Oil quality monitor sensor and system

• US 5,089,780 A
• Filed: 03/04/1991
• Issued: 02/18/1992
• Est. Priority Date: 10/04/1989
• Status: Expired due to Term

• Current Assignee: Hughes Aircraft Company (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Megerle, Clifford A.
• Primary Examiner(s): Wieder, Kenneth A.
• Application Number:
  US07/663,770
• Time in Patent Office: 351 Days
• Field of Search: 324/438, 324/439, 324/450, 324/444, 324/446, 324/448, 324/442, 324/698, 324/693, 324/713, 324/71.1, 324/694, 73/64, 73/116
• US Class Current: 324/448
• CPC Class Codes: G01N 27/07 Construction of measuring vessels; Electrodes therefor
• CPC Class Codes: G01N 33/2888 Lubricating oil characteristics, e.g. deterioration lubricating properties G01N33/30

Abstract

A sensor and system for monitoring the accumulation of contaminants in oil wherein the contaminants have an electrical conductivity which is different from the oil. An electrochemical cell is used to measure the alternating current conductivity of the oil to provide an indication of the amount of contaminants present in the oil. Acids and water are two common engine oil contaminants which are accurately monitored by this alternating current conductivity measurement system.

Claims

1. A system for monitoring the accumulation of water and sulfuric acid contaminants in internal combustion engine oil, wherein said contaminants have an electrical conductivity which is different from the electrical conductivity of said oil, said system comprising:

an electrochemical cell comprising two electrodes which are spaced apart at a constant spacing to provide a conductivity measurement zone of constant width located between said electrodes, said electrochemical cell being capable of being immersed in said oil;

means for applying to said electrochemical cell an alternating current voltage having a frequency within the range of 100 to 1000 hertz; and

means for measuring the alternating current conductivity of said oil in said conductivity measurement zone when said electrochemical cell is immersed in said oil to thereby indicate the amount of said water and sulfuric acid contaminants in said oil.

2. A system for monitoring the accumulation of contaminants in oil according to claim 1 which further includes warning means for indicating that the alternating current conductivity of said oil has reached a pre-selected maximum, said warning means being operable between an off mode when said alternating current conductivity is below said pre-selected maximum and an on mode when said alternating current conductivity is at or above said pre-selected maximum.

3. A system for monitoring the accumulation of contaminants in oil according to claim 1 wherein said electrodes comprise two concentric cylinders.

4. A system for monitoring the accumulation of contaminants in oil according to claim 3 wherein said oil is engine oil in an internal combustion engine and said electrodes are attached to a drain plug used for draining said oil from said internal combustion engine.

5. A system for monitoring the accumulation of contaminants in oil according to claim 3 wherein said concentric cylinders are made from metallic mesh.

6. A method for monitoring the accumulation of water and sulfuric acid contaminants in internal combustion engine oil wherein said contaminants have an electrical conductivity which is different from said oil and wherein said contaminants accumulate in said oil over a period of time to produce contaminated oil, said method comprising the steps of:

(a) providing two electrodes which are spaced apart at a constant spacing to provide a conductivity measurement zone of constant width located between said electrodes;

(b) immersing said two electrodes in said oil;

(c) applying an alternating current voltage to said two electrodes at a frequency within the range of 100-1000 hertz;

(d) measuring the alternating current voltage passing between said electrodes immersed in said oil during said period of time to thereby measure the alternating current conductivity of said oil in said conductivity measurement zone; and

(e) monitoring the level of said alternating current conductivity to thereby indicate the amount of said water and sulfuric acid contaminants in said oil.

7. A method for monitoring the accumulation of contaminants in oil according to claim 6 wherein said contaminants are water and/or acid produced during operation of an internal combustion engine.

8. A method for monitoring the accumulation of contaminants according to claim 7 wherein measurement of the alternating current conductivity of said oil is accomplished by measuring the alternating current conductivity of the oil located between two concentric cylindrical electrodes.

9. A method for monitoring the accumulation of contaminants in oil according to claim 6 wherein measurement of the alternating current conductivity of said oil is accomplished by measuring the alternating current conductivity of said oil located between two concentric cylindrical electrodes.

10. A method for monitoring the accumulation of contaminants in the oil in an internal combustion engine according to claim 9 wherein said concentric cylindrical electrodes are attached to a drain plug used for draining said oil from said internal combustion engine.