Abstract:
A fuel injector having a nozzle with depressions for increasing fluid turbulence and preventing deposit build up within the injector to increase performance, longevity and fuel economy.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    None. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    None. 
       BACKGROUND OF THE INVENTION 
       [0003]    1. Technical Field 
         [0004]    The present invention is related to fuel injectors for automotive engines and, more particularly, to fuel injector nozzles capable of maintaining performance in harsh engine operating conditions. 
         [0005]    2. Discussion 
         [0006]    Fuel injected internal combustion engines are well known in the industry. In direct injected engines, the injection tip of the fuel injector extends into the combustion chamber. The fuel may also be injected into the cylinder through port injection with the injector being located within the intake port. If the fuel is port injected, the fuel is first mixed with air before being drawn into the cylinder. Each fuel injector includes a perforated plate, also known as a metering plate, for dispersing and directing fuel into the cylinder. 
         [0007]    The metering plate is located on the end of the fuel injector, and particularly on the nozzle, and includes a variety of fuel flow passages that are configured to atomize the fuel into extremely small fuel droplets to meet stringent emission standards for internal combustion engines. The fine atomization of the fuel reduces exhaust emissions, improves cold weather start capabilities, reduces fuel consumption, and improves performance. Typically the optimization of the droplet size depends on the pressure of the fuel and requires high pressure delivery of roughly 7 to 10 MPa. However, such high fuel delivery pressures may cause greater dissipation of the fuel and propagate the fuel further outward from the injector, thereby making it more likely that fuel condenses on the walls of the cylinder and on the top surface of the piston or on the walls of the intake port instead of remaining atomized in the air. Any condensation on the walls or piston significantly decreases the efficiency of the combustion, thereby increasing emissions and decreasing performance of the engine. 
         [0008]    To address these problems, some manufactures utilize a low pressure fuel injection system which is still capable of sufficiently atomizing the fuel. To generate sufficient atomization at low pressure, fuel injectors typically employ sharp edges in the nozzle orifice for atomization and acceleration of the fuel. However, the relatively low pressure of the fuel and sharp edges result in the spray being difficult to direct and reduces the range of the spray. More particularly, the spray angle or cone angle produced by the injector is somewhat narrow. To tune the spray angle and to provide sufficient atomization, typically the fuel flow passages in the metering plate are located some distance from the longitudinal axis of the nozzle. Therefore, the fuel flows through a passage in the injector and outward along the dispersion side of the nozzle through an orifice cavity defined by the dispersion end of the nozzle and the metering plate. In particular to direct injected engines, the fuel injectors may experience build-up on the dispersion end of the nozzle and in particular on the dispersion end behind each of the fuel exit cavities or orifices in the metering plate. This build-up on the dispersion end of the nozzle may interfere with fuel delivery, interfere with the atomization of the fuel, and interfere with the spray angle, all of which may increase emissions and fuel consumption and decrease engine performance. Therefore it would be desirable to develop fuel injectors, whether low pressure fuel injectors or high pressure fuel injectors, that limit the effect of any build-up and improve the performance of the fuel injectors. 
       SUMMARY OF THE INVENTION 
       [0009]    In view of the above, the present invention is directed to a fuel injector including a nozzle having a longitudinal axis and a valve passage extending along the longitudinal axis. The nozzle also includes a dispersion end configured to receive a metering plate. The metering plate is in fluid communication with the passage extending through the nozzle. The fuel flows through the passage and along the dispersion end through an outlet cavity defined by the dispersion end and metering plate and then out the exit cavity on the metering plate. The dispersion end includes at least one depression arranged behind an exit cavity on the metering plate. The depression allows contaminants and impurities to build-up on the dispersion end without affecting the flow of the fuel through the exit cavities and, more particularly, without affecting the atomization or spray angle of the fuel. 
         [0010]    The depression may have any size, shape, or configuration so long as it does not detract from the performance of the fuel injector while yet providing a place for build-up to occur thereby increasing the longevity of the fuel injector. The depression may be formed in elliptical or circular shapes and in some embodiments is formed in a radial shape extending in a circular pattern about the longitudinal axis. In some embodiments, the depression may be formed with sharp edges to increase the fluid turbulence of the fuel and thereby improve atomization. 
         [0011]    Further scope of applicability of the present invention will become apparent from the following detailed description, claims, and drawings. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The present invention will become more fully understood from the detailed description given here below, the appended claims, and the accompanying drawings in which: 
           [0013]      FIG. 1  is a top plan view of exemplary metering plate; 
           [0014]      FIG. 2  is a plan view of an exemplary dispersion end of the nozzle; 
           [0015]      FIG. 3  is a plan view of the dispersion end of  FIG. 2 , with the metering plate of  FIG. 1  superimposed and portions of the dispersion end shown in phantom; 
           [0016]      FIG. 4  is a sectional view of the nozzle in  FIG. 3  along lines  4 - 4 ; 
           [0017]      FIG. 5  is a plan view of an exemplary dispersion end; 
           [0018]      FIG. 6  is a plan view of an exemplary metering plate; 
           [0019]      FIG. 7  is a plan view of the dispersion end of  FIG. 5  with the metering plate of  FIG. 6  superimposed in phantom; and 
           [0020]      FIG. 8  is a plan view of an exemplary nozzle on the dispersion end with an exemplary metering plate superimposed in phantom. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0021]    A fuel injector nozzle  20  is generally illustrated in partial cross-sectional view in  FIG. 4 . The nozzle  20  is formed at a lower end of a fuel injector, which is used to deliver fuel to a cylinder of an engine, such as an internal combustion engine of an automobile. The nozzle  20  defines a passageway  24  through which the fuel passes toward the dispersion end  22 . Although the fuel injector  10  may be formed of a variety of configurations, the nozzle  20  generally includes a needle valve  26  located within the passageway  24  and capable of engaging a valve seat  28 . The needle  26  and valve seat  28  cooperate to form a needle valve to start and stop fluid flow through the nozzle  20 . The nozzle  20  is generally aligned along a longitudinal axis  15  and the passageway  24  generally extends along or parallel to the longitudinal axis  15 . A lower end of the injector body or dispersion end  22  defines the valve outlet  36 . As illustrated in  FIG. 4 , the nozzle  20  may be formed from a nozzle body  32  and an injector body  23 . It should be recognized by those skilled in the art that the injector body  23  and nozzle body  32  may be separately formed and attached by welding or other known techniques. 
         [0022]    In either case, the nozzle  20  generally defines the valve seat  28  and the valve outlet  36 . The needle  26  is generally moved along the longitudinal axis  15 , in and out of engagement with the valve seat  28 , and is usually controlled by an electromagnetic actuator (not shown). In this manner, fluid or fuel flowing through the internal passageway  24  and around the needle  26  is permitted or prevented from flowing to the valve outlet  36  by the engagement or disengagement of the needle  26  with the valve seat  28 . 
         [0023]    The nozzle  20  further includes a metering plate  40  which is coupled to the nozzle at the dispersion end  22 . It will be recognized by those skilled in the art that the metering plate  40  may be integrally formed with the nozzle body or may be separately formed and attached as illustrated in  FIG. 4  by welding or other known techniques. In either case, the metering plate defines an orifice cavity  42  ( FIG. 4 ). The orifice cavity  42  may be generally defined by both the metering plate  40  and the lower portion, specifically the dispersion end  22 , of the nozzle. As illustrated further in  FIG. 4 , the metering plate also may define portions of the orifice cavity  42 . The orifice cavity  42  defined by the metering plate is defined by a bottom wall, a side wall, as well as a center wall as illustrated in  FIG. 4 , however, the metering plate used may be of any exemplary size, shape, and configuration thereby varying the configuration of the orifice cavity. 
         [0024]    The metering plate  40  may include an outer rim which may be at least partially recessed into the recessed area  39  defined by the nozzle  20  and specifically the dispersion end  22 . While the metering plate  40  is illustrated in the figures as being round, other shapes and configurations may be used, however a round metering plate  40  is easier to assemble as they are generally unidirectional. However, if the spray pattern produced by the metering plate  40  is directional or desirable to be keyed in a certain direction, the metering plate may be formed in other shapes and configurations to allow easy assembly of the metering plate  40  to the nozzle  20  with the desired directional spray pattern. As illustrated in  FIG. 8 , the metering plate and nozzle  20  may include a keyed mechanism  60  to align a round metering plate. 
         [0025]    The metering plate  40  generally includes at least one exit cavity  50 . The exit cavities may be configured in a wide variety of shapes, sizes, and geometrical configurations such as illustrated in  FIGS. 1-3  and  5 - 8 . In some embodiments, only a couple of exit cavities are needed such as illustrated in  FIG. 1 . In other embodiments, the metering plate may include a multitude of exit cavities in a ring about a center exit cavity, as illustrated in  FIG. 6 , and further may include, as illustrated in  FIG. 8 , an outer ring and inner ring centered about a center exit cavity. Of course, the exit cavities may vary in number, size, shape, and configuration and although the metering plate is shown in all of the figures as having a center exit cavity, this is not required as the location of the exit cavities on the metering plate are only exemplary. 
         [0026]    As illustrated in  FIGS. 2 and 3 , the dispersion end  22  of the nozzle  20  may include a set of depressions  70 . The depressions  70 , as illustrated in  FIG. 2 , on the dispersion end  22  are configured within the recessed area  39  to be aligned with the exit cavities. Therefore, a metering plate as illustrated in  FIG. 1 , having exit cavities  50  within the cavity axis  52 , will have the metering plate lined up such that the cavity axis  52  will pass through or intersect the dispersion end  22  approximately within the bounds of one of the depressions  70 . In each of the embodiments, the depressions appear under each exit cavity  50  due to the location or orientation of the fuel injector within the engine as the dispersion end  22  may not experience build-up and therefore not need the depressions  70  for consistent high performance. Some exit cavities experience build up, while other exit cavities may not experience build-up. Therefore, in some embodiments, the depressions  70  may be configured to only be located under exist cavities that do experience build-up. As illustrated in  FIGS. 1-3 , the center exit cavity is located approximately above the outlet passage  24  and therefore the cavity axis  52  for the center exit cavity  50  is substantially aligned with the longitudinal axis  15  and passes through the planar surface of the recessed area  39  on the dispersion end  22  at the outlet passage area. 
         [0027]    The depressions  70  may also be formed with a sharp edge  71  which increases fluid turbulence within the orifice cavity  42 . Any increase of fluid turbulence also helps to prevent build-up of deposits in the orifice cavity  42 , and in particular against the dispersion end  22  of the nozzle  20 . The increase in fluid turbulence also helps to improve atomization of the fuel as it leaves the metering plate. Improved atomization improves engine performance and fuel economy. 
         [0028]    As further illustrated in  FIGS. 5-7 , a metering plate as illustrated in  FIG. 6  may include a multitude of exit orifices  50 . Each of these exit orifices  50  could be configured to have an individual depression underneath, however, for ease of manufacture, it may be desirable to provide a depression in an arcuate shape that follows the arcuate shape of the exit cavities  50 . Therefore, as illustrated in  FIG. 7 , the exit cavities  50  on the metering plate  40  are shown and illustrated as lining up substantially over the depression  70  on the dispersion end  22 . As further illustrated in  FIG. 8 , other configurations such as having two rings of exit cavities on the metering plate may be used. In these particular embodiments, in addition to the potential for individual depressions arranged under each exit cavity, it may be desirable to provide an inner and outer ring of depressions  70 . 
         [0029]    The foregoing discussion discloses and describes an exemplary embodiment of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims that various changes, modifications and variations can be made therein without departing from the true spirit and fair scope of the invention as defined by the following claims.