Abstract:
A module insert includes at least one water level sensor, at least one valve and at least one flow channel for the water. The module insert has at least one container having sorbent mechanism for collecting contaminants from the separated water. A pressure-resistant housing is configured to protect an interior of the module insert from the pressure of the fuel.

Description:
CROSS-REFERENCES TO RELATED APPLICATION 
     This application claims priority to German patent application DE 10 2008 034 904.6 filed on Jul. 26, 2008 and PCT application PCT/EP2009/059228 filed on Jul. 17, 2009, which are hereby incorporated by reference in their entirety. 
     TECHNICAL FIELD 
     The present invention relates to a module insert for installation in a liquid filter for cleaning the separated water, in particular for installation in a fuel filter. 
     BACKGROUND 
     From WO 01/30478, a liquid filter is known which has a functional support insert. Said functional support is suitable to supply and discharge the fuel to be cleaned to the filter element and to receive several further elements such as, e.g., a check valve. The functional support is seated in the lower part of the filter housing and unpurified oil flows around it. The filter housing is closed by a base which has openings for the different ports of the functional support. Moreover, said functional support has a drainage channel which is necessary for changing the filter. Said functional support is designed for the use in oil filters and thus is not suited for the use in a fuel filter. 
     In U.S. Pat. No. 7,040,299, a fuel filter is shown in which in the lower part of the filter housing, a strainer with integrated fuel heater is inserted on the dirty side. The filter housing has a plurality of inlets and outlets and connection lines. Since the filter also separates the water contained in the fuel, a water drain with water level sensor is provided. A disadvantage of this construction is that the discharged water is not sufficiently cleaned. In order to clean it to an extent that it is safe to discharge the water into the environment, a further component, e.g., external component is necessary. 
     From EP 1 581 736 and from DE 10 2006 039 581, a fuel filter is known which has a further filter attached on the filter housing for cleaning the discharged water. 
     SUMMARY 
     Such a filter is also known from JP 63224707. However, a disadvantage of this type of fuel filter is that the filters are structured to have a relatively large volume and therefore there is the risk that they can freeze because a lot of water is accumulated in the sump before it is being discharged and cleaned in a second cleaning stage. A further disadvantage is that said fuel filters and the subsequent cleaning of the water are not designed for high pressures as they are common today. 
     It is the object of the present invention to improve a known fuel filter by means of a module insert for installation to the effect that the fuel filter is structured in particular more compact. 
     This problem is solved according to the invention by the subject matter of the independent claims. Advantageous embodiments are subject matter of the dependent claims. 
     Proposed is a module insert for installation in a liquid filter for cleaning the separated water, in particular for installation in a fuel filter, which comprises at least one water level sensor, at least one valve and at least one flow channel for the water, and at least one container having sorbent means for collecting contaminants from the separated water, wherein the module insert has a pressure-resistant housing by means of which the interior of the module insert is protected from the pressure of the fuel. 
     Further important features and advantages arise from the sub-claims, from the drawings, and from the associated description of the figures based on the drawings. 
     It is to be understood that the above mentioned features and the features yet to be explained hereinafter can be used not only in the respectively mentioned combination but also in other combinations or alone without departing from the context of the present invention. 
     Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in the following description in more detail, wherein identical reference numbers refer to identical, or similar, or functionally identical components. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       In the figures, schematically: 
         FIG. 1  shows a longitudinal section through a fuel filter according to the invention, 
         FIG. 2  shows a cut-out of  FIG. 1 , 
         FIG. 3  shows a plane view of the module insert, 
         FIG. 4  shows a side view with section of the module insert, 
         FIG. 5  shows a section of the module insert along the line A-A of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a longitudinal section of a fuel filter according to the invention. At the top, a filter housing  2  which receives a filter element  3  as well as a module insert  4  is closed with a cover  1 . Therebelow is a filter chamber  51  in which the fuel is cleaned from particulate material by means of the filter element  3 . There is also a preliminary cleaning for coarser particles which is not shown here, however. The detailed structure of the filter element  3  is disclosed in the  FIGS. 2 to 5 . The filter element  3  consists of a cylindrical inner support fame  34  on which the special paper is seated as filter  36 , and a lower end disk  33 , a bottom  35  with external ribs  35   a  and a basket-shaped strainer  31 . During the assembly of the fuel filter, said replaceable filter element  3  is slid over the functional support  80  which is fixedly attached in the filter housing  2  and conveys the media water and fuel. 
     The filter element  3  contains fine pored special paper or other materials as filter and the water present in the fuel can already coalescence here. In this case, the water flows as small droplets together with the fuel to the strainer  31 . The fuel passes through said strainer and reaches the clean side and exits the fuel filter via the functional support  80  and adequate outlets (not shown). The basket-shaped strainer  31  is formed from lipophilic material in such a manner that the water droplets already present continue to get bigger and are subsequently transported downwards by gravity into a water collection chamber  43 . The smaller the portion of particulate material in the fuel, the smaller is the fuel portion in the separated water; thus, the water separation is on the clean side of the filter element  3 . The module insert  4  is inserted from underneath in the water collection chamber  43  and screwed to the filter housing  2  or is fastened in a different manner. 
     The path of the water is illustrated as arrow  40 . The reference number  50  designates an inlet for the fuel; from here, the fuel gets into the fuel distribution chamber  51  and the fuel is pressed through the filter element  3  by the high pressure of approximately 5-10 bar in the fuel system. 
     Said high pressures with pressure peaks of more than 20 bar are also present in the water collection chamber  43 . However, since the interior of the module insert  4  is not pressure-resistant, it is protected by a pressure-resistant housing  44 . The interior of the module insert  4  is to be unpressurized in order that the water can discharge without being pressurized. The water level sensor  42  in the water collection chamber  43  ensures that the water, once it has reached a predetermined height, is discharged into the module insert  4 . The water remains for some time in the water collection chamber  43 ; thereby, the still present fuel portion can accumulate above the standing water. Said fuel portion is sucked off via the throttle or valve  55  which is arranged in the functional support  80  and then flows back into the fuel tank. 
       FIG. 2  shows a cut-out of  FIG. 1 . It is shown how the water passes from the strainer  31  via the openings  46  and  47  into the water collection chamber  43 . Through the outer shape of the pressure-resistant housing  44 , the flow of the water in the water collection chamber  43  can be influenced, e.g., by providing calming zones in the form of projections in the water collection chamber  43  (not shown). 
       FIG. 3  shows a plane view of the module insert  4 . In order to be able to receive at least one water level sensor  42 , the pressure-resistant housing  44  deviates from the circular shape. By means of the openings  71  in the protrusions  70 , the module insert  4  can be fastened to the filter housing  2 , e.g., by means of screws. 
       FIG. 4  shows an exterior view of the module insert  4 . It is a multi-piece construction with a pressure-resistant housing  44  on which a bottom  73  is mounted, e.g., by means of screws  72  or the like. For sealing with respect to the filter housing  2 , a seal  74  is used. Via a drain  49 , the purified and now clean water is discharged into the environment. 
       FIG. 5  shows the interior of the module insert  4  along the section A-A of  FIG. 3 . The water separated from the fuel and accumulated in the water collection chamber  43  takes the following path when the water level sensors  42  open the valves  65   a  and  65   b , e.g., solenoid valves. First, the water flows through a small strainer  64  into the flow channel  63  in which further sensors  62 ,  68  are located, and downstream of the flow channel  63 , the two valves  65   a  and  65   b  are arranged. In the flow channel  66  between the valves  65   a  and  65   b , a displacer element  67  is arranged which is intended to (prevent the water from freezing at this position; see also DE 10 2007 054 770 which is hereby incorporated by reference. Via the flow channel  69 , the water finally gets into the container  61  which is configured as cleaning cartridge and thus can be replaced. The container  61  can contain different materials which sorb the remaining rest of fuel which is still contained in the discharged water. As sorbent material, the container  61  can contain activated carbon as well as a fuel-absorbing fabric, mesh, textiles, carpet or the like. Even the material of the container  61  can be made of a plastic which swells by absorbing fuel and thus extracts the residual fuel from the separated water. The aim is that the separated water contains only approximately 2 ppm residual fuel which is a proportion that is considered as being harmless for the environment. 
     The module insert  4  is composed of a pressure-resistant housing  44  and the inner part  45  in which the channels  63 ,  66  and  69  are arranged. The module insert  4  is closed from underneath, on the one hand, with a bottom  76  which is fixedly connected to the inner part  45  and, on the other, with a lower cover  77  which allows that the container/cleaning cartridge  61  can be changed. Alternatively, the lower cover  77  can also be fixedly connected to an inner part  45  and the pressure-resistant housing  44 , e.g., by welding. 
     The water-conveying flow channel  69  and the container  61  in the module insert  4  which are downstream of the solenoid valves  65   a  and  65   b  should drain as slowly as possible to improve the adsorption conditions in the container  61 . Optimal conditions exist in case of a certain flow of the separated water through the container  61 ; preferably, it flows from the bottom upwards or, alternatively, it also can flow from the top downwards as shown here. The flow channels  63 ,  66 ,  69  necessary for this are provided in the inner part  45  as needed. 
     Downstream of the solenoid valves  65   a/b , the flow channel  69  is unpressurized and formed with air cushions; said volume reserve serves for absorbing volume changes, e.g. during freezing. For this reason, the pressure-resistant housing  44  is necessary for shielding this region from the pressure in the fuel. Due to the open ventilation of the drain  49  downstream of the container  61  with activated carbon filter, the water can drain off said region and lines (not shown) which are optionally connected downstream thereof. 
     There can also be a ventilation valve in the flow channel  69  and upstream of the container  61  which valve serves for allowing air to penetrate and the water to drain off the downstream container  61  and further lines connected to the drain  49 . Said ventilation valve opens unpressurized or in case of negative pressure and closes in case of pressure (not shown). The further sensors  62 ,  68  can be a temperature sensor and a heater for thawing or for the operation at sub-zero temperatures, wherein the use of the temperature sensor  62  and/or  68  and the associated signal. processing have to ensure that the solenoid valves  65  cannot be opened at sub-zero temperatures. 
     The module insert  4  has an integrated structure, i.e., due to the flow channels  63 ,  66  and  69  integrated in the inner part  45 , it contains the entire conduit for the water separated from the fuel. The module insert  4  provides the geometry for receiving the solenoid valves  65 , it integrates the container  61  with the absorber in a fixed or replaceable manner, it is connected to the power supply, it conducts flows and signals or provides installation space for components for signal processing. Furthermore, the module insert receives the water level sensors  42  for the detection of water, which sensors project into the water collection chamber  43  of the filter housing  2 . The solenoid valves  65  are arranged in such a manner that the solenoid valves  65  are closed when deenergized. The arrangement of the solenoid valves  65  is such that at least in case of one solenoid valve, the fuel pressure presses the valve shut and the valves has to open against the fuel pressure. 
     The module insert  4  has a three-piece structure for installation or integration into the fuel filter housing  2 . The water collection chamber  43  is formed by the free spaces between module insert  4  and filter housing  2 . A pressure-resistant housing  44  absorbs the forces caused by the fuel pressure. The pressure-resistant housing  44  can be made of aluminum or flame-resistant plastics thereby ensuring a leak-tightness for a sufficiently long time, even in case of a vehicle fire.