Method for analysis of a working fluid using impedance spectroscopy
First Claim
Patent Images
1. A method for determining the condition of a working fluid contained in a mechanical system and at a temperature above about 50°
- C. which comprises;
disposing a pair of spaced apart electrodes in the fluid;
imposing an AC signal over a range of 4 or more frequencies on the electrodes;
determining the impedance or admittance data as a function of the frequencies from electrical response to the imposed AC signals;
determining at least one of the following properties;
resistance, capacitance, Omega max, and time constant by plotting the frequency dependent impedance data in the form of a Nyquist plot by fitting the data to a curve where, in rectangular coordinates, imaginary impedance (Z″
) is plotted against real impedance (Z′
) or, in polar coordinates, Z=[(Z′
)2(Z″
)2)1/2 is plotted against Θ
, the phase difference between voltage and current, wherein said resistance, capacitance, Omega max, and time constant is calculated by determining the diameter of the curve; and
comparing one of the properties determined to a predetermined value of the said properties whereby an indication of the condition of the fluid is determined.
1 Assignment
0 Petitions
Accused Products
Abstract
An on-line method for determining the condition of low conductivity working fluids using alternating current, electro-impedance spectroscopy is provided by making measurements over a range of frequencies at temperatures at or above 50° C.
-
Citations
7 Claims
-
1. A method for determining the condition of a working fluid contained in a mechanical system and at a temperature above about 50°
- C. which comprises;
disposing a pair of spaced apart electrodes in the fluid; imposing an AC signal over a range of 4 or more frequencies on the electrodes; determining the impedance or admittance data as a function of the frequencies from electrical response to the imposed AC signals; determining at least one of the following properties;
resistance, capacitance, Omega max, and time constant by plotting the frequency dependent impedance data in the form of a Nyquist plot by fitting the data to a curve where, in rectangular coordinates, imaginary impedance (Z″
) is plotted against real impedance (Z′
) or, in polar coordinates, Z=[(Z′
)2(Z″
)2)1/2 is plotted against Θ
, the phase difference between voltage and current, wherein said resistance, capacitance, Omega max, and time constant is calculated by determining the diameter of the curve; andcomparing one of the properties determined to a predetermined value of the said properties whereby an indication of the condition of the fluid is determined. - View Dependent Claims (2, 3)
- C. which comprises;
-
4. A method for obtaining an indication of the performance additive levels of a industrial oil containing less than about 3 wt % performance additives, on active ingredient basis, where the oil is contained in a mechanical system comprising:
-
measuring the impedance data of the oil at a plurality and over a range of frequencies while the oil is contained in the mechanical system and is at 500°
C. or higher;obtaining a value for at least one of resistance, capacitance, Omega max, and time constant from the impedance data by plotting the frequency dependent impedance data in the form of a Nyquist plot by fitting the data to a curve where, in rectangular coordinates, imaginary impedance (Z″
) is plotted against real impedance (Z′
) or, in polar coordinates, Z=[(Z′
)2+(Z″
)2)1/2 is plotted against Θ
, the phase difference between voltage and current, wherein said resistance, capacitance, Omega max, and time constant is calculated by determining the diameter of the curve; andcomparing the obtained value or values with a value or values for a known additive level whereby an indication of the additive level is obtained. - View Dependent Claims (5, 6, 7)
-
Specification
-
- Resources
Litigation Campaign Assessment
Thank you for your request. You will receive a custom alert email when the Litigation Campaign Assessment is available.
×
-
Current AssigneeExxonMobil Research & Engineering Company (Exxon Mobil Corporation)
-
Original AssigneeExxonMobil Research & Engineering Company (Exxon Mobil Corporation)
-
InventorsVann, Walter David, Lira-Cantu, Monica M., Song, Limin, Schilowitz, Alan Mark
-
Primary Examiner(s)Deb, Anjan
-
Assistant Examiner(s)He, Amy
-
Application NumberUS10/439,156Publication NumberTime in Patent Office1,223 DaysField of Search324/663, 324/698, 324/664, 324691-697, 324658-662, 702/65US Class Current324/698CPC Class CodesG01N 27/026 Dielectric impedance spectr...G01N 33/2835 Specific substances contain...G01N 33/2888 Lubricating oil characteris...
