Abstract:
An injector valve armature/spacer is formed as an integral tri-function multiple thickness member for an engine fuel injector. The member includes an armature having a center portion with an upper side engagable by a biasing spring and an outer portion with spaced radial openings extending outward from the center portion. An outer rim is connected to the inner portion of the armature by flexible legs extending radially through the radial openings. The rim has a thickness greater than that of the armature by a differential dimension establishing a stroke of the armature. The legs have a thickness less than that of the armature to permit flexing of the legs upon movement of the armature. The integral member is designed for manufacture in multiple layers using electroforming, optionally combined with metal etching.

Description:
TECHNICAL FIELD 
     This invention relates to solenoid actuated fuel injectors for engines and, more particularly, to an injection valve armature/spacer formed as an integral dual function multiple thickness member. 
     BACKGROUND OF THE INVENTION 
     It is known in the art relating to solenoid actuated engine fuel injectors to provide a disk-like armature biased against a valve seat to cut off fuel flow and attractable to inner and outer magnetic poles to permit flow through the valve seat. A separate spacer may be provided to establish the stroke of the armature to control the rate of fuel flow. Flexible legs may be attached to the armature to guide its motion within a valve body and minimize friction during opening and closing motion. Typically, an armature includes multiple components requiring individual forming and machining or other processing and requiring assembly in an injector with other components to form a completed structure ready for use. A simpler armature assembly involving less costly or reduced processing steps is desired. 
     SUMMARY OF THE INVENTION 
     The present invention provides an improved and simplified armature/spacer member, which combines in an integral unit the functions of an armature and a stroke setting spacer. The member is preferably made using electroforming and/or metal etching processes. The member may be made in layers with differing materials, if desired, and with differing thicknesses to best accomplish the purposes of the integral member. 
     In a preferred embodiment, an injection valve armature/spacer, is formed as an integral tri-function multiple thickness valve member for an engine fuel injector. The member includes an armature having a center portion with an upper side engagable by a biasing spring and an outer portion with spaced radial openings extending outward from the center portion. An outer rim is spaced outward of the armature and is connected to it by a plurality of flexible legs extending radially in the radial openings from the center portion of the armature to the rim. 
     The legs are flexible axially but stiff radially to maintain the radial position of the armature while allowing it to move axially between lower and upper positions that respectively open and close a valve seat. The rim positions the legs and also acts as a spacer that established the armature stroke. Thus, the integral member functions as a valve member, armature guide and stroke setting spacer. 
     The armature has a flat lower surface engagable with the valve seat and a flat upper surface engagable with inner and outer magnetic poles of a solenoid. The outer rim also has flat upper and lower surfaces, respectively engagable with surfaces coplanar with the magnetic poles and the valve seat. 
     The rim has a thickness greater than that of armature by a differential dimension which establishes the stroke of the armature. The legs have a thickness less than that of the armature to permit flexing of the legs upon movement of the armature. 
     The member may be formed in layers including a first layer comprising the rim, legs and armature, a second layer formed on the first layer and comprising the rim and armature, and a third layer formed on the second layer and comprising the rim. Electroforming, metal etching or a combination of these processes may be used to form the armature/spacer member. The resulting member may be made to the desired dimensions with required flat sealing and mounting surfaces without additional machining or other finishing. A simple but effective member thus results. 
     These and other features and advantages of the invention will be more fully understood from the following description of certain specific embodiments of the invention taken together with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a cross-sectional view of an exemplary solenoid actuated fuel injector having an integral armature/spacer member according to the invention; 
     FIG. 2 is a top view of the integral member of FIG. 1; 
     FIG. 3 is a cross-sectional view from the line  3 — 3  of FIG. 2; 
     FIGS. 4-6 are top views of first, second and third metal layers applied in forming the integral member of FIGS. 2 and 3; and 
     FIGS. 7 and 8 are views similar to FIGS. 2 and 3 respectively but showing an alternative embodiment of integral armature/spacer member. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring first to FIG. 1 of the drawings in detail, numeral  10  generally indicates an exemplary solenoid actuated fu al injector for an engine. Injector  10  includes a non-magnetic cover  12  enclosing a solenoid coil  14 . A fuel tube extends through the coil and acts as an inner magnetic pole  16 . An outer strap  17  connects with the inner pole  16 , extends around the coil  14  and connects with an annular member forming an outer magnetic pole  18 . A nonmagnetic spacer  19  provides a seal between the inner and outer poles below the coil. 
     The outer pole  18  includes a skirt  20  that is fixed to a lower housing  22  defining an external seal groove  24 . Housing  22  has a flat upper wall  26  that opposes and is spaced from coplanar flat lower surfaces  28 ,  30  of the inner and outer poles, respectively. The housing  22  also has a central opening  31  through the upper wall  26  and connecting with an enlarged open area below for the passage of fuel spray from the injector. 
     Disposed between the housing upper wall  26  and the magnetic pole lower surfaces  28 ,  30  is an injection valve comprising a valve seat and spray director unit  32 , mounted on the housing upper wall  26 , and an armature/spacer member  34 . Seat/director unit  32  is made as an integral member including subject matter claimed in copending U.S. patent application Ser. No. 09/660,950, filed concurrently with the present application on Sep. 13, 2000. Unit  32  is shaped as a circular disk, which includes a flat lower surface  36  that seats against the flat upper wall  26  of the lower housing  22 . A thickened outer rim or concentric outer ribs  38  form a periphery of the disk while one or more raised ribs in a central portion  40  of the disk form a valve seat  42 . Spray holes  44  within the central portion act as a director plate to form a spray of fuel passing through the holes  44 . The rim or outer ribs  38  and the valve seat  42  preferably have equal thickness dimensions so that the rim upper surface  45  is coplanar with the valve seat  42 . A biasing spring  46 , seats against a calibration sleeve  48  fixed in the pole  16  and engages member  34  for a purpose to be subsequently described. 
     The armature/spacer member  34  is formed in accordance with the present invention and is shown enlarged in FIGS. 2 and 3. Member  34  includes a movable armature  50  having a center portion  52  with a flat upper side  54  engaged by the spring  46  and engagable with the magnetic poles  16 ,  18 . The spring biases a flat lower surface  56  of the armature against the valve seat  42  to cut off fuel flow through the injector. Armature  50  also includes an outer portion  58  having annularly spaced radial openings  60  extending outward from the center portion  52 . A plurality of relatively thin flexible legs  62  extend radially out from the center portion  52  and connect with an outer rim  64  spaced outward of the armature  50 . Rim  64  preferably has a flat upper surface  65  and may include inwardly extending portions  66  that extend into cutouts  68  in the armature outer portion  58 . Fuel openings  70  are provided in the center portion  52 . A raised inner guide  72  is also preferably provided on the center portion  52  to locate the lower end of the spring  46  against the armature  50 . 
     The armature  50 , legs  62  and rim  64  are formed as integral elements of member  34 , in which the flat lower surface  56  preferably extends from the armature  50  through the legs  62  into the outer rim  64 . The portions of the lower surface in the elements  50 ,  62 ,  64  of member  34  preferably remain coplanar while armature  50  is seated against the valve seat  42 . 
     The thickness of the various elements may differ as needed to accomplish their various purposes. The legs  62  are made thin to maintain flexibility needed to allow axial movement of the armature. The armature  50  is made thicker to carry magnetic flux between the inner and outer poles  16 ,  18  of the injector when the coil  14  is energized. The rim  64  is made slightly thicker than the armature  50  to act as a spacer that is clamped between the rim or outer ribs  38  of the seat/director unit  32  and the outer magnetic pole  18  of the injector. The difference, or increase in thickness of the rim (spacer)  64  over the armature  50 , establishes the allowable stroke of the armature from its closed position on the valve seat to its open position engaging the inner and outer poles  16 ,  18 . 
     In operation of the injector in an engine, pressurized fuel is admitted to the full tube/inner pole  16  and flows through armature openings  70  to the upper surface of the valve seat/director unit  32 , where it is blocked while the armature  50  remains seated against the valve seat  42 . When the solenoid coil  14  is energized, armature  50  is drawn upward, with the upper side  54  against the magnetic poles  16 ,  18 , by an axial displacement equal to the difference in thickness between the armature and the thicker outer rim  64 . The legs  62  flex to allow this motion of the armature relative to the rim of the integral armature/spacer member  34 . The upward stroke of the armature opens valve seat  42  and allows fuel flow through the spray holes  44  of the integral spray director. The fuel flow continues until the coil  14  is deenergized and the spring  46  again forces the armature  50  to engage the valve seat  42 . 
     The armature/spacer member  34  of FIGS. 2 and 3 may be made by any suitable process. However, it has been particularly designed to permit manufacture by electroforming or a combination of metal etching with electroforming. FIGS. 4-6 illustrate the steps involved in certain processing methods in which the member  34  is formed in layers. 
     FIG. 4 illustrates a first layer  74 , which includes parts of all elements of the member  34 . Layer  74  may be electroformed of nickel or etched from a martensitic stainless steel mandrel. In either case, the first layer  74  has the thickness of the flexible legs  62 . The material is selected to meet the requirements of the legs in maintaining the armature  50  centered while allowing axial stroking of the armature between its open and closed positions. 
     FIG. 5 illustrates on a second layer  75  of iron, which is preferably eletroformed onto the first layer. The thicknesses of the armature  50  and the outer rim  64  are thereby increased to the desired thickness of the armature. However, the legs are not included since they have been formed in the desired thickness and material in the first layer  74 . 
     FIG. 6 illustrates a third layer  76  of iron, which is electroformed onto the second layer  75 . The third layer  76  increases the thickness of the outer rim  64  to its desired thickness by adding the rim thickness needed to establish the desired stroke of the armature  50 . The thickness of the outer portion  58  of the armature  50  is, of course, not increased by addition of the third layer  76 . Preferably, the third layer also adds the inner guide  72  to the center portion  52  of the armature, since this can be done with the same electroforming step. 
     The completed layered armature/spacer member  34  is formed by electroforming, or a combination with metal etching, to net shape dimensions that do not require further metal finishing steps. Thus, an integral multiple function armature, guide and spacer is formed by known processes without further assembly or machining steps being required. 
     FIGS. 7 and 8 illustrate an exemplary alternative embodiment of armature/spacer member  78  according to the invention. Member  78  is similar to member  34  in that it includes a movable armature  80  having a center portion  82 . Armature  80  also includes an outer portion  84  having annularly spaced radial openings  86  extending outward from the center portion  82 . A plurality of relatively thin flexible legs  88  extend radially out from the center portion  82  and connect with an outer rim  90  spaced outward of the armature  80 . Rim  90  includes inwardly extending portions  92  that extend into flared portions of the radial openings  86  in the armature outer portion  84 . Fuel openings  94  are provided in the center portion  82 . A raised inner guide  96  is also provided on the center portion  82  to locate the lower end of a biasing spring  46  against the armature  80 . Outside the guide  96 , an annular recess  98  is provided to receive the spring  46 . 
     The use, manufacture and general characteristics of member  78  are otherwise similar to those of member  34 , illustrated in FIGS. 1-6 so that further discussion is not required. 
     While the invention has been described by reference to certain preferred embodiments, it should be understood that numerous changes could be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the disclosed embodiments, but that it have the full scope permitted by the language of the following claims.