Liquid purification or separation – Filter – Within flow line or flow line connected close casing
Reexamination Certificate
1998-04-27
2001-02-13
Savage, Matthew O. (Department: 1723)
Liquid purification or separation
Filter
Within flow line or flow line connected close casing
C210S450000, C210SDIG009, C210S443000
Reexamination Certificate
active
06187191
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a filter for filtering a flowing substance, such as lubricating oil and hydraulic liquid.
BACKGROUND OF THE INVENTION
One of the applications of encased cylindrical filters is filtering lubricating oil in combustion motors so as to keep the oil free of impurities. A second typical field of application for filters of this type is filtering hydraulic liquid in hydraulic systems. Since the filter is fouled in operation and has to be replaced at intervals, the filter casing must be removable from the device assembly, to which it is attached.
There are previously known oil filters, in which the filter means and the surrounding casing have been constructed as a solid unit, and are replaceable. However, such a design is a waste of material and also produces landfill waste.
From an ecological viewpoint, it is preferable to devise a casing that can be opened, so that the clogged filtering means alone is replaced and the casing is put back in position with the device assembly. U.S. Pat. No. 5,342,519 is cited as an example of such a design, in which the assembled oil filter comprises a cylindrical, replaceable filter means, a perforated support pipe within the filter means, a collar as an extension of the support pipe, a casing surrounding the filter means and a joint ring at the casing opening. This filter design includes two threaded joints with O-ring seals, one of which connects the casing to the joint ring and the other which connects the assembled filter with the collar to the device assembly so as to provide a seal between the joint ring and the device assembly. There are also conventional operable filter designs in which one single threaded joint is sufficient to connect a unit consisting of a filter means, a casing and any joint members to the device assembly.
In replaceable filters, the casing must be tightly sealed to the device assembly, since otherwise the medium to be filtered, such as pressurized lubricating oil or hydraulic liquid, will extrude through the joints between the elements into the environment. Such a visible leak will immediately reveal the deficiency or absence of a seal. In contrast, current filter designs do not show outwardly whether the filter means is fitted in position or not. With such filters, it is quite possible to remove a clogged filter means and subsequently put the casing back in position, without replacing the removed filter means. Obviously, as a result of such a mistake filtering will no longer take place.
SUMMARY OF THE PRESENT INVENTION
The purpose of the present invention is to reach a solution in which the risk of misuse mentioned above is eliminated, while providing a more straightforward filter design. The filter in accordance with the invention is characterized by the fact that the cylindrical filter means includes an end flange, whose circumferential outer edge acts as a seal for the casing end and where this edge includes one or more flow openings, through which the outside of the filter means mantle communicates with the inlet or outlet duct for flow to be filtered in the device assembly.
If a filter means is not present in the fitted casing, the casing will be unsealed, and a leak will immediately occur in operation at the casing joint. It will be impossible in practical operation to run a motor, a hydraulic system or the like over a long period of time without filtering. The filter in accordance with the invention has the further advantage of reducing the number of separate components in the design and of providing a less complex assembly, owing to the combined seal for the filter means and the casing end.
The filter casing is usually sealed to the device assembly at one end, the one end including both an inlet duct for the flow to be filtered and an outlet duct for the filtered flow. The casing is closed at its opposite end. The outer edge of the end flange of the filter means forms an O-seal ring, and the outside of the filter means mantle communicates through the flow opening or openings in this ring with the flow duct in the device assembly. Typically this flow duct is an inlet duct for the flow to be filtered, the flow being directed from the outside of the cylindrical filter means to its inside, from where the filtered flow continues into an outlet duct in the device assembly; however, an inverse flow direction would be quite as possible.
A preferred embodiment of the present invention is characterized in that the annular seal formed by the end flange of the filter means bears against the outer surface of the casing opening such that the pressure prevailing within the casing will increase the strain on the seal. The seal position in accordance with the present invention, which in fact is independent of the seal design, will provide tighter sealing during the filtering process, unlike many conventional sealing arrangements, including the solution described in U.S. Pat. No. 5,342,519, in which the seal ring is placed inside the casing end.
Besides a casing and a replaceable filter means, the filter design in accordance with the present invention preferably comprises a perforated support member with an associated collar within the filter means, and a joint ring between the casing and the device assembly. In this case, the end flange of the filter means acts as a seal between the casing and the joint ring, and the assembled filter can be connected to the device assembly as a unit by screwing the collar thread into the device assembly.
The filter provided with a replaceable filter means in accordance with the invention is particularly suitable as a hydraulic or lubricating oil filter, but is also usable as any liquid filter, such as a water or fuel filter.
REFERENCES:
patent: 2055180 (1936-09-01), Nelson
patent: 2995253 (1961-08-01), Belgarde et al.
patent: 3256989 (1966-06-01), Hultgren
patent: 4721563 (1988-01-01), Rosaen
patent: 5171430 (1992-12-01), Beach et al.
patent: 5342519 (1994-08-01), Friedman et al.
patent: 5681461 (1997-10-01), Gullett et al.
patent: 5779903 (1998-07-01), Smith et al.
patent: 1933 283 (1971-01-01), None
patent: 41 27 031 A1 (1993-02-01), None
patent: WO 95/00232 (1994-06-01), None
Kangasniemi Marko
Koivula Tuomo
Hunter Christopher H.
Ocampo Marianne
Parker Hannifin Oy
Savage Matthew O.
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