Liquid purification or separation – Magnetic
Reexamination Certificate
2000-10-12
2003-05-06
Reifsnyder, David A. (Department: 1723)
Liquid purification or separation
Magnetic
C184S006250
Reexamination Certificate
active
06558541
ABSTRACT:
TECHNICAL FIELD
This invention relates to a magnetic contaminant capture device and a method for use in applications requiring the capture and removal of contaminants from a moving fluid that can be in either a gas, vapor, mist, or liquid state. The invention is directed to various embodiments that include applications in recirculating fluid systems and single-use fluid systems. The invention has application in recirculating lubrication systems that experience degradation in performance due to mechanical wear induced contaminants, and premature deterioration of lubricating fluid.
BACKGROUND OF THE INVENTION
In every industry, often continuously, various types of machines operate under heavy-duty loading conditions. All of these machines must be lubricated. Automotive engines, compressors, gearboxes and crankcases of all types, including transmissions and transaxles, are all subject to costly wear and damage. Proper lubrication and maintenance can minimize such problems. However, despite regular servicing of the lubrication systems, which includes changing myriad filters and fluids, considerable and sometimes catastrophic damage is experienced in such machines. That damage has often been deemed to be difficult, if not impossible to minimize. The primary cause of such damage has been well-defined and includes the wear resulting from metal surfaces moving against other metal surfaces, which creates metallic shavings, chips, and micron sized particles. The latter micron-sized, wear metal particles can operate as free metal catalysts that degrade lubricant effectiveness by oxidation of both desirable hydrocarbon chains and lubricity enhancing additives.
Lubrication of metal surfaces can substantially reduce wear and includes, among other methods, the application of surface coatings, interface materials, and petroleum-based oils and greases. In most machines, various types of oil and grease are used to lubricate the metal bearing surfaces that endure wear due both to metal on metal friction and to particulate abrasion. The former is generally controlled by periodic replacement of the lubricating fluid and, in some case, replacement or remachining of bearing surfaces. The latter is also controlled by regular changes of the lubricating fluid, but also primarily by filtration of circulating lubricants during operation.
However, another significant and harmful source of damage, which has been identified in recent years, results from the abrasive and catalyst effects of micron-sized particles and dust. In the past, these small particles have been known contaminants, but were deemed to be insignificant sources of wear; it was also not known that they attack the lubricity properties of the lubricants. Such contaminants are created under normal operation as wear and abrasion by-products of machine operation.
Various means have been employed to detect wear and damage to engines and machinery so that repairs and maintenance could be undertaken before catastrophic failure. One such means includes visual inspection of lubricant filters to detect debris and damaged components. Many types of equipment are also monitored using spectrographic analysis of the lubricant for purposes of detecting elemental components of frictional and abrasional wear by-products that are undetectable by visual observation. Other means of predictive wear analysis includes use of microscopes to count contaminant particles of various sizes, which can be indicative and predictive of failures of certain engine, machine, compressor, and gear box components. However, none of these sampling methods is all-inclusive, and the latter is ordinarily uneconomical and in some geographic regions, it is completely unavailable. Spectrographic analysis cannot identify potentially catastrophic failure due to chipped or otherwise damaged components, such as broken gear teeth, but it is useful for predicting wear patterns and in identifying drastic changes in the wear characteristics of equipment from one inspection to the next. A visual inspection is useful in detecting large metal shavings and a broken gear tooth, but it cannot identify the significant changes in wear patterns that predict major bearing surface failures. What is needed is a device that will augment these existing preventative methods while also incorporating the capability to capture and remove large shavings and broken pieces, as well as the smaller particles.
Those with skill in the art have known for some time that removal and replacement of lubricating fluid and real-time filtration is helpful to extending the life span of machine and engine components. It has only recently been discovered that even the best of removal and replacement operations and the best of filtration devices fail to remove highly damaging, micron-sized contaminants from the reservoirs, the fluid pathways, and the metal surfaces present inside such machines, engines, compressors, gear boxes and the like. Even if extremely thorough cleanings are accomplished during the removal and replacement of lubrication fluids, new particulate matter forms almost immediately upon renewed operation.
Most engines, gearboxes, and machinery do not incorporate filters capable of removing particles as small as 1, 2, and 5 to 10 microns from the lubrication fluid. This is primarily because such filters become clogged rapidly in pressurized, circulating lubricant systems, which can altogether prevent proper lubrication. In many types of gearboxes, such as, for example, various types of transaxles, a pressurized, circulating lubricant system is not practical from either an economic or operating workspace perspective. As a result, in such systems, even though lubricant is circulated during operation, there is no means to remove newly created debris and contaminants, except for isochronol removal and replacement of the lubricant. Here again, moments after a lubricant change, new debris and contaminants form upon renewed operation.
What has been missing from the art is a device that can work in conjunction with existing circulating lubricant systems and various types of machines and engines, which can augment existing filtration systems, and which can operate in the absence of any filtration system. Some attempts have been made in the past to create such a system. Fink et al. in U.S. Pat. Nos. 5,949,317 and 6,111,492 describes one such device. Fink et al. incorporates a magnet joined to an ordinary drain plug that is installed at the bottom of an engine crankcase oil pan. While Fink et al. maintains that claimed device attracts and captures magnetic particles from the circulating oil as it passes by the magnet, there are several shortcomings that prevent the concept from being effective in operation. First, when used in engines, which operate at high temperatures, the exposed magnet is susceptible to corrosion and deterioration of magnet strength, especially in engines operating at high diesel fuel temperatures. Even if coated as Fink et al. suggests, contact with abrasives and wear metals in the oil bath will destroy the coating and subject the magnet to oxidation and corrosion. If the corrosion resistant materials suggested by Fink et al. are used, only relatively low field strengths are available, which cannot capture a significant amount of debris and contaminants. If higher field strengths are desired, then rare earth permanent magnet materials must be used, which are highly susceptible to corrosion and damage in normal engine operating environments. Moreover, the rare earth magnets are also far more fragile and susceptible to fracture and damage under the high stress, high shock environments experienced in most engines, heavy-duty machinery, and gearboxes. Such magnet would not function in Fink et al.'s intended configuration.
Other attempts have been to monitor debris collection in a circulating oil system, such as that disclosed in U.S. Pat. No. 5,196,112, and to magnetically remove ferrous materials, such as the devices disclosed in U.S. Pat. Nos. 5,383,534 and 4,995,971. Each of these devices are capable o
AV Lubricants, Inc.
Casey Sean M.
Reifsnyder David A.
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