Abstract:
A valve subassembly of a fuel injector that allows spray targeting and distribution of fuel to be configured using non-angled or straight orifice having an axis parallel to a longitudinal axis of the subassembly. Metering orifices are located about the longitudinal axis and defining a first virtual circle greater than a second virtual circle defined by a projection of the sealing surface onto the metering disc so that all of the metering orifices are disposed outside the second virtual circle. The projection of the sealing surface converges at a virtual apex disposed within the metering disc. At least one channel extends between a first end and second end. The first end is disposed at a first radius from the longitudinal axis and spaced at a first distance from the metering disc. The second end is disposed at a second radius with respect to the longitudinal axis and spaced at a second distance from the metering disc such that a product of the first radius and the first distance is approximately equal to a product of the second radius and the second distance. Methods of controlling spray distribution and targeting are also provided.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     Most modern automotive fuel systems utilize fuel injectors to provide precise metering of fuel for introduction into each combustion chamber. Additionally, the fuel injector atomizes the fuel during injection, breaking the fuel into a large number of very small particles, increasing the surface area of the fuel being injected, and allowing the oxidizer, typically ambient air, to more thoroughly mix with the fuel prior to combustion. The metering and atomization of the fuel reduces combustion emissions and increases the fuel efficiency of the engine. Thus, as a general rule, the greater the precision in metering and targeting of the fuel and the greater the atomization of the fuel, the lower the emissions with greater fuel efficiency.  
         [0002]     An electromagnetic fuel injector typically utilizes a solenoid assembly to supply an actuating force to a fuel metering assembly. Typically, the fuel metering assembly includes a seat and closure member, which reciprocates between a closed position, where the closure member is seated in a seat to prevent fuel from escaping through a metering orifice into the combustion chamber, and an open position, where the closure member is lifted from the seat, allowing fuel to discharge through the metering orifice for introduction into the combustion chamber.  
         [0003]     The fuel injector is typically mounted upstream of the intake valve in the intake manifold or proximate a cylinder head. As the intake valve opens on an intake port of the cylinder, fuel is sprayed towards the intake port. In one situation, it may be desirable to target the fuel spray at the intake valve head or stem while in another situation, it may be desirable to target the fuel spray at the intake port instead of at the intake valve. In both situations, the targeting of the fuel spray can be affected by the spray or cone pattern. Where the cone pattern has a large divergent cone shape, the fuel sprayed may impact on a surface of the intake port rather than towards its intended target. Conversely, where the cone pattern has a narrow divergence, the fuel may not atomize and may even recombine into a liquid stream. In either case, incomplete combustion may result, leading to an increase in undesirable exhaust emissions.  
         [0004]     Complicating the requirements for targeting and spray pattern is cylinder head configuration, intake geometry and intake port specific to each engine&#39;s design. As a result, a fuel injector designed for a specified cone pattern and targeting of the fuel spray may work extremely well in one type of engine configuration but may present emissions and driveability issues upon installation in a different type of engine configuration. Additionally, as more and more vehicles are produced using various configurations of engines (for example: inline-4, inline-6, V-6, V-8, V-12, W-8 etc.,), emission standards have become stricter, leading to tighter metering, spray targeting and spray or cone pattern requirements of the fuel injector for each engine configuration.  
         [0005]     It is believed that one approach to meeting emission standards in a fuel injector is to minimize the so-called “sac volume.” As it is used in this disclosure, sac volume is defined as a volume downstream of a closure member/seat sealing perimeter and upstream of the orifice hole(s), which can be also viewed as the volume of fuel remaining in the interior of the tip of the injector. This volume of fuel is believed to affect combustion and unwanted emission at the end of a fuel injection cycle, and therefore, it is believed that such sac volume should be minimized.  
         [0006]     It is also believed that a metering disc can be deformed to provide a dimpled surface. Such dimpled surface is believed to allow a metering orifice to be oriented relative to a referential datum by a single included angle. However, by orientating the metering orifice with a single included angle, such metering disc apparently fails to permit targeting of the fuel spray consonant with the metering, spray targeting and spray or cone pattern requirements particular to each type of engines. Moreover, such metering disc, when used in a fuel injector, may cause the fuel injector to have a large sac volume that could affect combustion and unwanted emission in the engine in which such injector is utilized therein.  
       SUMMARY OF THE INVENTION  
       [0007]     The present invention provides fuel targeting and fuel spray distribution with non-angled metering orifices in a metering disc that can be deformed to provide a metering orifice oriented with respect to two referential datum planes. In a preferred embodiment, a fuel injector is provided. The fuel injector comprises a seat, movable closure member, and a metering disc. The seat includes a passage extending along a longitudinal axis between an inlet and outlet. The movable member cooperates with the seat to permit and prevent a flow of fuel through the passage. The metering disc includes peripheral, central and intermediate portions. The peripheral portion extends generally parallel to a base plane, and the base plane being generally orthogonal with respect to the longitudinal axis. The intermediate portion is disposed radially with respect to the longitudinal axis between the peripheral and central portions. The intermediate portion includes a plurality of surfaces intersecting with the base plane and a plurality of metering orifices disposed on respective plurality of surfaces. The metering orifices penetrating the intermediate portion, and each of the plurality of orifices extends along a respective orifice axis at a first angle relative to a radial axis from the longitudinal axis through the metering orifice axis, and at a second angle relative to the longitudinal axis.  
         [0008]     In yet another embodiment, a method of controlling a spray angle of fuel flow through at least one metering orifice of a fuel injector is provided. The fuel injector has an inlet and an outlet and a passage extending along a longitudinal axis therethrough. The outlet has a seat and a metering disc. The metering disc includes peripheral, central, and intermediate portions. The peripheral portion extends generally parallel to a base plane, and the base plane being generally orthogonal with respect to the longitudinal axis. The intermediate portion is disposed radially with respect to the longitudinal axis between the peripheral and central portions. The method can be achieved by locating a plurality of metering orifices about the longitudinal axis such that the metering orifices extend generally parallel to the longitudinal axis through the metering disc to define respective generally parallel metering axes; and deforming at least one of the intermediate and central portions of the metering disc so that each of the metering axes extend along a respective orifice axis at a first angle relative to a radial axis from the longitudinal axis through the metering orifice axis, and at a second angle relative to the longitudinal axis.  
     
    
     BRIEF DESCRIPTIONS OF THE DRAWINGS  
       [0009]     The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate an embodiment of the invention, and, together with the general description given above and the detailed description given below, serve to explain the features of the invention.  
         [0010]      FIG. 1  illustrates a preferred embodiment of the fuel injector.  
         [0011]      FIG. 2A  illustrates a close-up cross-sectional view of an outlet end of the fuel injector of  FIG. 1 .  
         [0012]      FIG. 2B  illustrates a plan view of the metering disc of  FIG. 2A  denoting respective axes of each metering orifice as referenced to a radial axis passing through a longitudinal axis A 1 -A 2  and intersecting with the metering orifice axis so that each axis of the metering orifices can be located, in part, by a first angle on the dimpled surface.  
         [0013]      FIG. 2C  illustrates an enlarged cross-sectional view of the metering disc of  FIG. 2B   
         [0014]      FIG. 3  illustrates a perspective view of the dimpled portion of the metering disc of  FIG. 2B .  
         [0015]      FIG. 4  illustrates a relationship of respective axes of each metering orifice as referenced to a longitudinal axis of the metering disc so that each metering orifice can be located, in part, by a second angle on the dimpled surface of the disc. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]      FIGS. 1-4  illustrate the preferred embodiments. In particular, a fuel injector  100  having a preferred embodiment of the metering disc  10  is illustrated in  FIG. 1 . The fuel injector  100  includes: a fuel inlet tube  110 ; an adjustment tube  112 ; a filter assembly  114 ; a coil assembly  120 ; a coil spring  116 ; an armature  124 ; a closure member  126 ; a non-magnetic shell  110   a ; a first overmold  118 ; a valve body  132 ; a valve body shell  132   a ; a second overmold  119 ; a coil assembly housing  121 ; a guide member  127  for the closure member  126 ; a seat  134 ; and a metering disc  10 .  
         [0017]     The guide member  127 , seat  134 , and metering disc  10  form a stacked assembly that is coupled at the outlet end of fuel injector  100  by a suitable coupling technique, such as, for example, crimping, welding, bonding or riveting. Armature  124  and the closure member  126  are coupled together to form an closure assembly  126  assembly. It should be noted that one skilled in the art could form the assembly from a single component instead of a plurality of components.  
         [0018]     Coil assembly  120  includes a plastic bobbin on which an electromagnetic coil  122  is wound. Respective terminations of coil  122  connect to respective terminals  122   a ,  122   b  that are shaped and, in cooperation with a connector portion  118   a  formed as an integral part of overmold  118 , to form an electrical connector for connecting the fuel injector  100  to an electronic control unit (not shown) that operates the fuel injector.  
         [0019]     Fuel inlet tube  110  can be ferromagnetic and includes a fuel inlet opening at the exposed upper end. Filter assembly  114  can be fitted proximate to the open upper end of adjustment tube  112  to filter any particulate material larger than a certain size from fuel entering through inlet opening before the fuel enters adjustment tube  112 .  
         [0020]     In the calibrated fuel injector, adjustment tube  112  has been positioned axially to an axial location within fuel inlet tube  110  that compresses preload spring  116  to a desired bias force that urges the closure assembly  126  such that the rounded tip end of closure member  126  can be seated on seat  134  to close the central hole through the seat. Preferably, tubes  110  and  112  are crimped together to maintain their relative axial positioning after adjustment calibration has been performed.  
         [0021]     After passing through adjustment tube  112 , fuel enters a volume that is cooperatively defined by confronting ends of inlet tube  110  and armature  124  and that contains preload or bias spring  116 . Armature  124  includes a passageway  128  that communicates volume  125  with a passageway  113  in valve body  130 , and guide member  127  contains fuel passage holes  127   a ,  127   b . This allows fuel to flow from volume  125  through passageways  113 ,  128  to seat  134 .  
         [0022]     Non-ferromagnetic shell  110   a  can be telescopically fitted on and joined to the lower end of inlet tube  110 , as by a hermetic laser weld. Shell  110   a  has a tubular neck that telescopes over a tubular neck at the lower end of fuel inlet tube  110 . Shell  110   a  also has a shoulder that extends radially outwardly from neck. Valve body shell  132   a  can be ferromagnetic and can be joined in fluid-tight manner to non-ferromagnetic shell  110   a , preferably also by a hermetic laser weld.  
         [0023]     The upper end of valve body  130  fits closely inside the lower end of valve body shell  132   a  and these two parts are joined together in fluid-tight manner, preferably by laser welding. Armature  124  can be guided by the inside wall of valve body  130  for axial reciprocation. Further axial guidance of the closure assembly  126  assembly can be provided by a central guide hole in member  127  through which closure member  126  passes. The construction of fuel injector  100  can be of a type similar to those disclosed in commonly assigned U.S. Pat. Nos. 4,854,024; 5,174,505; and 6,520,421 with respect to details that are not specifically portrayed in  FIG. 1 , and which are incorporated by reference in their entirety into this application.  
         [0024]     Referring to a close up illustration of the seat subassembly of the fuel injector in  FIG. 2A  which has a closure member  126 , seat  134 , and a metering disc  10 . The closure member  126  includes a spherical member  126   a  disposed at one end distal to the armature. The spherical member  126   a  engages the seat  134  on seat surface  134   a  so as to form a generally line contact seal between the two members. The seat surface  134   a  tapers radially downward and inward toward the seat orifice  135  such that the surface  134   a  is oblique to the longitudinal axis A 1 -A 2 . As used herein, the words “inward” and “outward” refer to directions toward and away from, respectively, the longitudinal axis A 1 -A 2 . The line contact seal can be defined as a sealing circle  140  formed by contiguous engagement of the spherical member  126   a  with the seat surface  134   a , shown here in  FIG. 2A . The seat  134  includes a seat orifice  135 , which extends generally along the longitudinal axis A 1 -A 2  of the housing  20  and is formed by a generally cylindrical wall  134   b . Preferably, a center  135   a  of the seat orifice  135  is located generally coincident on the longitudinal axis A 1 -A 2 .  
         [0025]     Downstream of the circular wall  134   b , the seat  134  tapers along a portion  134   c  obliquely towards a bottom surface  134   e . The taper of the portion  134   c  preferably can be linear or curvilinear with respect to the longitudinal axis A 1 -A 2 , such as, for example, a curvilinear taper that forms an interior dome. In one preferred embodiment, the taper of the portion  134   c  is linearly tapered ( FIG. 2A ) downward and outward at a predetermined taper angle, and thereafter extends along and generally parallel to the longitudinal axis so as to preferably form cylindrical wall surface  134   d . The wall surface  134   d  extends downward and subsequently extends in a generally radial direction to form the bottom surface  134   e , which is preferably perpendicular to the longitudinal axis A 1 -A 2 .  
         [0026]     A central interior face  44  of the metering disc  10  is provided in a facing arrangement with the orifice  135 . The metering disc  10  includes a first surface  10   a  facing towards the inlet of the fuel injector  100  and a second surface  10   b  spaced from the first surface  10   a . The first surface  10   a  is preferably contiguous to the bottom surface  134   e  of the seat  134 .  
         [0027]     Viewing the surface  10   b  in the plan view of  FIG. 2B , it can be seen that the disc  10  has a generally planar peripheral portion  10   c  surrounding an intermediate portion  10   d . The intermediate portion  10   d  thereafter surrounds a central portion  10   e . The intermediate and central portions can include dimpled surfaces (indicated generally as surfaces  20 ) of the metering disc  10  with metering orifices located on the dimpled surfaces. In particular, the dimpled surfaces  20  of the metering disc  10  can be obtained by a suitable material deforming technique on a generally planar workpiece such as for example, faceted, ball or cylindrical dimpling of the generally flat workpiece. As used herein, the term “dimpling” indicates a permanent material deformation, preferably by deforming the material until the plastic yield point of the material is reached so that the dimpled surfaces intersect a virtual extension of the planar surfaces of the work piece. For example, the central portion  10   e  can be dimpled with a curved tool so that the surface of the workpiece can be plastically deformed or permanently elongated into a dimpled central portion  40  and the intermediate portion  10   d  can be dimpled with a planar dimpling tool to provide for one or more of curved, planar or compound dimples.  
         [0028]     Preferably, the dimpled central portion  40  includes a curved or radiused dimple  42  ( FIG. 2C ). The curved dimple  42  has an apex  44  extending towards the inlet end of the fuel injector  100 . The dimpled central portion or depression  40  in the surface of the work piece (i.e., non-planar dimple) can be provided proximate the center of the work piece to provide for a minimal sac volume in the fuel injector  100 . In particular, the surface  10   b  (i.e. the fuel outlet side) can be dimpled towards the upstream direction with a suitable tool that preferably forms a radiused portion  42 . The radiused portion  42  can form a volume that intersects a referential datum plane B-B so as to define the sac volume of the fuel injector. That is to say, the volume can project toward the seat orifice  135  to provide the interior volume between the closure member  126   a  and the metering disc  10 , which interior volume provides the minimal space required for the fuel injector to operate and provides as small a sac volume as possible. Preferably, the radiused portion  42  is contiguous to the referential datum plane B-B.  
         [0029]     In the preferred embodiment of  FIG. 2B , the dimpled surface can be formed either before or after the forming metering orifices on the generally flat work pieces. Preferably, ten metering orifices, denoted here as  1 ,  2 ,  3 ,  4 ,  5 ,  6 ,  7 ,  8 ,  9 , and  10 , are formed so that the metering orifices are located on a circle  30  with the respective orifice axes extending generally parallel to the longitudinal axis A 1 -A 2 . Thereafter, the generally flat work pieces can be dimpled to provide generally at least two planar facets (e.g., facetted dimples) oriented oblique to the generally planar surface of the peripheral portion  10   c  of the disc  10 . Preferably, the intermediate portion  10   d  is dimpled with a suitable tool so that planar facets A-K are provided on the generally planar disc  10  subsequent to the formation of metering orifices  1 - 10 . Also, each of the plurality of metering orifices has a diameter ranging from approximately 100 microns to approximately 600 microns, and preferably from 125 microns to 400 microns.  
         [0030]     Referring to  FIG. 3 , each of the metering orifices  1 - 10  is preferably located on respective planar facets of the dimpled surfaces A-K. As shown in  FIG. 2B , at least two of the metering orifices are located on the facets such that a centerline extending through the metering orifice is oriented at a first angle ∀ n  (i.e., alpha-sub-n where the subscript “n” denotes orifice number in  FIG. 2B ) with respect to a plane P n  passing through the longitudinal axis and the respective centerline of the orifice, i.e., orifice axis Fn. For example, a plane P 1  extends through longitudinal axis A 1 -A 2  and orifice axis F 1  so that the orifice axis F 1  is oriented at angle ∀ 1 . In another example, the orifice axis F 3  is coplanar with the plane P 3  such that the angle ∀ 3  for orifice  3  is about zero. In the preferred embodiment, at least two of the metering orifices are oriented at a first angle with respect to a plane passing through both metering orifices and the longitudinal axis and generally parallel to the longitudinal axis.  
         [0031]     Furthermore, each of the metering orifices  1 - 10  can be oriented at a second angle ∃ n  with respect to a longitudinal axis Z n  generally parallel to the longitudinal axis A 1 -A 2  as shown in  FIG. 4 . For example, the orifice F 1  extends at an angle ∃ n  relative to longitudinal axis Z 1  in  FIG. 4 . Similarly, each of the orifices n (where n=a suitable number of orifices) extends at a second angle ∃ n  relative to the respective longitudinal axes Z n . Thus, the orientation of each orifice n (i.e., orifice axis F n ) can be located by two referential datum: (1) a plane parallel to and passing through the longitudinal axis and the orifice axis to define a first angle ∀ n , and (2) a longitudinal axis generally parallel to the longitudinal axis to define the second angle ∃ n  as provided in Table I below.  
                                           TABLE I                           Orientation of Orifices            Orifice   ∀ n  (degrees)   ∃ n (degrees)                    1   2   8       2   2   10       3   0   9       4   2   10       5   2   9       6   2   8       7   2   10       8   0   9       9   2   10       10   2   8                  
 
         [0032]     The surface  10   a  and surface  10   b  can be performed simultaneously or one surface can be deformed during a time interval that may overlap a time interval of the deformation of the other surface. Alternatively, the first surface  10   a  can be deformed before the second surface  10   b  is deformed. In a preferred embodiment, the surface  10   a  is deformed at a time interval that substantially overlaps the time interval of the deformation of the second surface  10   b.    
         [0033]     In operation, the fuel injector  100  is initially at the non-injecting position shown in  FIG. 1 . In this position, a working axial gap exists between the annular end face  110   b  of fuel inlet tube  110  and the confronting annular end face  124   a  of armature  124 . Coil housing  121  and tube  12  are in contact at  74  and constitute a stator structure that is associated with coil assembly  120 . Non-ferromagnetic shell  110   a  assures that when electromagnetic coil  122  is energized, the magnetic flux will follow a path that includes armature  124 . Starting at the lower axial end of housing  34 , where it is joined with value body shell  132   a  by a hermetic laser weld, the magnetic circuit extends through valve body shell  132   a , valve body  130  and eyelet to armature  124 , and from armature  124  across working gap to inlet tube  110 , and back to housing  121 .  
         [0034]     When electromagnetic coil  122  is energized, the spring force on armature  124  can be overcome and the armature is attracted toward inlet tube  110  reducing working axial gap. This unseats closure member  126  from seat  134  to open the fuel injector so that pressurized fuel in the valve body  132  flows through the seat orifice and through orifices formed on the metering disc  10 . When the coil  122  ceases to be energized, preload spring  116  pushes or biases the closure member  126  against the seat  134  to prevent fuel flow to the orifice  135 .  
         [0035]     As described, the preferred embodiments, including the techniques of controlling spray angle targeting and distribution are not limited to the fuel injector described but can be used in conjunction with other fuel injectors such as, for example, the fuel injectors set forth in U.S. Pat. No. 5,494,225 issued on Feb. 27, 1996, or the modular fuel injectors set forth in U.S. patent application Ser. No. 09/828,487 filed on 9 Apr. 2001, which is pending, and wherein both of these documents are hereby incorporated by reference in their entireties herein.  
         [0036]     While the present invention has been disclosed with reference to certain embodiments, numerous modifications, alterations and changes to the described embodiments are possible without departing from the sphere and scope of the present invention, as defined in the appended claims. Accordingly, it is intended that the present invention not be limited to the described embodiments, but that it has the full scope defined by the language of the following claims, and equivalents thereof.