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Methods for detecting oil deterioration and oil level

  • US 20090063060A1
  • Filed: 09/05/2007
  • Published: 03/05/2009
  • Est. Priority Date: 09/05/2007
  • Status: Active Grant
First Claim
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1. A method for detecting oil deterioration and oil level, comprising the steps of:

  • a. providing an oil in use, said oil in use is placed in an oil system of a machine;

    b. providing a reference oil being free of water, said reference oil is disposed in a sealed container which is located in a common temperature environment with said oil;

    c. providing a measurement sensor which includes a first capacitor;

    d. providing a reference sensor which includes a second capacitor, said second capacitor is immersed in said reference oil;

    e. positioning said measurement sensor wherein said first capacitor is immersed in said oil in use;

    f. measuring an electrical property of said first capacitor and an electrical property of said second capacitor, wherein said electrical property is one of;

    an impedance of the respective said first and said second capacitors;

    a current passing through the respective said first and said second capacitors;

    a voltage developed across the respective said first and said second capacitors;

    g. combining said electrical property of said first capacitor with said electrical property of said second capacitor to obtain a measured temperature compensated electrical property of said first capacitor, which represents a measured temperature compensated electrical property EPT(M) of said oil in use;

    h. following the steps (a) to (g) establishing a predicted temperature compensated electrical property profile for said oil, which reflects a normal oil deterioration for said oil, said predicted profile includes an electrical property (EPT,N), which is equal to a measured property EPT(M) of said oil if it is unused and dry, and another electrical property (EPT,S), which is equal to the measured property EPT(M) of said oil if it is spent and dry;

    i. establishing a full range of usage of said oil as Δ

    UF=(US

    UN) according to change of said electrical properties (EPT,N

    EPT,S), wherein U represents an actual oil usage which is an independent variable to said property EPT;

    said UN is an actual usage of said unused oil and said US is an actual usage of said spent oil;

    j. defining a measured normalized remaining usage ratio RM of said oil having said property EPT(M) as;

    RM=[EPT(M)−

    EPT,S]/[EPT,N

    EPT,S],wherein R is a remaining usage ratio and ranges from one for said unused oil to zero for said spent oil;

    k. defining a measured remaining usage of said oil as (RMΔ

    UF);

    l. from said predicted property profile, determining a predicted temperature compensated electrical property EPT(P) according to a same usage moment as compared with said measured property EPT(M), establishing a predicated remaining usage ratio as Rp=[EPT(P)-EPT,S]/[EPT,N-EPT,S], from which to obtain a predicted remaining usage (RpΔ

    UF);

    m. determining said normal deterioration of said oil which occurs in the absence of said water if said measured remaining usage (RMΔ

    UF) is similar to said predicated remaining usage (RpΔ

    UF), and confirming said measured remaining usage which represents an actual remaining usage of said oil;

    n. determining an abnormal deterioration of said oil which occurs in the presence of said water if said measured remaining usage (RMΔ

    UF) is less than said predicted remaining usage (RpΔ

    UF); and

    o. determining a top level of said oil which is reduced to a top level of a predetermined threshold amount of said oil if said measured remaining usage (RMΔ

    UF) is larger than said predicted remaining usage (RpΔ

    UF).

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