Abstract:
A liquid filtering device having a pack of cylindrical filter member discs ( 70 ) with an arrangement for reversed, filter flushing flow cycles. An integrally formed filter core ( 24 ) is provided comprising tubular nozzled conduits ( 30   a   , 30   b,    30   c ) so that water under pressure within the conduits becomes discharged in jet forms to enable free rotation of the filter discs. One-way valve ( 90 ) in the form of a funnel shaped rubber sleeve allows the flow of filtered water to the outlet port ( 20 ) but impedes the flow of flushing water from the outlet port through the filter member ( 70 ) in the direction of the inlet port ( 16 ).

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to liquid filters, particularly for water irrigation systems, however also useful for other industrial or domestic applications. 
     More specifically, the invention concerns filter devices of the type disclosed in our U.S. Pat. No. 4,655,910 issued Apr. 7, 1987, the contents of which is hereby incorporated by reference (hereinafter called “the Patent”). 
     The Patent has introduced for the first time the concept of using filter devices—in particular of the type utilizing a battery of filter discs—with reverse flushing water flow cycles wherein the discs were caused to spin under the impact of water jets impinging thereon (hereinafter referred to as “Spin-Clean Filters”). 
     The various constructional examples disclosed in the Patent had in common a centrally extending conduit serving the dual function of leading the flushing water to a series of nozzles provided thereon, and of supporting the spinning movement of the discs. 
     This feature of construction presented, however, certain disadvantages: the operation of the hydraulic cylinder system, responsible for relieving the pack of discs from the compact, filtering position, was mainly dependent upon the level of back-pressure applied by the reverse water flow, dictated, among others, by a relatively large diameter piston; rather cumbersome valve means had to be used for directing the reverse flow of water into the nozzled conduit; and generally—an excessive number of parts and components had to be used, causing respective increase of the manufacture, assembly and maintenance costs of the product. 
     It is thus the general object of the present invention to overcome the above-listed deficiencies of the conventional spin-clean filters. 
     It is a further object of the invention to simplify the design of the spin-clean filters, by providing a core member of the filter device of a unitary and integral construction, readily produced by plastics injection molding process, that will effectively serve the combined functions of: 
     generating the water jets; 
     supporting the revolving movement of the filter discs (or integral filter member of different types such as screen filters); 
     providing convenient access to the hydraulic piston assembly by external pressure control means; 
     forming a seat for a simple, elastic sleeve-type valve member responsive to the oppositely directed water flows during the filtering and the flushing modes of operation, respectively; and 
     providing a centrally extending tube through which pressure commands are admitted for the operation of the hydraulic piston, controlling the disengagement of the filter discs. 
     It is a still further object of the invention to provide a filter device with one or more jets generating conduits which extend off-centrally relatively to the axis of the filter member, along and adjacent to a generatrix line thereof. 
     It is a still further object of the present invention to provide a ribbed structure for supporting the spinning motion of the filter element(s) independently of jet generating conduit(s). 
     SUMMARY OF THE INVENTION 
     It is therefore proposed according to the present invention to provide a liquid filtering device, particularly for irrigation water installations of the type comprising a cylindrical housing with an inlet port and an outlet port and a cylindrical filter member installed within the housing so that water flowing from the inlet to the outlet enters the filter member in a radial direction, and discharged through the outlet port, and vice-versa during a reversed, filter flushing flow cycles, the device comprising a filter core member centrally mounted within the cylindrical space defined by the filter member, the core member comprising at least one tubular conduit extending within, adjacent to, and along a generatrix line of the filter member, the conduit being closed at one end and in free communication with the outlet port through its other end; a series of nozzles associated with the conduit so that water under pressure within the conduit becomes discharged in jet forms and a filter support structure configured to enable free rotation of the filter member therearound; one-way valve means adapted to allow the flow of filtered water from the filter member to the outlet port but to impede the flow of flushing water from the outlet through the filter in the reverse direction; a fixed member at one side, and a displaceable member at the other side of the filter member; means for urging the displaceable member against the filter member to clamp same between the displaceable and the fixed members; hydraulic activating means associated with the displaceable member and external controllable pressure means operatively coupled to the displaceable member, the arrangement being such that upon a pressure command by the pressure means, the displaceable member is moved away from the filter member to relieve the clamping engagement thereof, and upon application of the filter flushing flow the water jets are sprayed to rinse the filter member. 
     According to a preferred embodiment of the invention, the filter core member is integrally formed by plastics injection molding process. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and additional constructional features and advantages of the present invention will become more clearly understood in light of the ensuing description of a preferred embodiment thereof, given by way of example only, with reference to the accompanying drawings, wherein 
     FIG. 1 is a longitudinal cross-sectional view of a filter device according to a preferred embodiment of the invention shown in the normal, filtering mode of operation; 
     FIG. 2 is an exploded cross-sectional view of the filter assembly of FIG. 1; 
     FIG. 3 is a section taken along line  3 — 3  of FIG. 1; 
     FIG. 4 is a section taken along line  4 — 4  of FIG. 1; 
     FIG. 5 is a section taken along line  5 — 5  of FIG. 1; 
     FIG. 6 is a sectional view taken along line  6 — 6  of FIG. 1; 
     FIG. 7 is a section taken along line  7 — 7  of FIG. 1; 
     FIG. 8 is a section taken along line  8 — 8  of FIG. 1; 
     FIG. 9 is a perspective view of a rubber sleeve one-way valve employed in the filter of FIG. 1; 
     FIG. 10 shows the filter device of FIG. 1 in the reverse flush flow, spin-cleaning mode of operation. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to FIG. 1, the filter device generally designated  10  comprises a two-member housing, namely, the first dome-shaped cover member  12  and second inlet/outlet ports member  14 . 
     The housing members are mounted to each other in any conventional manner such as tightening bands or the like (not shown). The second housing member  14  comprises inlet port  16 , preferably with a first pressure gauge nipple  18  for measuring inlet pressure conditions; and outlet port  20  with a second pressure gauge nipple  22 . 
     The integral main filter core member generally denoted  24  (see FIG. 2) comprises the following sub-structure components: a centrally extending, pressure commands communication tube  26 , which leads to hydraulic piston system assembly, generally denoted  28 , as will be described below; an array of three, off-centrally located flushing nozzled conduits  30   a,    30   b  and  30   c  (see FIG. 3) each provided with a plurality of jet-forming nozzles denoted N; a structure comprised of three filter-supporting vanes  32   a,    32   b,    32   c;  a cone-shaped valve-seat cavity walls  34  (see FIG. 2) with a plurality of filtered water discharge slits S deployed around an intermediate wall portion thereof; a fixed element backing flange  36 , combined with mounting screw-threaded ring  38 ; a first cylindrical cavity  39 ; and a second, concentrical, cavity  40 , the latter forming the piston cylinder  40  for hydraulic or pneumatic piston  58 , as will be explained below. 
     Further notice should be taken of three passages  42  (only one seen in FIGS. 1 and 2) and three or more screw-receiving bores  44 —the major point being that the core member  24 , including all the above-detailed parts and components, can readily be manufactured, as a one-piece, solid article, by state-of-the-art plastics injection molding process. 
     Reference shall now be made to the hydraulic (or pneumatic) cylinder and piston system assembly  28 , seen in FIG. 1, and more clearly in FIGS. 2,  7  and  8 . In the present example, it comprises a coil spring  52 , compressed between rim  54   a  of perforated base  54   b  of cross-shaped rod  54  (so that water can uninterruptedly flow therealong), and disc  56  fastened by self-tapping screws  56   a  driven into the pre-formed screw receiving bores  44 . 
     Piston  58  with sealing gasket  58   a  (see FIG. 1) is slidable within the second concentrical cavity, which formed the piston cylinder denoted  40 . A cap member  60  is dressed over the piston cylinder  40 , tightened to the piston  58  by butterfly nut  62  fastened to bolt thread portion  54   c  of the cross-shaped rod  54 . 
     The cap member  60  possesses a cap flange  60   a,  forming the counter-part of the fixed element backing flange  36 , and comprises the displaceable hydraulic piston system assembly  28 , achieving the relief of the clamping of filter discs battery generally denoted  70 . 
     Referring back to the leading end of the integral main filter core member  24  (FIGS. 1,  2  and  6 ), it is seen that the mounting screw-threaded ring  36  is coupled to an intermediate mounting fitting  80  via ring  82  (with O-rings  80   a  and  80   b ), and is thus mounted to and forms an extension of the outlet port  20 . 
     In-between, a funnel-shaped sleeve, serving as one-way valve  90  is provided, fitting into the cone-shaped valve-seat cavity walls  34 , (see FIG.  2 )—having three mounting legs  90   a,    90   b  and  90   c  (see FIG.  9 ). Three cut-out portions  90   d,    90   e  and  90   f  (not shown) are made, so that in the assembled position the openings of the tubes  30   a,   30   b  and  30   c  will remain open, while the outlet slits S of cone-shaped valve-seat: cavity walls  34  are elastically sealed. 
     Mounting of the funnel-shaped valve  90  is conveniently attained by insertion of the legs  90   a - 90   c  through the passages  42  left for that purpose during the molding of the integral main filter core member  24 . 
     The rubber funnel-shaped valve  90  is preferably made of Latex rubber or equivalent synthetic elastic material. 
     Finally, the pressure control commands leading tube  26  is extended as by an L-shaped tubular member  80   c,  preferably integrally molded with the intermediate mounting fitting  80  (see FIG.  6 ). Communication to the pressurized fluid (hydraulic or pneumatic) source (not shown) is then completed by extension tube  100  with nipple  100   a  projecting from the wall of the housing inlet-outlet ports member  14 . 
     The operation of the filter device  10  will be now described with reference to FIGS. 1 and 10. Water to be filtered is admitted through the inlet port  16 , surrounds the integral main filter core member  24  with filter discs battery  70 , penetrates through said filter discs battery  70 , pushes its way through the slits S by deforming inwardly the one-way funnel-shaped sleeve valva  90 , and becomes discharged through the outlet  20 . 
     It should be noticed, that at this, normal filtering operational stage, the pressure prevailing within the filter is the outlet pressure, namely close to the atmospheric; and that no pressure command is applied to the piston system  28 . Therefore, the force applied by the cap member  60  on the filter discs battery  70  equals to the inlet pressure (usually about 3-5 atm.) multiplied by the (projected) area of the piston  58  plus the force of the compression spring  52 . 
     The flushing cycle proceeds as follows (see FIG.  10 ). The inlet flow is first interrupted, relieving the piston  58  from the inlet pressure (while the force of the compression spring  52  is still applied). It is the pressure command delivered from the control system (not shown), through the nipple  100   a,  tube  80   c,  tube  26 , and around the cross-shaped rod  54 , that causes the displacement of the piston  58  (and cap member  60 ) away (to the left of the drawing, see FIG.  10 ), and thus the release of the filter discs battery  70  from the previous compact state is achieved, as a preparatory stage before their spin-cleaning. 
     Flushing water is admitted through the outlet port  20 , freely entering the nozzled conduits  30   a - 30   c  (see FIG. 2) and discharged in inclined jet forms against the filter discs  70 , to perform the spinning and rinsing operation. The discs are free to revolve about the edges of the three vanes  32   a - 32   c  (see FIG. 3) (although the option to support the discs directly by the nozzled conduits  30   a - 30   c  is also available). 
     Water does not reach the inner space of the skeleton-like core member, since the wall of the elastic funnel-shaped sleeve valve  90  becomes pressed against the cone-shaped valve-seat cavity walls  34 , sealing thereby the water discharge slits S. 
     The rinsing stage operation is thus completed independent of the flushing, reverse flow pressure level, as far as the displacement of the cap member  60  is concerned—in distinction to the state of the art devices including those of our Patent. 
     It will be thus appreciated by those skilled in the art that the construction proposed according to the invention is advantageous in the relevant respect of production technology, number of parts and assembly costs, and maintenance requirements, mainly due to the unique structure of off-central location of the jet generating nozzled conduit(s)  30 . 
     While the above description contains many specificities, these should not be construed as limitations on the scope of the invention, but rather as an exemplification of preferred embodiments. Those skilled in the art will envision other possible variations that are within its scope. Accordingly, the scope of the invention should be determined not by the embodiment illustrated, but by the appended claims and their legal equivalents. 
     Thus, for example even a single jet-generating nozzled conduit  30  may suffice, however, three, of course, present more symmetric and balanced construction. Furthermore, the spin-supporting function can be fulfilled by the nozzled conduits  30  properly, without the need to provide for the vanes  32  altogether.