Abstract:
A filtering device ( 10 ) comprises a plurality of layers of paper ( 40 ). The paper ( 40 ) is formed with projections ( 120 )) so that cavities ( 122 ) are located between adjacent layers of paper ( 40 ). A liquid being filtered passes between adjacent layers, filling at least some of the cavities ( 122 ).

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a filtering device.  
           [0002]    It is known to require filtering devices mounted to engines in order to filter contaminants, small particles and moisture from oil and or fuel used in the engines. A common type of filtering device used for this purpose is constructed from folded cardboard through which the oil or fuel is required to pass.  
           [0003]    Another type of filtering device is known as an edge-on filter. This type of filtering device consists of a roll of paper. The oil or fuel passes along the roll of paper, with contaminants and small particles being held between the sheets of paper. Known edge-on filters are not capable of removing a significant amount of moisture from the fuel or oil passing through them. Known papers used in edge-on filters have also been found to leech contaminants remaining from the paper manufacturing process into the substance being filtered, thus reducing the effectiveness of the filtration.  
           [0004]    The present invention attempts to overcome at least in part some of the aforementioned disadvantages of previous filtering devices.  
         SUMMARY OF THE INVENTION  
         [0005]    In accordance with one aspect of the present invention there is provided a filtering device comprising a plurality of layers of paper, characterised in that the paper has a surface formed with projections such that the projections cause a plurality of cavities to be located between adjacent layers, the filtering device having a first end and a second end with the layers of paper being aligned between the first end and the second end, and the filtering device being arranged to allow a liquid substance to pass layers from the first end to the second end, the liquid substance passing through at least some of the cavities as it passes from the first end to the second end. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:  
         [0007]    [0007]FIG. 1 is an exploded view of a filtering device in accordance with the present invention;  
         [0008]    [0008]FIG. 2 is a cross sectional view of the filtering device of FIG. 1 shown in its assembled condition;  
         [0009]    [0009]FIG. 3 is a perspective view of a roll of paper used in the filtering device of FIG. 1;  
         [0010]    [0010]FIG. 4 is an enlarged view of a portion of a cross sectional view of the roll of paper shown in FIG. 3; and  
         [0011]    [0011]FIG. 5 is a plan view of the surface of the roll of paper shown in FIG. 3. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0012]    It will be appreciated that although the embodiment shown is arranged as a filter for fuel, the invention is also envisaged in an alternative embodiment as a filter for oil.  
         [0013]    Referring to the Figures, there is shown a filtering device  10  comprising a housing  12  and a filtering portion  14 . The housing  12  is substantially cylindrical in shape, and includes a substantially circular base portion  20  at a first end  16  of the housing  12  and a substantially cylindrical side wall  22 . The housing  12  includes a fuel inlet  24  in the form of an aperture in the base portion  20 , and a fuel outlet  26  in the form of a hollow cylindrical portion extending from the side wall  22  near a second end  18  of the housing  12 .  
         [0014]    The base portion  20  includes a centrally disposed substantially cylindrical projection  27 . The projection  27  extends from the base portion  20  internally of the housing  12 . The projection  27  includes a radial lip portion  29  disposed about the projection  27  at an end thereof remote from the base portion  20 .  
         [0015]    The housing  12  further includes a cylindrical shaft  28  disposed centrally of the housing  12 , extending from a first end  30  attached to the centre of the projection  27  to a second end  31  extending past the second end  18  of the housing  12 . The cylindrical shaft is externally threaded at the first end  30  and the second end  31 . The projection  27  includes an internally threaded aperture  33  into which the first end  30  of the cylindrical shaft  28  is engaged. The cylindrical shaft may be welded into position relative to the projection  27 .  
         [0016]    A fuel receiver  32  is disposed adjacent the fuel inlet  24 . The fuel receiver  32  is substantially cylindrical in shape, and extends from the base portion  16  of the housing in a direction towards the second end  18  of the housing. The fuel receiver  32  has a substantially cylindrical side wall  34  and a substantially circular top plate  36 . The fuel receiver  32  has an aperture  38  located in the side wall  34  adjacent the top plate  36 , and oriented towards the shaft  28 . In use, fuel enters the fuel receiver  32  through the fuel inlet  24  and exits through the aperture  38 . The fuel receiver  32  may include baffles or sharp edges in order to break any relatively large particle contained in the fuel.  
         [0017]    The housing portion  12  further includes a baffle member  60 . The baffle member  60  includes a plate portion  62 , a separating portion  64  and a top portion  66 . The plate portion  62  is substantially annular, and has an outside diameter similar to the internal diameter of the side wall  22  of the housing portion  12  and an internal diameter smaller than the diameter of the lip portion  29  of the projection  27 . The separating portion  64  is substantially frusto conical in shape, and extends from the internal diameter of the plate portion  62  towards a central axis of the baffle member  60 . The top portion  66  is substantially annular, and extends inwardly of the separating portion  64  with an internal diameter similar to the diameter of the cylindrical shaft  28 . In use, the baffle member  60  locates around the cylindrical shaft  28  with the top portion  66  oriented towards the second end  18  of the housing  12 , and the plate portion  62  in contact with the lip portion  29  of the projection  27 . The plate portion  62  includes apertures  68  which allow fuel or oil to pass through the plate portion  62 .  
         [0018]    The filtering portion  14  includes a roll of paper  40  having a first end  42  and a second end  44 . The roll of paper  40  is wound around a hollow tube  46 . The tube  46  may be composed of cardboard. The outside diameter of the roll of paper is substantially similar to the interior diameter of the housing  12 .  
         [0019]    The filtering portion  14  further includes a first cover member  48  and a second cover member  50 . The cover members  48 ,  50  are of a substantially disc like configuration, and have a similar diameter to the roll of paper  40 . The first and second cover members  48 ,  50  are arranged at the first and second ends respectively of the roll of paper  40 , and include apertures  51  located, in use, adjacent the roll of paper  40 . The cover members  48 ,  50  each include a centrally disposed sealing portion  52 . The sealing portions  52  are substantially frusto-conical in shape and extend in use from each cover member  48 ,  50  internally of the hollow tube  46 . The sealing portions  52  are arranged such that the diameter of each sealing portion  52  where the sealing portion  52  meets the respective cover member  48 ,  50  is similar to the diameter of the hollow tube  46 .  
         [0020]    The filtering portion  14  further includes a sealing tube  70 . The sealing tube  70  is substantially cylindrical in shape, and includes a first end  72  and an externally threaded second end  74 . The sealing tube  70  is of substantially similar external diameter to the internal diameter of the sealing portions  52 . Extending radially around the first end  72  of the sealing tube  70  is an annular base member  76 . The annular base member  76  has an external diameter slightly larger than the diameter of the hollow tube  46 . In use, the sealing tube  70  is arranged about the cylindrical shaft  28  with the annular base member  76  in contact with the top portion  66  of the baffle member  60 . The first cover member  48 , the roll of paper  40  and the second cover member  50  are arranged along the sealing tube  70  from the first end  72  to the second end  74 .  
         [0021]    The filtering portion  14  still further includes a clamping member  80  and a sealing nut  82 . The clamping member  80  is substantially flat and hexagonal in shape, and includes an internally threaded, centrally disposed aperture  84 . The aperture  84  is arranged to threadedly engage with the externally threaded second end  74  of the sealing tube  70 .  
         [0022]    The sealing nut  82  comprises a substantially cylindrical portion  86  and a frusto-conical portion  88 . The sealing nut  82  includes a centrally disposed, internally threaded aperture  90  which is arranged to threadedly engage with the second end  31 ) of the cylindrical shaft  28 . In use, the frusto-conical portion  88  is oriented towards the first end  29  of the cylindrical shaft  28  such that a peak of the frusto-conical portion  88  is engaged within the second end  31  of the sealing tube  70 .  
         [0023]    The housing  12  further includes a cap portion  94 . The cap portion  94  comprises a lid portion  96 , a handle portion  98  and a resilient sealing member  100 . The lid portion  96  is substantially flat and circular, and has an external diameter slightly greater than the diameter of the side wall  22  of the housing  12 . The lid portion  96  has an inner surface  102  oriented, in use, towards the first end  16  of the housing  12  and an outer surface  104  oriented, in use, away from the housing  12 . The inner surface  102  includes an annular recess  106  extending inwardly of the surface  102  near an outer edge of the inner surface  102 . The diameter of the recess  106  is equal to that of the side wall  22  of the housing  12 . The recess  106  is arranged to receive the resilient sealing member  100 .  
         [0024]    The lid portion  96  further includes a centrally disposed aperture  108 .  
         [0025]    The handle portion  98  comprises a first cylindrical portion  110 , a second cylindrical portion  112  and a rod portion  114 . The first cylindrical portion  110  is of the same diameter as the aperture  108  of the lid portion  96 , and locates, in use, within the aperture  108 . The second cylindrical portion  112  is of larger diameter than the aperture  108 , and locates in use adjacent the outer surface  104  of the lid portion  96 . The rod portion  114  extends from the second cylindrical portion  112  in a direction transverse to a longitudinal axis of the first and second cylindrical portions  110 ,  112 . An internally threaded aperture  116  extends inwardly of the first and second cylindrical portions  110 ,  112  along their longitudinal axis. The internally threaded aperture  116  is arranged to engage, in use, with the second end  31  of the cylindrical shaft  28 . A resilient ring seal may be provided between the second cylindrical portion  112  and the outer surface  104 .  
         [0026]    The roll of paper  40  is preferably constructed from virgin paper fibre. The properties of the virgin paper fibre are typically as follows:  
                                       Weight:   In the range 30 GSM to 60 GSM. Preferably in the range           40 GSM to 50 GSM. Particularly preferably           about 42 GSM.       Thickness:   In the range 153 μm to 100 μm. Preferably in           the range 125 μm to 175 μm. Particularly           preferably about 153 μm.       Pulp   27% bi sulphide pine, chlorine free, manufactured using       Composition:   magnesium sulphide process           35% Thermo Mechanical Pulp, mechanical           ground for fibre pulp           35% Unbleached Pulp           Balance broke, recycling of virgin pulp.       Tensile   MD 65 (factor)       strength:   Machine direction strength 65 (internal test           4 × 75 mm paper tear factor).           CD (Cross direction) 30           Wet strength factor 7           Stretch factor 8%       Appearance   52% Brightness (Hunter Lab Test)       Chemicals   Base pulps, thermo mechanical measures           Main chemical magnesium sulphide, totally chlorine free.                  
 
         [0027]    The roll of paper  40  is further embossed with small, circumferentially aligned projections  120  as shown in FIG. 3. The projections  120  appear in the roll of paper  40  as small, circumferentially aligned cavities  122  as shown in FIG. 4.  
         [0028]    The projections  120  may be substantially rectangular in shape, with dimensions of about 2 mm×0.5 mm. The projections  120  may be arranged in an array with a gap of about 2 mm between each adjacent projection  120 . The depth of each projection  120  may be about 1 mm.  
         [0029]    The roll of paper  40  may be impregnated with an additive substance which is required to leech into the substance being filtered. The additive substance may, by way of example, be an oil additive.  
         [0030]    To prepare for use, the filtering device  10  is arranged with the cylindrical shaft  28  extending from the projection  27  of the housing  12  as described hereinabove. Disposed about the cylindrical shaft  28  are the baffle member  60  adjacent the projection  27 , then the sealing tube  70 , first cover member  48 , the roll of paper  40 , the second cover member  50 , the clamping member  80  and the sealing nut  82 . The sealing nut may then be tightened in order for the first cover member  48  to seal against the base member  76  of the sealing tube  70  and the second cover member  50  to seal against the clamping member  80 . The cap portion  94  is then sealingly fitted to the housing  12  by engagement of the second end  31  of the cylindrical shaft  28  in the internally threaded aperture  116  of the cap portion  94 .  
         [0031]    In use, fuel is fed to the filtering device  10  through the inlet  24  into the fuel receiver  32 . As it passes through the fuel receiver  32  relatively large particles may be broken down as they pass over the sharp edges therein. The fuel leaves the fuel receiver  32  through the aperture  38  and then passes through the baffle  60 . The fuel then passes through the apertures  51  of the first cover member  48  and into the roll of paper  40 .  
         [0032]    As the fuel passes through the roll of paper it passes through numerous cavities  122 .  
         [0033]    Whilst passing through these cavities  122 , small particles are retained within cavities  122 , and are thus filtered from the fuel. Some contaminants such as water may be leeched from the fuel and absorbed by the paper through which the fuel is passing.  
         [0034]    The fuel exits the paper through the apertures  51  in the second cover member  50 , and then exits the filtering device  10  through the fuel outlet  26 .  
         [0035]    Where the filtering device  10  is arranged to filter oil, the flow of the oil may be from the second end  18  of the filtering device  10  to the first end  16 . In this embodiment of the invention, it may not be necessary to include the fuel receiver  32  or the baffle member  60 . The flow rate of oil is typically between three and seven litres per minute.  
         [0036]    Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.