Patent Publication Number: US-2004040905-A1

Title: Filter device, especially for a liquid

Description:
[0001] The invention relates to a filter device according to the generic term of claim 1.  
       [0002] Filter devices and especially disc filters of various designs are prior art. Types of filter whose gap between discs is determined by the thickness of star-type intermediate layers made from metal may be suitable for oil, but not for purifying dirty water or similar.  
       [0003] Commercial sand filters are normally massive and heavy in execution because of the necessarily high volume of sand. There is also the problem with the latter that when back-flowing to clean the sand by forcing the water upwards from below that what are known as waterways are formed, the result of which is that the water flows almost without resistance through the channels thereby formed in the sand and the water pressure at the inlet nozzles is massively reduced. This means the sand is no longer consistently cleaned over its entire volume and this also leads to high water consumption.  
       [0004] The problem of the present invention consists in the creation of a filter for unpurified liquids which is intended to offer effective cleaning of the liquid with a simple construction and can also be easily cleaned.  
       [0005] The invention with which this problem is solved can be seen from the characteristics of the criterion in claim 1.  
       [0006] By this arrangement of a number of such filter rings layered on top of each other, these latter can be combined into filter packs of varying heights where they are very advantageously self-centring. The filter gap is determined mechanically by the dimensions of cams and recesses which engag with each other. This means that by pre-sel cting the filter gap and the height of the filter package, both the precipitation characteristics and the through-flow rate can be adapted precisely to the respective requirements. 
     
    
    
     The drawings show design examples of the object of the invention and are described in more detail below. These show:  
     [0007]FIG. 1 a longitudinal section through a filter device according to invention with a back-flow device.  
     [0008]FIG. 2 a section of the nozzle body of the back-flow device according to FIG. 1,  
     [0009]FIG. 3 a top view of a disc part of the nozzle body according to FIG. 2,  
     [0010]FIG. 4 a side view of a filter ring of the device according to FIG. 1,  
     [0011]FIG. 5 a top view of the filter ring according to FIG. 4,  
     [0012]FIG. 6 a cut-out of the filter ring according to circle C in FIG. 4 on a larger scale,  
     [0013]FIG. 7 a section along the line A-A according to FIG. 5 with two filter rings lying on top of each other  
     [0014]FIG. 8 a longitudinal section through a filter device with rotating brush,  
     [0015]FIG. 9 a view of a brush with helically-arranged bristles,  
     [0016]FIG. 10 a longitudinal view of a variant of a filter device according to invention, and  
     [0017]FIG. 11 a longitudinal section of the filter device according to FIG. 10 in the cleaning position. 
    
    
     [0018] A filter element ( 8 ) of a filter device, especially a gap-type filter device, as can be seen from FIG. 1 or FIG. 8, is especially suited to filtration of contaminated water, such as for example the water in swimming pools. It can, however, also be used for other purposes. It has also been shown that for example, water mixed with chemicals, such as for example water mixed with dye, can be purified, with the dye being completely precipitated from the water.  
     [0019] According to invention the filter element  8  displays a number of filter rings  2  loosely stacked on top of each other, which are each designed in such a way that when layered they lie in a self-centring concentric arrangement on top of each other and form gaps  7  in between to allow liquid to pass through.  
     [0020] Each filter ring  2 , according to FIG. 4 to FIG. 7, displays a number of cams evenly distributed over its area, for example thirty cams, and diametrically opposed recesses  4  of the same size. The cams  3  and the recesses  4  are laid out such that when stacked on top of each other the cams  3  lie flush in the recesses  3  [sic;  4 ] of the adjacent ring. The lateral areas  5  of the centring cams  3  and of the recesses  4  each have a sloping incidence of an acute angle α, preferably of some 30°. This allows stacks of filters  6  to be formed from the individual filter rings  2  which are independent of each other in variable heights where the filter rings  2  centre themselves with respect to each other, since several centring cams  3  and recesses  4  are provided which are pointing towards the centre of the ring.  
     [0021] When the filter rings  2  are laid concentrically on top of each other so that cams  3  and recesses  4  lie flush on top of each other, a filter gap  7  forms between every two cams of a filter ring. This filter gap  7  extends in the direction of the ring centre, as can be seen from FIG. 4. The aperture angle β, running in a plane at right angles to the longitudinal extension of the ring, is some 12°. The narrowest gap width can be between a few hundredths and a few tenth of a millimetre by selection of the filter ring design, depending on the desired filter property. The liquid to be filtered then flows from th outside of the ring towards the centre, with th impurities being precipitated on the outside of the ring.  
     [0022] As the result of the one-piece execution of these individual filter rings  2  made from plastic, preferably from a PVC or ABS material, these can be fabricated very economically in large quantities. Obviously these rings could also be made from a metal, e.g. from die-case aluminium.  
     [0023]FIG. 1 shows a filter device  60  with a filter element  8  in which according to invention a number of such filter rings  2  are laid on top of each other, where this filter element is surrounded by a tubular housing  61 , between which a ring chamber  68  is provided. The housing  61  preferably has an inlet nozzle  62  at approximately half its height and an outlet nozzle  63  aranged on the upper end of the filter elemet  8 . Also, for the back-wash, there is an additional inlet  64  above the outlet nozzle  63  and an outlet  65  provided on the lower end of the housing  61 , which can be closed in normal operation by a valve, not shown in more detail. The otherwise sealed housing  61  has a pedestal  67  on its underside, by means of which it can be fastened to a floor or similar.  
     [0024] A very advantageous back-flow device is fitted to the filter element  8  in the frame of the invention by means of which the impurities deposited in the gaps  7  between the filter rings  2  can be completely flushed out.  
     [0025] This back-flow device advantageously displays two nozzle bodies  70  arranged in the filter element  8  attached to a hollow shaft  75 , which are arranged at a distance from each other. The nozzle bodies  70  which are identical are each provided with nozzle openings  74  distributed over the entire area, pointing radially outwards to the gaps  7 , as can also be seen from FIG. 2 and FIG. 3. On the outer perimeter these nozzle bodies  70  are guided around the cylindrical inner sid of the filter element  8  to form a seal, where O-ring seals  77  or similar are provided on both sides of the nozzl openings  74 . This means that the liquid flowing through the nozzle openings  74  cannot flow away laterally. Thus, too, by comparison with sand filters, there are no concerns that the backing-up pressure of the liquid used for back-flow could drop.  
     [0026] These two disc-shaped nozzle bodies  70  are mounted together with the hollow shaft  75 , in such a way that they are concentric and height-adjustable, in the filter element  8 . With these nozzle bodies  70  all gaps  7  in the filter element  8  can be flushed out in sequence. To this end, the hollow shaft  75  is connected via a screw thread with two spindles  76  rotating in the housing  61 . For their part, these spindles  78  are actuated via a gearwheel drive  89  or similar by a manual crank  79  located outside the housing, or an actuation motor, not shown in more detail. Furthermore a scraper ring  88  encircling the filter element  8  is assigned to each of the two nozzle bodies  70 . These scraper rings  88  are coupled via a rod linkage  86 ,  87  with the hollow shaft  75  and they are therefore moved up and down during back-flow with the latter. In the starting position they are, as with the nozzle bodies, advantageously pushed upwards.  
     [0027] In the filter of this filter device  60 , the liquid, especially contaminated water, is let in at the inlet nozzle  62 , until the ring chamber  68  is full and the liquid is forced through the gaps  2  into the interior of the filter element  8 . The liquid thus purified then flows away upwards through tho oblique passages  83  of the nozzle bodies  70  at the outlet nozzles  63 , where the inlet and outlet nozzles are each attached to a pipe, not shown in more detail. The inlet  64  and the outlet  65  are closed during filtering.  
     [0028] During backflow, when inlet and outlet nozzles  62 ,  63  are closed, clean liquid is let in through the open inlet  64  into a chamber  69  formed in the upper part of the housing  61  and from this through th holl w shaft  75 . The liquid is then sprayed through the openings in the nozzle bodies  70  into the gaps in the filter element  8  and subsequently guided away downwards through the open outlet  65 . By means of turning the hand crank  79  during backflow, the nozzle bodies  70  and the scraper rings  88  on the outside are moved down and then up again, in order to clean the gaps and the surface area of the filter element  6  over the entire height. Obviously this back-flow process can be automated so that the valve closure and the movement of the nozzle bodies can occur without manual actuation.  
     [0029]FIG. 2 shows an enlarged view of the nozzle body  70 , which is attached to the hollow shaft  75  and displays two disc parts  71 ,  72  screwed together. Starting from the hollow shaft  75 , through-openings  75 ′,  76 ,  76 ′ and a ring chamber  81  are provided through which the liquid is fed to the nozzle openings  74  contained in a ring  82 . The ring  82  is now clamped between the disc parts  71 ,  72 . The O-ring seals  77  are arranged at a distance from each other of two ring thicknesses  2 . This makes it possible for only the gap  7  corresponding with the nozzle opening  74  to be open, while those adjacent to the O-rings  77  are covered.  
     [0030]FIG. 3 shows the disc part  72  of the nozzle body  70  which is in the form of a wheel and accordingly has four large oblique passages  83  which enable a maximum passage cross-section for the purified liquid in the filter element  8 . The through-openings  75 ′,  76 ,  76 ′ open into the ring chamber  81  from which the liquid is guided into the nozzle openings  74 , which can be designed as holes distributed over the perimeter or as slots.  
     [0031] According to FIG. 8 the filter element  8  formed from a number of filter rings  2  layered on top of each other is located in the interior of a housing  12  which has a base  14  and a cover  16 . This base and cover are braced by threaded rods  18 .  
     [0032] The individual filter rings  2  are layered on top of each other into a filter pack, which is supported underneath by a flange  20 . Against the upper of the filter packs lies a deck flange  24  pressed against the filter rings by a spring  22 . The hollow in the filter pack is pierced by a rod  26 , which is supported underneath in a bearing  28 . The deck flange  24  and the rod  26  are fixed integrally to each other. The upper rod end is connected to a means of rotary actuation, not described in more detail, for example a manual crank. Underneath the cover  16  there is a gearwheel  30  integrally fixed to the rod  26 , which engages in a first pinion  32 . This pinion  32  sits integrally fixed on a brush rod  34 . An upper journal  36  of the brush rod  34  and a lower journla  38  are each pivoted in a bearing bush  40 ,  42 .  
     [0033] To stabilise the filter rings  2  which are arranged on top of each other at least one support hub  21  is provided, which is centred or fastened internally on the rod  26  and on the outer perimeter is clamped between two filter rings  2 . Obviously, depending on the height of the filter pack, there may be several such support hubs  21 .  
     [0034] The brush  46  equipped with bristles  44  abuts the perimeter of the filter pack and serves to scrape off the filter residues. The length of the brush  46  is shorter than the length of the filter pack, hence the brush  46  can be moved vertically. To this end, there is a vertical spindle  48  which can be turned by a second pinion  50 . A carrier  54  sitting on the brush axis  52  engages in the thread  56  of the spindle  48 . When thus the second pinion  50  is turned, the brush  46  slides down the brush axis  52  and is thereby able to scrape the entire height of the filter pack clean of filter residues. When the rod  26  is turned together with the filter pack, the brush axis  52  is also turned by the gearwheels  30  and  32 .  
     [0035] The carrying-off of the purified liquid from th hollow of the filter elem nt occurs on the ground through a waste pipe  55 . The supply of unpurified liquid into the housing  10  occurs via a pipe not shown in FIG. 8, whereby the inlet is arranged advantageously in the upper part of the housing  12 . In order to let out the filter residues, a closable outflow pipe can also be arranged on the ground  14 . If necessary, in addition to the brush—or in place of it—a backflow can be provided to cleanse the filter element, thus a liquid movement against the normal direction of filter flow.  
     [0036] One design variant of FIG. 8 consists in designing the brush  46  of a length such that it extends over the entire height of the filter element. This makes the spindle  48  unnecessary. Otherwise the structure and mode of action are identical to the description in connection with FIG. 8.  
     [0037] As can be seen from FIG. 9, one such vriant with a brush  46 , with a brush axle  52  and helically-arranged bristles  44  can be provided, which advantageously extends over the entire height of the filter element  8 . The direction of rotation of the brush  46  is selected such that the helical bristles are in contact with the outer sheath of the filter element from top to bottom and that the material brushed off is removed by suction.  
     [0038]FIG. 10 shows a filter device  90 , of which the filter element  8  and the centring sheaths  91  holding this on both sides are shown. This filter element  8  and obviously contained in a housing, not shown in more detail, similar to that according to FIG. 8 and said filter element is composed of a number of filter rings  92  which are formed identically to those according to FIG. 4 and FIG. 5, with the sole difference that these are each provided with two diametrically opposed through-openings  92 ′. These latter make it possible for a guide rod  93  with both ends movably mounted on the centring sleeves  91  to project through these through-openings  92 ′. The centring sleeves  91  for their part are held so as to be axially adjustabl on two diametrically opposed rods  94 . Also indicated is a pipe conduit  95  arranged concentrically in the filter element  8  with radial openings  96 , through which the purified liquid escapes.  
     [0039]FIG. 11 shows the filter device  90  in the cleaning position, in which one centring sleeve  91  is pushed away from the other. At the ends of the rod  94  are fixed screws  96  or similar which serve as limit stops for the displaced centring sleeves  91  against each other. In this released position, these filter rings  92  are held loosely against each other on the guide rod  93 , so that the cleaning liquid passed between them can completely clean in particular these faces of the rings  92  forming the gaps.  
     [0040] The invention is sufficiently demonstrated by the design examples explained above. In principle, the gaps could also be designed such that the liquid in the filter element would be led from the interior to the exterior. A back-flow device could also in principle be provided with a nozzle body arranged outside the filter element, which would surround the filter element as a ring and in which the nozzle openings would advantageously point radially inwards.  
     [0041] The filter rings could also display an external form other than that illustrated, for example polygonal or similar.