Patent Publication Number: US-6655608-B2

Title: Ball valve fuel injector

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 08/997,274, filed Dec. 23, 1997, now U.S. Pat. No. 6,047,907 which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to solenoid operated fuel injectors of the spherical valve ball type used to control the injection of fuel into an internal combustion engine; 
     BACKGROUND OF THE INVENTION 
     It is known in the fuel injection art to utilize a spherical valve ball within a solenoid operated fuel injector to close a fuel passageway in the injector. In such injectors, it is common to fabricate a flat on the ball valve and use the ball in combination with a collar that provides an annular cradling surface for the ball. A spring disc interfaces with the ball and urges the ball into an open position. Fuel is communicated around an armature and through the spring disc to establish fuel flow when the ball is in an unseated position. The ball must be guided to center itself on a seat of the fuel passageway and the armature requires a surface to keep the ball at least proximately concentric within the axis within the radial confinement imposed on the ball by the tip end of the armature. 
     With such assemblies, the dynamic flow rate of the fuel is set through the spring rate and selecting the spring becomes critical. These injectors require a non-magnetic plug in the bottom of their armatures to reduce wear and have a coil that is contacted by the fuel. 
     SUMMARY OF THE INVENTION 
     The present invention provides a solenoid actuated fuel injector having a simplified construction wherein a return spring biases a spherical valve ball onto a seating surface and, upon actuation of a solenoid coil, an armature picks the valve ball off the seat. When the coil is deactivated, the armature releases the ball, allowing the ball to return to the center of the seating surface. 
     According to the invention, the solenoid actuated fuel injector comprises a housing having a longitudinal axis and a valve body fixed to the housing. The valve body has a cylindrical sidewall coaxial with the housing longitudinal axis that laterally bounds the interior of the valve body. A valve seat at one end of the valve body includes a seating surface facing the interior of the valve body. The seating surface includes a fuel outlet opening centered on the axis and is in communication with means for conducting pressurized fuel into the valve body against the seating surface. The seating surface may be frustoconically shaped or of a concave shape. 
     A spherical valve ball within the injector is moveable between a seated position, wherein the ball is urged against the seating surface to close the outlet opening against fuel flow, and an open position, wherein the ball is spaced from the seating surface to allow fuel flow through the outlet opening. Biasing means, such as a coil spring, in the valve body is provided for biasing the valve ball toward the seated position. 
     An armature axially moveable in the valve body includes valve ball capturing means at an end proximate the seating surface. The valve ball capturing means engages with the ball outer surface adjacent the seating surface. A solenoid coil is operable to draw the armature away from the seating surface, thereby moving the valve ball to the open position and allowing fuel to pass through the fuel outlet opening. Deactivation of the solenoid coil allows the biasing means to return the valve ball to the seated position against the seating surface and to align itself in the seated position, thereby closing the outlet opening against the passage of fuel. 
     The armature includes an axially extending through-bore that allows fuel to pass and receives the valve ball. A fuel passage extending from the through-bore to an outer surface of the armature allows fuel to be communicated around the valve ball. The valve ball capturing means engages the ball at a diameter of the ball that is less than the major diameter of the ball and at a position between the major diameter of the ball and the seating surface. Herein the valve ball capturing means is an end of the armature wherein the through bore has a reduced diameter less than the major diameter of the ball. Alternatively the capturing means may be a plurality of fingers extending from the armature. 
     A method of assembling the solenoid actuated fuel injector comprises the steps of: 
     assembling a valve group subassembly; 
     assembling a coil group subassembly; 
     assembling together the valve group sub-assembly and coil group subassembly; and 
     snap fastening together cooperating snap features on the valve group and coil group subassemblies. 
     These and other features and advantages of the invention will be more fully understood from the following detailed description of the invention taken together with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a sectional view of a solenoid actuated fuel injector of the ball valve type constructed in accordance with the present invention; 
     FIG. 2 is an enlarged sectional view of the solenoid actuated fuel injector of FIG. 1 illustrating the valve body assembly in a seated position of the valve ball and the armature resting on the seating surface; 
     FIG. 3 is an enlarged sectional view of the solenoid actuated fuel injector of FIG. 1 illustrating the valve body assembly in an open position of the valve ball wherein the armature captured valve ball is raised off the seating surface; and 
     FIG. 4 is a sectional view of a solenoid actuated fuel injector of the ball valve type constructed in accordance with the present invention having an extended tip and illustrating a guide and lower screen incorporated into the injector. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings in detail, numeral  10  generally indicates, a solenoid actuated fuel injector of the top feed type for use in an internal combustion engine. The fuel injector  10  includes a housing  12  having a longitudinal axis A and a valve body  14  fixed to the housing. The valve body  14  has a cylindrical sidewall  16  coaxial with the housing longitudinal axis A that laterally bounds the interior of the valve body  14 . 
     A valve seat  18  at one end  20  of the valve body  14  includes a seating surface  22  of a frustoconical or concave shape facing the interior of the valve body. The seating surface  22  includes a fuel outlet opening  24  centered on the axis A and is in communication with an inlet connector or fuel tube  26  for conducting pressurized fuel into the valve body  14  against the seating surface  22 . Fuel tube  26  includes a mounting end  28  having a retainer  30  for mounting the injector in a fuel rail (not shown) as is known. An o-ring  32  is used to seal the mounting end  28  in the fuel rail. 
     A spherical valve ball  34  within the injector  10  is moveable between a seated position shown in FIG. 2, wherein the ball is urged against the seating surface  22  to close the outlet opening  24  against fuel flow, and an open position shown in FIG. 3, wherein the ball is spaced from the seating surface to allow fuel flow through the outlet opening. A spring  36 , in valve body  14  is provided for biasing the valve ball  34  toward the seated position. 
     An armature  38  axially moveable in the valve body  14  includes valve ball capturing means  40  at an end  42  proximate the seating surface  22 . The valve ball capturing means  40  engages with the ball  34  outer surface adjacent the seating surface  22  and rests on the seating surface in the seated position of the valve ball. 
     A solenoid coil  44  is operable to draw the armature  38  away from the seating surface  22 , thereby moving the valve ball  34  to the open position, FIG. 3, and allowing fuel to pass through the fuel outlet opening  24 . Deactivation of the solenoid coil  44  allows the spring  36  to return the valve ball  34  to the seated position, FIG. 2, against the seating surface  22  and to align itself in the seated position, thereby closing the outlet opening  24  against the passage of fuel. 
     The armature  38  includes an axially extending through-bore  46  that allows fuel to pass. Through-bore  46  also receives the valve ball  34  in a close tolerance fit yet allows the ball to move freely in the through-bore whereby the valve ball is self aligning upon seating. A fuel passage  48  extends from the through-bore  46  to the outer surface  50  of the armature  38 , juxtaposed the seating surface  22 , allowing fuel to be communicated around the valve ball  34 . 
     The valve ball capturing means  40  engages the ball  34  at a diameter of the ball that is less than the major diameter of the ball and at a position between the major diameter of the ball and the seating surface  22 . Herein the valve ball capturing means  40  is a reduced diameter aperture having a diameter less than the major diameter of the valve ball  34  on the axially extending through-bore  46  in the armature  38  or a plurality of fingers extending from the armature. 
     With further reference to FIG. 1, an electrical connector  52  is provided for connecting an electrical power supply (not shown) to power the armature  38 . The valve body  14  includes a mounting end  54  for mounting the injector  10  in an intake manifold (not shown) as is known. An o-ring  56  is used to seal the mounting end  54  in the intake manifold. An orifice disk  58  may be provided proximate the outlet opening  24  for controlling the fuel communicated through the outlet opening. A back-up washer  60  is used to mount the orifice disk  58  in the valve body  14  and an o-ring  62  is mounted between valve body and valve seat  18  adjacent the orifice disk. 
     Injector  10  is made of two subassemblies that are each first assembled, then snapped together to form the injector. 
     Accordingly, the injector  10  includes a valve group subassembly and a coil subassembly as hereinafter more fully described. 
     In the valve group subassembly, the valve seat  18 , o-ring  62 , snap orifice disk  58  and backup washer  60  are loaded into the valve body  14 , held in a desired position, and the end  64  of the valve body is bent inwardly. The valve ball  34  is placed into the armature  38  and the armature and valve ball are assembled in the valve body  14 . A measurement is taken between the top  66  of the valve body  14  and the top of the armature  38  with the armature pulled up against the ball  34 . 
     A non-magnetic sleeve  68  is pressed onto one end of the inlet connector  26  and the sleeve and inlet connector are laser welded together. The sleeve  68  and inlet connector  26  are then pressed into the valve body  14  and the sleeve and valve body are welded together completing the assembly of the valve group subassembly. 
     The coil group subassembly is constructed as follows. A plastic bobbin  72  is molded with straight terminals. Wire is wound around the plastic bobbin  72  and the bobbin assembly is placed into a metal can which defines the housing  12 . A metal plate that defines the housing cover  74 , is pressed into the housing  12 . The terminals are bent to their proper location. The housing  12  and coil  44  assembly are then overmolded to complete the coil group subassembly. 
     The over-molded coil subassembly is then pressed and snapped onto the inlet connector  26  and held together by a snap feature  78  molded into the plastic over-mold  76 . The upper o-ring retainer  30  is then installed and crimped into place on the inlet connector  26 . The spring  36  and adjusting tube  80  are installed in the inlet connector  26  and the injector is calibrated by adjusting the relative positioning of the adjusting tube in the inlet connector and crimping the adjusting tube in place. A filter  82  is then mounted in the inlet connector  26 . 
     FIG. 4 illustrates an alternative injector  110  having an extended tip section. In the description of injector  110  which follows, similar structure as previously referenced in FIGS. 1-3 is referred to by similar reference characters. Injector  110  includes a guide and screen member  84  mounted in the valve body  114 . Guide and screen member  84  includes a centered aperture  86  for receiving and guiding the armature  138  and to keep the armature from moving off the longitudinal axis A during operation. Guide and screen  84  includes openings, preferably slotted openings of a size smaller than the injector opening, to allow fuel to pass and trap stray particles larger than the openings in the guide and screen. 
     Although the invention has been described by reference to a specific embodiment, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiment, but that it have the full scope defined by the language of the following claims.