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Methods for detecting oil deterioration and oil level

  • US 7,729,870 B2
  • Filed: 09/05/2007
  • Issued: 06/01/2010
  • Est. Priority Date: 09/05/2007
  • Status: Expired due to Fees
First Claim
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1. A method for detecting oil deterioration and oil level, comprising the steps of:

  • a. providing an oil which does not contain water, said oil is disposed 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;

    f. using a measuring device for measuring an electrical property of said first capacitor and an electrical property of said second capacitor from a first measurement, wherein said electrical property is one of;

    an impedance of said first capacitor and an impedance of said second capacitor;

    a current passing through said first capacitor and a current passing through said second capacitor;

    a voltage developed across said first capacitor and a voltage developed across said second capacitor;

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

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

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

    UF=(US

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

    EPT,S), wherein a symbol U represents an actual usage of said oil which is an independent variable to a temperature compensated electrical property EPT;

    said UN is an actual usage of said oil which is unused or new and dry and said US is an actual usage of said oil which is spent and dry;

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

    RM,i=[EPT,i(M)−

    EPT,S]/[EPT,N

    EPT,S], said RM,i ranges from one for said oil which is new or unused and dry to zero for said oil which is spent and dry, wherein said first measured property EPT,i(M) correlates to a first actual usage Ui of said oil and defines a first measured remaining usage of said oil as (RM,i Δ

    UF);

    k. from said predicted temperature compensated electrical property profile, determining a first predicted property EPT,i(P) according to said first actual usage as compared with said first measured property EPT,i(M), from which establishing a first predicated remaining usage ratio as RP,i=[EPT,i(P)−

    EPT,S]/[EPT,N

    EPT,S] and a first predicted remaining usage (RP,iΔ

    UF) of said oil;

    l. repeating steps (f) and (g) from a second measurement to obtain a second measured temperature compensated electrical property of said first capacitor which represents a second measured temperature compensated electrical property of said oil according to said first actual usage of said oil, from which obtaining a second measured remaining usage ratio and second measured remaining usage;

    m. determining a normal deterioration of said oil which occurs in the absence of water if said second measured remaining usage is similar to said first predicated remaining usage (RP,i Δ

    UF), and confirming said second 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 water if said second measured remaining usage is less than said first predicted remaining usage (RP,iΔ

    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 second measured remaining usage is larger than said first predicted remaining usage (RP,iΔ

    UF).

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