Measuring and testing – Liquid analysis or analysis of the suspension of solids in a... – Viscosity
Reexamination Certificate
1999-04-27
2001-03-06
Williams, Hezron (Department: 2856)
Measuring and testing
Liquid analysis or analysis of the suspension of solids in a...
Viscosity
C073S053010, C073S023210, C422S082010
Reexamination Certificate
active
06196057
ABSTRACT:
TECHNICAL FIELD
The present invention generally relates to an integrated multi-element lubrication sensor and health assessment system.
BACKGROUND OF THE INVENTION
Dynamoelectric machines such as motors and generators and other rotating machines such as gears and bearing systems are widely employed in industrial and commercial facilities. These machines are relied upon to operate with minimal attention and provide for long, reliable operation. Many facilities operate several hundred or even thousands of such machines concurrently, many of which are integrated into a large interdependent process or system. Like most machinery, at least a small percentage of such equipment is prone to failure. Some of such failures can be attributed to loss of lubrication, incorrect lubrication, lubrication breakdown or lubrication contamination.
Depending on the application, the failure of a machine in service can possibly lead to system or process down time, inconvenience, material scrap, machinery damage, hazardous material cleanup and possibly even a dangerous situation. Thus, it is desirable to diagnose the machinery for possible failure or faults early in order to take preventive action and avoid such problems. Absent special monitoring for certain lubrication problems, the problem may have an insidious effect in that although only a minor problem on the onset, the problem could become serious if not detected. For example, bearing problems due to inadequate lubrication, lubrication contamination or other causes may not become apparent until significant damage has occurred.
Proper lubrication facilitates the extension of machinery life. For example, when motor lubricant is continuously exposed to high temperatures, high speeds, stress or loads, and an oxidizing environment, the lubricant will deteriorate and lose its lubricating effectiveness. The loss of lubricating effectiveness will affect two main functions of a lubrication system, namely: (1) to reduce friction; and (2) to remove heat. Continued operation of such a degraded system may result in even greater heat generation and accelerated system degradation eventually leading to substantial machinery damage and ultimately catastrophic failure. To protect the motor, the lubricant should be changed in a timely fashion. However, a balance must be struck—on one hand it is undesirable to replace an adequate lubricant but on the other hand it is desired to replace a lubricant that is in its initial stages of breakdown or contamination before equipment damage occurs. Since each particular application of a lubricant is relatively unique with respect to when the lubricant will breakdown or possibly become contaminated, it becomes necessary to monitor the lubricant.
Various techniques for analyzing lubricants are known. For example, measuring a dielectric constant change in the lubricant or recording a thermal history of the lubricant have been employed for monitoring the lubricant's condition. However, these methods measure a single parameter and require the use of the same lubricant or assume no machinery malfunctions throughout the measurements. Furthermore, these monitoring techniques are generally not performed in situ and typically require that a sample of the lubricant be extracted and analyzed using laboratory grade equipment to determine the condition of the lubricant. The need to monitor and determine the current and future health of lubricants include grease and oils such as used in bearing systems for motors, gears, pillow blocks, hydrodynamic bearings as well as hydraulic fluids such as found in pumps and pump systems, and cutting fluids to name a few.
Single parameter sensors only provide a narrow view of a lubricant quality and/or health. Accurate lubricant health assessment and lifetime prediction is virtually impossible to achieve via sensing a single parameter of the lubricant. The need for more information about the lubricant is readily apparent from the many parameters which are reported in a typical laboratory report of lubricant condition.
In view of the above, there is a need for an improved sensor for detecting an operating state of a lubricant.
SUMMARY OF THE INVENTION
The present invention relates to a microfabricated integrated electrochemical and viscosity sensor. In particular, the present invention relates to an integrated multi-element lubrication sensor and health assessment system. The lubrication sensor is made using integrated circuit-like microfabrication techniques (e.g., silicon based fabrication and deposition techniques). As a result, the lubrication sensor of the present invention provides for substantial advantages in terms of performance, reduced size, weight and costs—especially since the wafer level technology employed affords for automated and batch production of numerous lubrication sensors on a single wafer. As will be described in greater detail in the foregoing discussion, the present invention also provides for integrated signal processing and sensor fusion as well as communications.
The lubrication sensor includes multiple elements (e.g., sensing devices) for sensing various characteristics of a lubricant. For example, the lubrication sensor includes a pH sensor, an electrochemical sensor, a conductivity sensor, viscosity sensor and temperature sensor. The reduced size of the lubrication sensor of the present invention provides for continuous in situ monitoring of the lubricant. In other words, the lubrication sensor of the present invention affords for monitoring the lubricant within its operating environment as compared to extracting a sample and testing the lubricant at a remote site. Signal data from each of the sensing devices is combined within a data fusion framework to obtain useful information relating to the condition of the lubricant as well as the machine and/or process employing the lubricant.
The present invention employs data fusion because of information fission which is inherent to a process relating to sensing a physical environment through several different sensor modalities. In particular, each sensing element provides a unique window into the physical environment where the phenomena to be observed is occurring. Because the complete details of the phenomena being studied (e.g., detecting the operating state of the lubricant or the process) are not contained within a single sensing element window, there is information fragmentation which results from this fission process. These information fragments associated with the various sensing devices contain both independent and dependent components. The independent components are used to further fill out (or span) the information space and the dependent components are employed in combination to improve the quality of common information recognizing that all sensor data is subject to error and noise. In this context, data fusion is algorithmic processing of sensor data to compensate for the inherent fragmentation of information because a particular phenomena may not be observed directly using a single sensing element. In other words, the data fusion architecture provides a suitable framework to facilitate condensing, combining, evaluating and interpreting the available sensed information in the context of the particular application.
Thus, the present invention provides for a micro multi-element lubrication sensor which affords in situ monitoring of a plurality of lubricant parameters. Furthermore, the present invention employs a data fusion framework and algorithms to facilitate condensing, combining, evaluating and interpreting various sensed data. The present invention also facilitates establishing a health state of a system employing the lubrication sensor of the present invention, as well as predicting a future state of the lubricant and/or system employing the lubrication sensor. Additionally, the lubrication sensor may communicate raw data, diagnostic data and state data to a remote device.
In accordance with one aspect of the present invention, a multi-element fluid sensor system includes: at least two sensors, each senso
Amin Himanshu S.
Horn John J.
Reliance Electric Technologies LLC
Walbrun William R.
Wiggins David J.
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