Abstract:
A permanent fluid filtering system includes a cylindrical body having an upper end, to which an inlet tube is connected, and a lower end, to which an outlet tube is connected, and a latitude thread filter assembly disposed within the cylindrical body. The latitude thread assembly is compressible and expandable in accordance with a fluid flowing direction, thereby varying a porous structure of the filter assembly. The permanent fluid filtering system further includes a fluid flow stabilizing plate for stabilizing the flow of dirty fluid fed inside the body through the inlet tube.

Description:
BACKGROUND OF THE INVENTION 
     1) Field of the Invention 
     The present invention relates to a fluid filtering system, and more particularly, to a permanent fluid filtering system in which a filter layer can be effectively refined by pressurized air and clean fluid that are reversely fed into the system in a state where a filter layer is varied. 
     2) Description of Related Arts 
     Generally, a micro fluid filtering system is used, in a filtration plant, for pre-treating dirty and polluted fluid by filtering suspended solids contained in the fluid before the fluid goes to next highly processing steps (active carbonate, ozone, photocatalyst, and/or membrane separation processes). 
     The micro fluid filtering system has a filter provided with a fixed porous structure. This fixed porous structure makes it difficult or impossible to reversely refine the filter when the fixed porous structure is obstructed by dirty residue after being used for predetermined hours. Therefore, the filter must be replaced. 
     That is, since the porous structure is not changed during the reverse refining process of the system using pressurized air and clean fluid, the dirty residue obstructed in the porous structure is not easily removed, thereby reducing the reverse washing rate. 
     SUMMARY OF THE INVENTION 
     Therefore, the present invention has been made in an effort to solve the above described problems. 
     It is an object of the present invention to provide a permanent fluid filtering system which can be effectively refined by varying a porous structure of a filter layer during a refining process using pressurized air or clean fluid. 
     It is another object of the present invention to provide a permanent fluid filtering system which can precisely adjust a porous structure of a filter layer by forcedly compressing and expanding the filter layer, thereby improving filtering effect. 
     To achieve the above objects, the present invention provides a permanent fluid filtering system comprising a cylindrical body having an upper end, to which an inlet tube is connected, and a lower end, to which an outlet tube is connected; and a latitude thread filter assembly disposed within the cylindrical body, the latitude thread assembly being compressible and expandable in accordance with a fluid flowing direction, thereby varying a porous structure of the filter assembly. 
     The permanent fluid filtering system may further comprises a fluid flow stabilizing plate for stabilizing the flow of dirty fluid fed inside the body through the inlet tube. The filter assembly is reversely refined by feeding pressurized air and clean fluid reversely fed into the body through the outlet tube in a state where the assembly is expanded. 
     The filter assembly comprises a plurality of latitude threads and upper and lower holders for supporting the latitude threads. 
     The permanent fluid filtering system may further comprises a fluid collecting plate, which defines a hollow portion with the lower end of the body and is provided with a plurality of discharge apertures for discharging filtered fluid through the outlet tube. 
     The permanent fluid filtering system may further comprises a piston assembly for forcedly compressing and expanding the latitude thread. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention, and, together with the description, serve to explain the principle of the invention: 
     FIG. 1 is a partly broken perspective view of a fluid filtering system according to a first embodiment of the present invention; 
     FIG. 2 is a partly broken perspective view of a latitude thread filter assembly depicted in FIG. 1; 
     FIG. 3a is a schematic sectional view illustrating a filtering process of a fluid filtering system depicted in FIG. 1; 
     FIG. 3b is a schematic sectional view illustrating a refining process of a fluid filtering system according to a preferred embodiment of the present invention; and 
     FIG. 4 is a partly broken perspective view of a fluid filtering system according to a second preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. 
     FIG. 1 shows a fluid filtering system according to a first embodiment of the present invention, and FIG. 2 shows a latitude thread assembly depicted in FIG. 1. 
     Referring first to FIG. 1, a fluid filtering system comprises a cylindrical pressure body 3, an upper flange plate 6 mounted on an upper end of the cylindrical pressure body 3, a lower flange plate 4 mounted on a lower end of the cylindrical pressure body 3, an inlet tube 7 fixed on the upper flange plate 6 to feed dirty fluid into the body 3, and an outlet tube 8 fixed on the lower flange plate 4 to discharge filtered fluid. 
     Disposed inside the cylindrical pressure body or housing 3 is a fluid flow stabilizing plate 5 for stabilizing the flow of dirty fluid fed inside the body 3 through the inlet tube 7. The fluid flow stabilizing plate 5 is provided with a plurality of apertures and fixed on an inner wall of the body 3. 
     Disposed inside the cylindrical pressure body 3 under the fluid flow stabilizing plate 5 is a latitude thread filter assembly. As shown in FIG. 2, the latitude thread filter assembly comprises an upper holder 10, a lower holder 11, and a plurality of latitude threads 9 supported between the upper and lower holders 10 and 11. The plurality of latitude threads 9 are divided into an outer thread group 1 and an inner thread group 2 disposed on an inner circumference of the outer thread group 1 at a predetermined space therefrom. The number of threads 9 can be varied in accordance with the size of the system. 
     The threads 9 may be made of a synthetic resin such as polyester, nylon and polypropylene, that are flexible and durable. The upper holder 10 is preferably made of a plastic material so that the same is vertically movable by buoyancy. The shapes of the upper and lower holders 10 and 11 are determined in accordance with a shape of the inner wall of the body 3. That is, the shapes of the upper and lower holders 10 and 11 are designed to be complemental to that of the inner wall of the body 3. 
     The lower holder 11 is fixed on a fluid collecting plate 14, which defines a hollow portion 13 with the lower flange plate 4 and is provided with a plurality of discharge apertures 12 for discharging filtered fluid through the outlet tube 8. 
     Now, the operation of the above described fluid filtering system will be described hereinafter with reference to FIGS. 3a and 3b. 
     In a filtering operation, when dirty fluid is fed into the body 7 through the inlet tube 7, the upper holder 10, and the outer and inner latitude thread groups 1 and 2 are received a constant fluid pressure as the fluid passes through the fluid flow stabilizing plate 5, thereby compressing the outer and inner latitude thread groups 1 and 2 toward the lower flange plate 4 to provide a minute porous filter layer 20. Therefore, when pressure within the body 3 is increased by the filter layer 20, the suspended solids 25 contained in the dirty fluid are filtered while passing through the filter layer 20. Next, filtered fluid is collected into the hollow portion 13 through the apertures 12 of the collecting plate 14 and then discharged through the outlet tube 8 (See FIG. 3a). 
     When the filter layer 20 is contaminated by the suspended solids 25 above an allowable value, the latitude thread filter assembly is reversely refined. This will be described more in detail with reference to FIG. 3b. 
     The reverse refining process is performed in a state where the compression applied to the filter layer 20 is released. That is, when pressurized air and clean fluid are fed into the body through the outlet tube 8, the compression applied to the filter layer 20 is released, and the upper holder 10 is moved upward, thereby increasing the porous structure of the outer and inner latitude filter groups 1 and 2. Therefore, the suspended solids 25 are easily removed from the outer and inner latitude filter groups 1 and 2 by emerging force of pressurized air bubbles and the swirl of the applied clean fluid. The cleaning fluid is exhausted outside through the inlet tube 7 together with the removed suspended solids 25. 
     As described above, since the porous structure of the filter layer defined by the outer and inner latitude thread groups 1 and 2 is varied in its size during the filtering and refining processes, the filtering efficiency and the refining efficiency are simultaneously improved. Therefore, without replacing the filter assembly, the system can be permanently used. 
     FIG. 4 shows a fluid filtering system according to a second preferred embodiment of the present invention. 
     The fluid filtering system according to this embodiment further comprises a compressing piston assembly 40 which can further apply compressing force to the outer and inner latitude thread groups 1 and 2 which are applied with fluid pressure. 
     The compressing piston assembly 40 includes a piston plate 35 supporting an upper holder 10, a piston rod 45 fixed on the piston plate 35 and extending out of the body 3, and a handle 50 formed on an outer end of the piston rod 45. 
     Therefore, in a filtering operation, the piston plate 35 is compressed using the handle 50 to further increase the compressing force applied to the latitude thread groups, thereby reducing the size of the porous structure to increase the filtering efficiency. 
     In addition, in a refining operation, when pulling the piston plate 35 using the handle 50, the compressed latitude thread groups can be quickly widely extended, thereby increasing the refining efficiency. 
     Since other parts of this embodiment are equal to those of the first embodiment, the description thereof will be omitted herein. 
     Other embodiments of the invention will be apparent to the skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.