Abstract:
A fuel injector is provided for use in an internal combustion engine. The fuel injector includes an injector body having an axially extending fuel passage for fuel flow, an injection valve movable in the passage for controlling fuel flow therein, a valve seat adjustably positioned into an outlet end of the fuel passage, and a valve seat retainer for applying an axial load onto the valve seat and securely attaching the valve seat into the fuel passage of the injector body.

Description:
TECHNICAL FIELD 
     The present invention relates generally to fuel injectors for use in an internal combustion engine and, more particularly, to a valve seat retainer for securely attaching the valve seat into the fuel passage of the fuel injector. 
     BACKGROUND OF THE INVENTION 
     It is well known in the automotive engine art to provide solenoid actuated fuel injectors for controlling the injection of fuel into the cylinders of an internal combustion engine. Fuel injectors generally include a body having internal and external components which are assembled together to provide an internal fuel passage for fuel flow therein. An injector valve is actuated within the fuel passage to control fuel flow, such that the injector valve axially separates from the a valve seat in an open position and sealingly engages the valve seat in a closed position. 
     In constructing the fuel injector, the valve seat and associated components are adjustably positioned in an outlet end of the fuel passage. A clamp load is then applied to the valve seat assembly and it is securely attached into the fuel passage of the injector. It is imperative that the magnitude and direction of the clamp load be accurately controlled in order to minimize distortion of the valve seat and to keep it precisely in position over the life of the fuel injector. 
     Two techniques are typically used to attached the valve seat into the fuel passage. First, a weld is placed between the valve seat and the inner surface of the fuel passage. However, the welding process introduces heat between the components which may distort them, thereby causing fuel leaks. Second, an extending flange portion of the injector body may be crimped over the end of the fuel passage, thereby securing the valve seat within the fuel passage of the injector. In this case, the crimped flange portion of the body applies the clamp load to the valve seat. Since the crimped flange portion may experience some spring back, the magnitude and direction of the clamp load is unknown. 
     Therefore, it is desirable to provide a valve seat retainer for securely attaching the valve seat into the fuel passage of the fuel injector, such that the magnitude and direction of the clamp load is accurately known and maintained over the life of the fuel injector. It is also desirable that the valve seat retainer be designed to flex under load in order to maintain the clamp load during and after the assembly process. The valve seat retainer may also serve as a fuel director retainer for securely attaching the fuel director to the valve seat. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a fuel injector is provided for use in an internal combustion engine. The fuel injector includes an injector body having an axially extending fuel passage for fuel flow therein, an injection valve movable in the passage for controlling fuel flow, a valve seat adjustably positioned into an outlet end of the fuel passage, and a valve seat retainer for applying an axial load onto the valve seat and securely attaching the valve seat into the fuel passage of the injector body. 
     For a more complete understanding of the invention, its objects and advantages, refer to the following specification and to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary cross-sectional view of an exemplary fuel injector embodying features of the present invention; 
     FIGS. 2A and 2B are fragmentary cross-sectional views of an exemplary fuel injector illustrating a first preferred embodiment of a valve seat retainer in accordance with the present invention; 
     FIG. 3 is a fragmentary cross-sectional view of an exemplary fuel injector illustrating a second preferred embodiment of a valve seat retainer in accordance with the present invention; 
     FIG. 4 is a fragmentary cross-sectional view of an exemplary fuel injector illustrating a third preferred embodiment of a valve seat retainer in accordance with the present invention; and 
     FIG. 5 is a fragmentary cross-sectional view of an exemplary fuel injector illustrating a fourth preferred embodiment of a valve seat retainer in accordance with the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A solenoid actuated fuel injector  10  embodying features of the present invention is depicted in FIG.  1 . The fuel injector  10  generally includes an injector body  12 , a solenoid actuator assembly  14 , a valve assembly  16  and a valve seat assembly  18 . While the following description is provided with reference to a particular fuel injector, it is readily understood that the broader aspects of the present invention are applicable to other types of and configurations for fuel injectors. 
     In the illustrated construction, the injector body  12  is a hollow, cylindrical configuration defining a central axis  13  and having an axially extending fuel passage therethough. The solenoid actuator assembly  14  is disposed within the upper portion of the injector body  12 . The solenoid assembly  14  is comprised of a magnetic pole piece  22  fixed within the fuel passage of the injector body  12  and a solenoid actuator  24  extending around the magnetic pole piece  22 . 
     The valve assembly  16  includes a valve element  30  and a rod-shaped armature  32  that extends axially within the lower portion of the injector body  12 . A spherical ball  34  positioned within a circular socket  36  of the armature  32  may serve as the valve element  30 . The radius of the valve element  30  is selected for seating engagement with the valve seat assembly  18 . It is envisioned that other embodiments of the valve assembly are within the scope of the present invention. 
     The valve element  30  is normally biased into a closed, seated engagement with the valve seat assembly  18  by a biasing member such as a coil spring  42 . The coil spring  42  is positioned between a calibration sleeve  44  and the armature  32  of the valve assembly  16  as shown in FIG.  1 . In this way, the position of the calibration sleeve  44  within the pole piece  22  adjusts the spring force exerted on the valve assembly  16 . 
     The valve seat assembly  18  is primarily comprised of a valve seat  52  which is fixed at an outlet end of the fuel passage. The valve seat  52  provides a central discharge opening  54  to allow fuel flow through the injector  10 . The central discharge opening  54  is further defined as having a conical surface  56  which engages the spherical ball  34  of the valve assembly  16 . The valve seat assembly may optionally include a valve guide  58  that guides that valve assembly  16  into contact with the valve seat  52 . The valve guide  58  is positioned between the valve seat  52  and the flange-like surface formed by an expanded diameter portion of the injector body  12 . The valve guide  58  also include openings which allow fuel flow though the valve guide  58 . An outer seal ring  60  may be captured in an outer groove  62  of the valve seat  60 , thereby preventing fuel from leaking around the valve seat and bypassing the discharge opening. 
     Furthermore, the central discharge opening  54  connects with a circular recess  64  on the underside of the valve seat  52 . A fuel spray director plate  66  may be press fitted or otherwise retained in the circular recess  64  of the valve seat  52 . A fuel director retainer  67  may optionally be used to secure the director plate  66  into the recess of the valve seat  52 . Fuel passing through the central discharge opening  54  is delivered to the director plate  66 , where it is distributed across a plurality of fuel directing openings  68  extending therethrough. The fuel directing openings  68  are oriented to generate a desired spray configuration in the fuel discharged from the injector. 
     In operation, energizing of the solenoid actuator  24  draws the valve assembly  16  upward into engagement with the pole piece  22 , thereby axially separating the valve assembly  16  from the central discharge opening  54  in the valve seat  52 . Thus, fuel is allowed to flow through the injector into an associated intake manifold or inlet port of an internal combustion engine (not shown). Upon de-energization of the solenoid actuator  24 , the coil spring  42  biases the valve assembly  16  back towards the valve seat  52 , thereby closing the injector. Other types of actuators as well as modes of operation for the injector are within the broader aspects of the present invention. 
     In accordance with the present invention, a valve seat retainer  70  is used to securely attach the valve seat assembly  18  into the outlet end of the injector body  12 . Generally, the valve seat retainer provides a means for applying an axial load onto a bottom surface of the valve seat and a means for coupling the valve seat to the injector body. While the following description is provided with reference to specific constructions for the valve seat retainer, it is readily understood that other configurations are within the scope of the present invention. 
     A first preferred embodiment of a valve seat retainer  72  is shown in FIGS. 2A and 2B. The valve seat retainer  72  is defined as a circular channel member having an inner wall  74  and an outer wall  76 , where the outer wall  76  further includes an offshoot  78  which protrudes outward and axially upward above the inner wall  74 . During assembly, the valve seat retainer  72  is pressed against the valve seat  52 , such that the top of the inner wall  74  engages a bottom surface of the valve seat  52 . The valve seat retainer  72  is further displaced until it contacts the bottom of the injector body  12 . This flexes or deflects the inner wall  74 , thereby applying an axial force onto the valve seat  52 . In this way, the direction and magnitude of the clamp load on the valve seat  52  are accurately controlled. In this embodiment, the bottom surface of the valve seat  52  is positioned flush with the bottom of the injector body  12 . As best seen in FIG. 2B, the valve seat  52  is then retained in position by crimping the offshoot  78  of the valve seat retainer  72  over an outwardly extending flange  80  on the lower portion of the injector body  12 . 
     A second preferred embodiment of a valve seat retainer  82  is illustrated in FIG.  3 . When the valve seat  52  is positioned into the outlet end of the fuel passage, the lower expanded diameter portion of the injector body  12  extends beyond the bottom surface of the valve seat  52 . In this case, the valve seat retainer  82  is a hollow cylinder  84  that is inserted into the lower expanded diameter portion of the injector body  12 . The top surface of the cylinder is pressed against the bottom surface of the valve seat  52 , thereby applying the clamp load onto the valve seat  52 . The valve seat retainer  82  is then held in place by a weld  86  positioned between the outer surface of the cylinder and the inner surface of the injector body. In order to maintain the clamp load throughout the assembly process, a portion of the valve seat retainer  82  is designed to deflect under load. In particular, the cylinder includes a corrugated area  88  which deflects under load. 
     A third preferred embodiment of a valve seat retainer  92  is illustrated in FIG.  4 . The valve seat retainer  92  is an inverted cup-shaped member  94  that is inserted into the lower expanded diameter portion of the injector body  12 . The cup-shaped member includes an opening  96  through the top of the cup-shaped member, thereby forming a radially inwardly extending lip  98 . To apply the clamp load to the valve seat  52 , the lip  98  of the cup-shaped member  94  is pressed against the bottom surface of the valve seat  52 . Again, the valve seat retainer  92  is then held in place by a weld  99  positioned between the outer surface of the retainer and the inner surface of the injector body. In this case, the lip  98  is designed to deflect under load in order to maintain the clamp load during and after the assembly process. 
     In either of these last two embodiments, an optional director retainer  100  may be used to securely attach the fuel director plate  66  to the valve seat  52 . The fuel director plate  66  is adapted to engage a protruding area  102  along the bottom surface of the valve seat  52 . In the event the fuel director is not press fit or otherwise retained on the protruding area  102 , a unshaped director retainer  100  may be used to retain the fuel director plate  66 . The director retainer  100  is pressed against the director plate  66  and then spot welded to the inner surface of the valve seat retainer. An inner lip  103  of the director retainer  100  is again designed to deflect under load in order to maintain the clamp load during and after the assembly process. As best seen in FIG. 4, the director retainer  100  may farther include a flange portion  104  that extends around the bottom end of the injector body  12 . In this way, the director retainer also engages an annular O-ring seal  106  positioned between the injector body and an associated inlet port of an internal combustion engine (not shown). 
     Referring to FIG. 5, a fourth preferred embodiment of a valve seat retainer  110  doubles as the director retainer. After the valve seat  52  is positioned in the injector body  12 , the fuel director plate  66  is placed over the protruding area  102  of the valve seat  52 . In this instance, the valve seat retainer  94  is an upright cup-shaped member  112  with an opening  114  in the bottom of the cup-shaped member, such that a lip  116  is formed around the opening  114 . The valve seat retainer  110  is then positioned over the protruding area  102 , such that lip  116  of the retainer  110  engages at least a portion of the fuel director plate  66 . In this way, the fuel director plate  66  is held in place by the valve seat retainer  110 . In order to apply a clamp load, the valve seat retainer  110  is pressed against the fuel director plate  66  which is turn pushes against the bottom surface of the valve seat. Again, the lip  116  is designed to deflect under load in order to maintain the clamp load during and after the assembly process. Lastly, the valve seat retainer  110  is securely attached by a weld  118  positioned between the outer surface of the retainer and the inner surface of the injector body. 
     While the above description constitutes the preferred embodiment of the invention, it will be appreciated that the invention is susceptible to modification, variation, and change without departing from the proper scope or fair meaning of the accompanying claims.