Patent Publication Number: US-6708907-B2

Title: Fuel injector producing non-symmetrical conical fuel distribution

Description:
FIELD OF INVENTION 
     This invention relates to fuel injectors in general and particularly high-pressure, direct-injection fuel injectors. More particularly, high-pressure, direct-injection fuel injectors using a non-uniform plurality of slots in the swirl disk to produce a non-symmetric fuel cone. 
     BACKGROUND OF THE INVENTION 
     It is known to use a high-pressure direct-injection (HPDI) fuel injector to spray fuel directly into the combustion chamber of an internal combustion engine. The amount of fuel sprayed by the fuel injector must be accurately metered. In addition, the fuel delivered to the combustion chamber must be properly atomized. In order to achieve proper atomization of the fuel, it is known to use a swirl disk to impart an angular velocity or spin to the fuel just upstream of an interface between the needle and the seat of the fuel injector. It is believed that a combination of the spin and the high pressure delivery from the fuel injector creates proper atomization in the form of a hollow cone of fuel exiting from the tip of the injector. 
     It is known that the geometry of the swirl generator determines the shape of the fuel spray exiting from the injector. It is known to use a symmetric swirl generator to create fuel spray in the shape of a symmetric hollow cone. However, specific applications can require a fuel spray in the shape of an atomized non-symmetric hollow cone, such as a hollow oval or shell shape spray. For these reasons, it is desirable to use a non-symmetric swirl generator to generate a non-symmetric conical fuel spray. 
     SUMMARY OF THE INVENTION 
     The present invention provides a fuel injector including a body having an inlet, an outlet, and a fuel passageway extending from the inlet to the outlet along a longitudinal axis. An armature is proximate the inlet of the body. A needle is operatively connected to the armature. A seat is proximate the outlet of the body. A guide member is disposed within the body, the guide member including an aperture that guides the needle. A flat metering disk is disposed between the seat and the guide member, the flat metering disk including a central aperture, a perimeter, and a plurality of slots. Each of the plurality of slots is disposed about the central aperture and extends from the central aperture toward the perimeter to define a volume. The plurality of slots are configured so that the volumes of two of the plurality of slots are non-uniform, and/or the plurality of slots are non-uniformly disposed about the central aperture 
     In a preferred embodiment, the plurality of slots includes a first slot, a second slot, and a third slot disposed radially around a central aperture. The first slot is disposed 60 degrees from each of the second slot and the third slot. The second slot is disposed 120 degree from the third slot. A length of the first slot is greater than a length of the second slot, and a length of the second slot is greater than a length of the third slot. A width of the first slot is greater than a width of the second slot, and the width of the second slot is greater than a width of the third slot. A fuel passage opening of the first slot has a diameter greater than a diameter of a fuel passage opening of the second slot, and the diameter of the fuel passage opening of the second slot is greater than a diameter of the fuel passage opening of the third slot. 
     The present invention also provides a method of delivering fuel from a fuel injector including flowing fuel tangentially in a non-uniform distribution through a swirl disk toward a seat, and metering fuel through the seat to provide a non-symmetric fuel cone. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate presently preferred embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain features of the invention. 
     FIG. 1 is a cross-sectional view of the fuel injector of the present invention taken along its longitudinal axis. 
     FIG. 2 is an enlarged top view of the guide member shown in FIG.  1 . 
     FIG. 3 is an enlarged top view of the swirl disk shown in FIG.  1 . 
     FIG. 4 is an isometric view of the non-symmetric fuel cone. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
     FIG. 1 illustrates a preferred embodiment of the fuel injector  10 , in particular a high-pressure, direct-injection fuel injector  10 . The fuel injector  10  has a housing, which includes a fuel inlet  12 , a fuel outlet  14 , and a fuel passageway  16  extending from the fuel inlet  12  to the fuel outlet  14  along a longitudinal axis  18 . The housing includes an overmolded plastic member  20  cincturing a metallic support member  22 . 
     Inlet member  24  with an inlet passage  26  is disposed within the overmolded plastic member  20 . The inlet passage  26  serves as part of the fuel passageway  16  of the fuel injector  10 . A fuel filter  28  and an adjustable tube  30  are provided in the inlet passage  26 . The adjustable tube  30  is positionable along the longitudinal axis  18  before being secured in place to vary the length of an armature bias spring  32 , which control the quantity of fluid flow within the injector. The overmolded plastic member  20  also supports a socket that receives a plug (not shown) to operatively connect the fuel injector  10  to an external source of electrical potential, such as an electronic control unit ECU (not shown). An elastomeric o-ring  34  is provided in a groove on an exterior extension of the inlet member  24 . The o-ring  34  is biased by a flat spring  38  to sealingly secure the inlet source with a fuel supply member, such as a fuel rail (not shown). 
     The metallic support member  22  encloses a coil assembly  40 . The coil assembly  40  includes a bobbin  42  that retains a coil  44 . The ends of the coil assembly  40  are operatively connected to the socket through the overmolded plastic member  20 . An armature  46  is axially aligned with the inlet member  24  by a spacer  48 , a body shell  50 , and a body  52 . The armature  46  has an armature passage  54  aligned along the longitudinal axis  18  with the inlet passage  26  of the inlet member  24 . 
     The spacer  48  engages the body  52 , which is partially disposed within the body shell  50 . An armature guide eyelet  56  is located on an inlet portion  60  of the body  52 . An axially extending body passage  58  connects the inlet portion  60  of the body  52  with an outlet portion  62  of the body  52 . The armature passage  54  of the armature  46  is axial aligned with the body passage  58  of the body  52  along the longitudinal axis  18 . A seat  64 , which is preferably a metallic material, is located at the outlet portion  62  of the body  52 . 
     The body  52  has a neck portion  66 , which is, preferably, a cylindrical annulus that surrounds a needle  68 . The needle  68  is operatively connected to the armature  46 , and is, preferably, a substantially cylindrical needle  68 . The cylindrical needle  68  is centrally located within the cylindrical annulus. The cylindrical needle  68  is axially aligned with the longitudinal axis  18  of the fuel injector  10 . 
     Operational performance of the fuel injector  10  is achieved by magnetically coupling the armature  46  to the inlet member  24 , near the inlet portion of the body  60 . A portion of the inlet member  24  proximate the armature  46  serves as part of the magnetic circuit formed with the armature  46  and coil assembly  40 . The armature  46  is guided by the armature guide eyelet  56  and is responsive to an electromagnetic force generated by the coil assembly  40  for axially reciprocating the armature  46  along the longitudinal axis  18  of the fuel injector  10 . The electromagnetic force is generated by current flow from the ECU through the coil assembly  40 . Movement of the armature  46  also moves the operatively attached needle  68 . The needle  68  engages the seat  64 , which opens and closes the seat passage  70  of the seat  64  to permit or inhibit, respectively, fuel from exiting the outlet of the fuel injector  10 . The needle  68  includes a curved surface  72 , which is preferably a spherical surface, that mates with a conical end of a funnel that serves as the preferred seat passage  70  of the seat  64 . Further detailed description of the interaction of the curved surface of the needle  68  and the conical end of the funnel of the seat  64  is provided in commonly assigned U.S. Pat. No. 5,875,972, which is expressly incorporated herein in its entirety by reference. During operation, fuel flows in fluid communication from the fuel inlet  12  source (not shown) through the inlet passage  26  of the inlet member  24 , the armature passage  54  of the armature  46 , the body passage  58  of the body  52 , and the seat passage  70  of the seat  64  to be injected from the outlet of the fuel injector  10 . 
     The inserts  82 ,  92  include a guide member  82 , shown in FIG. 2, having a plurality of angularly spaced circumferentially extending openings  84  between the perimeter of the guide member  82  for supplying fluid to the downstream disk  92 , and a central aperture  86  for guiding the needle  68 . The guide member  82  can be in the shape of a disk. The location and size of the openings  84  in the guide member  82  are related to the geometry of the downstream disk  92 , as described below. The guide member  82  can be a conventional guide disk that includes plugged openings incapable of supplying fluid to the downstream disk  92 , or can be manufactured with openings  84  in only desired locations and of desired sizes. 
     The downstream or swirl disk  92 , shown in FIG. 3, is disposed between the guide member  82  and the seat  64 . The disk  92  includes a plurality of slots  94  axially aligned with the openings  84  in the guide member  82 , for directing and metering the fuel flow from the body passage  58  to the seat passage  70 , and a central aperture  96 . The plurality of slots  94  can be disposed about the central aperture  96  and can extend from the central aperture  96  toward the perimeter of the disk  92  to define a volume. The plurality of slots  94  are configured so that the volumes of two of the plurality of slots are non-uniform, and/or the plurality of slots are non-uniformly disposed about the central aperture  96 . The non-uniform, non-symmetric plurality of slots  94  in the swirl disk  92  produces a non-symmetric fuel cone. Thus, it is to be understood that the volumes of at least two of the plurality of slots (or all of the plurality of slots) can be uniform, while the at least two of the slots (or all of the plurality of slots) can be non-uniformly disposed on the swirl disk. Also, at least two of the slots (or all of the plurality of slots) can be uniformly disposed on the swirl disk, while the volumes of at least two of the plurality of slots (or all of the plurality of slots) can be non-uniform. The non-symmetric fuel cone is produced by a non-uniformity in either or both of the volumes and the dispositions of the slots on the swirl disk. 
     Each of the plurality of slots  94  can includes a channel  941  and a fuel passage opening  942 . The channel  941  can extend from the central aperture  96  along a length L and have a width. The channel  941  can have a non-uniform cross-sectional area—that is, the width of the channel can vary along the length L of the channel. The channel  941  can also terminate in the fuel passage opening  942 . 
     The plurality of slots  94  can include three slots—a first slot, a second slot, and a third slot, the length of the first slot being greater than the length of the second slot, and the length of the second slot being greater than the length of the third slot. The width of the first slot can be greater than the width of the second slot, and the width of the second slot can be greater than the width of the third slot. The fuel passage opening of the first slot can have a diameter greater than a diameter of the fuel passage opening of the second slot, and the diameter of the fuel passage opening of the second slot can be greater than a diameter of the fuel passage opening of the third slot. The volume of each of the first, second, and third slots can be non-uniform, or different from one another. 
     As shown in the drawing, the plurality of slots  94  can be radially disposed about the central aperture  96 , and can be disposed within an angle of 120 degrees of one another. 
     The plurality of slots  94  can include three slots—a first slot, a second slot, and a third slot, the first slot disposed 60 degrees from each of the second slot and the third slot, and the second slot disposed 120 degree from the third slot. 
     FIG. 4 shows an example of a non-symmetric fuel cone that can be produced by an arrangement of a preferred embodiment of the invention that uses a non-symmetric disk to allow for a novel method of delivering fuel. The non-symmetric and non-uniform volumes and radial disposition of the plurality of slots  94  in the disk  92  can be varied to produce a non-symmetric fuel cone  201 . The fuel cone  201  can be in the shape of a non-symmetric hollow cone. 
     The preferred embodiment of the disclosed fuel injector provides a method of delivering fuel. The method of delivering fuel from a fuel injector can include flowing fuel tangentially in a non-uniform distribution through a swirl disk (e.g., disk  92 ) toward a seat (e.g., seat  64 ) and metering fuel through the seat to provide a non-symmetric fuel cone (e.g., fuel cone  201 ). The metering can include forming a cone with a hollow shape. 
     The method can include flowing fuel through a disk including a central aperture and a plurality of slots, each of the plurality of slots being disposed about the central aperture and extending from the central aperture toward the perimeter to define a volume. The plurality of slots can be configured so that the volumes of two of the plurality of slots are non-uniform, and/or the plurality of slots are non-uniformly disposed about the central aperture. Thus, a non-uniform and non-symmetric disk is used to produce a non-symmetric fuel cone. In a preferred embodiment, fuel is delivered to the seat from a one third sector of the disk. 
     While the invention has been disclosed with reference to certain preferred embodiments, numerous modifications, alterations and changes to the described embodiments are possible without departing from the sphere and scope of the invention, as defined in the appended claims and equivalents thereof. Accordingly, it is intended that the invention not be limited to the described embodiments, but that it have the full scope defined by the language of the following claims.