Miniature sensor for lubricant analysis

• US 6,204,656 B1
• Filed: 05/29/1997
• Issued: 03/20/2001
• Est. Priority Date: 05/29/1997
• Status: Expired due to Fees

• Current Assignee: Predict, Inc.
• Original Assignee: Reid Asset Management Company
• Inventors: Bush, Wayne A., Cheiky-Zelina, Margaret A.
• Primary Examiner(s): Ballato, Josie
• Assistant Examiner(s): Solis, Jose M.
• Application Number:
  US08/865,503
• Time in Patent Office: 1,391 Days
• Field of Search: 340/631, 324/71.4, 324/204, 324/687, 324/690
• US Class Current: 324/71.4
• CPC Class Codes: G01N 33/2858 metal particles
• CPC Class Codes: G01R 27/2617 Measuring dielectric properties, e.g. constants testing dielectric strength G01R31/12; detecting insulation faults G01R31/52; G01R27/2688 takes precedence

Abstract

A fluid contamination analyzer employs one or more micro-miniature sensors which provide for a substantial reduction in sensor dimensions form prior art dimensions of approximately 2 in.×2 in. to approximately 1 mm×1 mm. The sensors are incorporated into probes for easy lubricant fluid accessibility or alternatively may be employed in an on-line analyzer residing in the fluid flow path. The sensors sense an impedance of the fluid which is a function of its contamination and communicates the impedance to analysis circuitry via either a hard-wired or RF data link. An array of sensors may also be utilized in conjunction with a magnetic field intensity gradient to obtain a particulate distribution across the array. Impedance information, which is indicative of the particulate distribution, is communicated to analysis circuitry individually or in a multiplexed format for fluid contamination analysis. The use of micro-miniature sensors allows for substantial improvements in fluid contamination analysis by making fluid analysis procurement easy while increasing the number of applications in which such analysis may be employed.

Claims

1. A fluid contamination analyzer, comprising:

a probe; and

at least one micro-miniature sensor at one end of the probe, wherein the at least one sensor includes;

a substrate;

a plurality of conductors formed over the substrate, wherein each is coupled to one of two leads; and

an insulating layer disposed between the plurality of conductors and the substrate;

wherein the conductors form electrodes of the sensor and when a fluid contacts the sensor an impedance of the fluid may be determined using the leads of the sensor, thereby providing an indication of fluid contamination.

10. The analyzer of claim 1, further comprising an array of micro-miniature sensors located within a path of fluid flow, wherein the array of sensors are utilized to improve the accuracy of fluid contamination analysis by providing multiple data samples for subsequent statistical analysis.

11. The analyzer of claim 10, wherein at least one of the sensors has a spacing between the conductors that differs from the other sensors.

2. An on-line fluid contamination analyzer, comprising:

an array of micro-miniature sensors located within a path of fluid flow; and

a selectively activatable electromagnet in proximity to the array of micro-miniature sensors, wherein the electromagnet may be activated and deactivated in response to control signals and provides a magnetic gradient across the sensor array, and wherein the magnetic gradient provides a contaminant size distribution across the sensor array.

14. The analyzer of claim 2, wherein at least one of the array of micro-miniature sensors comprise:

a substrate; and

a plurality of conductors formed over the substrate, wherein each is coupled to one of two leads,

wherein the conductors form electrodes of the sensor and when a fluid contacts the sensor an impedance of the fluid may be determined using the leads of the sensor, thereby providing an indication of fluid contamination.

15. The analyzer of claim 14, further comprising an insulative layer disposed between the plurality of conductors and the substrate.

16. The analyzer of claim 14, further comprising an insulative layer overlying the plurality of conductors.

17. The analyzer of claim 14, further comprising a conductive layer overlying the conductors, thereby forming a cavity for fluid flow analysis between the conductive layer and the conductors, wherein when a voltage is applied to the conductive layer, an electrostatic filed develops within the cavity, thereby dislodging any particulates that may have become stuck in the sensor and thereby improving fluid contamination analysis accuracy.

18. The analyzer of claim 14, wherein at least one of the sensors has a spacing between the conductors that differs from the other sensors.

3. A fluid contamination analyzer, comprising:

a probe;

at least one micro-miniature sensor at one end of the probe, wherein the at least one sensor includes;

a substrate;

a plurality of conductors formed over the substrate, wherein each is coupled to one of two leads; and

an insulating layer overlying the plurality of conductors; and

a conductive layer overlying the conductors, thereby forming a cavity for fluid flow analysis between the conductive layer and the conductors,

wherein the conductors form electrodes of the sensor and when a fluid contacts the sensor an impedance of the fluid may be determined using the leads of the sensor, thereby providing an indication of fluid contamination; and

when a voltage is applied to the conductive layer, an electrostatic field develops within the cavity, thereby dislodging any particulates that may have become stuck in the sensor and thereby improving fluid contamination analysis accuracy.

4. A fluid contamination analyzer including a micro-miniature sensor, comprising:

a substrate;

a plurality of conductors formed over the substrate, wherein each is coupled to one of two leads, wherein the conductors form electrodes of the sensor and when a fluid contacts the sensor an impedance of the fluid may be determined using the leads of the sensor, thereby providing an indication of fluid contamination; and

a conductive layer overlying the conductors, thereby creating a cavity for fluid flow analysis between the conductive layer and the conductors, wherein when a voltage is applied to the conductive layer, an electrostatic field develops within the cavity, thereby dislodging with an electrostatic force any particulates that may have become stuck within the sensor due to static charge on the particulates and thereby improving fluid contamination analysis accuracy.

9. The analyzer of claim 4, further comprising an array of micro-miniature sensors located within a path of fluid flow, wherein the array of sensors are utilized to improve the accuracy of fluid contamination analysis by providing multiple data samples for subsequent statistical analysis.

19. The analyzer of claim 4, further comprising an insulative layer disposed between the plurality of conductors and the substrate.

20. The analyzer of claim 4, further comprising an insulative layer overlying the plurality of conductors.

21. The analyzer of claim 9, wherein at least one of the sensors has a spacing between the conductors that differs from the other sensors.

5. An on-line contamination analyzer, comprising:

an array of micro-miniature sensors located within a path of fluid flow, wherein each sensor includes a plurality of conductors which serve as electrodes and wherein a spacing between the electrodes within each sensor is constant and at least one of the sensors has an electrode spacing which varies from another sensor electrode spacing; and

a selectively activatable electromagnet in proximity to the array of micro-miniature sensors, wherein the electromagnet may be activated and deactivated in response to control signals and provides a magnetic field intensity gradient across the sensor array, thereby resulting in a contaminant size distribution across the sensor array.

6. The analyzer of claim 5, further comprising an insulative layer disposed between the plurality of conductors and the substrate.

7. The analyzer of claim 5, further comprising an insulative layer overlying the plurality of conductors.

8. The analyzer of claim 5, further comprising a conductive layer overlying the conductors, thereby forming a cavity for fluid flow analysis between the conductive layer and the conductors, wherein when a voltage is applied to the conductive layer, an electrostatic filed develops within the cavity, thereby dislodging any particulates that may have become stuck in the sensor and thereby improving fluid contamination analysis accuracy.

12. A fluid contamination analyzer, comprising:

a probe;

at least one micro-miniature sensor at one end of the probe, wherein the at least one sensor includes;

a substrate;

a plurality of conductors formed over the substrate, wherein each is coupled to one of two leads; and

an insulating layer overlying the plurality of conductors;

an array of micro-miniature sensors located within a path of fluid flow, wherein the array of sensors are utilized to improve the accuracy of fluid contamination analysis by providing multiple data samples for subsequent statistical analysis; and

an electromagnet in proximity to the array of sensors, wherein the electromagnet provides a magnetic gradient across the sensor array, thereby providing a fluid contaminant size distribution across the sensor array,

wherein the conductors form electrodes of the sensor and when a fluid contacts the sensor an impedance of the fluid may be determined using the leads of the sensor, thereby providing an indication of fluid contamination.

13. The analyzer of claim 12, wherein the electromagnet is selectively activatable, thereby allowing the electromagnet to be turned on and off.