Continuous on-board diagnostic lubricant monitoring system and method

• US 20020178780A1
• Filed: 06/17/2002
• Published: 12/05/2002
• Est. Priority Date: 10/12/2000
• Status: Active Grant

• Current Assignee: Bhupinder Singh Dayal, Jennifer H. Van Mullekom, Michael Charles Melnyk
• Original Assignee: Bhupinder Singh Dayal, Jennifer H. Van Mullekom, Michael Charles Melnyk
• Inventors: Dayal, Bhupinder Singh, Van Mullekom, Jennifer H., Melnyk, Michael Charles
• Granted Patent: US 6,644,095 B2
• Time in Patent Office: Days
• US Class Current: 73/10
• CPC Class Codes: F01M 11/04 Filling or draining lubricant of or from machines or engines
• CPC Class Codes: F01M 11/06 Means for keeping lubricant level constant or for accommodating movement or position of machines or engines
• CPC Class Codes: F01M 11/10 Indicating devices; Other safety devices
• CPC Class Codes: F01M 2011/0475 with combustion of used lubricant in the engine
• CPC Class Codes: F16N 2250/08 Temperature

Abstract

A continuous on-board diagnostic lubricant monitoring system and method evaluates lubricant quality and detects incipient lubricant failure due to contamination by measuring physical characteristics of the lubricant itself. The lubrication system (1) employs a diagnostic cell (27) which samples engine lubricant (EL) from an engine (2), and exposes the samples to sensors (28) which measure its physical characteristics. The senors (28) preferably include a permittivity sensor, a viscosity sensor, and a temperature sensor. Diagnostic testing based on the measurements can be carried out on-board via a controller (30) running selected algorithms or processes. A time to condemning limit for the lubricant, i.e., the time until the lubricant has degraded to given quality level, is calculated based on permittivity data received by the controller (30) from the sensors (28). Likewise, a time to condemning limit is calculated based on viscosity data. Based on the permittivity and temperature data, the controller (30) is able to detect incipient failure of the lubricant due to water or coolant contamination. Additionally, based on the monitored lubricant viscosity, the controller (30) is able to detect fuel contamination. In this manner, a superior lubricant monitoring system and method is achieved which is particularly applicable to railroad locomotives, mining machinery, and other off-highway vehicles.

Claims

1. A method of monitoring a lubricant, said method comprising:

(a) measuring the lubricant'"'"'s temperature;

(b) measuring the lubricant'"'"'s permittivity;

(c) compensating for temperature dependence in the permittivity; and

,

(d) determining if the lubricant has been contaminated by a coolant.

2. The method according to claim 1, said method further comprising:

determining a rate of change of the lubricant'"'"'s permittivity for a first period of time; and

,

determining a rate of change of the lubricant'"'"'s temperature for a second period of time;

wherein the lubricant is determined to be contaminated by a coolant if the rate of change of the lubricant'"'"'s permittivity for the first period of time is greater than a first threshold, and an absolute value of the rate of change of the lubricant'"'"'s temperature for the second period of time is less than a second threshold.

3. The method according to claim 2, wherein the first and second periods of time are the same periods of time.

4. The method according to claim 3, said method further comprising:

determining a rate of change of the lubricant'"'"'s temperature for a third period of time, said third period of time being greater than the first and second periods of time;

wherein for a determination to be made that the lubricant is contaminated by a coolant, it has to also be found that the rate of change of the lubricant'"'"'s temperature for the third period of time is less than a third threshold.

5. The method according to claim 3, said method further comprising:

selecting a minimum temperature from those used to determine the rate of change of the lubricant'"'"'s temperature for the second time period;

wherein for a determination to be made that the lubricant is contaminated by a coolant, it has to also be found that the minimum temperature is greater than a threshold temperature.

6. A method of monitoring a lubricant, said method comprising:

(a) obtaining, over time, permittivity data from measured permittivity values of the lubricant;

(b) determining a rate of degradation of the lubricant'"'"'s quality based on changes in the permittivity data over time; and

,

(c) determining an amount of time until the lubricant reaches a set degraded quality level.

7. The method according to claim 6, said method further comprising:

determining if the lubricant has been changed or topped-off by detecting changes in the permittivity data which exceed a threshold level.

8. The method according to claim 6, wherein the amount of time until the lubricant reaches the set degraded quality level is given by:

(cond_limit−

current_perm)/perm_slope

where, cond_limit represents a condemning limit defined by the lubricant'"'"'s permittivity when the lubricant has reach the set degraded quality level;

current_perm represents the lubricant'"'"'s current determined permittivity; and

perm_slope represents the determined rate of degradation of the lubricant'"'"'s quality based on changes in the permittivity data.

9. The method according to claim 8, wherein the current determined permittivity of the lubricant is a median of a plurality of most recently obtained permittivity data.

10. A lubrication system for an engine, said lubrication system comprising:

a lubricant; and

,

a diagnostic cell which samples the lubricant for diagnostic testing thereof, said cell including;

a permittivity sensor which monitors the lubricant'"'"'s permittivity; and

,

a temperature sensor which monitors the lubricant'"'"'s temperature.

11. The lubrication system according to claim 10, wherein said diagnostic cell further includes:

a manifold in which the permittivity and temperature sensors are mounted, said manifold being arranged such that sampled lubricant is selectively made to encounter the permittivity and temperature sensors.

12. The lubrication system according to claim 10, further comprising:

a controller which interfaces with the diagnostic cell to carry out the diagnostic testing, said controller receiving permittivity data from the permittivity sensor and temperature data from the temperature sensor.

13. The lubrication system according to claim 12, wherein the diagnostic testing carried out includes determining if the lubricant has been contaminated by a coolant.

14. The lubrication system according to claim 13, wherein the controller determines a rate of change of the lubricant'"'"'s permittivity for a first time period based on the permittivity data it receives, and the controller determines a rate of change of the lubricant'"'"'s temperature for a second time period based on the temperature data it receives, such that the controller determines that the lubricant has been contaminated by a coolant if the rate of change of the lubricant'"'"'s permittivity for the first time period is greater than a first threshold and an absolute value of the rate of change of the lubricant'"'"'s temperature for the second time period is less than a second threshold.

15. The lubrication system according to claim 14, wherein the first and second time periods are the same.

16. The lubrication system according to claim 15, wherein the controller further determines a rate of change of the lubricant'"'"'s temperature for a third time period based on the temperature data it receives, said third time period being longer than the first and second time periods, such that for the controller to determine that the lubricant has been contaminated by a coolant, the controller has to also find that the rate of change of the lubricant'"'"'s permittivity for the third time period is less than a third threshold.

17. The lubrication system according to claim 15, wherein the controller further determines a minimum lubricant temperature for the second time period from the temperature data it receives, such that for the controller to determine that the lubricant has been contaminated by a coolant, the controller has to also find that the minimum lubricant temperature is greater than a threshold temperature.

18. The lubrication system according to claim 12, wherein the controller determines a time to condemning limit for the lubricant based on the permittivity data received.

19. The lubrication system according to claim 18, wherein the time to condemning limit is given by:

(cond_limit−

current_perm)/perm_slope

where, cond_limit represents a condemning limit defined by the lubricant'"'"'s permittivity when the lubricant has reach a selected level of degradation;

current_perm represents the lubricant'"'"'s current determined permittivity; and

perm_slope represents a rate of lubricant quality degradation as determined from the permittivity data.

20. The lubrication system according to claim 10, wherein the engine is selected from the group consisting of a railroad locomotive engine, and a mining vehicle engine.

21. A method of monitoring a lubricant, said method comprising the steps of:

(a) obtaining measurements of the lubricant'"'"'s viscosity;

(b) obtaining measurements of the lubricant'"'"'s temperature;

(c) normalizing the viscosity measurements based on the temperature measurements such that the normalized viscosity measurements all relate to a common reference temperature; and

,

(d) diagnosing a condition of the lubricant based on the normalized viscosity measurements.

22. The method according to claim 21, wherein step (d) comprises:

diagnosing fuel contamination of the lubricant based on the normalized viscosity measurements.

23. The method according to claim 22, wherein step (d) further comprises:

distinguishing between different degrees of fuel contamination based on the normalized viscosity measurements.

24. The method according to claim 22, said method further comprising:

(e) determining, based on the normalized viscosity measurements, a time to condemning limit for the lubricant due to fuel contamination.

25. The method according to claim 21, wherein step (d) comprises:

diagnosing quality degradation of the lubricant based on the normalized viscosity measurements.

26. The method according to claim 25, said method further comprising:

(e) determining, based on the normalized viscosity measurements, a time to condemning limit for the lubricant due to quality degradation.

27. The method according to claim 21, said method further comprising:

(e) determining, based on the normalized viscosity measurements, a time to condemning limit for the lubricant.

28. The method according to claim 27, wherein the time to condemning limit is selected from the group consisting of:

an upper viscosity limit under which it is desired that the lubricant'"'"'s viscosity remain, and a lower viscosity limit over which it is desired that the lubricant'"'"'s viscosity remain.

30. The lubrication system according to claim 29, wherein the condition diagnosed is selected from the group consisting of fuel contamination of the lubricant, and quality degradation of the lubricant.

31. The lubrication system according to claim 29, wherein the viscosity data and the temperature data are processed to determine a time to condemning limit for the lubricant.

32. The lubrication system according to claim 29, wherein the viscosity sensor is a dynamic viscometer.

33. The lubrication system according to claim 29, further comprising:

a data link which transfers data between the lubrication system and a site remote from the lubrication system.

34. The lubrication system according to claim 29, further comprising:

a manifold in which the viscosity and temperature sensors are mounted, said manifold being arranged such that sampled lubricant is selectively made to encounter the viscosity and temperature sensors.

35. The lubrication system according to claim 29, further comprising:

indicating means for providing a human perceivable indication of the condition of the lubricant.

36. The lubrication system according to claim 29, further comprising:

a storage device in which the viscosity and temperature data are saved.

37. The lubrication system according to claim 29, further comprising:

lubricant refreshing means for selectively carrying out one or more functions in response to the diagnosed condition of the lubricant, said functions being selected from the groups consisting of;

removing lubricant from the lubrication system, and adding fresh lubricant to the lubrication system.

38. The lubrication system according to claim 29, wherein the engine is selected from the group consisting of a railroad locomotive engine, and a mining vehicle engine.

29. A lubrication system for an engine, said lubrication system comprising:

a lubricant;

a diagnostic cell which samples the lubricant for diagnostic testing thereof, said cell including;

a viscosity sensor which monitors the lubricant'"'"'s viscosity; and

,

a temperature sensor which monitors the lubricant'"'"'s temperature; and

,

a controller which interfaces with the diagnostic cell to carry out the diagnostic testing, said controller receiving viscosity data from the viscosity sensor and temperature data from the temperature sensor, wherein the viscosity and temperature data is processed to diagnose a condition of the lubricant.