Patent Publication Number: US-2007114165-A1

Title: Fuel filter

Description:
TECHNICAL FIELD  
      The present invention is drawn to a method and apparatus adapted to remove impurities from fuel.  
     BACKGROUND OF THE INVENTION  
      Diesel powered vehicles generally include a diesel fuel water separator to prevent water from entering the engine and to optimize vehicle performance. Conventional diesel fuel water separators contain filtration elements made of cellulose that has been chemically modified to induce water coalescence. However, these conventional separators may be rendered ineffective by large amounts of polar materials that are soluble in diesel fuel such as, for example, detergent additives and biodiesel additives.  
     SUMMARY OF THE INVENTION  
      The present invention includes a method and apparatus configured to remove impurities from fuel. The method and apparatus of the present invention implement a molecular sieve adapted to remove impurities such as water from the fuel and which is not rendered ineffective by polar materials. As is known in the art, polar materials are materials composed of molecules having a permanent electric dipole moment.  
      According to a preferred embodiment, the apparatus includes a housing disposed between a fuel tank and a diesel engine of the diesel powered vehicle. The housing defines a generally cylindrical main body, an inlet port disposed at an end portion of the main body, and an outlet port disposed at an opposite end portion of the main body. A fuel diffuser is disposed within the main body of the housing and is in fluid communication with the inlet port. A fuel collector is disposed within the main body of the housing and is in fluid communication with the outlet port. A molecular sieve is disposed within the main body of the housing between the fuel diffuser and the fuel collector. According to the preferred embodiment, the outlet port of the housing is attached to a cellulose filter.  
      According to one aspect of the invention, the molecular sieve is a type 3A molecular sieve adapted to filter water from the fuel.  
      According to another aspect of the invention, the molecular sieve is a type 4A molecular sieve adapted to filter water from the fuel.  
      According to yet another aspect of the invention, the housing is composed of injection molded plastic such that cost and weight are minimized.  
      A preferred method of the present invention includes transferring fuel from a fuel tank to a filter apparatus such as, for example, with a fuel pump. The fuel in the filter apparatus is then diffused to increase the flow area. The diffused fuel is then filtered through a molecular sieve within the filter apparatus to remove impurities such as water. Thereafter, the fuel is transferred from the filter apparatus to the engine.  
      According to one aspect of the invention, the fuel is transferred to a collector or reservoir prior to transferring the fuel to the engine.  
      According to another aspect of the invention, the fuel is transferred through a cellulose filter prior to transferring the fuel to the engine.  
      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  
       FIG. 1  is a schematic diagram of a vehicle having a diesel fuel water filter apparatus according to the present invention; and  
       FIG. 2  is a more detailed schematic diagram of the diesel fuel water filter apparatus of  FIG. 1 .  
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Referring to the drawings, wherein like reference numbers refer to like components,  FIG. 1  shows a schematic depiction of a diesel powered vehicle  10  according to a preferred embodiment of the present invention. The vehicle  10  includes a diesel engine  12 , a fuel tank  14 , and a filter assembly  16  disposed therebetween. A fuel pump  18  is adapted to transfer diesel fuel  20  from the fuel tank  14 , through the filter assembly  16 , and to the diesel engine  12 . It should be appreciated that the fuel pump  18  is shown disposed between the fuel tank  14  and the filter assembly  16  for exemplary purposes; however, the fuel pump  18  may alternatively be disposed in other locations such as, for example, within the fuel tank  14 . The filter assembly  16  is configured to remove water from the diesel fuel  20  to protect the diesel engine  12  and optimize performance of the vehicle  10 .  
      Referring to  FIG. 2 , the filter assembly  16  is shown in more detail. The filter assembly  16  includes a housing or cartridge  22 . The housing  22  is preferably composed of injection molded plastic to minimize the cost and weight of the filter assembly  16 . Alternatively, the housing  22  may be composed of any conventional material such as, for example, metal. The housing  22  defines a generally cylindrical main body  24 , an inlet port  26 , and an outlet port  28 . The inlet port  26  and outlet port  28  are preferably disposed at opposite end portions of the main body  24 . A fuel diffuser  30 , a molecular sieve  32 , and a fuel collector  34  are preferably disposed within the main body  24  of the housing  22 . The fuel diffuser  30  is disposed within the main body  24  near the inlet port  26  and is in fluid communication therewith. The fuel collector  34  is disposed within the main body  24  near the outlet port  28  and is in fluid communication therewith. The molecular sieve  32  is disposed within the main body  24  between the fuel diffuser  30  and the fuel collector  34 .  
      The fuel diffuser  30  is preferably a conventional nozzle design, and is adapted to increase the flow area of the diesel fuel  20  (shown in  FIG. 1 ) such that the fuel  20  is distributed more evenly across the surface of the molecular sieve  32 . It has been observed that, by distributing the fuel  20  across a larger molecular sieve surface area with the diffuser  30 , more water may be filtered from the fuel  20  and the life of the filter assembly  16  may be prolonged.  
      According to a preferred embodiment, the molecular sieve  32  is composed of adsorbent materials such as aluminosilicate crystalline polymers, or zeolites (not shown). It should be appreciated, however, that the molecular sieve  32  may alternatively include other compositions such as, for example, a synthetic molecular sieve. The zeolites form a three-dimensional interconnecting network having a plurality of well defined openings or pores (not shown). Molecules that fit into the pores are filtered out or trapped as they flow across the filter, whereas larger molecules are allowed to pass through. The molecular sieve  32  is preferably a type 3A or 4A molecular sieve which has pores that are sized to filter out water molecules. As is known in the art, “type 3A” and “type 4A” are common manufacturing designations for molecular sieves.  
      The molecular sieve  32  is thereby configured to remove water from diesel fuel and biodiesel without removing larger diesel fuel, biodiesel, or fuel additive molecules. Additionally, the filter assembly  16  is not rendered inactive by polar materials, and will continue to remove water from the diesel fuel  20  (shown in  FIG. 1 ) until the molecular sieve  32  is saturated. As is known in the art, polar materials are materials composed of molecules having a permanent electric dipole moment. After the molecular sieve  32  becomes saturated, it may be recharged in a conventional manner to remove the water therefrom. One method for recharging a saturated molecular sieve includes washing the sieve with a solvent adapted for such a purpose, drying the sieve, and thereafter heating the sieve at approximately 200 degrees Centigrade for several hours.  
      The fuel collector  34  is preferably a reservoir or container adapted to hold the fuel  20  transferred through the molecular sieve  32  before the diesel fuel  20  passes through the outlet port  28 .  
      According to a preferred embodiment of the present invention, the water filter  16  includes a cellulose filter  40  attached to the output port  28  of the housing  22 . The cellulose filter  40  is preferably implemented as a precautionary measure in case the molecular sieve  32  breaks down. More precisely, the cellulose filter  40  is implemented to prevent the constituent materials of a broken down molecular sieve from reaching the engine  12  (shown in  FIG. 1 ).  
      While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.