Patent Publication Number: US-2012031824-A1

Title: Module insert for installation in a liquid filter

Description:
The present invention relates to a module insert for installation in a liquid filter for cleaning the water separated out, in particular for installation in a fuel filter. 
     U.S. Pat. No. 5,501,723 discloses a filter with active carbon for cleaning the waste air from a fuel tank of a motor vehicle. To clean the air over the fuel in the tank, a filter with active carbon is inserted into a waste air channel. To increase the cleaning efficiency, the filter is configured with different successive chambers, through which the waste air must flow. Active carbon is contained in each chamber. 
     DE 10 2006 039 581 discloses a fuel filter in which a further filter for cleaning the water separated out is attached to the filter housing and has active carbon as the further filter material. The question of how the filter containing the active carbon is configured remains open, however. 
     The object of the present invention is to improve a known fuel filter by means of a module insert for installation in the same, in that the module insert contains a compact and efficient additional filter. 
     This problem is solved according to the invention by the subject matter of the independent claims. Advantageous embodiments form the subject matter of the dependent claims. 
     The invention is based on the general idea of providing a module insert for installation in a fuel filter for cleaning the water separated out, which module insert has a reservoir with sorbent means for absorbing impurities from the water separated out, which means are arranged in the reservoir in such a manner that the longest possible dwell time of the water in the region of the sorbent means can be achieved. A particularly high cleaning level of the water separated out can be achieved thereby. 
     Further important features and advantages of the invention can be found in the subclaims, the drawings and the associated description of the figures using the drawings. 
     It is self-evident that the features which are mentioned above and those which are still to be explained below can be used not only in the combination specified in each case, but also in other combinations or alone without departing from the scope of the present invention. 
    
    
     
       Preferred exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description, with the same reference symbols referring to the same or similar or functionally identical components. 
       In the figures, 
         FIG. 1  shows a longitudinal section through a fuel filter according to the invention, 
         FIG. 2  shows a plan view of the module insert, 
         FIG. 3  shows a section along line A-A of  FIG. 2  of the module insert, 
         FIG. 4  shows a detail of  FIG. 3 , 
         FIG. 5  shows a detail of  FIG. 3  in a different embodiment. 
     
    
    
       FIG. 1  shows a complete fuel filter according to the invention in longitudinal section. A filter housing  2 , which accommodates a filter element  3  and a module insert  4 , is closed from above with a lid  1 . Under this there is a filter chamber  51  in which the fuel is cleaned of suspended particles by means of the filter element  3 . There is also a precleaning means for coarser particles, but this is not shown here. The detailed structure of the filter element  3  is shown for example in  FIGS. 4 and 5 . The filter element  3  consists of a cylindrical inner frame  34 , on which the special paper sits as the filter  36 , as well as of an upper end disc  32  and a lower end disc  33 , a base  35  with outer ribs  35   a  and a basket-shaped screen  31 . When the fuel filter is assembled, this replaceable filter element  3  is pushed over the functional carrier  80  which is attached fixedly in the filter housing  2  and conducts the media water and fuel. The filter element  3  contains as the filter special paper or other materials; the water present in the fuel can coalesce here. It then flows as tiny droplets with the fuel to the screen  31 . The fuel passes through this screen  31  to the clean side and exits the fuel filter via the functional carrier  80  and corresponding outlets (not shown). The basket-shaped screen  31  is formed from a lipophilic material in such a manner that the water droplets already present enlarge further and are then transported downwards by gravity into the water collection chamber  43 . The smaller the amount of suspended material in the fuel, the lower the fuel fraction in the water separated out, therefore the water is separated out on the clean side of the filter element  3 . The module insert  4  is inserted from below into the filter housing  2  in the water collection chamber  43  and screwed fast or otherwise fixed. 
     The path of the water is shown as an arrow  40 . The inlet for the fuel is labelled with reference symbol  50 ; the fuel passes from here into the fuel distribution chamber  51  and is pushed through the filter element  3  by the high pressure of approximately 5-10 bar in the fuel system. These high pressures with pressure peaks of over 20 bar are also present in the water collection chamber  43 . As the interior of the module insert  4  is not pressure-stable, it is protected by a pressure-stable housing  44 . The water level sensor  42  in the water collection chamber  43  ensures that the water is drained into the module insert  4  when it reaches a predefined height. The water remains in the water collection chamber  43  for some time, the fuel fraction still present can thereby collect over the standing water. This fuel fraction is extracted via the throttle or valve  55  which is situated in the functional carrier  80  and then flows back into the fuel tank. 
     The flow of the water can be influenced in the water collection chamber  43  by the outer shape of the pressure-stable housing  44 , in that for example calming zones are created by projections in the water collection chamber  43  (not shown). 
       FIG. 2  shows a plan view of the module insert  4 . To be able to accommodate at least one water level sensor  42 , the pressure-stable housing  44  differs from the circular shape. The module insert  4  can be fixed to the filter housing  2  by means of openings  71  in the indentations  70 , for example by means of screw fastenings. The module insert  4  has a multi-part structure, the base  73  being fixed to the pressure-stable housing  44  for example by screw fastenings  72  or the like. The seal  74  is used to seal off from the filter housing  2 . The purified and now clean water is drained into the environment via the outlet  49 . 
       FIG. 3  shows the interior of the module insert  4  along section A-A from  FIG. 2 . The water which has separated out of the fuel and collected in the water collection chamber  43 , takes the following path when the water level sensors  42  open the valves  65   a  and  65   b , for example solenoid valves. The water first flows through a small screen  64  in the flow channel  63  in which further sensors  68  are situated; the two valves  65   a  and  65   b  are attached to the flow channel  63 . A displacer element  67  lies in the flow channel  66  between the valves  65   a  and  65   b , which displacer element is intended to prevent the water from freezing, see DE 10 2007 054 770 which is hereby incorporated by reference. The water then passes via the flow channel  69  into the reservoir  61  which is configured as a cleaning cartridge and therefore can be replaced. Different materials can be present in the reservoir  61  which absorb the remnants of fuel which are still contained in the water separated out. 
     The reservoir  61  can contain active carbon and a fuel-absorbing woven or nonwoven fabric, textile carpet or similar as the sorbent. Even the material of the reservoir  61  itself can consist of sorbent material which swells due to the absorption of fuel and thus removes the remaining fuel from the water separated out. The aim is that the water separated out contains only approximately 2 ppm of fuel residue; this proportion is considered safe for the environment. According to the invention, the sorbent means are arranged in the reservoir  61  in such a manner that a dwell time of the water separated out in the module insert  4  is extended, as a result of which a particularly high cleaning level can be achieved. 
     The module insert  4  is composed of the pressure-stable housing  44  and an inner part  45  in which the channels  63 ,  66  and  69  are arranged. The module insert  4  is closed from below with a base  76  which is connected fixedly to the inner part  45  and a lower lid  77  which should make it possible to change the reservoir  61 . Alternatively, the lower lid  77  can also be connected fixedly, for example by welding, to the inner part  45  and pressure-stable housing  44 . 
     The water-conducting flow channel  69  and the reservoir  61  in the module insert  4  which are situated downstream of the solenoid valves  65   a  and  65   b  should idle as slowly as possible to improve the adsorption conditions in the reservoir  61 . Optimal adsorption conditions prevail with a certain flow of the water separated out through the reservoir  61 ; it flows preferably from bottom to top, alternatively it can flow from top to bottom, as shown here. The flow channels  63 ,  66 ,  69  necessary for this are provided as required in the inner part  45 . 
     The flow channel  69  downstream of the solenoid valves  65   a/b  is pressureless with air cushions; this volume reserve is used to absorb volume changes such as during freezing. The pressure-stable housing  44  is therefore also necessary to shield this region from pressure in the fuel. The free ventilation of the outlet  49  downstream of the reservoir  61  with the active carbon filter means that the water can drain out of this region and any lines connected downstream (not shown). Furthermore, a ventilation valve can also be present in the flow channel  69  upstream of the reservoir  61 , which valve ensures that air can enter and the water drains out of the downstream reservoir  61  and lines. This ventilation valve opens pressurelessly or when there is a vacuum and closes with pressure (not shown). 
     The further sensors  68  can be a temperature sensor and a heating system for thawing or operation at sub-zero temperatures; the use of the temperature sensor  68  and the associated signal processing should ensure that the solenoid valves  65  are not opened at sub-zero temperatures. 
     The modular insert  4  has an integrated structure, that is, it contains all the lines for the water separated out of the fuel through the flow channels  63 ,  66  and  69  integrated in the inner part  45 . The module insert  4  has the accommodating geometry for the solenoid valves  65 , it integrates the reservoir  61  with the absorber fixedly or replaceably, it has a connection to the power supply, it conducts currents and signals or has installation space for signal processing components. Furthermore, it accommodates the water level sensors  42  for the detection of water, which project into the water collection chamber  43  of the filter housing  2 . The solenoid valves  65  are configured in such a manner that the solenoid valves  65  are closed without current. The arrangement of the solenoid valves  65  is such that, at least in one solenoid valve, the fuel pressure pushes the valve closed, and the valve must open against the fuel pressure. 
     The modular insert  4  has a three-part structure for installation or integration in the fuel filter housing  2 . The water collection chamber  43  is formed by the free spaces between the module insert  4  and the filter housing  2 . A pressure-stable housing  44  absorbs the forces due to the fuel pressure. The pressure-resistant housing  44  can consist of aluminium or flame-resistant plastics and thereby ensures the tightness of the fuel system for a sufficiently long time, even in the event of a vehicle fire. 
     So that the dwell time of the water in the reservoir  61  is as long as possible, conducting elements  100  are provided which point away from the outer wall  105 . The active carbon granules  110  are situated in the interspaces as shown. The size of the granules shown here is variable according to requirements and should actually only illustrate how the active carbon granules  110  are approximately arranged in the reservoir  61 . For the sake of clarity, the whole reservoir  61  in  FIG. 3  has not been filled with the active carbon granules, which is of course the case in a real product. The conducting elements  100  must be arranged in the reservoir  61  in such a manner that accelerated drainage of the water due to creep effects cannot occur. There is also the possibility of layering both active carbon granules and active carbon fibres in the reservoir  61 . The conducting elements  100  preferably consist of a material which also adsorbs the fuel, just like the outer walls  105  of the reservoir  61 . 
       FIG. 4  shows an enlarged detail of  FIG. 3 . In this exemplary embodiment a nonwoven or knitted fabric or other fibres  108  are arranged between the conducting elements  107 . The conducting elements  107  are not connected to the outer wall  105  but lie loosely between the fibre layers  108 . The fibres  108  can consist of active carbon or other fuel-storing materials. 
     Alternatively, chips can be added to the active carbon granules, which are then arranged randomly and likewise result in an increase of the dwell time of the water in the reservoir  61 . These chips could consist of a plastic like the conducting elements  107  so that they also store fuel (not shown). 
     In all the alternatives presented, neither the active carbon granules nor the conducting elements  105  introduced are so loose that they can be displaced. At the lower end of the reservoir  61  there is a baseplate  102  with holes through which water can drain. It then flows into the lid  76  which closes the reservoir  61  from below and can drain via the outlet  49  into the environment. 
       FIG. 5  shows a further exemplary embodiment. In this case a spiral-shaped conducting element  106  has been placed into the reservoir  61  and active carbon granules  110  have been used. This conducting element  106  should also be configured in such a manner that water cannot bypass the active carbon granules due to creep effects and exit the reservoir  61  without being cleaned. Alternatively, a plurality of reservoirs  61  can be contained in the module insert  4 , through which water to be cleaned flows successively. Each of these reservoirs  61  can be structured differently in its interior as required.