COOLING SYSTEM DIAGNOSTIC METHOD

• US 20160230644A1
• Filed: 02/09/2015
• Published: 08/11/2016
• Est. Priority Date: 02/09/2015
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Dudar, Aed M., Jentz, Robert Roy
• Granted Patent: US 9,790,842 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: F01P 11/16 concerning coolant temperature F01P11/20 takes precedence
• CPC Class Codes: F01P 11/18 concerning coolant pressure, coolant flow, or liquid-coolant level

Abstract

A method for operating an engine cooling system is provided. The method includes monitoring a coolant temperature profile after engine shut-down and indicating a low coolant level based on the coolant temperature profile determined after engine shut-down.

Claims

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

monitoring a coolant temperature profile after engine shut-down; and

indicating a coolant level based on the coolant temperature profile determined after engine shut-down.

2. The method of claim 1, wherein the indicating includes indicating a coolant level lower than a minimum threshold acceptable for engine operation, the method further comprising implementing one or more of the following actions in response to indicating the low coolant level;

reducing engine power output during a subsequent start-up, inhibiting engine operation until a low coolant level is not indicated, limiting boost provided to the engine by a compressor during a subsequent start-up, decreasing airflow to the engine during a subsequent start-up, limiting engine fuel injection, and inhibiting of spark retard during a subsequent start-up.

3. The method of claim 1, where monitoring includes determining the coolant temperature profile after engine shut-down and further includes sending power to a controller receiving a temperature signal from a temperature sensor in the engine and determining the coolant temperature profile based on the temperature signal.

4. The method of claim 3, further comprising discontinuing power transfer to the controller before monitoring the coolant temperature profile.

5. The method of claim 1, the coolant level is also indicated based on environmental conditions.

6. The method of claim 1, where the coolant temperature profile is compared to a predicted coolant temperature profile to determine when the coolant level is indicated to be lower than a threshold.

7. The method of claim 6, where the predicted coolant temperature profile is generated based on an exponential decay.

8. The method of claim 1, where determining the coolant temperature profile is initiated in response to an engine shut-down event, the method further comprising monitoring engine temperature during engine combustion operation and indicating the coolant level further based on the monitored engine temperature.

9. The method of claim 1, where determining the coolant temperature profile is initiated in response to a climate control unit generating heat less than a threshold value.

10. The method of claim 1, where indicating the coolant level includes triggering a low coolant level indicator in a cabin of a vehicle.

11. The method of claim 1, further comprising increasing an output of a heat exchanger fan during a subsequent engine start-up in response to indicating the low coolant level.

12. An engine cooling system comprising:

a cooling circuit circulating coolant through passages traversing an engine;

a heat exchanger coupled to the cooling circuit;

a temperature sensor coupled to at least one of the cooling circuit and the engine; and

a controller configured to;

after engine shut-down, receive power;

determine a coolant temperature profile based on a signal sent from the temperature sensor; and

indicate a low coolant level based on the coolant temperature profile determined after engine shut-down.

13. The engine cooling system of claim 12, where the coolant temperature profile is compared to a predicted coolant temperature profile to determine when the low coolant level is indicated.

14. The engine cooling system of claim 13, where the predicted coolant temperature profile is included in a set of predicted coolant temperature profiles that are predicted and stored in memory in the controller.

15. The engine cooling system of claim 12, where the controller is configured to receive power after engine shut-down and determine the coolant temperature profile in response to one of an engine shut-down event and a cabin heat exchanger coupled to the cooling circuit generating heat less than a threshold value.

16. The engine cooling system of claim 12, where indicating the low coolant level includes generating a diagnostic trouble code.

17. A method for operating an engine cooling system comprising:

after engine shut-down and vehicle off condition, maintaining power to a controller that determines a coolant temperature profile over time;

comparing the coolant temperature profile to a predicted coolant temperature profile; and

if the deviation between the determined coolant temperature profile and the predicted coolant temperature profile exceeds a threshold value, indicating a low coolant level based on the coolant temperature profile determined after engine shut-down.

18. The method of claim 17, where comparing the coolant temperature profile to the predicted coolant temperature profile includes determining differences between a plurality of coolant temperatures in each profile and summing the temperature differences to determine if the profile deviation is greater than the threshold value.

19. The method of claim 17, where the coolant temperature profile is determined in direct response to an engine shut-down event and comparing the coolant temperature profile to the predicted coolant temperature profile is implemented during engine shut-down.

20. The method of claim 17, further comprising after engine shut-down and before determining the coolant temperature profile, sending power to the controller and inhibiting power transfer to the controller after the low coolant level is indicated.