Abstract:
A device ( 8 ) for a fuel filter system ( 10, 14 ) separates water from the fuel. The water takes on a property enhancing the separation by the device ( 8 ) by the action of a medium ( 42 ).

Description:
FIELD OF THE INVENTION 
     The invention relates to a device for a fuel filter system that separates water from the fuel. 
     BACKGROUND OF THE INVENTION 
     Fuel filter systems for supplying drives of a variety of kinds are configured, according to the prior art, in such a way that not only the contaminants, like suspended particles, dust, and the like, are removed, but that water is also removed. Such filter systems are used especially in diesel engines for the purpose of protecting the injection systems. EP 1 669 590 A1 discloses, for example, a filter system that provides a water separation in the course of supplying fuel to motor vehicles. 
     High efficiency of the water separation is important for the safe and reliable operation of the systems to be supplied by a respective fuel system. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide a device for a fuel filter system that guarantees an especially effective separation of the water contained in fuels, in particular, diesel fuels. 
     The invention basically achieves this object with a device causing the properties of the water to change through the use of a medium to the effect that the associated filter system improves the separation of water. This strategy offers the possibility of achieving maximum separation of the water from the “pre-treated” fuel with the conventional designs of filter systems that are arranged downstream of the device according to the invention. 
     Especially advantageously, the volume of water droplets increases subject to the action of the medium. 
     In principle, the water separation can be enhanced in that the medium to be used influences, as the precursor to the separation process taking place in the downstream filter system, the coalescing properties in a suitable way. 
     To enhance the coalescence, the water can undergo a polarization and/or ionization subject to the action of the medium. 
     The coalescence enhancing medium can be synthesized on the basis of salt in an especially advantageous way. The resulting effects produced in the fuel cause the water to collect so as to form larger conglomerates. The use of sodium chloride (NaCl) has proven to be especially advantageous. 
     Advantageously, the device can have at least one housing for accommodating a fill amount of the salt, with which the fuel flowing into the filter system can make contact in the housing. 
     In this case, the housing can be inserted in an especially advantageous way into the fuel line extending to the filter system and can have a fuel inlet and a fuel outlet as well as an insert comprising the salt filling. This insert, through which the fuel can flow, is located between said fuel inlet and said fuel outlet. 
     For this purpose, especially preferred, the insert containing the salt filling has the form of a cartridge that is disposed in a replaceable manner in the housing and is configured in such a way that it fills in a substantially fitting manner the housing between the inlet and the outlet. As a result, all of the fuel flow passing through the fuel line, flows through the salt filling. 
     Especially preferred, the cartridge forms a partial casing of the salt filling. 
     That design of the cartridge is especially advantageous when it contains salt in the loose state. 
     As an alternative, the cartridge can be formed by a stick containing salt in the solid state. 
     Preferably, a screen is provided to prevent the uncontrolled leakage of salt, at least at the outlet of the housing. 
     Especially advantageously, this screen at one end of the casing of the cartridge so that when the cartridge is replaced, the respective screen can also be replaced at the same time. 
     Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring to the drawings which form a part of this disclosure: 
         FIG. 1  is a simplified function diagram of a fuel filter system intended for supplying fuel to a diesel engine and provided with a device according to an exemplary embodiment of the invention; 
         FIG. 2  is a perspective view of the exemplary embodiment of the device drawn approximately to the natural size of a practical embodiment; 
         FIG. 3  is a side elevational view in section of the device of  FIG. 2 ; 
         FIG. 4  is a perspective view in section of the device of  FIG. 2 ; and 
         FIG. 5  is a simplified, schematic side elevational view in section of a fuel filter system, to which the device according to the invention is assigned. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is an overview of a fuel filter system for supplying a diesel engine  2  with diesel fuel from a fuel tank  4  by way of a fuel line  6 . Line  6  runs to an inventive device  8  of the exemplary embodiment to be described herein. The device is depicted in greater detail in  FIGS. 2 to 4 . The fuel line extends from the device  8  to a first water separating filter system  10  and from there by way of a fuel pump  12  to a second water separating filter system  14 . From system  14 , the cleaned, water-free fuel is delivered to the motor  2  by an injection pump  16 . The filter system  10  serving as the prefilter and the filter system  14  serving as the main filter are shown in greater detail in  FIG. 5 . Instead of two water separating filter systems  10  and  14 , just the prefilter  10  or just the main filter  14  can be provided for the water separating. The device  8  could also be disposed at any point inside the fuel line or the return line. 
     According to  FIGS. 2 to 4 , the device  8  has a housing  1  in the shape of a circular, cylindrical sleeve that is closed at one end  18  with the exception of a centrally located fuel outlet  20 . At the opposite end, the main part of the housing is closed by a screwed on closing cap  22 . A seal is provided with an O-ring  24  at closing cap  22 . The cap  22  has a centrally located fuel inlet  26 . 
     When the cap  22  is unscrewed, the interior space of the main part of the housing is accessible to put in an insert in the form of a salt cartridge  28 . In the housing  1 , cartridge  28  forms a salt filling  42 , in the example, sodium chloride. Especially when the salt filling  42  has loose salt, the cartridge  28  has preferably a casing  30 . The shape of the cartridge  28  is adapted to the circular cylindrical interior space of the housing  1  such that the result is a substantially abutting fit with the inner walls. The entire stream of fuel then makes contact with or flows through the salt filling  42 . To prevent the salt from escaping when the fuel flows through, a screen  32  is arranged upstream of the fuel outlet  20 . This screen may be a part of the casing  30  or may be mounted on the end cap  22 . When the screen  32  is located on the casing  30 , this screen is replaced at the same time that the salt cartridge  28  is replaced. A suitable fineness of the screen  32  lies in a range of aperture diameters of 25 μm. 
     Instead of using loose salt inside a casing  30 , the cartridge  28  can be formed by a solid block of salt or a partially plasticized stick. After the fuel has made contact with the salt filling  42 , the fuel is conditioned by the effect of the coalescing property such that a significantly improved water separation is guaranteed in the respective fuel filter system  10 ,  14 , arranged downstream of the device  8 . 
     A suitable design of the filter system, arranged downstream of the device  8 , is shown in detail in  FIG. 5 . According to the drawing in  FIG. 1 , a first filter system  10  is provided as the prefilter and a second filter system  14  is provided as the main filter. 
       FIG. 5  shows an exemplary embodiment with a filter housing  40 . The upper side of filter housing  40  is closed tightly with a removable closing cover  3 . The housing  40  has, with the exception of a bottom part  5 , an essentially circular cylindrical shape with a central vertical axis  7 . A coaxial inner body  9  is inserted into the housing  1 , starting from the upper side of the housing  1  that is open when the cover  3  is removed. The coaxial inner body is sealed off from the housing walls by sealing arrangements  11 ,  13 ,  15 , and  17 . The inner body  9  forms with its coaxial inner tube  19  an evaporator housing, the details of which will be discussed below. 
     The outside of the inner tube  19  is adjacent to the clean side  21  of a concentric fuel filter device  23  that is mounted on the inner body  9 . As shown simply by the flow arrow  27 , the diesel oil is fed through a fuel inlet (not shown) to the dirty side  25  of the fuel filter system. After flowing through the filter device  23  from the outside to the inside, the diesel oil passes out of the clean side  21  to a bottom side fuel outlet  29 . 
     The filter device  23  is constructed conventionally such that the water is separated in the separating zone  31 . As indicated by the arrow  33 , the separated water passes together with the diesel oil into a collection chamber  35  formed by the bottom housing section adjacent to the bottom part  5 . Due to the specific weight of the water being higher than that of the diesel oil, in operation a bottom side sump  37  of the separated water is formed in the collection chamber  35 . The upper separating line between the separated water and the lighter diesel oil lying thereon is designated as reference numeral  39 . The level height of the separating line  39  between the sump  37  of the separated water and the diesel oil lying thereon is detected by a water level sensor  41 . 
     As indicated with the flow arrow  43 , a dispensing device  45  is attached to the bottom of the sump  37 . The operation of the dispensing device can be controlled as a function of the signals of the water level sensor  41 . In the present embodiment, the fuel pump is disposed downstream of the fuel outlet  29 . In operation, a negative pressure then prevails in the filter housing  40 . The dispensing device  45  has a pump  47 . The operation of the pump is controlled by the water level sensor  41  such that in operation so much water of the sump  23  is drained from the collection chamber  35  that the separating line  39  does not fall to the connecting point on the dispensing device  45 . The pump  47  then conveys the separated water into a water receiving and evaporator device  49 . 
     The inner tube  19  of the inner body  9  forms, as part of the water receiving and evaporator device  49 , an evaporator housing, extending upstream of the dispensing device  45  coaxially upward to an evaporating water outlet  51 . An evaporating water outlet  53  in the cover element  3  is attached to water outlet  51 . 
     To control the evaporation of the water  55 , conveyed through the pump  47  into the evaporator housing  19 , the base of the evaporator housing has an element  57  for controlled heat dissipation. In this case, a separate heating device or a heat exchanger for the supply of engine heat, exhaust gas heat, or coolant heat can be provided. 
     Especially advantageously, a PTC element, that is, a resistance element with a positive curve of the temperature coefficient, can be used to dispense with the regulating and control devices or a thermal cutoff fuse. 
     The water  55 , delivered by the pump  47  and pre-cleaned by a gravity induced layer separation process in the collection chamber  35 , evaporates to form water vapor or fog. The vapor or fog rises, as indicated in  FIG. 5 , in the inner tube  19  and passes to the outside through the evaporating water outlet  51  of the inner tube  19  and the evaporating water outlet  53  in the cover element  3 . 
     As stated above, the water receiving and evaporator device  49  includes a safety device in the form of a valve arrangement that closes as a function of an inadmissible quantity of non-evaporated, collected water  55 . For this purpose, the present embodiment provides a float valve, having, as the closing body, a float ball  49 . Float ball  49  interacts with a valve seat area  61  on the evaporating water outlet  51  and closes the outlet by floating upward and resting against the valve seat area  61 . In the instance that the amount of fluid controlled by the operation of the pump  47  is normal in the evaporator housing, the float ball  59  is located, as shown in  FIG. 5 , at a distance from the valve seat surface  61 , where the ball  59  rests on holding ribs  63 . 
     While one embodiment has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.