Abstract:
An assembly for a fuel injector includes a fluid transportation member having a first portion that defines an internal passageway configured to convey fluid through the first portion, and a second portion in fluid communication with the first portion. The second portion defines at least one conduict configured to communicate fluid from the internal passageway out of the fluid trasnsportation memeber and a structural reinforcement portion is colocated with the second portion. A housing is configured to receive at least a portion of the transpotation member.

Description:
BACKGROUND 
   The present invention relates to fuel injectors, and more particularly to an assembly and poppet for use in fuel injectors. 
   Conventinal fuel injectors are configured to deliver a quantity of fuel to a combustion cylinder of an engine. To increase combustion efficiency and decrease pollutants, it is desirable to atomize the delivered fuel. Generally speaking, atomization fo fuel can be achieved by supplying high pressure fuel to conventional fuel injectors, or by atomizing low pressure fuel with pressurized gas, i.e., “air assist fuel injection.” 
   A conventional air assist fuel injector receives a metered quantity of low pressure fuel from a conventional fuel injector (not illustrated) and pressurized air from a rail (not illustrated). The air assist fuel injector atomizes the low pressure fuel with the pressurized air as it conveys the air and fuel mixture to the combustion chamber of an engine. 
   The pressurized air from the rail and the metered quantity of fuel from the conventional fuel injector enter the air assist fuel injector through a cap, which delivers the fuel and air to a conduit of an armature. Thereafter, the fuel and air travel through a passageway of a fluid transportation member or poppet, and exit the poppet through small slots near the end or head of the poppet. The poppet is typically attached to the armature, which is actuated by energizing a solenoid coil. When the solenoid coil is energized, the armature will overcome the force of a spring and move. Because the poppet is attached to the armature, the head of the poppet will lift off a seat when the armature is actuated so that the metered quantity of fuel is atomized as it is delivered to the combustion chamber of the engine. Hence, besides conveying liquid fuel and air, the poppet repeatedly opens to inject fuel and closes to define a seal that prevents the injection of fuel. Because of this function, the poppet is a critical component of most fuel injectors and is typically fabricated from a high strength, tough, and wear resistant material, such as AISI 440 stainless steel. For example, the conventional poppet is typically formed from stainless steel bar stock by: (1) machining the bar stock to a cylindrical blank; (2) gun-drilling the internal cylindrical passageway of the poppet; (3) heat treating the part; (4) grinding the exterior surface of the poppet; and (5) electrical discharge machining (“EDM”) the slots. Unfortunately, it was discovered that the intersection between the gun-drilling of the internal passageway and the formation of the slots in the poppet via the EDM process produces stress concentration areas. These stress concentration areas, in conjunction with the micro-cracks typically resulting from the EDM process, have caused the poppet to fail at or near the slots. Additionally, it is difficult to bore the internal and elongated passageway of the poppet and there are reported failures due to excessive run-out during this operation. Despite these problems, the above-described manufacturing process was thought to be the only suitable method of manufacturing the poppet, largely because the shape, features, and requirements of conventional poppets are not well-suited for other, traditional fabrication processes. 
   SUMMARY 
   An assembly for a fuel injector includes a fluid transportation member having a first portion defining an internal passageway configured to convey fluid through the first portion, and a second portion in fluid communication with the first portion. The second portion defines at least one conduit configured to communicate fluid from the internal passageway out of the fluid transportation member, and a structural reinforcement portion is colocated with the second portion. A housing is configured to receive at least a portion of the fluid transportation member. 
   Other advantages and features associated with the embodiments of the present invention will become more readily apparent to those skilled in the art from the following detailed description. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modification in various obvious aspects, all without departing from the invention. Accordingly, the drawings in the description are to be regarded as illustrative in nature, and not limitative. 

   
     BRIEF DESCRIPTIONS OF THE DRAWINGS 
       FIG. 1  is a cross-sectional view of an air assist fuel injector according to one embodiment of the invention. 
       FIG. 2A  is cross-sectional view of a portion of a fluid transportation member according to one embodiment of the invention. 
       FIG. 2B  is cross-sectional view of a portion of a drilled fluid transportation member. 
       FIG. 3  is a perspective view of a portion of a transportation member illustrating a failure mode. 
       FIG. 4  is a cross-sectional view of a portion of an assembly for an air assist fuel injector according to one embodiment of the invention. 
       FIG. 5  is a cross-sectional view taken along line  5 — 5  in  FIG. 4 . 
       FIG. 6  is a cross-sectional view of a portion of a fluid transportation member according to one embodiment of the invention. 
       FIG. 7  is a cross-sectional view taken along line  7 — 7  in  FIG. 6 . 
       FIG. 8  is a cross-sectional view of a portion of a fluid transportation member according to one embodiment of the invention. 
       FIGS. 9A and 9B  are each cross-sectional views taken along line  9 A— 9 A and  9 B— 9 B respectively in  FIG. 8 . 
       FIG. 10  is a cross-sectional view of a portion of a fluid transportation member according to one embodiment of the invention. 
       FIG. 11A  is a cross-sectional view taken along lines  11 A— 11 A in  FIG. 10 ; and  FIG. 11B  is a cross-sectional view of an optional embodiment of a poppet according to the invention. 
       FIG. 11C  is a cross-sectional view taken along line  11 C— 11 C in  FIG. 10 . 
       FIG. 12  is a cross-sectional view of a portion of a fluid transportation member according to one embodiment of the invention. 
       FIG. 13  is a cross-sectional view taken along line  13 — 13  in  FIG. 12 . 
       FIG. 14  is a perspective view of a reinforcement insert according to one embodiment of the invention. 
       FIG. 15  is a cross-sectional view of a portion of a fluid transportation member according to one embodiment of the invention including a reinforcement insert. 
       FIG. 16  is a cross-sectional view of a portion of a fluid transportation member according to one embodiment of the invention including a reinforcement insert. 
   

   DETAILED DESCRIPTION 
     FIG. 1  generally illustrates an air assist fuel injector  100  incorporating one embodiment of the invention. The air assist fuel injector  100  is configured to utilize pressurized gas to atomize low pressure liquid fuel, which together travel through the air assist fuel injector along a direction of flow f as indicated in  FIG. 1 . In some embodiments, the air assist fuel injector  100  is configured for use with a two-stroke internal combustion engine. When installed in an engine, the air assist fuel injector  100  is located such that the atomized low pressure fuel that exits the injector  100  is delivered to the internal combustion chamber of an engine. For example, the injector  100  may be located in a cavity of a two-stroke internal combustion engine head such that the fuel injector delivers a metered quantity of atomized liquid fuel to the combustion cylinder of the two-stroke internal combustion engine where it is ignited by a spark plug or otherwise. In alternative embodiments the air assist fuel injector is configured for operation with other engines and other applications. For example, the air assist fuel injector  100  may be configured for operation with a four stroke internal combustion engine or a rotary engine and may inject liquids other than fuel. 
   In some embodiments, the air assist fuel injector  100  is located adjacent a conventional fuel injector (not illustrated), which delivers metered quantities of fuel to the air assist fuel injector. The conventional fuel injector may be located in the cavity of a rail or within a cavity in the head of an engine. The air assist fuel injector  100  is referred to as “air assist” because it preferably utilizes pressurized air to atomize liquid fuel. Although it is preferred that the air assist fuel injector  100  atomize liquid gasoline with pressurized air, it will be appreciated that the air assist fuel injector  100  may atomize many other liquids with any variety of gases. For example, the air assist fuel injector  100  may atomize oil, water, kerosene, or liquid methane with pressurized gaseous oxygen, propane, or exhaust gas. Hence, the term “air assist fuel injector” is a term of art, and as used herein is not intended to dictate that the air assist fuel injector  100  be used only with pressurized air and only with liquid fuel. 
   The air assist fuel injector  100  shown in  FIG. 1  includes a housing  124 , a poppet  118  attached to an armature  116 , and a seat member  143 . Seat member  143  may be a separate component as shown or alternatively, may be formed integrally with housing  124 . Because poppet  118  is attached to armature  116 , poppet  118  will move with armature  116  when armature  116  is actuated by an energized solenoid coil  115 . Poppet  118  shown in  FIG. 1  is a member that opens and closes to control the discharge of fuel from the fuel injector  100 . Poppet  118  includes a head  138 , a stem  136 , and an internal passageway  144  that extends from an inlet  132  to an outlet or conduit  146  located upstream of head  138 . Poppet  118  is also received within housing  124 . When poppet  118  opens and closes, it reciprocates within a channel  134  of housing  124 . Head  138  includes a sealing surface  140  that abuts an impact surface  142  of seat member  143  when the fuel injector is closed. When the fuel injector is open, sealing surface  140  is spaced away from the impact surface  142  as poppet  118  is moved in a direction with the flow of fluid. In another embodiment, the poppet  118  is an inwardly opening poppet. That is, to discharge the fuel from the fuel injector, the poppet and armature move opposite the direction of flow f such that the poppet head  138  lifts inwardly off of seat  143  to discharge fuel from the air assist fuel injector. 
   A cross-sectional view of a portion of an assembly  117  for an air assist fuel injector is shown in  FIG. 4 . Assembly  117  includes a fluid transportation member or poppet  118  received within a housing  124 , and a seat member  143 . Assembly  117  and/or poppet  118  may be incorporated in a typical air assist fuel injector such as the one described above. 
   Poppet  118  includes an improved structural configuration and may be manufactured utilizing a number of different processes. These processes were previously thought to be an unsuitable method of manufacturing a poppet, largely because of the shape, features, and requirements of conventional poppets. Such processes include casting, molding, metal injection molding (MIM), cold heading, cold forging and powdered metal processing, all of which are known processes available in the art. For example, a MIM process, which uses machinery similar to plastic injection molding, can be used to mold a poppet blank. The MIM process involves molding a poppet blank from a powdered metal mix that includes a binder. After molding, the binder is removed from the poppet blank through a heating/melt process. The poppet blank then undergoes a sintering, heat treating and grinding process. Poppet  118  may be fabricated from a variety of different metallic materials such as iron, aluminum, titanium, and their alloys, as well as austenitic, ferretic, or martensitic stainless steel and 400 series stainless steel. 
   The portion of an assembly  117  shown in  FIG. 4  is a cross-sectional view taken along a line cut longitudinally through the center of an assembly  117 .  FIG. 5  illustrates a cross-sectional view of a portion of the poppet  118  shown in  FIG. 4  taken along a line cut laterally through a portion of the outlets  146  of poppet  118  and pointing in a direction opposite the flow f. As illustrated in  FIGS. 4 and 5 , poppet  118  includes a first portion  147  having a first wall thickness  148  and a second portion  150  having a second wall thickness  152 . The first portion  147  includes at least a portion of the stem  136  of poppet  118 . In some embodiments, second wall thickness  152  is larger than first wall thickness  148  and includes a structural reinforcement portion  154  colocated with second wall thickness  152 . Processes used to manufacture poppet  118  enable the formation of multiple wall thicknesses along poppet  118  such as the larger wall thickness  152  of second portion  150 . In addition, the interior surface of a poppet  118  is devoid of tool marks and sharp edges, as shown in  FIG. 2A . In comparison, a poppet configured and manufactured with conventional designs and methods can contain sharp transition edges S as a result of the gundrill process to bore the internal passageway of the poppet as shown in  FIG. 2B . Sharp edges such as those shown in  FIG. 2B  are a primary cause of failures in conventional poppets, as a fracture typically occurs in this location between the outlets. An illustration of an example poppet that has failed due to the presence of sharp edges and associated fatigue points/weaknesses is shown in  FIG. 3 . 
   In the embodiment shown in  FIG. 4 , the second portion  150  and the first portion  147  are in fluid communication with one another in that fluid flows through internal passageway  144  of poppet  118  and passes through first portion  147  and second portion  150 . At least one outlet or conduit  146  is located on poppet  118  within second portion  150 . Conduit(s)  146  permits the fluid to exit from poppet  118  when the solenoid  116  is activated and poppet  118  is moved to an open position. The embodiment shown in  FIG. 4  illustrates poppet  118  with second portion  150  having four conduits  146  (three of which are visible in  FIG. 4 ). In this embodiment, second portion  150  and structural reinforcement portion  154  include a cross-sectional perimeter having a substantially constant wall thickness and substantially circular shape, as shown in  FIG. 5 . 
   In alternative embodiments, poppet  118  may be configured with one or more conduits  146 , and a variety of different wall thicknesses and shapes. For example, as illustrated in  FIGS. 6 and 7 , second portion  150  includes a cross-sectional perimeter and reinforcement portion  154  having a constant wall thickness, but with only a single conduit  146 .  FIG. 6  illustrates a cross-sectional view of a portion of a poppet  118  taken along a line cut longitudinally through the center of poppet  118 , and  FIG. 7  illustrates a cross-sectional view of a portion of the poppet  118  taken along a line cut laterally through a portion of the outlets  146  of poppet  118  and pointing in a direction opposite the flow f. 
     FIG. 8  illustrates a cross-sectional view of a portion of a poppet  118  taken along a line cut longitudinally through the center of a poppet  118 , and  FIGS. 9A and 9B  illustrate a cross-sectional view of a portion of the poppet  118  taken along lines cut laterally through the poppet  118  and pointing in a direction opposite the flow f.  FIG. 9B  is a view from a line cut laterally through a portion of the outlets  146  and  FIG. 9A  is a view from a line cut laterally through first portion  147 .  FIGS. 8 ,  9 A and  9 B illustrate an embodiment with a first portion  147  having a non-circular cross-sectional perimeter and varying wall thickness ( FIG. 9A ) and a second portion  150  having a non-circular cross-sectional perimeter, two conduits  146  and a non-circular structural reinforcement portion  154  with varying wall thicknesses ( FIG. 9B ). Internal passageway  144  may be a variety of different shapes and sizes and may vary in size and shape along the length of poppet  118 . 
   Structural reinforcement portion  154  may also include at least one buttress  156  formed on either an interior surface or exterior surface of poppet  118 . Buttress(es)  156  may be formed by a number of different processes such as casting, molding, metal injection molding, cold heading, cold forging, and powdered metal processing.  FIG. 10  is a cross-sectional view of a portion of a poppet  118  taken along a line cut longitudinally through the center of poppet  118  and illustrates a poppet  118  having four buttresses  156  (two of which are illustrated) disposed between adjacent conduits  146  on interior surface  164  of poppet  118 .  FIG. 11A  is a cross-sectional view of poppet  118  taken along a line cut laterally through a portion of the outlets  146  of poppet  118  and pointing in a direction opposite the flow f.  FIG. 11A  illustrates the second portion  150  having a cross-sectional perimeter with a substantially constant wall thickness.  FIG. 11B  illustrates a cross-sectional perimeter of a second portion  150  of an optional embodiment of a poppet  118  taken along a line cut laterally through a portion of outlets  146  of a poppet  118  having a non-constant wall thickness.  FIG. 11C  illustrates a cross-sectional perimeter of the first portion  147  with a substantially constant wall thickness. 
   A variety of buttress configurations, shapes and sizes may be incorporated, including positioning the buttresses  156  on the outer surface of poppet  118  as shown in  FIGS. 12 and 13 .  FIG. 12  illustrates a cross-sectional view of a portion of a poppet  118  taken along a line cut longitudinally through a center of poppet  118 , and  FIG. 13  illustrates a cross-sectional view of a portion of the poppet  118  taken along a line cut laterally through the outlets  146  of poppet  118  and pointing in a direction opposite the flow f In this embodiment of poppet  118 , the cross-sectional perimeter includes a non-constant or variable wall thickness, but it is to be understood that a constant wall thickness may also be utilized. 
   In another embodiment of the invention, a reinforcement member  158  may be coupled to second portion  150  to further reinforce second portion  150 . Reinforcement member  158  may be used alone or in combination with reinforcement portion  154 . It includes apertures or openings  159  arranged to align with outlets  146  when reinforcement member  158  is operatively coupled to poppet  118 . Reinforcement member  158 , may be coupled to second portion  150  on an interior surface  164  of poppet  118 , as shown in  FIG. 15 . The coupling may be accomplished by a variety of known attachment methods such as welding, friction fit or threaded fasteners. Alternatively, reinforcement member  158  may be configured to couple to second portion  150  on an exterior surface  166  of poppet  118 , as shown in  FIG. 16 . Reinforcement member  158  may be fabricated from a metallic material, such as iron, aluminum, titanium, and their alloys, ferretic, as well as austenitic or martensitic stainless steel. Reinforcement member  158  provides further reinforcement and strength to poppet  118  to further eliminate product failures. 
   The fluid transportation members described above and other poppets fabricated as described herein may be used with fuel injectors with differing constructions where fuel is discharged in the form of a plume, including inwardly and outwardly opening fuel injectors where fuel alone is injected and where fuel is entrained in a gas, such as air. 
   The principles, embodiments, and modes of operation of the present invention have been described in the foregoing description. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such variations, changes, and equivalents that fall within the spirit and scope of the present invention as defined in the claims be embraced thereby.