Abstract:
A water separator for a fuel supply system of an internal combustion engine has a housing with an inlet and an outlet for fuel and further has a separating chamber and a collecting chamber for collecting water. The separating chamber is arranged above the collecting chamber. A separating element is arranged in the separating chamber, wherein the separating element has a first separating stage and a second separating stage. The first separating stage has a hydrophilic filter medium. An element with a plurality of through openings surrounds the hydrophilic filter medium. The element forms an outlet contour and generates downstream of the hydrophilic filter medium and the element droplets of water separated from the fuel.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    Priority is claimed based on Federal Republic of Germany patent application no. 10 2009 009 420.2 filed Feb. 18, 2009, the entire application incorporated by reference herein. 
       TECHNICAL FIELD 
       [0002]    The invention concerns a water separator, in particular for a fuel supply system of an internal combustion engine in motor vehicles. 
       BACKGROUND OF THE INVENTION 
       [0003]    A water separator for a fuel supply system of an internal combustion engine in motor vehicle includes a separating chamber formed in a housing and a separating element arranged in the separating chamber as well as a collecting chamber arranged below the separating element for collecting water separated from the fuel. The housing has an inlet and an outlet for the fuel. The separating element comprises two separating stages wherein the first separating stage contains a hydrophilic filter medium. 
         [0004]    Devices for separating water from fuel in fuel supply systems are frequently combined with a fuel filter. U.S. Pat. No. 4,740,299 discloses a fuel filter that has in its housing a collecting chamber for the water separated from the fuel. The fuel is supplied from above into the filter housing wherein it is assumed that the heavier water component in the fuel will sink to the bottom and collect in the collecting chamber. A portion of water emulsified in the fuel is however entrained by the fuel and transported through the filter material so that water is still present in the fuel at the outlet side of the filter. 
         [0005]    EP 1 256 707 A2 discloses a fuel filter with water separating means. This fuel filter that is especially provided for diesel fuels of an internal combustion engine comprises two filter stages wherein the first filter stage is provided for particle filtration. This filter stage is comprised of a hydrophilic filter material that causes water that is finely distributed in the fuel to coalesce to larger water particle elements. A second filter stage of hydrophobic material is arranged downstream of the first filter stage and is positioned coaxially within the first filter stage. This arrangement is selected so that fuel that leaves the first filter stage and contains a water component will impact on the material of the last filter stage without being deflected. For this type of configuration of a fuel filter large surface areas of the hydrophilic material of the first stage as well as of the hydrophobic material of the second stage are required. 
       SUMMARY OF THE INVENTION 
       [0006]    It is therefore an object of the present invention to provide a water separator of the aforementioned kind that has a simple configuration and enables generation of a defined droplet size at a separating stage. 
         [0007]    In accordance with the present invention, this is achieved in that the hydrophilic filter material is surrounded by an element with a plurality of through openings that forms an outlet contour and generates drops of water, separated from the fuel, downstream of the filter medium and of the element. 
         [0008]    The invention has the advantage that the coalesced water droplets are separated in a defined droplet size from the fuel; this is achieved by a plurality of through openings in the element that surrounds the filter medium. The element is preferably a perforated sheet metal, a perforated synthetic (plastic) material or ceramic material; alternatively, tight-mesh screens, synthetic grids or fabric are also conceivable. 
         [0009]    In a further embodiment, the element that is present in the form of perforated sheet metal, perforated plastic material, ceramic material, tight-mesh screen or synthetic grid or fabric is embodied as liquid-permeable half shells wherein two half shells can be joined and in this way surround the filter element of the first separating stage. When joined, the half shells have the shape of a cylinder. The half shells are preferably connected to one another by lock connections or clip connections wherein a support element that is surrounded by the filter medium is clamped between edges of the half shells. In this way, a fixation of the first separating stage on the support element is provided. 
         [0010]    The filter medium preferably comprises a single layer or multilayer filter material, wherein the filter material may be selected from in particular glass fibers or a synthetic foam or also a combination of the two. The filter material of the filter medium preferably has a thickness of at least 0.5 mm and maximally 30 mm. An especially suitable pore size of the filter material is in the range of 0.3 μm to 500 μm. 
         [0011]    According to a further embodiment of the invention the hydrophilic filter medium is arranged on a support body that is provided with radial openings and the element with the plurality of through openings is resting immediately on the filter medium. The element that surrounds the filter medium has preferably a thickness of &lt;5 mm. The through openings present in the element are expediently round, oval, polygonal, kidney-shaped, bone-shaped, of a circular or semi-circular shape. The configuration of the profile of the through openings in the direction of flow is preferably cylindrical, concave, convex or funnel-shaped. It is also advantageous that the surface of the through openings, as a result of the manufacturing process or a subsequent surface treatment, is smooth. 
         [0012]    Moreover, with respect to the droplet formation, it is expedient that the through openings have a separating edge whose radius is &lt;1 mm. The open surface area that is formed by the through openings is preferably &lt;20 mm 2 . The through openings form expediently in the element a relative free surface area between 15% and 65%. It is also possible that the element with the through openings has a spacing between 0.1 mm and 5 mm relative to the filter medium. 
         [0013]    The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The accompanying Figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate various embodiments and to explain various principles and advantages all in accordance with the present invention. 
           [0015]    Features of the present invention, which are believed to be novel, are set forth in the drawings and more particularly in the appended claims. The invention, together with the further objects and advantages thereof, may be best understood with reference to the following description, taken in conjunction with the accompanying drawings. The drawings show a form of the invention that is presently preferred; however, the invention is not limited to the precise arrangement shown in the drawings. 
           [0016]      FIG. 1  shows a longitudinal section of housing in the shape of a tubular body with separating chamber and collecting chamber, consistent with the present invention; 
           [0017]      FIG. 2  is an illustration of several components of the separating element, partially in an exploded view, consistent with the present invention; 
           [0018]      FIG. 3  is a variant of the embodiment of  FIG. 2 , consistent with the present invention; and 
           [0019]      FIG. 4  is a longitudinal section of a water separator, consistent with the present invention. 
       
    
    
       [0020]    Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention. 
       DETAILED DESCRIPTION 
       [0021]    Before describing in detail embodiments that are in accordance with the present invention, it should be observed that the embodiments reside primarily in combinations of method steps and apparatus components related to a water separator as disclosed herein. Accordingly, the apparatus components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. 
         [0022]    In this document, relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element preceded by “comprises . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. 
         [0023]    In  FIG. 1 , a housing  2  is illustrated that is substantially embodied as a tubular body  3  that has a longitudinal direction LA and at the ends  4 ,  5  is formed like a spherical segment, respectively. The housing  2  has transversely to the longitudinal direction LA a separating plane TE so that two housing parts  6 ,  7  when joined together at the separating plane TE form the tubular body  3 . The separating plane TE is positioned adjacent to an inlet  8  so that the housing part  6  comprises approximately only the spherical segment of the end  4  while the housing part  7  comprises the main component of the tubular body  3 . At the inner side of the housing part  6  a socket  9  is formed that is substantially coaxial to the inlet  8  and is monolithic with the housing part  6 . 
         [0024]    A partition  10  is attached to the other end  5  of the housing  2  and extends to the separating plane TE in the longitudinal direction LA at a level somewhat below the center. The partition  10  divides in this way the interior of the housing  2  into a separating chamber  11  and a collecting chamber  12  wherein only in the area of the housing part  6  an opening  13  is provided that realizes a connection between the separating chamber  11  and the collecting chamber  12 . At the end  5  an outlet  14  for the fuel is provided that extends in the same direction as the inlet  8  at the opposite end  4 . At the inner side of the housing part  7  a socket  15  is arranged that extends at least approximately coaxially to the outlet  14 . At the end  5  of the housing part  7 , a water drainage socket  17  is provided below the outlet  14  and immediately above the bottom  16  of the collecting chamber  12 . The housing part  7  is preferably a monolithic injection-molded part including the partition  10 , the outlet  14 , the socket  15 , and the water drainage socket  17 . The housing parts  6 ,  7  are comprised preferably of plastic material and are welded or fused in the area of the partition plane TE so that a seal-tight connection is achieved that is fuel-resistant. 
         [0025]      FIG. 2  shows a separating element  18  that is comprised of several components; for ease of understanding, the components are partially shown in an exploded view. The separating element  18  is embodied as a tubular element  19  conceived for a horizontal arrangement in the separating chamber  11  in the housing  2 , as shown in  FIG. 1 . The tubular element  19  comprises a support body  20  provided with radial openings  21  in the form of longitudinal slots. The support body  20  is surrounded across the length of the longitudinal slots by a filter medium  22  that, in turn, is enveloped by an element  35  and forms together with it a first separating stage A 1 . The element  35  is, for example, a tight-mesh screen, a perforated sheet metal  36 , synthetic grid, or a fabric and is embodied as half shells  23 ,  24  of a cylindrical shape. 
         [0026]    The half shells  23 ,  24  are comprised of a thin-wall material formed to a half cylinder  25  and a frame  26  that extends around the edges of the half cylinder  25 . The two frames  26  can be provided with clips or locking elements in order to connect the two half shells  23 ,  24  with one another and to effect in this way an attachment on the support body  20 . The manufacture of the half shells  23 ,  24  as two separate parts, i.e., the half cylinder  25  and the frame  26 , provides the possibility of using a material combination of synthetic (plastic) material and metal, but the half shells can also be made from the same material (monolithic). 
         [0027]    Inside the support body  20  there is a partition  27  extending transversely to its longitudinal direction; it is positioned at a minimal spacing to the rearward end of the openings  21  when viewed in the flow direction S of the fuel. A guiding element  31  for guiding the flow is inserted into the interior of the support body  20  so far into the support body  20  that it contacts the partition  27 . The guiding element  31  is designed such that the flow cross-section within the support body  20  in the flow direction S becomes smaller. In this way, a uniform loading of the first separating stage A 1  across its entire length is provided. 
         [0028]    Downstream of the support body  20  on the other side of the partition  27  a tubular section  28  adjoins the partition  27 . The tubular section  28  has radial cutouts  29 . The tubular section  28  is surrounded by a separating nonwoven  30  that covers the cutouts  29 . The separating nonwoven  30  is comprised of a hydrophobic material and forms in this way a second separating stage A 2 . The mesh width of the separating nonwoven  30  can be, for example, between 5 μm and 500 μm. 
         [0029]    In  FIG. 3  an embodiment variant of  FIG. 2  is illustrated with a separating element  18  that differs from that of  FIG. 2  in that the half cylinder  25  and frame  26  of the half shell  23 , on the one hand, and of the half shell  24 , on the other hand, are formed as a monolithic part and therefore are comprised of the same material, either synthetic (plastic) material or metal. All other features in  FIG. 3  are the same as those of  FIG. 2  so that for same parts the same reference numerals are used. 
         [0030]      FIG. 4  shows a longitudinal section of a completely assembled water separator  1 . The housing  2  is comprised of housing parts  6 ,  7  that form the tubular body  3  whose interior is separated by the partition  10  extending in the longitudinal direction LA of the housing  2  into the separating chamber  11  and the collecting chamber  12 . In the separating chamber  11  the separating element  18  in the form of tubular element  19  is arranged. The tubular element  19  comprises the support body  20  and the tubular section  28  that are positioned behind one another in the flow direction in an aligned arrangement. On the support body  20  the filter medium  22  is arranged as well as the element  35  with the plurality of through openings. On the left end of the support body  20  shown in  FIG. 4  a sleeve  32  is integrally formed that is matched with its outer circumference to the inner size of the socket  9  at the inlet  8  and is received therein. The right end of the tubular section  28  is matched to the inner size of the socket  15  at the outlet  14  and is secured therein. 
         [0031]    Mounting of the tubular element  19  in the housing  2  is possible in a simple way in that first the completed separating element  18  is inserted, with the free end of the tubular section  28  leading, into the separating chamber  11  and is pushed into the socket  15 . If required, measures for a radial sealing action between the socket  15  and the tubular section  28  are to be provided. Subsequently, the housing part  6  is guided in the direction toward the housing part  7  and the socket  9  at the inlet  8  is pushed onto the sleeve  32  wherein also measures for a radial sealing action may be provided. The housing part  6  is moved so far in the direction toward the housing part  7  that the leading edge  33  of the housing part  6  engages a groove  34  of the housing part  7  and is connected seal-tightly therewith. Between the first separating stage A 1  and the housing part  7  as well as the partition  10  there remains an annular chamber that ensures sufficient flow. In  FIG. 4  all other reference numerals are the same as those in  FIGS. 1 to 3  for same parts. 
         [0032]    The fuel flows into the water separator  1  through inlet  8  in the direction of arrow S 1  and passes through the sleeve  32  into the interior of the support body  20 . Because of the partition  27  the fuel in accordance with arrow S 2  passes through the openings designed as slotted holes (compare  FIGS. 2 and 3 ) and father in radial direction through the filter medium  22  and the half shells  23 ,  24  into the annular chamber defined between the half shells  23 ,  24  and the inner wall of the housing part  7  as well as the partition  10 . Uniform loading of the first separating stage A 1  is ensured by the guiding element  31  for guiding the flow in the interior of the support body  20 . When the fuel with the emulsified water component passes through the separating element  18  that has a coalescing effect, water droplets are formed that as a result of the horizontal arrangement of the housing  2  sink onto the partition  10 . The water droplets are guided along the partition  10  and reach through the opening  13  the collecting chamber  12 . 
         [0033]    The fuel from which the water component has been substantially separated by the separating stage A 1  flows as a result of a vacuum effect at the outlet  14  into the tubular section  28 , namely through the second separating stage A 2  that is formed by the separating nonwoven  30  and the radial cutouts  29 , in accordance with arrow S 3 . Since the material of the separating nonwoven  30  has a hydrophobic effect, the water component that is still emulsified within the fuel, and also already formed water droplets that have been entrained by the flow, are retained by the separating nonwoven  30  so that exclusively fuel will reach the tubular section  28  and the outlet  14 . The water collected in the collecting chamber  12  can be removed by devices known in the art and connectable to the water drainage socket  17 . 
         [0034]    In the foregoing specification, specific embodiments of the present invention have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.