Abstract:
Method for preventing carbon build-up on fuel spray guiding surfaces proximate a nozzle of a fuel injector. Liquid fuel handling surfaces of the fuel injector can remain cool while providing very hot surfaces to burn off carbon particles before carbon deposits can build up and change the spray characteristics. In the method, a spray guiding structure guides the fuel spray after exiting from the fuel injector and a deflector member is arranged around the injector body. The spray guiding structure is thermally insulated from the fuel injector, and this thermal insulation enables the spray guiding structure to be heated to a temperature above about 900° F. to prevent build up of carbon thereon.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to an arrangement and method for preventing carbon formation in spray guiding structures and more specifically to an arrangement and method for preventing carbon formation in spray guiding structures of fuel injectors. The present invention also relates generally to arrangements and methods for enabling improved heating of the spray medium of fuel injectors to aid vaporization and atomization of the spray, and/or for preventing cracking of the fuel during the heating process. 
       BACKGROUND OF THE INVENTION 
       [0002]    It is well known that surfaces in engines which operate above about 900° F. or below about 400° F. do not accumulate carbon. In the first case at temperatures above about 900° F., carbon accumulates, but is burned off. In the second case at temperatures below about 400° F., fuel and oil do not thermally decompose and carbon does not form. 
         [0003]    Fuel injectors have historically operated in the cold region of the spectrum, i.e., below about 400° F., because there has been no commercially viable way to transition between cold and hot without plugging the location of transition since the fuel will decompose even in the absence of air. 
         [0004]    A wide variety of fuel injectors have been disclosed previously. Some of these are described in: 
         [0005]    U.S. Pat. No. 3,069,099 entitled “Fuel Injection nozzle and spray device” issued Dec. 18, 1962 to Graham; 
         [0006]    U.S. Pat. No. 4,270,257 entitled “Method for manufacturing a fuel injection valve” issued Jun. 1, 981 to Kimata et al.; 
         [0007]    U.S. Pat. No. 4,550,875 entitled “Electromagnetic unit fuel injector with piston assist solenoid actuated control valve” issued Nov. 5, 1985 to Teerman et al.; 
         [0008]    U.S. Pat. No. 4,572,433 entitled “Electromagnetic unit fuel injector” issued Feb. 25, 1986 to Deckard; 
         [0009]    U.S. Pat. No. 4,693,424 entitled “Poppet covered orifice fuel injection nozzle” issued Sep. 15, 1987 to Sczomak; 
         [0010]    U.S. Pat. No. 4,750,675 entitled “Damped opening poppet covered orifice fuel injection nozzle” issued Jun. 14, 1988 to Sczomak; 
         [0011]    U.S. Pat. No. 4,813,610 entitled “Gasoline injector for an internal combustion engine” issued Mar. 21, 1989 to Renowden; 
         [0012]    U.S. Pat. No. 4,852,853 entitled “Pressure balance type solenoid controlled valve” issued Aug. 1, 1989 to Toshio et al.; 
         [0013]    U.S. Pat. No. 4,932,591 entitled “Pulverizer, fluid” issued Jun. 12, 1990 to Cruz; 
         [0014]    U.S. Pat. No. 5,088,467 entitled “Electromagnetic injection valve” issued Feb. 18, 1992 to Mesenich; 
         [0015]    U.S. Pat. No. 5,191,867 entitled “Hydraulically-actuated electronically-controlled unit injector fuel system having variable control of actuating fluid pressure” issued Mar. 9, 1993 to Glassey; 
         [0016]    U.S. Pat. No. 5,551,638 entitled “Valve member for fuel injection nozzles” issued Sep. 3, 1996 to Caley; 
         [0017]    U.S. Pat. No. 5,833,142 entitled “Fuel injector nozzles” issued Nov. 10, 1998 to Caley; 
         [0018]    U.S. Pat. No. 5,979,803 entitled “Fuel injector with pressure balanced needle valve” issued Nov. 9, 1999 to Peters et al.; 
         [0019]    U.S. Pat. No. 6,055,948 entitled “Internal combustion engine control system” issued May 2, 2000 to Shiraishi et al.; 
         [0020]    U.S. Pat. No. 6,247,450 entitled “Electronic controlled diesel fuel injection system” issued Jun. 19, 2001 to Jiang; 
         [0021]    U.S. Pat. No. 6,435,429 entitled “Fuel injection valve” issued Aug. 20, 2002 to Eichendorf et al.; 
         [0022]    U.S. Pat. No. 6,446,597 entitled “Fuel delivery and ignition system for operation of energy conversion systems” issued Sep. 10, 2002 to McAlister; 
         [0023]    U.S. Pat. No. 6,568,080 entitled “Air assist fuel injectors and method of assembling air assist fuel injectors” issued May 27, 2003 to Kimmel et al.; 
         [0024]    U.S. Pat. No. 6,708,905 entitled “Supersonic injector for gaseous fuel engine” issued Mar. 23, 2004 to Borissov et al.; 
         [0025]    U.S. Pat. No. 6,725,838 entitled “Fuel injector having dual mode capabilities and engine using same” issued Apr. 27, 2004 to Shafer et al.; 
         [0026]    U.S. Pat. No. 6,755,175 entitled “Direct injection of fuels in internal combustion engines” issued Jun. 29, 2004 to Mckay et al.; 
         [0027]    U.S. Pat. No. 6,923,387 entitled “Deposit control in fuel injector nozzles” issued Aug. 2, 2005 to Carlisle et al.; 
         [0028]    U.S. Pat. No. 6,978,942 entitled “Shockwave injector nozzle” issued Dec. 27, 2005 to Murdoch; 
         [0029]    U.S. Pat. No. 7,083,126 entitled “Fuel injection arrangement” issued Aug. 1, 2006 to Lehtonen et al.; 
         [0030]    U.S. Pat. No. 7,137,571 entitled Fuel injector nozzles” issued Dec. 21, 2006 to Caley et al.; U.S. Pat. No. 7,350,539 entitled “Electromagnetic controlled fuel injection apparatus with poppet valve” issued Apr. 1, 2008 to Kaneko; 
         [0031]    U.S. Pat. No. 7,353,806 entitled “Fuel injector with pressure balancing valve” issued Apr. 8, 2008 to Gant; 
         [0032]    U.S. Pat. No. 7,387,289 entitled “Method and apparatus for driving a solenoid proportional control valve utilized for flow rate control” issued Jun. 17, 2008 to Kubota et al.; 
         [0033]    U.S. Pat. No. 7,942,349 entitled “Fuel injector” issued May 17, 2011 to Meyer; and 
         [0034]    U.S. Pat. No. 7,740,002 entitled “Fuel injector” issued Jun. 22, 2010 to Zeng et al. 
         [0035]    All of the foregoing patents are incorporated by reference herein. 
         [0036]    Of particular interest, U.S. Pat. No. 7,942,349, the inventor&#39;s earlier patent, discloses a fuel injector body having a fuel chamber and a valve seat around a fuel outlet. A valve body is positioned at the valve seat and a valve stem extends through the fuel outlet and fuel chamber. Engagement (disengagement) of valve body and valve seat closes (opens) the injector. The injector body or the valve body may include one or more spray-shaping surfaces arranged to direct the fuel sprayed from the fuel outlet. The spray-shaping surfaces are arranged on the injector body around all or part of the valve seat, or on the valve body around all or part of a valve-seat-engaging portion of the valve body. The spray-shaping surfaces are thus formed on the injector body or the valve body. 
       OBJECTS AND SUMMARY OF THE INVENTION 
       [0037]    It is an object of the present invention to provide an arrangement and method for improving operation and/or use of spray guiding structures of, for example, fuel injectors. 
         [0038]    A fuel injection arrangement for an engine in accordance with the invention includes a fuel injector having an injector body and a valve body and that is configured to inject fuel in spray form into a combustion chamber in the engine, a spray guiding structure that guides the fuel spray after exiting from the fuel injector, and a deflector member arranged around the injector body. The spray guiding structure is thermally insulated from the fuel injector to enable the spray guiding structure to be heated to a temperature above about 900° F. and thereby prevent build up of carbon on the spray guiding structure. 
         [0039]    A method for improving use of a fuel injector for an engine in accordance with the invention includes interposing a deflector member between the fuel injector and the engine, guiding the fuel spray after exiting from the fuel injector by means of a spray guiding structure supported by the deflector member, and providing thermal insulation to insulate the spray guiding structure from the fuel injector. As in the arrangement, the thermal insulation of the spray guiding structure from the fuel injector enables the spray guiding structure to be heated to a temperature above about 900° F. to prevent build up of carbon on the spray guiding structure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0040]    The invention may best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
           [0041]      FIG. 1  is a cross-sectional view of one embodiment of an outwardly opening poppet fuel injector placed in an engine in accordance with the invention. 
           [0042]      FIG. 2  is a cross sectional representation of a conventional multi-orifice injector placed in an engine in accordance with the invention. 
           [0043]      FIG. 3  is a cross-sectional view of an embodiment of a fuel injector in accordance with the invention including electric heating elements. 
           [0044]      FIG. 4  is a cross-sectional view of an embodiment of a fuel injector in accordance with the invention including an insulating material fastened to the injector, and is an alternative example of how the injector could be made. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0045]    As shown in  FIG. 1 , a fuel injector  10  in accordance with the invention includes an injector body  12  defining an interior cavity in which a poppet or fuel metering valve body  14  reciprocates. A fuel passage  16  is defined between an inner surface of the injector body  12  and an outer surface of the valve body  14 . These features are mostly conventional for a poppet style fuel injector  10  and shown to enable explanation of the invention. Thus, the invention is not limited to any particular form of injector body  12  and valve body  14  and is applicable to fuel injectors with other forms and shapes of these components, such as illustrated in  FIG. 2 . The manner in which the injector body  12  and valve body  14  cooperate to provide the known functions of a fuel injector are known to those skilled in the art, and described, for example, in U.S. Pat. No. 7,942,349. 
         [0046]    In accordance with the invention, a deflector member  18  is arranged around the injector body  12 , which deflector member  18  is also considered a heat shield. Deflector member  18  may be designed to completely surround the injector body  12 , i.e., it defines a cylindrical cavity in which the injector body  12 , and valve body  14  therein, is placed. The deflector member  18  includes a substantially cylindrical side wall  20  and a lower, end wall  22  having an aperture  24  through which the fuel from the fuel injector  10  is sprayed. End wall  22  is appropriately termed a lower end wall when the fuel injector  10  has the configuration shown in  FIG. 1  but when the fuel injector  10  has other configurations, the lower end wall  22  is not required to be at a lower edge of the cylindrical wall  20 . 
         [0047]    An air gap  26  may be formed between the inner surface of the cylindrical side wall  20  of the deflector member  18  and the outer surface of the injector body  12 . The air gap  26  functions as insulation, and as an alternative to air, an insulating material may be arranged in this gap. 
         [0048]    A lower portion  20   a  of the cylindrical side wall  20  has a smaller thickness than an upper portion  20   b  and serves as a heat control wall. The transition area between the lower and upper portions  20   a ,  20   b  may be at or proximate the edge of an engine  28  in which the fuel injector  10  is housed. 
         [0049]    The deflector member  18  is constructed so that the surfaces defining the aperture  24  in the lower end wall  22  bear against outer surfaces of the injector body  12 . This contact area  30  between the injector body  12  and the deflector member  18  enables alignment of the injector body  12  when engaged with the deflector member  18  as well as sealing of the air gap  26 . Further, an upper portion of the deflector member  18  is constructed to enable secure coupling to the engine  28  (as shown in the upper, left portion of  FIG. 1 ). 
         [0050]    Deflector member  18  provides several functions. First, the deflector member  18  serves as a heat shield to prevent heat transmission between the fuel injector  10  and the combustion chamber  40  into which the fuel injector  10  extends. Second, the deflector member  18  supports spray guiding structure  32  that guides the fuel being sprayed from the fuel injector  10 . 
         [0051]    The spray guiding structure  32  is arranged on the lower surface of the lower end wall  22  and comprises spray guiding surfaces that modify the spray coming out of the fuel injector  10 . The spray guiding surfaces may have any of the forms disclosed in U.S. Pat. No. 7,942,349, wherein they are alternatively referred to as spray shaping surfaces. The spray guiding structure  32  may be integral or monolithic with the deflector member  18  or a separate component. 
         [0052]    The spray guiding structure  32  is arranged around the circumference of the lower end wall  22 , i.e., around the circumference of the injector body  12  and therefore inherently around the circumference of the valve body  14  since a portion of the injector body  12  interposes between the surface of the lower end wall  22  defining the aperture  24  and the valve body  14  in view of contact between the lower end wall  22  and the injector body  12 . Thus, the spray guiding structure  32  has an annular form. The spray guiding structure  32  does not need to be continuous around the circumference of the injector body  12  or valve body  14 . 
         [0053]    The spray guiding structure  32  and specifically the spray guiding surfaces, are insulated from the injector fuel passages and valve seat. This is done because they are exposed to the combustion chamber  40  and thus heated to a temperature at which carbon deposits burn off (typically above 1000° F.). In the exemplary case of  FIG. 1 , a minimal area of un-insulated contact occurs between the deflector  18  and the injector body  12  in order to provide good alignment between the two structures. Instead of or in addition to the heat being supplied by exposure to medium from the combustion chamber in the engine  28 , heat may also be supplied by auxiliary heating as for example by electric heat or catalytically augmented chemical reactions. The electrically heated case is shown in  FIG. 3 ; the catalytically heated case is not shown. 
         [0054]    The material providing thermal insulation between the spray guiding structure  32  and the fuel injector  10  may be monolithic or integral with the injector body  12  if a material with adequate properties can be found, for example, an engineered ceramic may provide insulation and adequate strength. In this embodiment, at least a portion of the injector body  12 , namely that portion alongside the lower end wall  22  of the deflector member  18  on which the spray guiding structure  32  is arranged, is formed as an insulative member. Specific insulating material may not be necessary because of the small contact area between the deflector member  18  and the injector body  12 . 
         [0055]    As an alternative, the insulating material may be arranged as a separate element between the engine  28  and the deflector member  18 , or between the injector body  12  and the deflector member  18 , or monolithic or integral with the deflector member  18 , or in any other way which provides thermally isolated surfaces which operate at high temperatures to guide the spray. Generally then, the spray guiding structure  32 , whether formed on the deflector member  18  or separate therefrom, is thermally insulated from the fuel injector  10 . 
         [0056]    In the embodiment shown in  FIG. 1 , the fuel comes out from the fuel injector  10  in a sheet between the injector body  12  and the valve body  14 . The fuel spray impacts the spray guiding structure  32 , bounces off the spray guiding structure  32  and is redirected to a desirable spatial location in the engine  28 . As such, an important advantage of the invention is obtained in that the spray guiding structure  32  does not become involved with the fuel stream until after the fuel has exited the fuel injector  10 , i.e., exited from the fuel passage  16  between the injector body  12  and the valve body  14 . At this stage, the fuel is, by virtue of the operation of the valve body  14  relative to the injector body  12 , starting to break up into droplets and mix with air in order to burn. 
         [0057]    Since the fuel injector  10  operates at temperatures below about 400° F., no carbon builds up on the internal fuel passages  16 . Since the deflector member  18  operates at temperatures above 900° F., no carbon builds up on the deflector member  18 . The temperature of the heat deflector  18  can be controlled by any one or more of the following parameters: 1) the degree to which the fuel injector  10  and surround deflector member  18  and spray guiding structure  32  penetrates or projects into the combustion chamber of the engine  28  (designated by reference numeral  34 ), 2) the characteristics of the contact area  30  between the injector body  12  and the deflector member  18 , and 3) the characteristics, such as the length and thickness, of the cylindrical side wall  20  and lower end wall  22  of the deflector member  18 , 4) the clearance between the deflector member  18  and the engine  28 , and 5) any additional or auxiliary heat input. 
         [0058]    With the foregoing structure, it is possible to make the spray guiding surface or other spray guiding structure  32  operate at hot temperature or sufficiently high temperatures to burn off any carbon build up. A similar technique has been used for many years in spark plugs, where any build up of carbon causes a short circuit between the plug electrodes and prevents spark formation. Various heat range spark plugs have been developed and reliability for hundreds of hours has been provided. 
         [0059]    Furthermore, the deflector member  18  in combination with the spray guiding structure  32 , when placed around a fuel injector  10  enables carbon formation on the spray guiding structure  32  to be prevented in view of the capability of increasing the heat at the spray guiding structure  32 . 
         [0060]    As additional description of the alternative embodiments shown in  FIGS. 2-4 , in  FIG. 2 , the injector body  12  includes a closed tip and several orifices around the tip. These orifices provide communication between the fuel passage  16  and the combustion chamber  40 . In  FIG. 3 , the lower portion  20   a  of the cylindrical side wall  20  includes an auxiliary heating system, represented by the conduits  36  through which a heating media can be directed. In  FIG. 4 , the deflector member  18 , serving partly as an insulating member, is fastened to the injector body  12  using, for example, adhesive or compressive bonding. Also, a portion of the injector body  12  that is not surrounded by the deflector member  18  directly faces the cylindrical cavity in the engine  28  (in contrast to the embodiment shown in  FIG. 1  wherein the deflector member  18  interposes completely between the injector body  12  and the cylindrical cavity of the engine  28 ). 
         [0061]    As used herein, “sufficiently high” and “hot” temperatures mean temperatures hot enough to keep carbon build up from forming. 
         [0062]    Having described exemplary embodiments of the invention with reference to the accompanying drawings, it will be appreciated that the present invention is not limited to those embodiments, and that various changes and modifications can be effected therein by one of ordinary skill in the art without departing from the scope or spirit of the invention as defined by the appended claims.