Liquid purification or separation – Filter – Movable medium
Reexamination Certificate
1999-10-18
2001-10-02
Reifsnyder, David A. (Department: 1723)
Liquid purification or separation
Filter
Movable medium
C210S167150, C210S305000, C184S006240, C494S046000, C494S060000, C494S068000, C494S069000
Reexamination Certificate
active
06296765
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to filters and more particularly relates to oil filters for engine and vehicle applications.
BACKGROUND OF THE INVENTION
Current heavy-duty diesel engines put a moderate amount of soot (a form of unburned fuel) into the oil pan. This soot is generated due to the fuel hitting the cold cylinder walls and then being scraped down into the oil sump when the pistons reciprocate in the cylinders. Up until recently, the nitrous oxide emission regulations in the USA and other countries have been high enough that the fuel injection timing could be such that the level of soot generated was not high. In typical applications, the soot level would be under 1% (by weight) of the engine oil at oil drain time. At these low levels, soot in the oil does not cause any wear problems.
Recently, there has been a move to significantly lower nitrous oxide emissions which requires much retarded fuel injection timing, which significantly increases the amount of soot being generated. At reasonable oil drain intervals, the soot level may be as high as 4 or 5% with retarded injection timing. When the soot level gets this high, lubrication at critical wear points on the engine becomes so poor that high wear results, significantly decreasing the miles to overhaul and causing high operator expense.
Thus, the engine manufacturer has two choices, suffer very high warranty costs and low miles to overhaul, or significantly lower oil drain intervals to keep high soot levels out of the oil. Neither of these choices is desirable, so there is a current strong need to have a means of getting the soot out of the oil, the subject of this invention.
A problem with removing the soot from oil is that it is very small in size—around 0.1 to 2.0 micrometers. To remove such small particles from oil using barrier filtration is not feasible due to the large filter size required and the very high probability that the filter will become plugged very rapidly due to trying to filter to such a fine level.
One way that is feasible to remove the soot from the oil is by using a centrifuge, a device that removes the soot from the oil using centrifugal force. This type of device is used to separate blood constituents from blood and has many other applications in typical laboratory applications. The use of a centrifuge for an engine brings a requirement of doing it in a very inexpensive and reliable manner with the centrifuge being easily changed at oil change time. Heretofore, centrifugal filters have not been able to sufficiently remove soot from oil, sufficiently retain the soot, nor reliable enough for use in engine and vehicle applications.
SUMMARY OF THE INVENTION
It is therefore the general aim of the present invention to provide a highly practical and reliable filter for removing soot from oil in vehicle and engine applications to maintain or extend drain intervals at which oil must be replaced for the engine. In accordance with these and other objectives, the present invention is directed at a housing which can retain, operate and drive a centrifuge cartridge at sufficiently high speeds to remove soot from oil. The present invention includes several aspects which lead to reliable and practical soot removal in a vehicle/engine environment.
One aspect of the present invention is the provision of vibration isolators which carry the bearings which facilitate high speed rotation of the cartridge. Because the bearings need to have a long life requirement, the vibration isolators reduce wear on the bearings from engine vibrations and vehicle induced shock loads.
Another aspect of the present invention is the provision of a support and drive element that extends through the cartridge to include a stationary shaft and a rotatable drive tube. The drive tube is journalled in bearings which in turn are mounted on the support shaft.
Another aspect of the present invention is the provision of at least one beveled or conical alignment and retention contact surface on the support and drive element of the housing. The conical contact surface ensures that the cartridge is automatically aligned when it is inserted into the centrifuge housing.
Yet another aspect of the present invention is the provision of a side oil outlet which feeds oil into the centrifuge cartridge at a point offset from the predetermined axis of rotation. Thus, introduction of oil is not necessary through the support and drive element for the cartridge. The housing also includes a restriction orifice provided between the external inlet and the side oil outlet. The restriction orifice meters oil into the cartridge at a predetermined rate.
Another aspect of the present invention is that centrifuge housing that includes a casing and a lid, in which the lid is removable from the top end of the housing to facilitate maintenance from the top end of the housing.
The present invention is also directed at a method for removing soot from oil. The method includes mounting a centrifuge cartridge for rotation about an axis inside a centrifuge housing. The method also includes metering oil into the cartridge at a selected rate using a restriction orifice, rotating the cartridge at a speed sufficient to remove soot from oil, and sizing the oil holding capacity of the filter cartridge and the restriction orifice relative to each other in order to achieve an adequate residence time for oil in the cartridge. This allows soot to centrifugally separate out of the oil. Preferably, the centrifuge housing is mounted on the frame of the vehicle rather than the engine to allow a heavier carrying capacity and therefore a larger centrifuge cartridge with a larger oil holding capacity.
Other objects and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
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Brown Gene W.
Calcaterra Farrell F.
Merritt Steven J.
Baldwin Filters, Inc.
Leydig , Voit & Mayer, Ltd.
Reifsnyder David A.
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