On-site analyzer

• US 6,452,179 B1
• Filed: 08/12/1999
• Issued: 09/17/2002
• Est. Priority Date: 08/14/1998
• Status: Expired due to Term

• Current Assignee: Spectro Scientific, Inc.
• Original Assignee: Global Technovations, Inc.
• Inventors: Coates, John, Rosenbaum, Neil, Abuneaj, Yosef
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): HANIG, RICHARD E
• Application Number:
  US09/372,968
• Time in Patent Office: 1,132 Days
• Field of Search: 250/339.09, 250/338.1, 356/307, 356/313, 702/8
• US Class Current: 250/339.09
• CPC Class Codes: G01J 3/28 Investigating the spectrum using colour filters G01J3/51
• CPC Class Codes: G01J 3/443 Emission spectrometry
• CPC Class Codes: G01N 21/274 Calibration, base line adjustment, drift correction
• CPC Class Codes: G01N 21/3577 for analysing liquids, e.g. polluted water
• CPC Class Codes: G01N 21/67 using electric arcs or discharges
• CPC Class Codes: G01N 21/69 specially adapted for fluids , e.g. molten metal
• CPC Class Codes: G01N 33/2847 Water in oils
• CPC Class Codes: G01N 33/2858 Metal particles
• CPC Class Codes: G01N 33/2888 Lubricating oil characteristics, e.g. deterioration lubricating properties G01N33/30
• CPC Class Codes: G01N 33/30 for lubricating properties

Abstract

An apparatus (10) for analyzing lubricant oils and functional fluids includes an optical emission spectrometer (OES) (26) having a substantially continuously valued wavelength versus intensity output (140). The OES (26) analyzes light captured from a spark emission stand (58) through which the fluid sample is flowed. An expert system (160-172) operates according to a set of Rules that corrects background influence from the electrodes, and generates diagnostic text (174) for an operator based on the information about the fluid sample provided by the OES (26) and other measurement devices. The apparatus (10) is reduce in size, weight and cost.

Claims

1. A method of normalizing an intensity of and regularizing a sample spectrum of a fluid sample generated by a spectrometer having a pair of electrodes, the method comprising the steps of normalizing the intensity by:

selecting a background spectral feature from a plurality of spectral features of a background spectrum that is indicative at least in part of the composition of the electrodes wherein the background spectral feature has an intensity variation characteristic; and

transforming the sample spectrum with respect to intensity in accordance with an intensity of said selected background spectral feature as indicated in the sample spectrum;

the method comprising regularizing the intensity by;

(A) defining a background spectrum having a plurality of spectral features indicative at least in part of the composition of the electrodes;

(B) selecting at least a first background spectral feature from said plurality of spectral features wherein the first background spectral feature has a predetermined wavelength value associated therewith;

(C) determining a measured wavelength value of the at least first background spectral feature in the sample spectrum; and

(D) translating the sample spectrum with respect to wavelength in accordance with said predetermined wavelength value, said measured wavelength value, and a predetermined translation strategy.

2. The method of claim 1 wherein the sample spectrum comprises an array of values representative of wavelengths and spectral intensities associated therewith over a spectral range, wherein said plurality of spectral features are defined by corresponding emission lines, and wherein step (B) is performed by the substep of:

selecting a plurality of emission lines from the background spectrum wherein each selected emission line has a respective predetermined wavelength value associated therewith.

3. The method of claim 2 wherein step (C) is performed by the substeps of:

identifying the plurality of selected background emission lines in the array of values; and

,

determining a respective measured wavelength value of the identified emission lines in the array.

4. The method of claim 3 wherein step (D) is performed by the substeps of:

determining a respective wavelength offset between the predetermined wavelength values and the measured wavelength values;

converting the wavelength offsets into a composite wavelength offset for the sample spectrum;

determining a pixel shift number as a function of the composite wavelength offset; and

,

shifting the spectral intensities of the array of values by the pixel shift number to thereby regularize the sample spectrum with respect to wavelength.

5. The method of claim 1 wherein the fluid sample comprises one of used lubricating oil and used functional fluid, and step (A) includes the substeps of:

exciting a new sample of said one of lubricating oil and functional fluid corresponding in type and grade to the used sample to spectroemissive levels to thereby generate radiation;

acquiring a background spectrum responsive to the radiation; and

,

storing the background spectrum for subsequent use.

6. A method of normalizing an intensity of a sample spectrum of a fluid sample by a spectrometer having a pair of electrodes, the method comprising the steps of:

(A) selecting a background spectral feature from a plurality of spectral features of a background spectrum that is indicative at least in part of the composition of the electrodes wherein the background spectral feature has an intensity variation characteristic; and

(B) transforming the sample spectrum with respect to intensity in accordance with an intensity of said selected background spectral feature as indicated in the Sample spectrum;

the method further comprising the step of regularizing the sample spectrum.

7. The method of claim 6 wherein the step of regularizing the sample spectrum comprises translating the sample spectrum with respect to wavelength in accordance with a first background spectral feature having a known wavelength selected from a background spectrum having a plurality of spectral features indicative at least in part of the composition of the electrodes.

8. The method of claim 7 wherein the sample spectrum is one of a lubricating oil sample and a functional fluid sample having one or more constituent elements, further comprising the steps of:

determining an intensity of a second background spectral feature having an intensity variation characteristic;

determining an intensity of a characteristic emission line associated with at least one of the constituent elements;

transforming the constituent element intensity into a concentration parameter using (i) the intensity of the second background spectral feature in the sample spectrum, (ii) the intensity of the constituent emission line, and (iii) predetermined data.

9. The method of claim 6 further comprising the step of subtracting a reference spectrum from said sample spectrum.

10. The method of claim 9 further comprising the step of adjusting intensity of said reference spectrum before the step of subtracting.

11. The method of claim 10 wherein the step of adjusting is performed with reference to a spectral space where there are no significant spectral features.

12. The method of claim 9 wherein said step of subtracting is performed on a point-by-point basis.

13. A method of normalizing an intensity of a sample spectrum of a fluid sample by a spectrometer having a pair of electrodes, the method comprising the steps of:

(A) selecting a background spectral feature from a plurality of spectral features of a background spectrum that is indicative at least in part of the composition of the electrodes wherein the background spectral feature has an intensity variation characteristic; and

(B) transforming the sample spectrum with respect to intensity in accordance with an intensity of said selected background spectral feature as indicated in the sample spectrum;

wherein the fluid sample contains constituents, and wherein step (A) is performed by the substeps of;

identifying an emission line associated with at least one constituent;

selecting a first set of spectral features from the plurality of spectral features of the background spectrum;

obtaining a predetermined number of spectra of the fluid sample using the pair of electrodes;

determining a first intensity variation of said identified emission line over said predetermined number of spectra;

determining, for each spectral feature in said first set, a respective second intensity variation over said predetermined number of spectra;

selecting spectral features from said first set that have a respective second intensity variation that is less than said first intensity variation to thereby form a second set of spectral features;

selecting one of the spectral features from said second set based on predetermined criteria.

14. The method of claim 13 wherein determining a respective second intensity variation step comprises the substeps of:

dividing, for each one of said predetermined number of spectra, the intensity of the identified emission line of the constituent by the intensity of the respective background spectral feature in the first set to thereby produce ratio values; and

,

calculating said second intensity variation using said ratio values.

15. The method of claim 13 wherein step (B) includes the substeps of:

measuring the intensity of the background spectral feature in the sample spectrum; and

,

ratioing at least a portion of the intensity of the sample spectrum by the measured intensity of the background spectral feature.

16. The method of claim 15 wherein the electrodes comprise silver material and the background spectral feature comprises a 336 nm silver emission line, and the measured intensity comprises area under a curve associated with the 336 nm silver line.

17. A method of analyzing a sample spectrum of one of lubricating oil sample and a functional fluid sample having one or more constituent elements wherein the sample spectrum is generated by a spectrometer having a pair of electrodes, the method comprising the steps of:

(A) translating the sample spectrum with respect to wavelength in accordance with a first background spectral feature having a known wavelength selected from a background spectrum having a plurality of spectral features indicative at least in part of the composition of the electrodes;

(B) determining an intensity of a second background spectral feature having an intensity variation characteristic;

(C) determining an intensity of a characteristic emission line associated with at least one of the constituent elements;

(D) transforming the constituent element intensity into a concentration parameter using (i) the intensity of the second background spectral feature in the sample spectrum, (ii) the intensity of the constituent emission line, and (iii) predetermined data.

18. The method of claim 17 wherein step (D) further includes the substep of:

subtracting a reference spectrum from the sample spectrum.

19. The method of claim 17 wherein the sample spectrum comprises an n-row array of values representative of wavelengths and spectral intensities associated therewith over a spectral range where n corresponds to a number of pixels of an imaging device in the spectrometer, and wherein step (A) is performed by the substeps of:

selecting multiple emission lines from the plurality of spectral features of the background spectrum wherein each emission line has a predetermined known, wavelength value;

determining a respective measured wavelength value for the multiple emission lines in the array of values;

determining a respective wavelength offset between the predetermined known wavelength values and the measured wavelength values, for each selected emission line;

determining a pixel shift number as a function of the wavelength offsets; and

,

shifting the spectral intensifies in the array by the pixel shift number.

20. The method of claim 19 further including the steps of:

evaluating a plurality of rules in response to the constituent concentration parameter and producing a plurality of output signals; and

,

determining a condition of a component of equipment from which the sample was drawn as a function of said output signals.