Abstract:
A urea strainer includes a mesh for removing impurities from urea passing therethrough and heatable wires to heat the urea as it passes through the mesh. The urea is provided to an emission control system of a diesel engine.

Description:
I. FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to simultaneously heating engine fluids and filtering the fluids, and more particularly to heated urea strainers for diesel engines. 
       II. BACKGROUND OF THE INVENTION 
       [0002]    Diesel engines are typically required by law to incorporate a method for reducing nitrous-oxide (NOx) emissions. To reduce the amount of NOx emitted, many diesel engines include what is known as Selective Catalytic Reduction (SCR) system. In an SCR system, a solution of urea and water is injected into a catalytic converter, which is part of the emission control system of a diesel engine. When the urea-water solution interacts with the NOx, the NOx is converted into nitrogen gas (N2) and water (H2O). 
         [0003]    The SCR system therefore requires a urea delivery system whereby the urea may be transferred from a urea tank to the catalytic converter when necessary. However, urea freezes at −11° C. In many parts of the world in which diesel engines are used, typical winter temperatures can dip below −25° C. Thus, a method for melting urea so that it may be injected into a catalytic converter while in extreme weather conditions is necessary. Currently, the predominant method for melting urea in an SCR system involves a coil heating element. 
       SUMMARY OF THE INVENTION 
       [0004]    As recognized herein, it is unfortunately the case that the above-mentioned coil heating element requires a high current draw from the diesel engine system, consuming energy that would be used elsewhere in the diesel engine system. Further, the present application recognizes that existing coils to melt urea are placed in a less than optimal position in terms of efficiency. As understood herein, a heating element should be positioned as close as possible to a urea strainer. 
         [0005]    Accordingly, a system includes a urea tank and a strainer through which urea from the tank passes to an emission control system of a diesel engine. At least portions of the strainer can be heated to heat urea passing through the strainer. 
         [0006]    The portions may include wires that may criss-cross each other. The strainer may be disc-shaped, and the strainer removes impurities from urea passing therethrough. Thus, the wires may be juxtaposed with material in a mesh to remove impurities from urea. An electrical connector can be provided that is configured for engaging a source of electricity. The connector is electrically connected to the wires. 
         [0007]    In another aspect, an apparatus includes a strainer engageable with a urea tank associated with a diesel engine for chemically reacting with nitrogen oxide. The strainer includes plural elements removing impurities from urea passing therethrough, with at least some elements being heatable by electricity to heat urea. An electrical connector is configured for engaging a source of electricity. The connector is electrically connected to at least some of the elements. 
         [0008]    In another aspect, a method includes removing impurities from urea and heating the urea as the impurities are being removed therefrom. 
         [0009]    The details of the present invention, both as to its structure and operation, can best be understood in reference to the accompanying drawings, in which like reference numerals refer to like parts, and in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a block diagram in accordance with one non-limiting embodiment of a diesel engine system; 
           [0011]      FIG. 2  is a perspective view of a non-limiting embodiment of a urea strainer capable of being heated to melt frozen urea; and 
           [0012]      FIG. 3  is a top plan view of the urea strainer shown in  FIG. 2 , with portions of the housing removed to expose the interior strainer mesh. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0013]    The present invention is intended for application in automotive vehicle systems and will be described in that context. It is to be understood, however, that the present invention could also be applied in other fuel delivery applications. 
         [0014]    Beginning initially with  FIG. 1 , a diesel engine system  10  is shown. The system  10  has a diesel engine  12  and a diesel fuel tank  14  which delivers diesel fuel to the engine  12  when necessary. Further, connected to the diesel engine  12  is a catalytic converter  16 , with the catalytic converter  16  receiving emissions produced by the diesel engine  12 . 
         [0015]    Attached to the catalytic converter  16  is a Selective Catalytic Reduction (SCR) system  18 . The purpose of the SCR system  18  is to reduce nitrous oxide (NOx) emissions created by the diesel engine  12  into nitrogen gas (N2) and water (H20). The SCR system  18  accomplishes this by injecting urea into NOx produced by the catalytic converter  16 . When the urea interacts with the NOx, the NOx is converted into N2 and H2O. 
         [0016]    Thus, the SCR system  18  requires a urea delivery system  20 . The urea delivery system  20  includes a urea tank  22  where urea may be stored, and a urea strainer  24  which, in accordance with principles explained further below, is made up of an electrically resistive mesh composition capable of both filtering and melting urea. Further, the strainer  24  has an energy source  26  which provides energy required by the strainer  24  to melt urea in the tank  22 . The energy source  26  may be the electrical distribution system of a vehicle and may include a battery. 
         [0017]    Further still, the catalytic converter  16  can be fluidly connected to a water tank  28 . The water tank  28  may receive H2O from the catalytic converter  16 . Lastly, a muffler  30  is connected to the catalytic converter  16 . Remaining emissions from the treated effluent of the catalytic converter  16 , e.g., N2, may travel to the muffler  30 , where the muffler  30  may then release the remaining emissions from the diesel engine system  10 . 
         [0018]    Moving to  FIG. 2 , a non-limiting embodiment of a urea strainer is shown embodied in a urea strainer assembly  32 . The assembly  32  may be placed in a urea tank. The assembly  32  can include a hollow metal or plastic strainer housing  34  and an outlet  36  formed on the housing  34  through which urea may pass from a urea tank, with fluid passing from the tank, into an inlet (not shown) on the side of the strainer opposite the outlet  36 , and then to the SCR system  18  described above. 
         [0019]    As set forth further below, the strainer in the housing  34  is at least partially composed of overlapping wires capable of being heated and cooled and may be submergible in liquid. The wires at least partially composing the strainer  34  will be discussed in further detail in  FIG. 3 . 
         [0020]    Continuing with  FIG. 2 , the assembly  32  also includes an electrical connector  38  that is electrically connected to the strainer through at least one wire  40 . The wire  40  transmits electricity from the connector  38  to the strainer  34 , and the connector  38  can be connected to a vehicle&#39;s electrical distribution system to thus send an electric current to the strainer, which in turn may be resistively heated to melt frozen urea. 
         [0021]    Additional details of the assembly  32  are shown in  FIG. 3 . As may be seen in  FIG. 3 , the strainer housing  34  holds a resistive mesh  50  that is at least partially composed of wires  52  which may be woven, overlapping, crisscrossing or the like. Further still, the wires  52  can be substantially in the same plane and may be interwoven with another material in the mesh  50  such as fabric or plastic to remove impurities from urea passing therethrough, although in some embodiments only electrically energizable wires, closely spaced, may be provided to undertake both the filtering and heating functions. When other materials are included in the strainer  44  in addition to energizable wires  52 , the other materials can not only provide structural support for the strainer, but also help strain urea going into a urea tank. Thus, the mesh  50  including wires  52  and other materials may form a disc with openings in it for urea to be strained through. 
         [0022]    Further still, the wires  52  may be excited by electricity from the connector  38  to warm urea. Thus, in its heated state, the strainer melts frozen urea at the point where the urea is filtered. Further, an external temperature sensor located on a vehicle in a non-limiting embodiment may be used to determine when current should be sent from the power source to the mesh  50  to melt frozen urea. 
         [0023]    Moreover, the maximum temperature to which the strainer may be heated may vary depending on the materials composing both the mesh  50  the strainer so as to not damage either the strainer mesh  50 . Regardless, the position of the strainer relative to a urea tank optimizes energy conservation by reducing the electrical draw required to heat frozen urea in a urea tank. 
         [0024]    It is to be understood that the present non-limiting embodiment may be used in other applications other than the filtering of urea. The present invention may be used in conjunction with diesel filtration systems or windshield wiper filtration systems, for example. 
         [0025]    While the particular HEATED UREA STRAINER FOR DIESEL ENGINE is herein shown and described in detail, it is to be understood that the subject matter which is encompassed by the present invention is limited only by the claims. For example, in addition to the above connection mechanisms, other quick connect/quick disconnect type of mechanisms may be used.