Liquid purification or separation – Filter – With residue removing means or agitation of liquid
Reexamination Certificate
1999-01-12
2001-11-20
Cintins, Ivars (Department: 1724)
Liquid purification or separation
Filter
With residue removing means or agitation of liquid
C210S413000
Reexamination Certificate
active
06318563
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to filters and particularly to multiple-disk type filters useful in filtering particles from water and in many other applications.
BACKGROUND OF THE INVENTION
Multiple-disk type filters generally include a housing in which the filter body within tile housing is in the form of a stack or like, centrally-apertured, filter disks of substantially uniform thickness along their widths and having grooved side faces defining filtering channels between the adjacent disks in the stack. In some applications of such filters, the outer face of the stack of filter disks constitutes the upstream side of the filter, in which case the fluid being filtered passes from the outer race to the inner face of the stack. In other applications of such filters, the inner face of the stack constitutes the upstream side of the filter, in which case the fluid being filtered passes from the inner to the outer face through the filter stack.
Multiple-disk type filters have a number of advantages over other known types of filters, for example, the cylindrical-screen type filter. The multiple-disk filter has a larger capacity for removing and retaining dirt particles, since these may be retained also between the side faces of the disks, in addition to being retained on the upstream surface as in the cylindrical-screen type filter. Another advantage in the multiple-disk filter is that it is not as easily ruptured as the screen type and therefore there is less danger that Because of a malfunction, unfiltered water may pass through and clog sprinklers or other devices downstream of the filter. The latter advantage is particularly important in self-cleaning filters wherein the upstream face of the filter is cleaned by a cleaning nozzle which, in the case of a screen-type filter, may rupture the screen by particles becoming wedged between the cleaning nozzle and the filter screen.
Back-flushable filters of various types are well known in the art for a great variety of applications. A particularly successful type of backflushable filter employing filter disks is described and claimed in the following patents of applicant: U.S. Pat. Nos. 4,026,806; 4,0112,501; 4,045,345; 4,271,018; 1,295,963.
SUMMARY OF THE INVENTION
There is provided in accordance with a preferred embodiment of the invention a fluid filter comprising a housing defining n fluid inlet and a fluid outlet; a filter element defining an upstream surface communicating with the fluid inlet and a downstream surface communicating with the fluid outlet, the filter element defining a hollow volume interior thereof; and backflushing apparatus associated with the filter element, the fluid inlet and the fluid outlet.
The present invention also provides an improved disk-type filter including a housing having an inlet connectable to an upstream pipe, and an outlet connectable to a downstream pipe; and a stack or disks disposed within the housing for separating solid particles from a fluid flowing between the disks from the upstream side of the stack to the downstream side thereof; characterized in that a filter aid is associated with the stack.
A filter aid is a finely divided solid, which may be precoated on the filter support, and is usually also mixed with a liquid to be filtered. It may also be a liquid, which is mixed with the liquid to be filtered. In the process of filtration, both the filter aid and foreign solids are removed from the liquid, and the filter aid, added to the liquid gradient, forms a rigid, permeable, incompressible “cake” on the filter. Whatever fine solids were originally suspended in the liquid are entrained in the cake as it Is built up. The porous nature of the cake prevents such solids from agglomerating and forming an impervious layer on the filter. This porous, bulky cake makes filtration more rapid and efficient than it would have been in the absence of a filter aid and greatly increases the time which elapses before the filter becomes clogged.
Various types of filter aid are known, including diatomaceous earth, plastic-coated diatomaceous earth, diatomaceous silica, bentonites, carbon, asbestos, cellulose; pumice, pumicite, obsidian, pitchstone, volcanic ash, volcanic glass, attapulgite clay, wood pulp, fly ash, kieselguhr, or calcium hypochlorite.
Filter aids are disclosed in the following US patents, the techniques of which are incorporated herein by reference: U.S. Pat. No. 2,508,602 to Goets, re-issue U.S. Pat. No. 26,709 to Vander Linden; U.S. Pat. No. 3,282,435 to Goldberg et al.; U.S. Pat. No. 3,278,0110 to Goldberg et al.; U.S. Pat. No. 3,233,741 to Bell et al.; U.S. Pat. No. 2,956,016 to Leppla et al.; U.S. Pat. No. 2,926,137 to Calvert; U.S. Pat. No. 2,892,2110 to Frankenhoff; and U.S. Pat. No. 2,696,306 to Gomory.
The backflushing apparatus includes inlet pressure responsive valve apparatus operative to open in response to a selected inlet pressure so as to permit fluid flow into engagement with the upstream surface and to close in the absence the selected inlet pressure, preventing backflow of fluid from the interior of the housing to the inlet.
In accordance with a preferred embodiment of the invention, the pressure responsive valve apparatus includes means for deflecting fluid entering the housing via the inlet from direct impingement with the facing upstream surface of the filter element.
Additionally in accordance with a preferred embodiment of the present invention the inlet pressure responsive valve apparatus includes apparatus for providing fluid coupling between the interior of the housing adjacent the upstream surface and a backflushing outlet when the valve apparatus closes off the fluid inlet from the interior of the housing.
Further in accordance with a preferred embodiment of the invention, the filter element is of generally cylindrical configuration defining an upstream cylindrical surface and a downstream cylindrical surface.
Additionally in accordance with a preferred embodiment of the present invention, the backflushing apparatus comprises a backflushing nozzle normally disposed within the hollow cylindrical volume and comprising a rotating head having fluid outlet means arranged to provide a generally radially directed pressurized jet and rotational motion of the rotating head.
The present invention also seeks to provide a backflushable filter, preferably of the disk type, which is suitable for any water filtration system, and which is characterized by a filter aid being associated with the filter.
The present invention also provides a backflushable filter preferably of the disk type, which is suitable for any water filtration system such as that used for a health tub or pool, and is particularly suitable for household use, in that it can readily be cleaned to a pristine state, without substantial disassembly.
There is also provided in accordance with an embodiment of the invention a filter element comprising a multiplicity of disk-like elements of a porous material separated by a multiplicity or grooved spacer elements, each spacer element defining axially tapered generally radially extending grooves.
Additionally in accordance with a preferred embodiment of the invention, each spacer element defines on a first side thereor axially tapered generally radially extending grooves opening to a downstream side and on a second side thereof axially tapered generally radially extending grooves opening to an upstream side.
Further in accordance with an embodiment of the invention, the grooves on the first and second sides are skewed with respect to each other so as to provide structural strength to the spacer elements.
In accordance with a preferred embodiment of the present invention the grooves disposed on opposite sides of the disk of porous material are arranged in mutually skewed orientation such that each groove on a given side of the porous material overlaps at least two and preferably three grooves on the opposite side or the porous material.
the above arrangement enables fluid passing through the filter element during normal filtering operation to ent
Cintins Ivars
Renner, Otto, Boiselle & Sklar LLP
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