Liquid purification or separation – With drip – overflow or content draining feature
Reexamination Certificate
1999-07-19
2001-11-27
Kim, John (Department: 1723)
Liquid purification or separation
With drip, overflow or content draining feature
C210S316000, C210S315000, C210S342000, C210S323200, C210S444000, C210S450000
Reexamination Certificate
active
06322697
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to filters. More particularly, the present invention relates to liquid filters (e.g., hydraulic fluid filters, engine oil filters or fuel filters) having replaceable filter elements.
BACKGROUND OF THE INVENTION
Although applicable to a number of fields, the present invention relates primarily to hydraulic oil filters. Filters have long been used in hydraulic systems to remove contaminants from hydraulic oil. It is well known that, with time, hydraulic oil filters become plugged or clogged with contaminants and are required to be replaced.
A typical hydraulic filter assembly includes a housing (e.g., a bowl or canister) containing a cylindrical filter element. The cylindrical filter element typically defines a central longitudinal opening in which a central core is mounted. The core provides support for preventing the filter element from collapsing inward. In use, oil is directed from a hydraulic system into an annular channel defined between the housing and the outer surface of the filter element. Pressure from the hydraulic system forces the hydraulic oil from the annular flow passage, through the filter element, and into the central opening of the filter element. From the central opening of the filter element, the filtered hydraulic oil is discharged from the filter assembly.
Disposable or “throw-away” type fluid filters are well known in the art. In this type of filter assembly, the filter element is permanently sealed within the housing. When the filter element becomes clogged with contaminants, the entire filter assembly is discarded and replaced with a new unit.
Oil filter assemblies having replaceable filter elements are also known in the art. Filter assemblies with replaceable filter elements are desirable because the housing can be reused thereby reducing the amount of waste that enters the waste stream. Consequently, as landfill costs increase, filter assemblies having replaceable filter elements will become increasingly more desirable.
Contamination is an important consideration relating to filter assemblies having replaceable filter elements. For example, prior art systems having replaceable filter elements can experience the accumulation of contaminants within the reusable housings that cover the replaceable filter elements. If this occurs, the “clean” side of new filter elements inserted within the contaminated housings can immediately become contaminated. There is a need in the art to prevent this type of contamination from occurring.
SUMMARY OF THE INVENTION
One aspect of the present invention relates to a filter insert adapted to be removably mounted within a filter housing. The filter insert includes a first filter element aligned along a longitudinal axis that extends between top and bottom ends of the first filter element. The first filter element includes an inner side that faces toward the longitudinal axis and defines a central opening that extends along the longitudinal axis. The first filter element also includes an outer side that faces away from the longitudinal axis. The filter insert also includes an insert body connected to the first filter element. The insert body includes a top end cap in which the top end of the first filter element is sealed and secured; a bottom end cap in which the bottom end of the first filter element is sealed and secured; and an outer wall that surrounds the first filter element. The outer wall is spaced-apart from the outer side of the first filter element such that a contaminant containment chamber is defined between the outer wall and the first filter element. The filter insert further includes a second filter element positioned outside the first filter element for filtering liquid that drains from the contaminant containment chamber.
Another aspect of the present invention relates to a filter insert adapted to be mounted within a filter housing. The filter insert includes structure for preventing contaminants from accumulating within the filter housing. The filter insert also includes structure for ensuring that contaminants located on the dirty side of the filter insert are carried along with the filter insert when the filter insert is removed from the housing.
A variety of advantages of the invention will be set forth in part in the description that follows, and in part will be apparent from the description, or may be learned by practicing the invention. It is to be understood that both the foregoing general description and the following detailed description are illustrative and explanatory only and are not restrictive of the invention as claimed.
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“RFM . . . SET”,HYDAC Technology Corporation, 6 pgs. (©1999).
Gustafson Michael Jon
Hacker John R.
Donaldson & Company, Inc.
Kim John
Merchant & Gould P.C.
Sorkin David
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