Abstract:
A valve actuator assembly is disclosed. The assembly comprises a stator; an armature housing; and an adjustable spacer coupled between the stator and the armature housing, wherein the spacer yields at a controlled rate when an axial load is applied thereto. The adjustable spacer is positioned between the stator and the armature housing such that when an axial load is applied, the adjustable spacer compresses at a controlled rate, thereby allowing adjustment of the valve stroke. A system and method in accordance with the present invention is applicable to any valve which includes a housing containing a seat, an armature, a stator, and a mechanism that is capable of applying a load to the housing.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application is a continuation-in-part of U.S. patent application Ser. No. 10/823,692, entitled “Solenoid Actuated Flow Controller Valve”, filed Apr. 14, 2004. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates generally to a solenoid actuated flow control valve for a fuel system, and more specifically to an adjustable spacer for the actuator stroke of such a valve.  
       BACKGROUND OF THE INVENTION  
       [0003]     Electromagnetically actuated control valves are widely used in fuel injectors and timing fluid/injection fuel metering systems for precisely controlling the timing and metering of the injected fuel as well as timing fluid. Precise control of the timing and metering of fuel as well as timing fluid is necessary to achieve maximum efficiency of the fuel system of an internal combustion engine. This requires valve designers to consider these performance requirements in their designs.  
         [0004]     In a typical fuel system the control valves control the timing and quantity of fuel delivered to the cylinder. The stroke of these control valves affects the quantity and rate shape of injected fuel. A problem with a conventional electromagnetic actuated control valve is that stroke is adjusted manually by grinding a plunger of the valve to a specific length. The process of grinding the plunger is extremely time-consuming by requiring an operator to assemble and disassemble a valve multiple times in the stroke setting operation. In production this issue has been addressed by providing a plurality of class sized plungers which will add considerable expense to the overhead of stocked parts. Even in the most optimized stage providing a plurality of different class sized plungers does not account for gauge error, orifice variation, and seat variation. The combination of these three variables is the largest source of part to part fueling variation for the control valve.  
         [0005]     Accordingly, what is needed is a system and method for minimizing the amount of time required for adjusting the stroke of a control valve. The present invention addresses such a need.  
       SUMMARY OF THE INVENTION  
       [0006]     A valve actuator assembly is disclosed. The assembly comprises a stator; an armature housing; and an adjustable spacer coupled between the stator and the armature housing, wherein the spacer yields at a controlled rate when an axial load is applied thereto. The adjustable spacer is positioned between the stator and the armature housing such that when an axial load is applied, the adjustable spacer compresses at a controlled rate, thereby allowing adjustment of the valve stroke.  
         [0007]     The present invention solves the above-identified problem by allowing a valve actuator assembly to be assembled at a nominal high stroke, and then to be adjusted to meet injector performance requirements at the end of line functional test through the use of an adjustable spacer between the armature housing and the stator. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1A  illustrates a perspective view of a solenoid actuated flow controller valve in accordance with the present invention.  
         [0009]      FIG. 1B  illustrates a valve actuation assembly in accordance with the present invention.  
         [0010]      FIG. 1C  is a cross-sectional view of a portion of the valve actuator assembly of  FIG. 1B .  
         [0011]      FIG. 2  is a simplified view of a valve actuator assembly illustrating the deflection of the spacer that allows for the change in valve stroke.  
         [0012]      FIG. 3  illustrates a preferred embodiment of the adjustable spacer in accordance with the present invention.  
         [0013]      FIG. 4  shows the performance of the adjustable spacer at a controlled rate.  
         [0014]      FIGS. 5   a  and  5   b  show fueling delivery curves. 
     
    
     DETAILED DESCRIPTION  
       [0015]     The present invention relates generally to a solenoid actuated flow control controller valve for a fuel system, and more specifically to an adjustable spacer for the actuator stroke of such a valve. The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the preferred embodiments and the generic principles and features described herein will be readily apparent to those skilled in the art. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features described herein.  
         [0016]      FIG. 1A  illustrates a perspective view of a solenoid actuated flow controller valve  10  in accordance with the present invention. This perspective view shows the valve housing  12  and the armature housing  24 .  
         [0017]      FIG. 1B  illustrates a valve actuator assembly in accordance with the present invention.  
         [0018]      FIG. 1C  is a cross-sectional view of a portion of the valve actuator assembly in accordance with the present invention.  
         [0019]     As shown in the cross sectional views of  FIGS. 1B and 1C , flow controller valve  10  generally includes valve housing  12 , valve plunger  14  mounted for reciprocal movement in valve housing  12 , valve actuator assembly  16  for selectively moving valve plunger  14  between extended and retracted positions, and an armature overtravel feature indicated generally at  18 .  
         [0020]     Valve housing  12  includes upper portion  20  containing cavity  22  and lower armature housing  24  mounted in compressive abutment against a lower surface of upper portion  20 . Upper portion  20  may include fuel passages  26  extending radially therethrough for communication with respective fuel passages for delivering fuel, for example, from a drain fuel source to an injector body and nozzle assembly (not shown) mounted adjacent to armature housing  24 . In this regard, flow control valve  10  is preferably utilized in a fuel system and is readily positionable in the upper portion of a fuel injector (not shown).  
         [0021]     Valve actuator assembly  16  includes solenoid assembly  30  having coil  32  mounted on bobbin  34  and extending around stator assembly  36 . Solenoid assembly  30  is positioned in cavity  22  and securely attached to upper portion  20  of valve housing  12 , preferably, by a metallic stator body  38 . Valve plunger  14  is mounted for reciprocal movement in an aperture extending through stator body  38 . A spring retainer and stop device  40  is mounted on an outer end of valve plunger  14  for receiving bias spring  42  for biasing valve plunger  14  downwardly as shown in  FIG. 1B .  
         [0022]     Valve actuator assembly  16  includes recess cavity  46  that is open toward coil  32  and stator assembly  36 , and houses armature  54 , adjustable spacer  55 , solenoid spacer  57 , and components of overtravel feature  18 . Valve plunger  14  extends through recess cavity  46 .  
         [0023]     U.S. patent application Ser. No. 10/823,692, entitled “Solenoid Actuated Flow Controller Valve”, and assigned to the assignee of the present invention, illustrates this feature and is incorporated by reference herein. The present invention is directed to the use of the adjustable spacer  55  to provide for the adjustment of the actuator valve stroke.  
         [0024]     The problem with a conventional electromagnetic actuated control valve is that stroke is adjusted manually by grinding a plunger of the valve to a specific length. The process of grinding the plunger is extremely time-consuming by requiring an operator to assemble and disassemble a valve multiple times in the stroke setting operation. In production this issue has been addressed by providing a plurality of class sized plungers which will add considerable expense to the overhead of stocked parts.  
         [0025]     The present invention solves the above-identified problem by allowing a valve actuator assembly to be assembled at a nominal high stroke, and then to be adjusted to meet injector performance requirements at the end of line functional test through the use of an adjustable spacer between the armature housing and the stator. The process allows all of the variables to be corrected, reducing assembly time and cost.  
         [0026]      FIG. 2  is a simplified view of a valve actuator assembly illustrating the deflection of the spacer that allows for the change in valve stroke. The valve actuator assembly  10  includes an armature housing  24 ′ containing a seat  50 ′, an armature (not shown), an adjustable spacer  55 ′, a valve plunger  14 ′ biased against the armature by a load, and a stator assembly  36 ′. A stator retainer  102  is coupled to the stator assembly  36 ′ via a threaded joint  104 . When an axial load is applied to the stator assembly  36 ′, the adjustable spacer  55 ′ yields in a controlled manner shown by the deflection  100  allowing the stroke to decrease with load.  
         [0027]     As before mentioned, the adjustable spacer  55 ′ is positioned between the stator assembly  36 ′ and the armature housing  24 ′, and is designed such that when an axial load is applied, the adjustable spacer  55 ′ yields at a controlled rate, thereby allowing adjustment of the valve stroke (i.e., the gap between the ball valve (not shown) and its valve seat  50 ′. To describe the features of embodiment of the spacer  55 ′ in more detail refer now to the following description in conjunction with the accompanying figures.  
         [0028]      FIG. 3  illustrates a preferred embodiment of the adjustable spacer  55 ′ in accordance with the present invention. The adjustable spacer  55 ′ is designed to yield at a controlled rate to allow the valve stroke (gap between ball valve and seat) to be adjusted. In this preferred embodiment, the adjustable spacer  55  has a ring-spaced design with raised pads  302   a - d  equally spaced apart the main body  304  of the spacer  55 ′, spaced apart an equal distance from each other, thereby allowing for compression in response to an axial force. In this embodiment, there are four pads  302   a - 302   d . However, it is readily apparent that any number of pads could be utilized and they would be within the spirit and scope of the present invention. The width of the pads  302   a - d , the thickness of the spacer  55 ′, and the materials used are factors which affect the compressibility of the spacer. For example, the materials could be a polymeric-elastomer, spring steel, or other material with a predictable rate of compressible deflection.  
         [0029]     It should also be understood there are a variety of other configurations and types of spacers that could be utilized and there use would be within the spirit and scope of the present invention. The main feature of the adjustable spacer is that it can be compressed in a controlled manner to allow for adjustment of the valve stroke.  
         [0030]      FIG. 4  shows the performance of the adjustable spacer  55 ′ at a controlled rate as is seen in the compression of the spacer can be controlled to provide the appropriate fuel delivery.  
         [0031]      FIGS. 5A and 5B  show fueling delivery curves utilizing the spacer  55 ′. There was no trim, about 10 mm  3  fueling spread, and a 50 usec. spread in start of opening time. Utilizing the adjustable spacer on an on-rig adjustment, injector to injector fueling and opening time variation can be greatly reduced, as shown in the fueling curves in  FIGS. 5   a  and  5   b.    
         [0032]     Although the present invention has been described in accordance with the embodiments shown, one of ordinary skill in the art will readily recognize that there could be variations to the embodiments and those variations would be within the spirit and scope of the present invention. For example, although a ring shaped adjustable spacer is shown, the spacer could be in a variety of shapes and the spacer would be within the spirit and scope of the present invention. In addition, the spacer could be a spring or the like and its use would be within the spirit and scope of the present invention. Accordingly, many modifications may be made by one of ordinary skill in the art without departing from the spirit and scope of the appended claims.