Method for on-line fuel-dilution monitoring of engine lubricant

• US 7,259,575 B2
• Filed: 04/08/2005
• Issued: 08/21/2007
• Est. Priority Date: 04/08/2005
• Status: Active Grant

• Current Assignee: The Lubrizol Corporation (Berkshire Hathaway Incorporated)
• Original Assignee: The Lubrizol Corporation (Berkshire Hathaway Incorporated)
• Inventors: Lvovich, Vadim F., Boyle, Frederick P.
• Primary Examiner(s): DEB, ANJAN K
• Application Number:
  US11/101,978
• Publication Number:
  US 20060229776A1
• Time in Patent Office: 865 Days
• Field of Search: 324/698, 324/664, 324/663, 324/667, 324/681
• US Class Current: 324/698
• CPC Class Codes: F01M 2001/165 according to fuel dilution in oil
• CPC Class Codes: F01M 2011/14 for indicating the necessity to change the oil
• CPC Class Codes: G01N 33/2835 specific substances contained in the oil or fuel
• CPC Class Codes: G01N 33/2888 Lubricating oil characteristics, e.g. deterioration lubricating properties G01N33/30

Abstract

A method for determining a fuel-dilution condition of a lubricant used in transportation and industrial equipment. The method uses apparatus that applies a high frequency and optionally a low frequency oscillating signal to electrodes immersed in the fluid and quantifies fluid response to the signals. Apparatus can further include means to control the lubricant temperature, or a temperature sensor to monitor the lubricant temperature at the electrodes. The method monitors response of the lubricant to the applied electrical signals and determines ratios of lubricant properties. The high-frequency lubricant property ratio or change of high frequency lubricant property as a function of a lubricant use-measure is compared to a predicted ratio based on lubricant use and an estimate of the lubricant'"'"'s fuel dilution determined. The optional low-frequency lubricant property ratio is compared to thresholds to determine when the lubricant loses the ability to control fuel dilution. The method outputs information relevant to the fuel-dilution condition of the lubricant.

Claims

1. A method for determining the fuel-dilution condition of a lubricant comprising:

a. applying a high-frequency voltage signal between electrodes immersed in a fluid,

b. measuring the lubricant dependent response to the applied high-frequency signal and determining a ratio of a high-frequency lubricant property to the high-frequency property when the lubricant is fresh, and

c. comparing at least one of the following properties selected from the group consisting of the determined high-frequency lubricant property ratio to a ratio predicted based on use since the lubricant was fresh, a change in the determined high-frequency lubricant property ratio as a function of use to a change predicted use-based change, and combination thereof, to estimate the fuel content of the lubricant,

wherein the applied signal is selected from at least one of the group consisting of essentially sinusoidal with an essentially defined frequency, essentially non-sinusoidal of frequency defined by the Fourier-transform base frequency, and combination thereof wherein each step is conducted continuously, intermittently, repeatedly and combinations thereof.

2. The method of claim 1 wherein the method further comprises:

a. applying an essentially sinusoidal low-frequency voltage signal between electrodes immersed in the fluid,

b. measuring a lubricant dependent response to the applied low-frequency signal and determining a ratio of a low-frequency property to a peak low-frequency property measured since the lubricant was fresh, and

c. comparing the determined low-frequency property ratio to at least one property ratio threshold, to determine the lubricant'"'"'s ability to control the fuel content,

wherein the a threshold for comparing the determined low-frequency property ratio is selected from at least one form the group consisting of fixed, updated by external input and combinations thereof wherein each step is conducted continuously, intermittently, repeatedly and combinations thereof.

3. The method of claim 2 wherein the lubricant response to the applied signal is measured at essentially fixed temperature with the temperature dependent upon the fluid employed, and wherein the temperature variation is less than 5°

C. and wherein the applied frequency is in the range of about 1 Hz to about 1 kHz.

4. The method of claim 2 wherein the lubricant response to the applied signal is measured at variable temperatures in the range of ambient temperatures to maximum operating temperatures and wherein the lubricant property determination is selected from at least one of the group consisting of converting the property to essentially a fixed-temperature property, minimizing the effect of temperature variation using a temperature dependent formula, using a temperature dependent look-up table and combinations thereof.

5. The method of claim 4 wherein the means for converting the fluid property to essentially fixed-temperature fluid property is selected from at least one of the group consisting of fixed, updated by external input, automatically updated when fluid temperature increases between two temperature thresholds at greater than a preset rate and combinations thereof.

6. The method of claim 2 wherein the determined low-frequency lubricant property is selected from at least one of the group consisting of real impedance, real impedance equivalent and combinations thereof.

7. The method of claim 2 that further includes resetting and updating values used for the comparisons under the conditions selected from the group consisting of an external input is provided that a fluid change has occurred, change in the determined fluid property is used to that a fluid change has occurred and combinations thereof.

8. An apparatus that collects data required for on-line monitoring and detecting fuel-dilution condition of a lubricant by the method of claim 2.

9. The method of claim 1 wherein the frequency of the applied signal is predetermined as a function of at least one of the following selected from the group consisting of electrode geometry, lubricant temperature, lubricant temperature range, composition of the lubricant being monitored and combinations thereof.

10. The method of claim 1 wherein the lubricant response to the applied signal is measured at essentially fixed temperature with the temperature dependent upon the fluid employed, and wherein the temperature variation is less than about 5°

C. and wherein the applied frequency is in the range of about 10 kHz to about 10 MHz.

11. The method of claim 1 wherein the lubricant response to the applied signal is measured at variable temperatures in the range of ambient temperatures to maximum operating temperatures and the lubricant property determination is selected from at least one of the group consisting of converting the property to essentially a fixed-temperature property, minimizing the effect of temperature variation, using a temperature dependent formula, using a temperature dependent look-up table and combinations thereof.

12. The method of claim 11 wherein the method for converting the fluid property to essentially fixed-temperature fluid property is selected from at least one of the group consisting of fixed, updated by external input, automatically updated when fluid temperature increases between two temperature thresholds at greater than a preset rate and combinations thereof.

13. The method of claim 1 wherein the determined high-frequency lubricant property is selected from at least one of the group consisting of permittivity, permittivity-equivalent and combinations thereof.

14. The method of claim 1 wherein the comparison used to estimate fuel content of the lubricant is made using a formula, a look-up table or combinations thereof.

15. The method of claim 1 wherein the comparison used to estimate fuel content of the lubricant is selected from at least one of the group consisting of fixed, updated by external input, updated by a determination that a complete lubricant change has occurred, updated by a determination that an addition of fresh lubricant was made, and combinations thereof.

16. The method of claim 1 wherein the lubricant use is measured based on at least one of the group consisting of equipment use-measure, a lubricant condition determined by other than the applied signals of this invention, and combinations thereof and wherein the use is measured from the point when the lubricant is fresh.

17. The method of claim 16 wherein equipment use-measure is selected from at least one of the group consisting of operating time, energy output, distance traveled, number of operating cycles, equipment temperature, fuel consumed, start/stop cycle and combinations thereof.

18. The method of claim 16 wherein lubricant condition is determined by at least one of the group consisting of lubricant response to one or more signals applied at frequencies other than the high-frequency signal of claim 1, viscosity, IR absorption, lubricant temperature and combinations thereof.

19. The method of claim 1 wherein the change of the determined high-frequency property is at least one selected from the group consisting of rate of property change as a function of lubricant use, the curvature of the property change as a function of lubricant use, and combinations thereof.

20. The method of claim 1 further includes resetting and updating values used for the comparisons under the conditions selected from the group consisting of an external input is provided that a fluid change has occurred, change in the determined fluid property is used to determine that a fluid change has occurred and combinations thereof.

21. An apparatus that collects data required for on-line monitoring and detecting fuel-dilution condition of a lubricant by the method of claim 1.

22. An apparatus that monitors and detects the fuel-dilution condition of a lubricant comprising:

d. applying a high-frequency voltage signal between electrodes immersed in a fluid,

e. measuring a lubricant response to the applied high-frequency signal and determining a ratio of a high-frequency lubricant property to the high-frequency property when the lubricant is fresh, and

f. comparing at least one of the following selected from the group consisting of the determined high-frequency lubricant property ratio to a ratio predicted based on use since the lubricant was fresh, a change in the determined high-frequency lubricant property ratio as a function of use to a change predicted use-based change, and combination thereof to estimate a fuel content of the lubricant,

wherein the applied signal is selected from at least one of the group consisting of essentially sinusoidal with an essentially defined frequency, essentially non-sinusoidal of frequency defined by the Fourier-transform base frequency, and combination thereof wherein each step is conducted continuously, intermittently, repeatedly and combinations thereof.

23. The apparatus of claim 22 where the apparatus further comprises:

a. applying an essentially sinusoidal low-frequency voltage signal between electrodes immersed in the fluid,

b. measuring a lubricant dependent response to the applied low-frequency signal and determining a ratio of a low-frequency property to a peak low-frequency property measured since the lubricant was fresh, and

c. comparing the determined low-frequency property ratio to at least one property ratio threshold, to determine the lubricant'"'"'s ability to control the fuel content,

wherein the a threshold for comparing the determined low-frequency property ratio is selected from at least one form the group consisting of fixed, updated by external input and combinations thereof wherein each step is conducted continuously, intermittently, repeatedly and combinations thereof.