Environmental control system fluid sensing system and method

#The present invention generally relates to the field of fluid sensors and more particularly to a fluid sensor incorporating a mechanical resonator adapted for and as used in an environmental control system, such as a refrigeration system or other temperature management system.

#The use of a quartz oscillator in a sensor has been described in U.S. Pat. No. 6,223,589. U.S. Pat. No. 5,741,961 also discloses a quartz resonator for use in an engine oil sensor. Yet another piezoelectric sensor for engine oil is disclosed in Hammond, et al., “An Acoustic Automotive Engine Oil Quality Sensor”, Proceedings of the 1997 IEEE International Frequency Control Symposium, IEEE Catalog No. 97CH36016, pp. 72-80, May 28-30, 1997.

#An improved system for measuring characteristics of fluids using mechanical resonators is disclosed in commonly-owned U.S. Pat. Nos. 6,401,519; 6,393,895; 6,336,353; and 6,182,499.

#FIG. 1 shows a schematic view of one system of the present invention.

#FIG. 2 shows a view of an illustrative resonator element of the present invention.

#FIGS. 3A-3G illustrate alternative structures for a resonator according to the present invention.

#As will be appreciated from the description herein, the present invention is directed primarily for analyzing fluids that are contained (whether in a sealed system, an unsealed system or a combination thereof) in a cooling apparatus or other environmental control system. One specific use of the present invention is the analysis of fluids (and particularly the viscosity, density, viscosity/density product, conductivity or dielectric properties of fluids) that are used in an environmental control system adapted for residential building use, commercial building use, industrial use (e.g., as part of a power plant system), transportation vehicle use (e.g., as part of a passenger environmental control system, as part of an engine or other vehicle component environmental control system, combinations thereof or the like), such as fluids that are part of a sealed and/or self-contained operating system, and more specifically, fluids that are part of a circulating or reservoir fluid system.

#As gleaned from the above, reference to an “environmental control system” in accordance with the present invention is not intended to limit the application of the present invention. Rather, “environmental control system” contemplates a system for application in heating, ventilation, air conditioning and refrigeration systems for residential use, commercial use, industrial use or two or more of the forenoted uses. “Environmental control system” may also contemplate a system for application in food processing, temperature management for food storage or material storage units (e.g., refrigerators, freezers, or the like). “Environmental control system” may further contemplate a passenger comfort system in transportation vehicles such as rail cars, ships, submarines, boats, aircraft, automotive vehicles, farming vehicles, earth-moving vehicles, heavy trucks, spacecraft, military vehicles, or the like. “Environmental control system” may also contemplate a system for controlling temperature in engines, other power plant devices, or other components (e.g., a radiator, an oil cooler, or both) for such transportation vehicles. “Environmental control system” may also contemplate another system, such as without limitation, chillers, nuclear, coal or gas fired power generation facility equipment environmental control system, incineration equipment environmental control system, industrial furnace environmental control system, reactors, baths, electronic component environmental control system, fluid dispensing system, ice rink system, materials processing heat treatment system, or otherwise. In short, the present invention contemplates application in any of a number of different types of environmental control systems, whether the systems are mobile, stationary or combinations thereof, or whether the environmental control system includes features such as humidity control, pressure control or otherwise.

#To the extent that heat exchangers are contemplated as within environmental control systems, it will be appreciated that in many such systems, the heat exchanger system contains one or more fluids such as refrigerants or other heat transfer fluids, aqueous based coolants, refrigerant oils and lubricants (e.g., to lubricate internal moving parts for machines used to compress, regulate and move fluids), protective fluids for corrosion protection and leak detection or visualization fluids. Thus, it should be appreciated that the present invention also contemplates within its scope the employment of the present sensors to monitor not only fluids that are used for accomplishing heat exchange, but fluids that are used elsewhere in an environmental control system, such as in generators (“gensets”) or motors used to drive compressors to move fluids for effecting temperature change.