Liquid purification or separation – Plural distinct separators – Filters
Reexamination Certificate
2000-01-19
2002-11-12
Savage, Matthew O. (Department: 1723)
Liquid purification or separation
Plural distinct separators
Filters
C210S342000, C210S416500, C210SDIG009
Reexamination Certificate
active
06478958
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a method and apparatus for filtering impurities out of a fluid, and more particularly to a method and an apparatus for filtering impurities out of lubrication oil for use in an internal combustion engine.
BACKGROUND OF THE INVENTION
In various kinds of apparatuses utilizing fluids (for example lubrication oil), fine particulate impurities may find their way into the fluid. If such impurities are not removed, the apparatus, such as an engine, may be damaged. To avoid such catastrophic failures, various kinds of filtering systems have been proposed.
In the most usual filtering systems, there is provided a filtering circulation system separately from a main circulation system and a filter having a filtering element of relatively high density is arranged in the filtering circulation system. The circulating fluid is pumped through the filter to remove impurities contained in the fluid.
Another known technique bypasses the fluid from the main circulation system through a valve for regulating the fluid's flow rate and forces the fluid to pass through a filter of high density. The filtered fluid is returned then for re-use.
A filter is also commonly inserted into the main circulation system. In such a system, since the filter may provide a very high resistance against the flow of the fluid, a high pressure is generated in the system and thus piping and filter must have a high mechanical strength. Therefore, main circulation system filters generally have a low density. This low density results in an inability to remove fine impurities effectively. Worse, these unremoved fine particles affect the system to the greatest extent.
To avoid some of these drawbacks, filters have been provided which have a large area so as to decrease the apparent resistance of the filter and to provide a fine filter in a by-path circuit. However it is necessary to flow the fluid forcedly through the by-path circuit, because the by-path circuit has a great resistance. Therefore, a separate pump must be provided to move the fluid through the by-path circuit.
One well-known type of apparatus utilizing fluids is the internal combustion engine. Internal combustion engines generally employ two types of filtration to clean the lubricating oil. These two types of filtration are commonly referred to as full flow filtration and bypass filtration. Traditionally, full flow filtering elements receive and filter (relatively coarsely) over 75% of the regulated oil pump output in such a system prior to supplying the oil to the engine components. Where a bypass filter is provided, the bypass filter typically receives only 5-10% of the pump output. The bypass filter is generally effective to “superclean” the oil. Most modern engines (gasoline and diesel) employ full flow filters. Heavy-duty engines (particularly diesel engines) are often equipped with bypass filters in addition to full flow filters. Historically, engines achieve combined full flow and bypass filtration by one of three methods.
The first method of creating combined full flow and bypass filtration is to place the full flow and bypass filters in separate containers and provide separate, individual flow circuits with a positive means of forcing flow through the bypass filter. The second method of achieving combined full flow and bypass filtration is to place the full flow and bypass filters in the same container with separate, individual flow circuits and with a positive means of forcing flow through the bypass filter. The requirement of both the first and second methods to possess more than one flow circuit increases both the internal and external plumbing of such systems, and therefore also increases cost of such systems.
The third method involves placing the full flow filter and the bypass filter in the same, single container but with a single flow circuit and without any positive means of forcing flow though the bypass filter. Such systems reduce the plumbing and expense associated with the first and second systems.
Systems based on the third method are known in the art. One problem associated with these systems is that they are able to create only parallel flow between the flow filter and bypass filter. In such parallel systems, flow passes either through the full flow filter or the bypass filter, but not all of the fluid passes through the full flow filter before exiting the system or passing through the bypass filter. To resolve this problem, some systems have been designed that incorporate a full flow filter that filters all fluid entering the filtering apparatus before the fluid either directly exits the apparatus through an outlet, or passes through a bypass filter and exits through a separate outlet. Examples of such systems are described in U.S. Pat. Ser. Nos. 5,078,877 and 5,342,511.
SUMMARY OF THE INVENTION
The present invention provides a filter apparatus for use in removing impurities contained in a fluid which includes a housing, a full flow filter, a bypass filter, and a conduit. The full flow filter, bypass filter and conduit are in the housing, the bypass filter is positioned downstream of the full flow filter, and the housing and the full flow filter are arranged such that the entirety of the fluid to be filtered by the filter apparatus passes through the full flow filter. The conduit including a pressure reduction section which is arranged to create a pressure differential across the bypass filter such that a predetermined portion of the fluid to be filtered by the filter apparatus passes through the bypass filter.
The invention further provides embodiments wherein the pressure reduction section includes either a thin-plate orifice, a long radius nozzle, a Dall nozzle, or, preferably, a venturi. In embodiments where the conduit is a venturi, the venturi desirably has a throat having an internal diameter of about 0.95 inches. In more specific embodiments the invention provides that at least one passageway passes through the wall of the pressure reduction section of the conduit. More particularly, the invention provides a conduit including two passageways each having a diameter of between about 0.17 to about 0.18 inches in diameter.
In other specific embodiments the invention provides a conduit wherein the inside diameter of the upstream end and downstream end of the conduit is between about 0.7 to about 1.2 inches, in further particular embodiments the inside diameter of the downstream end and upstream end of the conduit is about 1.125 inches.
Another embodiment of the invention provides a filter apparatus for use in removing impurities contained in a fluid by filtration including in concentric relationship a housing; a full flow filter; a full flow filter support; a full flow annulus; a bypass filter; a bypass filter support; a bypass annulus; and a conduit which includes a pressure reduction section in the form of a venturi, the conduit including at least one passageway through a wall of the conduit at the venturi. In such embodiments, the filter apparatus is arranged such that the fluid to be filtered by the filter apparatus flows into the housing, through the full flow filter, and into the full flow annulus, wherein a predetermined portion of the fluid is drawn through the bypass filter and the remainder of the fluid into the upstream end of the conduit. The fluid drawn through the bypass filter flows into the bypass annulus and then through the at least one passageway in the venturi and into the bypass conduit, and the fluid passing from the full flow annulus directly into the conduit flows through the venturi of the conduit causing a pressure differential across the bypass filter resulting in a predetermined amount of fluid passing through the bypass filter.
The invention further provides such apparatuses wherein the apparatus further includes a top end cap that engages the top end of the bypass filter. In more particular embodiments the top end cap includes a top end cap sealing member which has an o-ring groove, and an o-ring seal which is sealingly engaged in the O-ring groove
Beard John H.
Rodebush Michael J.
Baldwin Filters, Inc.
Leydig , Voit & Mayer, Ltd.
Savage Matthew O.
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