Oil monitor with magnetic field

• US 5,262,732 A
• Filed: 12/11/1991
• Issued: 11/16/1993
• Est. Priority Date: 12/11/1991
• Status: Expired due to Term

• Current Assignee: CSI Technology Incorporated (Emerson Electric Company)
• Original Assignee: Computational Systems Incorporated (Emerson Electric Company)
• Inventors: Kirkpatrick, James F., Johnson, Eric L., Hawn, Keith A., Dickert, Arby D.
• Primary Examiner(s): Wieder, Kenneth A.
• Assistant Examiner(s): BROWN, GLENN WARNER
• Application Number:
  US07/807,041
• Time in Patent Office: 706 Days
• Field of Search: 324/553, 324/663, 324/672, 324/676, 324/678, 324/686, 324/204, 324/361, 324/227, 324/228, 324/232, 73/53.05
• US Class Current: 324/672
• CPC Class Codes: F01M 2011/14 for indicating the necessity to change the oil
• CPC Class Codes: G01N 15/0656 using electric, e.g. electrostatic methods or magnetic methods by investigating individual particles G01N15/1031, G01N15/12
• CPC Class Codes: G01N 33/2858 metal particles
• CPC Class Codes: G01N 33/2888 Lubricating oil characteristics, e.g. deterioration lubricating properties G01N33/30

Abstract

An apparatus for detecting the degree of deterioration in lubricating oil including a grid-like capacitive sensor, that uses the lubricating oil as a dielectric medium, and a magnetic field imposed upon the oil to attract ferromagnetic wear particles into the vicinity of the sensor. Preferably, the magnetic field is generated by a permanent magnet and an electromagnetic aligned such that the magnetic field produced by each magnet acts upon the oil along the same axis.

Claims

1. An apparatus for monitoring the condition of and detecting a physical property of contaminants in a sample of lubricating oil comprising:

a. containing means for holding and confining the sample of lubricating oil, said containing means defining a substantially sealed chamber when in place in said apparatus and the sample of lubricating oil being substantially stagnant within said containing means;

b. magnet means for inducing a magnetic field upon the sample of lubricating oil in said containing means and for causing the migration of any magnetically responsive contaminants within the stagnant oil sample;

c. sensor means located in the magnetic field for sensing a physical property of the stagnant oil sample in the presence of the magnetic field and for generating a sensor signal corresponding to the value of the physical property sensed; and

d. analysis means having as input said sensor signal for sampling said sensor signal at discrete time intervals, determining the presence and type of contaminants in said lubricating oil, and determining the condition of said lubricating oil based upon the value of the sensor signal and the change in said sensor signal over said discrete time intervals.

2. The apparatus as defined in claim 1 wherein said magnet means comprises a permanent magnet.

3. The apparatus as defined in claim 1 wherein said magnet means comprises an electromagnet.

4. The apparatus as defined in claim 1 wherein:

said magnet means comprises a permanent magnet located relative to said sensor means for imposing a constant magnetic field on the oil proximate said sensor means; and

said sensor means comprises a sensor having at least two conductors exposed to the lubricating oil that provides an insulating dielectric medium between said conductors to form a capacitor.

5. The apparatus as defined in claim 1 further comprising:

a calibration oil;

a test oil; and

said sensor means producing a signal corresponding to physical properties of oil to which it is exposed, producing and storing calibration signals when exposed to said calibration oil, producing and storing test signals when exposed to said test oil, and determining a corrosion index corresponding to corrosion of the sample of oil based on a comparison of at least one said test signal to at least one said calibration signal.

6. The apparatus as defined in claim 1 wherein said sensor means generates a signal corresponding to physical properties of the oil, said sensor means further comprising processor means responsive to said signal for determining a contamination index based upon change of the signal over time.

7. The apparatus as defined in claim 1 wherein said sensor means comprises a sensor having at least two conductors exposed to the lubricating oil that provides an insulating dielectric medium between said conductors to form a capacitor.

8. The apparatus as defined in claim 1 wherein said sensor means comprises a sensor and monitor means for monitoring the output from said sensor.

9. The apparatus as defined in claim 1 wherein said sensor means comprises:

a sensor;

monitor means for monitoring the output from said sensor; and

processing means for interpreting the output from said monitoring means.

10. The apparatus as defined in claim 1 wherein said sensor means comprises:

a sensor; and

monitor means for monitoring the output from said sensor, said sensor having at least two conductors exposed to the lubricating oil that provides a dielectric medium between said conductors to form a capacitor.

11. An apparatus for monitoring the condition of lubricating oil comprising:

a. containing means for holding a sample of the lubricating oil;

b. magnet means for inducing a magnetic field upon the oil sample in said containing means;

c. sensor means located in the magnetic field for sensing a physical property of the oil sample in the presence of the magnetic field; and

wherein said magnet means further comprises;

d. a permanent magnet located relative to said sensor means for imposing a constant magnetic field on the oil and for attracting particles in the oil toward the sensor means;

e. an electromagnet located relative to said sensor means for imposing a pulsed magnetic field on the oil proximate to said sensor means;

f. an electric power source electrically connected to said electromagnet; and

g. switching means electrically connected between said power source and said electromagnet for alternating the polarity of said electromagnet.

12. An apparatus for monitoring the condition of lubricating oil comprising:

a. containing means for holding a sample of the lubricating oil;

b. magnet means for inducing a magnetic field upon the oil sample in said containing means;

c. sensor means located in the magnetic field for sensing a physical property of the oil sample in the presence of the magnetic field;

said magnet means includes an electromagnet and a switching means for changing the polarity of said electromagnet; and

said sensor means includes a sensor having at least two conductors exposed to the lubricating oil that provides an insulating dielectric medium between said conductors to form a capacitor.

13. The apparatus as defined in claim 12 wherein said magnet means further comprises a permanent magnet.

14. An apparatus for monitoring the condition of lubricating oil comprising:

a. containing means for holding a sample of the lubricating oil;

b. magnet means for inducing a magnetic field upon the oil sample in said containing means;

c. sensor means located in the magnetic field for sensing a physical property of the oil sample in the presence of the magnetic field; and

said magnet means further comprising an electromagnet and switching means for altering said magnetic field generated by said electromagnet.

15. The apparatus as defined in claim 14 wherein said magnet means further comprises a permanent magnet, said permanent magnet and said electromagnet both being located for imposing a magnetic field on the lubricating oil proximate to said sensor means.

16. The apparatus as defined in claim 14 wherein, said sensor means generates a signal corresponding to physical properties of the oil, and said sensor means further comprises processor means responsive to said signal for determining a magnetically responsive debris index based upon change of the signal when the switching means alters the magnetic field.

17. An apparatus for monitoring the condition of and detecting at least one physical property of contaminants in a sample of lubricating oil comprising:

a. a container for holding and confining the oil sample, said container having an opening, defining a substantially sealed chamber when in place in said apparatus and the oil sample being substantially stagnant within the container;

b. A sensor having at least two conductors, said sensor configured for covering the opening of said container and for being disposed below the container in a measurement position such that said lubricating oil flows into the sensor and becomes at least part of the insulating dielectric medium between said conductors, said conductors, when exposed to the lubricating oil, forming a capacitor which as a capacitance that varies in relation to at least the area of the conductors, the dielectric constant of the lubricating oil and the distance between the conductors;

c. a permanent magnet located proximate to said sensor for imposing a constant magnetic field on the oil;

d. an electromagnet located proximate to said sensor for imposing a pulsed magnetic field on the oil, said constant and pulsed magnetic fields for causing the migration of magnetically responsive contaminants to said sensor and said pulsed magnetic field further for varying the orientation of magnetically responsive contaminants;

e. monitor means for monitoring the capacitance of said sensor at discrete time intervals and determining the condition of and at least one physical property of contaminants in the oil sample based upon the capacitance of said sensor and the change in capacitance of said sensor over said discrete time intervals;

f. an electric power source electrically connected to said electromagnet; and

g. switching means electrically connected between said power source and said electromagnet for alternating the polarity of said electromagnet.

18. An apparatus for determining the possible presence of corrosive products, ferromagnetic particles and contamination in lubricating oil comprising:

a. a container for holding said lubricating oil, said container including a bottle having an open mouth and a removable and resealable lid for sealably attaching to the mouth;

b. a sensor having at least two ferromagnetic conductors disposed in a spaced apart side-by-side relationship in a grid-like formation, said sensor configured for being disposed below the container in a measurement position such that said lubricating oil flows into the sensor and becomes an insulating medium between said conductors, said a conductors, when exposed to the lubricating oil, forming a capacitor which has a capacity that varies in relation to at least the area of the conductors, the dielectric constant of the lubricating oil and the distance between the conductors;

c. a permanent magnet located proximate to said sensor for imposing a constant magnetic field on the oil in the vicinity of the sensor and attracting ferromagnetic particles int eh oil toward the sensor;

d. an electromagnetic having a magnetic field of lesser intensity than said permanent magnet, said electromagnet located proximate to said sensor for imposing a pulsed magnetic field on the oil in the vicinity of the sensor and for reorienting ferromagnetic particles in the oil;

e. an electric power source electrically connecting said electromagnet;

f. switching means electrically connected between said power source and said electromagnet for alternating the polarity of said electromagnet at a preselected switching frequency;

g. monitor means for monitoring the capacitance of said sensor and producing a capacitance signal corresponding to the capacitance; and

h. processing means for determining the level of corrosive products in the lubricating oil based upon the capacitance of said sensor, determining the contamination in the lubrication oil based upon a change in the capacitance of the sensor caused by change in the pulsed magnetic field.

19. An apparatus for determining the presence of magnetically non-responsive contaminants which will migrate due to the influence of gravity in used lubricating oil samples comprising:

container means for holding and confining the oil sample, said containing means defining a substantially sealed chamber when in place in said apparatus and the sample of lubricating oil being substantially stagnant within said containing means;

sensor means for capacitively sensing the presence of contaminants in the stagnant oil sample and generating a sensor signal corresponding to the contaminants present in the stagnant oil sample; and

monitor means having said sensor signal as input for monitoring said sensor means, sampling said sensor signal at a first time to produce a first measurement, waiting for a delay period of time, then sampling said sensor signal at at least a second time to produce a second measurement, and determining at least one physical property of contaminants in the oil based on the first and second measurements and the change in said measurements over the delay period.

20. The apparatus of claim 19 wherein said sensor means further comprises a capacitive sensor disposed in contact with the oil sample.

21. The apparatus of claim 19 wherein said monitor means samples said sensor signal after the contaminants in the oil sample have been allowed to migrate for a delay period of time of about five minutes.

22. The apparatus of claim 19 wherein said monitor means makes at least one intermediate sample of said sensor signal before the contaminants in the oil sample have migrated less than about 5 minutes and at least one final sample after the contaminants in the oil sample have been allowed to migrate for a period of time of about five minutes.

23. The apparatus of claim 19 wherein said monitor means samples said sensor signal a plurality of times at a uniform rate over a predetermined delay period of time.

24. The apparatus of claim 19 wherein said monitor means sample said sensor signal at a rate of one sample per second for a total of about 256 samples.