Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Reexamination Certificate
1999-11-19
2003-02-25
Le, Que T. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
C250S222200, C073S053070
Reexamination Certificate
active
06525334
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to detecting abrasive particles in a fluid. More particularly, but not exclusively, the present invention relates to an abrasive particle sensor that includes an electrically conductive film on an insulating substrate. Many machines employ fluid systems, to reduce wear, for heat transfer, to transfer power, etc. Common examples include hydraulic systems, pneumatic systems, pumping systems, air induction systems, oil lubrication systems, and water cooling systems. When abrasive particles accumulate in such systems they can cause equipment wear. In order to reduce parts wear, in many cases, the fluid is simply changed on a periodic basis. However, if abrasive particles accumulate at an unexpected rate, this practice results in either excessive wear, or unnecessary fluid changes. It is therefore useful to ascertain abrasive particle accumulation in situ. In many situations, previous attempts to monitor particle content of a fluid have been found to lack desired sensitivity, robustness, and/or cost effectiveness. Thus, there is a demand for further contributions in the area of abrasive particle monitoring technology.
SUMMARY OF THE INVENTION
One form of the present invention is a unique technique for monitoring particle content of a fluid. Other forms include unique systems and methods for monitoring particles with an electrically conductive member sensitive to particle erosion.
Another form of the present invention includes a method of observing erosion caused by particles in a fluid. Erosion is evaluated in accordance with one or more characteristics of an electrically conductive member that is exposed to the particles. For one variety of this form, the conductive member is at least partially composed of a metal, such as aluminum (Al), gold (Au), palladium (Pd), platinum (Pt), titanium (Ti), or alloys thereof. In another variety of this form, the conductive member is at least partially composed of a nitride, oxide, or silicide containing metal, such as tantalum nitride (TaN).
In still another form, an electrically conductive pathway senses erosion caused by particles in a fluid stream delivered from an orifice. The ratio of the cross-conductive width of the pathway to the diameter of the orifice is preferably between about 0.5 and about 1.5, and more preferably between about 0.75 and about 1.25.
A further form of the present invention includes a system for observing erosion caused by particles in a fluid by monitoring their effect on an electrically conductive film comprising aluminum (Al), gold (Au), palladium (Pd), platinum (Pt), titanium (Ti), tungsten (W), tantalum (Ta), rhodium (Rh), or alloys thereof; and/or a silicide, oxide, or nitride containing at least one metal element such as tantalum nitride (TaN). This system includes a fluid subsystem, a probe carrying the conductive film, and an electrical monitoring circuit for measuring changes in one or more electrical properties of the film.
Yet another form of the present invention includes a system for detecting particles in a fluid. The system includes an electrically conductive member in contact with the fluid and an electronic controller. The electronic controller receives one or more signals corresponding to one or more characteristics of the conductive member from which the presence of particles in the fluid may be determined. The electronic controller can adjust signals from the conductive member to account for variations due to factors such as temperature, viscosity, and pressure.
In another form, an engine with an air induction system and a particle sensor is provided that includes an electrically conductive particle sensing member in fluid communication with air from the induction system. An electrical monitoring circuit includes an electrical pathway that is at least partially provided by the particle sensing member. This circuit monitors variation of a property of the member corresponding to electrical resistance. This resistance changes in accordance with erosion of the member by particles from the air induction system.
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Fleetguard Inc.
Le Que T.
Woodard, Emhardt, Naughton Moriarty & McNett LLP
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