Measuring and testing – Liquid analysis or analysis of the suspension of solids in a... – Viscosity
Reexamination Certificate
2003-01-10
2004-11-02
Larkin, Daniel S. (Department: 2856)
Measuring and testing
Liquid analysis or analysis of the suspension of solids in a...
Viscosity
C073S053050, C073S054020, C073S054070, C250S343000, C702S108000, C702S130000
Reexamination Certificate
active
06810718
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus and method for fluid analysis. Particular embodiments of the present invention relate to on-board analysis of multiple attributes of operating machine fluids necessary for the determination of machine health.
BACKGROUND OF THE INVENTION
It is well known that chemical and physical analysis of a machine fluid can provide information about the condition of the fluid as well as the wear status of the machine in which the fluid is used. Machine fluid analysis is widely used for determination of lubricant condition, lubricant contamination and wear status in engines, drive components and hydraulic systems in fleet or industrial service. For example, lubrication oil analysis is widely used for railroad engines and is conducted by the military on most motorized equipment including aircraft and naval engines and lubricated drive components. In industry, commercial fluid analysis providers offer fluid analysis service for engine and drive train lubricants as well as hydraulic fluids.
Locomotive engine manufacturers such as General Electric (GE) and General Motors Electro-Motive Division (EMD) promulgate recommended limits for wear elements as determined by spectrographic analysis of lubrication oil samples. Manufacturers and railroad operators also set limits on such parameters as water or fuel dilution of lubricating oil, soot and pentane insolubles (compounds in oil that do not dissolve in pentane). These limits indicate when maintenance is required to prevent impending component failures that may result in severe and expensive engine damage. Properly interpreted, the analytical data can also indicate specific maintenance operations that need to be performed on the engine.
Traditionally, an oil sample has been taken from the lubricant reservoir on the engine being analyzed, and each of these parameters was then measured in the laboratory by different instruments for different purposes. Viscosity is measured with a viscometer and provides an indication of possible dilution of the oil by fuel or water. Viscosity can also indicate oil degradation from heat or oxidation. Chemical degradation of the oil (e.g., oxidation, nitration) is commonly determined by infrared (IR) spectrometric analysis, which may also be used to infer total acid number (TAN) and total base number (TBN) for the oil. Water in the oil may also be detected by IR analysis. Slow coolant leaks into the lubricating oil system may be detected by quantitative analysis of boron, chromium or other elements present in the coolant water as salts. Elemental analysis is typically accomplished by atomic emission spectrometry (AES) or other atomic spectroscopy methods, but may also be accomplished by X-ray fluorescence (XRF). Such analyses provide an indication of component wear according to the type and amount of metal(s) in the sample.
Monitoring of machine fluids to specifically determine the parameters described above presently requires that samples of the machine fluid(s) be obtained and sent to a laboratory for chemical and physical analysis. However, the machines for which laboratory analysis is most valuable are often mobile, and may at any time be in remote locations, making sampling and laboratory analysis impractical on a frequent or regular basis. Moreover, the small sample amounts obtained for analysis may not be representative of the bulk machine fluid, and analyses in the laboratory require a day or more to perform. The logistical impracticality of laboratory analysis is overcome in practice with scheduled maintenance and service for machines. Such routine maintenance schedules are designed so that machine fluid change-out occurs prior to the time damage to the machine may result, and are scheduled to ensure that they provide sufficient leeway before a problem is projected to occur. It is believed that the frequency of maintenance and service could be reduced by the use of more frequent and regular machine fluid analysis.
Additionally, there are environments wherein immediate indicators of machine health are critical. As an example, when an engine on a helicopter or airplane fails, the result to passengers can be disastrous. An indication to the pilot of a failing engine, prior to actual engine failure, may provide sufficient time to either save the engine from destruction, or provide time for the pilot to safely return to the ground under power.
On-board or in situ machine fluid analysis has been investigated with several proposed approaches. For example, Voelker et al (U.S. Pat. No. 5,789,665) described a method and apparatus for determining deterioration of lubricating oils by measuring electrical properties of a polymeric matrix or by exploiting volumetric change behavior of the polymeric matrix in the form of beads. Disadvantages of this approach include that it responds only to a single parameter (free water) but does not quantify the free water, and there is a need to replace used polymer beads.
Freese et al. (U.S. Pat. No. 5,604,441) relies on measurement of changes in dielectric properties of a lubricant (oil) in a changing magnetic field. The change in dielectric properties indicates a change in oil condition. Dielectric constant is non-specific and at best may provide an indirect indication of oil degradation. The magnetic field is also used to attract and quantify ferromagnetic particles.
Finally, Boyle et al. (U.S. Pat. No. 5,964,318) designed a system to measure the level and quantity of lubricant in an engine lubricant reservoir. On-board in situ sensors are provided to measure the quantity of lubricant in the system, as well as the quality (temperature, pressure, dielectric and/or viscosity). If the quality drops below a predetermined level, the system diverts a portion of the lubricant to a reservoir for storage or reintroduction as a fuel additive, and a coincident addition of fresh lubricant to the system to maintain the desired level of lubricant. However, the apparatus/process disclosed in the '318 patent is a totally self-contained system; it does not provide an indication to those remotely monitoring engine health of the current status of lubricant within the engine—it is solely an internally-monitored lubricant quality indicator.
The above-cited patents describe measurements that do not provide to remote observers information sufficient to determine the wear status of the machine containing the measured fluid, and so they cannot be used in lieu of standard laboratory oil analysis. In particular, the above-cited patents do not describe a system that allow real time and remote assessment of machine condition, because they lack the capability to determine wear metal concentrations.
On-board measurement and analysis of operational parameters, including determination of fluid levels and fluid and gas temperatures and pressures for a gas turbine engine, has been described (Greitzer et al, 1994). These authors described the use of sensors and artificial neural network software to analyze engine operational status and condition. This approach has been termed machine health monitoring. However, these authors did not attempt to measure standard laboratory analysis parameters for any machine fluid.
Hence, there remains a need for in situ or on-board analysis of machine fluid that provides information similar in nature and utility to that obtained from standard laboratory machine fluid analysis.
BRIEF SUMMARY OF THE INVENTION
The present invention is an apparatus and method for analyzing a fluid used in a machine or in an industrial process line. In one embodiment of the present invention, the apparatus has at least one meter (or sensor) placed proximate a machine and in contact with the machine fluid for measuring at least one parameter related to the machine fluid. The at least one parameter is a standard laboratory analysis parameter. The at least one meter includes, but is not limited to, viscometer, element meter, optical meter, particulate meter, and combinations thereof. Additionally, the results of this machine fluid analysi
Peters Timothy J.
Reeves James H.
Shepard Chester L.
Wilson Bary W.
Battelle (Memorial Institute)
Larkin Daniel S.
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