Abstract:
An injector for high pressure direct fuel injection in an internal combustion engine is disclosed. The injector has a downstream end and a longitudinal axis extending therethrough. The injector has an outlet orifice located at the downstream end. The outlet orifice has an outlet axis oblique to the longitudinal axis. The outlet orifice discharges a circular cone-shaped spray having a spray axis co-linear with the outlet axis. A method of forming a bent circular cone-shaped spray pattern is also disclosed.

Description:
FIELD OF THE INVENTION 
     The present invention relates to fuel injectors, specifically, fuel injectors which spray fuel in a cone-shaped spray at a bent angle to a longitudinal axis of the fuel injector. 
     BACKGROUND OF INVENTION 
     Prior art fuel injectors include a discharge end which sprays fuel at an angle oblique to a longitudinal axis of the injector. One design includes a discharge channel which extends along the longitudinal axis, but has a discharge end face which is oblique to the longitudinal axis. This design produces a spray pattern which sprays fuel at an angle oblique to the longitudinal axis of the injector, but is elliptical in shape. 
     It is believed that another design of fuel injectors includes a discharge channel which is at an angle oblique to the longitudinal axis and has a discharge face which is generally perpendicular to the discharge channel. The discharge face includes a circular exit orifice for discharging the fuel. However, the fuel can be discharged only at the angle of the discharge channel relative to the longitudinal axis. If a user requires a different spray angle, a different injector having the discharge channel at the different spray angle must be used, requiring a significant amount of tooling. 
     It would be desirable to have a fuel injector which discharges fuel at an angle oblique to the longitudinal axis of the injector, but discharges a circular spray of fuel from the injector, and can be manufactured to discharge the circular spray at one of a variety of desired angles. 
     SUMMARY OF THE INVENTION 
     Briefly, the present invention discloses an injector having a downstream end and a longitudinal axis extending therethrough. The injector comprising an outlet orifice located at the downstream end. The outlet orifice has an outlet axis oblique to the longitudinal axis. The outlet orifice discharges a cone-shaped spray having a spray axis co-linear with the outlet axis. 
     The present invention is also a valve seat for a fuel injector. The fuel injector comprises a longitudinal injector axis extending therethrough. The fuel injector also includes an upstream end having a fuel entrance orifice on the longitudinal injector axis and a downstream end having a fuel exit orifice. The fuel injector also includes a channel extending between the fuel entrance orifice and the fuel exit orifice. The fuel exit orifice has a channel axis oblique to the longitudinal injector axis. Fuel exiting the fuel exit orifice forms a symmetrical cone-shaped spray having a spray axis co-linear with the channel axis. 
     Further, the invention is a valve seat assembly for a fuel injector. The valve seat assembly comprises a valve seat and a bent stream insert. The valve seat includes a longitudinal axis extending therethrough, an upstream end having a seat entrance orifice on the longitudinal axis, and a downstream end having a seat exit orifice on the longitudinal axis. The valve seat also includes a seat channel extending between the seat entrance orifice and the seat exit orifice along the longitudinal axis and a recessed opening downstream of the seat exit orifice along the longitudinal axis. The recessed opening is larger than the seat exit orifice. The bent stream insert includes an upstream insert end having an insert entrance orifice, a downstream insert end, and a channel axis extending therethrough. The bent stream insert also includes an insert channel having an insert exit orifice at the downstream insert end, the outlet orifice having a channel axis oblique to the longitudinal injector axis and an insert projection extending from the upstream end. The insert projection is adapted to be retained in the recessed opening. The seat exit orifice is in fluid communication with the insert entrance orifice. The channel axis is at a first angle oblique to the seat axis. 
     The present invention is also a method of generating a cone-shaped bent spray from a fuel injector. The method comprises the steps of directing fuel into an entrance orifice in a valve seat, the entrance orifice being along a longitudinal axis of the fuel injector; directing the fuel from the entrance orifice, through a channel in the valve seat, and to an exit orifice, the channel being along a channel axis at an angle oblique to the longitudinal axis; and discharging the fuel from the exit orifice, the fuel forming a coneshaped spray having a spray axis co-linear with the channel axis. 
     Additionally, the present invention is a method of changing a fuel spray angle in a fuel injector comprising the step of substituting the first bent stream insert from a discharge end of a fuel injector, the first bent stream insert having a first spray angle, for a second bent stream insert into the discharge end of the fuel injector, the second bent stream insert having a second spray angle. 
     Further, the present invention is a method of providing multiple bent sprays from a single injector assembly comprising the steps of providing an injector having a discharge end, the discharge end being adapted to receive one of a plurality of inserts, each insert having a different pre-determined angle of discharge; selecting an insert with a pre-determined angle of discharge; and fixedly inserting the insert into the discharge end of the injector. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate the 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. In the drawings: 
     FIG. 1 is a side view, in section, of a fuel injector with a valve seat according to a first embodiment of the present invention; 
     FIG. 2 is a bottom plan view of the valve seat taken along line  2 — 2  of FIG. 1; 
     FIG. 3 is a bottom plan view of the fuel spray pattern taken along line  3 — 3  of FIG. 1; and 
     FIG. 4 is a side view, in section, of a valve seat according to a second embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A fuel injector  10  to which the present invention can be applied is disclosed by U.S. Pat. No. 5,875,972, which is owned by the assignee of the present invention and is incorporated herein by reference. In the drawings, like numerals are used to indicate like elements throughout. Referring to FIG. 1, the fuel injector  10  has a downstream end  102  and includes a housing  20  having a longitudinal axis  270  extending therethrough, a valve seat  30 , and a needle  40 . The injector  10  includes an outlet orifice or opening, generally indicated as  104 , located at the downstream end  102 . 
     A first embodiment of the present invention is shown in FIG.  1 . The valve seat  30  of the injector  10  includes an upstream end  302 , a downstream end  304 , and a beveled surface  310  for seating a sealing surface  402  on a downstream end  404  of the needle  40 . The beveled surface  310  also forms a transition cone  312 , centered around the longitudinal axis  270 , which directs fuel into a channel  320  which extends from the transition cone  312  to the downstream end  304 . An upstream end  322  of the channel  320  has a generally circular fuel entrance orifice  323  and is generally concentrically aligned with the transition cone  312  and the longitudinal axis  270 . The positioning of the upstream end  322  of the channel  320  with the longitudinal axis  270  provides for a round entrance to the channel  320  and helps to maintain a constant tangential velocity from a swirl disc (not shown). 
     A downstream end  324  of the channel  320  has a generally circular fuel exit orifice  325 . Preferably, the fuel exit orifice  325  is the same as the outlet orifice  104 , although those skilled in the art will recognize that the outlet orifice  104  can be located in another element of the fuel injector  10 , such as a metering orifice (not shown). The downstream end  324  is offset from the longitudinal axis  270 , forming the channel  320  at an angle Φ generally oblique to the longitudinal axis  270 . As shown in FIG. 1, the channel  320  has a longitudinal channel axis  326  at an angle of approximately 10° oblique to the longitudinal axis  270 , although those skilled in the art will recognize that the channel axis  326  can be at an angle of less than 10° or up to 30° with respect to the longitudinal axis  270 . The ability to select different angles allows for greater flexibility for different applications. 
     The downstream end  304  of the valve seat  30  includes a generally spherical surface or projection  330 . The fuel exit orifice  325  is located on the spherical projection  330 . As shown in FIG. 2, the spherical projection  330  allows for a round fuel exit orifice  325  with a sharp edge at the downstream end  324  of the channel  320 . The sharp edge at the exit orifice  325  maximizes flow turbulence at the exit orifice  325  and maintains a symmetrical cone-shaped spray. The sharp edge also provides an added benefit of reducing build up of deposits at the exit orifice  325 . Fuel exiting from the fuel exit orifice  325  at the downstream end  324  forms a generally symmetrical right circular cone C, which exits the valve seat  30  at along a cone axis  328  which is generally co-linear with the channel axis  326 , as shown in FIGS. 1 and 3. 
     Preferably, the valve seat  30  is constructed from 440C hardened stainless steel, although those skilled in the art will recognize that the valve seat  30  can be constructed of other, similar materials. The valve seat  30  can be heat treated by hardening, deep freezing and tempering to RC 55-60. To form the channel  320  in the valve seat  30 , a laser drilling process is preferred, although those skilled in the art will recognize that other, suitable methods can be used. 
     In a second embodiment, shown in FIG. 4, the one-piece valve seat  30  of the first embodiment can be replaced by a two-piece valve assembly  100  comprising a valve seat  50  and a first bent stream insert  60 , with the longitudinal axis  270  extending therethrough. The valve seat  50  includes an upstream end  502 , a downstream end  504  and a beveled surface  510  for seating the sealing surface  402  on the downstream end  404  of the needle  40 . The beveled surface  510  also forms a transition cone  512 , which directs fuel into a channel  520  which extends between the transition cone  512  and the downstream end  504  along the longitudinal axis  270 . An upstream end  522  of the channel  520  includes a seat entrance orifice  523  and a downstream end  524  includes a seat exit orifice  525 , with both the seat entrance orifice  523  and the seat exit orifice  525  being on the longitudinal axis  270 . The valve seat  50  also includes a recessed opening or enlarged bore  530  downstream of the seat exit orifice  525  along the longitudinal axis  270  for accepting and retaining an insert projection  606  of the insert  60  in the bore  530  as will be discussed later herein. The bore  530  is larger than the seat exit orifice  525  so that the insert  60  can be inserted into the bore  530  without restricting flow from the seat exit orifice  525 . 
     An upstream end  602  of the insert  60  includes an insert projection  606  which is adapted to be retained in the bore  530 . A downstream end  604  of the insert  60  includes a spherical portion  610 . An insert channel  620  having an insert entrance orifice  623  and an insert exit orifice  625  extends along a channel axis  626  through the projection  60 , between the insert entrance orifice  623  in the upstream end  602  and the insert exit orifice  625  in the downstream end  604 . 
     The insert entrance orifice  623  of the channel  620  is generally concentrically aligned with the transition cone  512  and the longitudinal axis  270  so that the insert entrance orifice  623  at the upstream end  622  of the channel  620  is fluidly connected to the seat exit orifice  525  in the seat  50 . However, the insert exit orifice  625  is offset from the longitudinal axis  270 , forming the channel  620  generally oblique to the longitudinal axis  270 . As shown in FIG. 4, the channel axis  626  is at an angle Φ of approximately 10° oblique to the longitudinal axis  270 , although those skilled in the art will recognize that the channel  620  can be at an angle less than 10° or up to 30° with respect to the longitudinal axis  270 . 
     Fuel exiting from the insert exit orifice  625  forms a generally symmetric right circular cone-shaped spray C 1 , which exits the insert  60  at along a cone axis  628  which is generally co-linear with the channel axis  626 , as shown in FIG.  4 . 
     To construct the valve seat assembly  100 , the projection  606  of the insert  60  is inserted into the enlarged bore  530  in the seat  50 . Preferably, the seat  50  and the insert  60  are laser welded together, although those skilled in the art will recognize that the seat  50  and the insert  60  can be connected by other means, including press fit. 
     The seat  50  and insert  60 , when the projection  606  of the insert  60  is inserted into the enlarged bore  530  in the seat  50 , operates in the same manner as the first embodiment valve seat  30  described above. A benefit of the second embodiment over the first embodiment is that, with a separate seat  50  and insert  60 , different materials can be used as desired. Preferably, the seat  50  is constructed from 440C stainless steel and the insert in constructed from 304 stainless steel, although those skilled in the art will recognize that the seat  50  and the insert  60  can be constructed of other materials, including but not limited to Fecralloy (iron-chrome-aluminum alloy) or ceramic material to reduce injector deposits. Additionally, the two-piece design allows the seat  50  to be a permanent part of the injector  10 , but allows for a second insert constructed from a different material and/or having a different pre-determined angle Φ to be substituted for the first insert  60  for different applications or requirements. Further, the two-piece assembly  100  also allows for more simplicity in the assembly process since the insert  60  can be inserted into the seat  50  at the end of the assembly line, minimizing the need for tooling changes, and an insert  60  having a particular pre-determined angle D can be used, depending upon customer needs. 
     It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.