# US 6,718,819 B2 · Oil quality sensor system, method and apparatus

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- Number: US 6,718,819 B2
- Document ID: US6718819B2
- Status: Granted
- Kind: B2
- Application number: 09/950,196
- Filed: 2001-09-10
- Published: 2003-03-13
- Granted: 2004-04-13
- Earliest claimed: 2001-09-10
- Assignees: Honeywell International Inc.
- Inventors: Jeffrey N. Schoess
- Web page: https://patentgrep.com/patent/US6718819B2

## CPC

- B01D 27/08: Construction of the casing
- B01D 29/60: integrally combined with devices for controlling the filtration
- G01N 33/2888: {Lubricating oil characteristics, e.g. deterioration (lubricating properties G01N33/30)}
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

An apparatus for determining the condition of engine lubricating oil includes a sensor having a plurality of spaced apart electrode pairs on a nonconductive polymer film. The sensor is operatively associated with an oil filter, which provides retro-fit capability and easy access for servicing and replacement. The multi-electrode pair design averages signal output to reduce operational electromagnetic interference noise. A forcing-function waveform reactive circuit is applied to the sensor input electrode as a common voltage potential. The output current from the sensor electrodes is then relayed to a current follower amplifier, which converts the output current into an equivalent voltage for comparison with predetermined values. Based on the voltage values, the on-board sensing system will determine the oil's condition, and will trigger a trouble code if the equivalent voltage falls within a predetermined range.

## Claims

### Claim 1

An oil quality sensing system, comprising:
an oil filter;
a conductivity sensor attached to the oil filter, said conductivity sensor comprising a plurality of spaced apart electrode pairs mounted on a nonconductive film substrate, configured as a linear array or said electrode pairs extending in a band around an inner wall of the oil filter;
a waveform generator;
a measuring device for measuring a signal reflected by the sensor,
a comparing device, and
a signal generator.

### Claim 2

An oil quality sensing system, comprising:
an oil filter;
a conductivity sensor attached to the oil filter, said conductivity sensor comprising a plurality of spaced apart electrode pairs mounted on a nonconductive film substrate, configured as a substantially circular array of said electrode pairs extending in an annular band around the underside of a tapping plate of said oil filter;
a waveform generator;
a measuring device for measuring a signal reflected by the sensor,
a comparing device, and
a signal generator.

### Claim 3

An oil quality sensing system, comprising:
an oil filter;
a conductivity sensor attached to the oil filter, said conductivity sensor comprising a plurality of spaced apart electrode pairs mounted on a nonconductive film substrate;
a waveform generator;
a measuring device for measuring a signal reflected by the sensor,
a comparing device,
a signal generator; and
a flexible electrical cable, electrically connected to said sensor and extending away from the oil filter, and a disconnectable plug attached to the cable.

### Claim 4

A sensor for immersing placement in oil to monitor the condition thereof, said sensor comprising:
a nonconductive film of a polymeric substrate; and
plurality of spaced apart electrode pairs applied to a first surface of the substrate; and
a pressure-sensitive adhesive applied to a second surface of the substrate opposite the first surface.

### Claim 5

A sensor for immersing placement in oil to monitor the condition thereof, said sensor comprising:
a nonconductive film of a polymeric substrate;
a plurality of spaced apart electrode pairs applied to a first surface of the substrate;
a first electrode connector strip extending laterally on the substrate;
a plurality of spaced apart electrodes extending from said first connector strip and in electrical communication therewith;
a second electrode connector strip extends laterally on the substrate, spaced from the second connector strip; and
a plurality of spaced apart electrodes extending from said second connector strip and in electrical communication therewith.

### Claim 6 (depends on 5)

The sensor of claim 5, wherein the electrodes of the first and second connector strips are interdigitated.