engine cooling system coupled to the engine block via each of a first loop and a second loop, the first loop including a first valve, the second loop including a second valve, the first and second loops intersecting at a thermostat;

a controller with computer readable instructions for;

during an engine cold-start,

closing one or more of the first and second valves to stagnate coolant at the engine and raise a first coolant temperature at the engine above a second coolant temperature at the thermostat.

17. The system of claim 16, wherein the cooling system further includes a radiator having a fan, and wherein the first coolant temperature at the engine is inferred based on each of a radiator fan speed, a vehicle speed, an ambient air temperature and the second coolant temperature

18. The system of claim 17, wherein the controller includes further instructions for, after the first coolant temperature is above a threshold temperature, opening at least the first valve to enable coolant at the first coolant temperature to be circulated at the thermostat, the threshold temperature based on an exhaust catalyst temperature.

19. The system of claim 18, wherein the controller includes further instructions for, after the first coolant temperature is above the threshold temperature, opening the second valve responsive to a vehicle cabin heating request.

20. The system of claim 18, wherein the controller includes further instructions for, while the first coolant temperature is below the threshold temperature, intermittently opening the first valve in response to a coolant pressure in the first loop engine being higher than a threshold pressure.