Abstract:
A solenoid operated valve with the armature disposed within the coil axially between first and second flux collectors. A flux director surrounding the armature has annular portions thereof contracting one of the flux collectors and has a plurality of fingers spaced circumferentially about the annular portion and extending inwardly toward the armature to increase and distribute the flux thereto for minimizing magnetic side loading due to eccentricity.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to solenoid operated valves and particularly valves of the type where an armature is disposed within the coil with an operating member for contacting and moving a valving element. Solenoid operated valves of the aforesaid type typically utilize an armature disposed within the coil forming an axial working air gap between the armature and the stationary pole piece or flux collector; however, an annular air gap is also formed about the armature by virtue of the arrangement of the armature within the coil.  
         [0002]     Where a solenoid armature is disposed within the coil, any eccentricities or off center disposition of the armature will result in a reduced radial air gap on one side of the armature . This eccentricity inherently increases the magnetic flux across the narrowest part of the gap creating an imbalance and consequently increases the radial or side loading on the armature which can result in increased friction and resistance to axial armature movement in response to coil energization.  
         [0003]     Heretofore, efforts to control the eccentricity of the annular air gap about a solenoid armature disposed within a coil have required tight control of tolerances on the manufacturing of the armature and the flux collector and a loss of the sliding bearing surfaces for positioning the armature within the coil, which has significantly increased the cost of manufacturing of the solenoid valve. Accordingly, it has been desired to provide a way or means of reducing the eccentricity of the annular air gap about an armature within the coil of a solenoid operated valve and to do so in a manner that is simple and relatively low in manufacturing cost thereby making the value suitable for high volume production of applications such as those employed for control functions in automotive applications.  
       BRIEF SUMMARY OF THE INVENTION  
       [0004]     The present invention provides a solution to the above described problem minimizing the eccentricity and side loading of an armature disposed within the coil of a solenoid operated valve. The solenoid valve of the present invention employs a flux director contacting one of the pole pieces about the armature with fingers extending inwardly to provide magnetically permeable surfaces closely adjacent or lightly contacting the surface of the armature to provide the increased flux at the tips of the fingers which are uniformly distributed about the periphery of the armature to thereby balance the magnetic side loading on the armature. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]      FIG. 1  is a sectional view taken the longitudinal centerline of an exemplary embodiment of the invention;  
         [0006]      FIG. 2  is an axonometric view from below of the flux director and spacer sub assembly of the embodiment of  FIG. 1 ;  
         [0007]      FIG. 3  is an axonometric view from above of the flux director of  FIG. 2 ; and,  
         [0008]     FIG .  4  is a cross sectional view of the sub assembly of  FIG. 2 . 
     
    
     DETAILED DESCRIPTION  
       [0009]     Referring to  FIG. 1 , a exemplary embodiment solenoid operated valve assembly employing the present invention is indicated generally at  10  and includes a valve body  12  with a moveable valve member such as, for example, spool  14  disposed in a valving bore  16  for valving flow between an inlet port  18  and an outlet  20  port. The valve body  12  is attached to a first or lower flux collector  22  which has mounted thereon coil bobbin  24  with a coil  26  wound thereon. The bobbin  24  has the ends of the coil  26  connected to electrical terminals such as terminal  28  which extends into an electrical receptacle or shell  30  attached to one end flange  32  on the bobbin.  
         [0010]     A second or upper flux collector  34  is disposed on the end of coil  26  opposite flux collector  22  and has a portion thereof extending within the coil and forms an axial working air gap with an armature  36  disposed within the coil is surrounded by a casing or shell  35  which interconnects flux collectors  22  and  34 .  
         [0011]     An operating rod  38  is attached armature  36  and is journaled at its upper end within a bearing  40  disposed and the upper flux collector  34 . The lower end of the operating rod extends downwardly and is journaled in a second bearing  40  disposed in the first flux collector  22 . The lower end of the operating rod contacts the upper end of the valve member  14  for effecting movement thereof upon engergization of coil  26 .  
         [0012]     The upper end of the operating rod  38  may have a spring retainer  42  provided thereon which has registered there against the lower end of a spring  44  which has its upper end retained by an adjustment member  46  threadedly received in the flux collector  34  and is rotatable therein for adjusting the preload on spring  44  for calibrating the valve in a manner well known in the art.  
         [0013]     The upper end of the armature  36  has a tapered portion  48  provided thereon which cooperates with a correspondingly tapered recess  50  formed in the lower end of flux collector  34  forming therebetween a working air gap for, upon electrical energization of the coil, effecting axial movement of the armature and operating rod  38  to effect movement of the valving member  14 .  
         [0014]     Referring to  FIGS. 1 through 4 , a flux director end spacer sub assembly is indicated generally at  52  and includes annular mounting ring or spacer  54  with cutouts  56  formed circumferentially there about and generally equally spaced arrangement.  
         [0015]     A flux director indicated generally at  53  generally ring shaped or annular portion  58  formed of magnetically permeable material has disposed thereabout, in generally circumferentially equally spaced arrangement a plurality of inwardly extending fingers or wipers  60  which may have a fold or bend  62  formed thereon to provide a discrete surface for positioning about the periphery of the armature  36 . The flux director  53  may be formed from a flat blank from sheet stock of magnetically permeable material, and is shown in  FIG. 3  in the formed conditions. The flux director  53  may be formed of spring tempered material.  
         [0016]     Referring to  FIGS. 2 and 4 , the flux director  53  is shown assembled onto a spacer  54  which may be formed of plastic material, by deforming the fingers  60  and allowing the ends thereof to extend through the cutouts  56  to the interior of the spacer. The subassembly  52  of the annular flux director member  53  and spacer  54  maybe installed as a unit into the valve and configured to closely interfit the inner periphery of the bobbin  24  with the lower surface of member  58  contacting the upper end of the first flux collector  22  for providing a direct path of flux communication between the two members. The folds or bends  62  of the fingers  60  are positioned closely adjacent or lightly contacting the periphery of the armature to thereby provide equalized flux concentration about the periphery of the armature to thereby reduce the magnetic side loading thereon. This arrangement of the subassembly  52  allows it to be installed between the flux collectors of an existing solenoid operated valve construction without redesigning or retooling the parts thereof. The bends of folds  62  and the finger  60  may be either closely spaced to the armature or in light wiping contact therewith.  
         [0017]     The present invention thus provides a simple relatively low cost and easy to assemble technique for reducing the magnetic side loading on the armature of the solenoid operated valve due to eccentricities of the armature with the coil and flux collectors and provides a subassembly of a flux director which may be assembled into an existing valve design without any significant modification thereof.  
         [0018]     Although the invention has hereinabove been described with respect to the illustrated embodiments, it will be understood that the invention is capable of modification and variation and is limited only by the following claims.