Abstract:
A solenoid valve moves an armature back and forth translationally between valve open and valve closed positions without the armature having any sliding engagement with any fixed valve part. This is accomplished by supporting the armature with a spring having one periphery engaging a fixed valve surface and another periphery engaging the armature so that armature movement causes flexure of the spring, but no sliding contact. This helps prevent generation of dirt within the valve and ensures accurate armature movement to make the valve durable and reliable. Springs in both washer and cylindrical helical shapes can accomplish this, and the armatures supported by such springs can accommodate valve closing seals of different materials and shapes.

Description:
RELATED APPLICATIONS 
   This application is a continuation-in-part of copending application Ser. No. 10/953,648, filed 29 Sep. 2004, entitled “Non-sliding Valve”. 

   BACKGROUND 
   Meeting the most challenging reliability standards requires solenoid valves to operate cleanly without developing any contamination particulates within the valve during repeated actuations. For example, solenoid valves must be especially free of particles to be deployed in space vehicles and satellites where valve performance must be highly reliable and valve failure can be disastrously expensive. 
   This invention involves recognition of ways that particles are created during operation of solenoid valves, and ways to avoid such particle contamination. Besides avoiding valve failures from internal contamination, the invention aims at more reliable valve operation accomplished by especially accurate valve opening and closing motions. While combining particle avoidance and accurate movements, the invention also aims at ensuring valve durability and dependability at an affordable price. 
   SUMMARY 
   The inventive valve avoids internal particle generation by avoiding sliding contact between a movable armature and fixed valve surfaces during valve operation. Experiments have established that sliding contact between valve parts produces tiny contaminant particles that can migrate to sensitive internal regions of the valve and cause leakage or mal-performance. The invention thus aims at a cleaner and more reliably operating valve by eliminating such sliding contact. 
   In addition to eliminating contamination from sliding contact, the invention also aims at consistently moving a valve closing puck or seal into engagement with a valve seat so that contact between the seal and the seat always occurs in precisely the same region of the seal or puck. This ensures that leakage does not occur from eccentric seating ring engagement between the seal and the valve seat. 
   A spring support and guidance system accomplishes the movement of an armature of a solenoid clear of any sliding contact with valve parts. The armature preferably carries a valve-closing seal and is supported by a spring system to move axially in translation without moving radially or rotationally. The armature can engage a non-magnetic stop when moved to a fully open position by the solenoid, but such engagement does not involve any sliding contact and does not produce noticeable particles. 
   One spring system for accomplishing this uses a washer shaped annulus that connects to an armature at an internal periphery and connects to a valve body at an external periphery. Such an arrangement ensures that the armature cannot move radially or rotationally and is able to translate only axially during valve opening and closing. Another spring support embodiment uses a generally helical cylindrical spring flanged at one end to fit a fixed valve surface and flanged at another end to fit to and support the movable armature. Helical turns of the spring between the flanged ends flex to allow the armature to move translationally but not radially, with neither the spring nor the armature involved in any sliding contact with any valve surface. 

   
     DRAWINGS 
       FIG. 1  is a fragmentary cross-sectional view of a preferred embodiment of the inventive non-sliding valve shown in a closed valve position, 
       FIG. 2  is a fragmentary cross-sectional view similar to the view of  FIG. 1 , showing a valve open position. 
       FIGS. 3A–C  are plan views of alternative variations in spring supports such as used in  FIGS. 1 and 2 . 
       FIG. 4  is a fragmentary cross-sectional view of a helical spring embodiment of the invention showing the valve in a closed valve position. 
       FIG. 5  is a fragmentary cross-sectional view showing a seal of the type illustrated in  FIG. 4  applied to an armature supported by a washer shaped spring such as illustrated in  FIGS. 1 and 2 . 
       FIGS. 6 and 7  are cross-sectional views of the inventive valve arranged in tandem, as is preferred for space vehicle purposes, and supplied with washer-shaped spring supports providing respectively one pound and five pound closure forces for mono propellants. 
       FIG. 8  is a cross-sectional view of another version of the inventive valve arranged in tandem and using washer-type spring supports deployed for five pound closure forces and a seal arrangement suitable for bi-propellant. 
       FIG. 9  is a cross-sectional view of another variation of the inventive valve arranged in tandem and having helical spring supports exerting five pound closure forces on seals suitable for bi-propellants. 
   

   DETAILED DESCRIPTION 
   One preferred embodiment of a non-sliding valve  10 , as shown in  FIGS. 1 and 2 , includes armature  20  supported by spring  30  and carrying valve closing puck or seal  25  and solenoid  11  formed of coil  12 , non magnetic flux stop  13  and non-magnetic core or abutment  14 . A flux path transmitted from coil  12  through solenoid body  15  to a periphery of armature  20  draws armature  20  against stop  14  to open valve  10 , as shown in  FIG. 2 . The seal  25  that is shown in  FIGS. 1 and 2  is a cylindrically shaped puck of a flexible material that is available for valve closing seals. Seals of other materials and forms are also possible, and one of these is illustrated in  FIGS. 4 and 5  and explained below. 
   In the position of  FIG. 1 , puck  25 , which is elastomeric or compressible, engages a valve seat  26  in valve body  27  to close valve  10 . Armature  20  moves linearly and axially toward and away from valve seat  26 , without engaging valve parts in any sliding contact. Spring  30 , which makes this possible, is shaped as a plane annular disk resembling a washer, as shown in  FIG. 3 . An internal or inside diameter  31  of a central opening in spring  30  engages armature  20 , and an outside diameter or outer periphery  32  is seated in a groove  28  in valve body  27 . 
   In the position shown in  FIG. 1 , spring  30  is biased to press armature  20  and puck  25  against valve seat  26  in a normally closed valve position. When solenoid  11  actuates, it draws armature  20  against the bias of spring  30  to the open valve position shown in  FIG. 2  in which puck  25  moves away from valve seat  26  and allows fluid flow. 
   The connection between spring  30  and armature  20  is preferably made by a close tolerance fitting of an internal diameter  31  of spring  30  into groove  21  in armature  20 . This is preferably accomplished by chilling armature  20  to a low temperature, while keeping spring  30  at a higher temperature so that the ID  31  of spring  30  can be snapped into groove  21  for a snug fit when armature  20  and spring  30  reach the same temperature. 
   The outer perimeter  32  of spring  30  is preferably secured in valve body groove  28  by means of a spacer ring  29  having a press fit within valve body part  27 . As spring  30  flexes between the closed valve position of  FIG. 1  and the open valve position of  FIG. 2 , its outer perimeter  32  moves slightly within groove  28 , but this movement has been shown by experiment not to produce any significant contamination particulate. The movement is very slight and is confined within a substantially closed groove  28 . 
   The valve closing bias of spring  30  is affected by how tightly ring spacer  29  encloses the outer perimeter  32  of spring  30  within groove  28 . The correct adjustment of this is preferably accomplished by machining ring spacer  29  until its press fit into valve body part  27  produces the correct clearance for groove  28  to give spring  30  its closing bias. This closing bias is also selected to be overcome by solenoid  11  when actuated to open valve  10 . 
   The movement of armature  20  against the fixed, non-magnetic abutment  14  is a non-sliding, tapping motion that essentially does not produce particles. Such a tapping motion contrasts significantly with a sliding motion of an armature or its guide against a fixed valve surface. The lack of particles from a non-sliding motion has been established by tests involving many millions of openings for valve  10 . 
   The geometry of spring  30  ensures that armature  20  cannot depart from a linear axial movement toward and away from valve seat  26 . Such movement is physically defined as a translation involving movement of every point of armature  20  parallel to, and at the same distance as, every other point of armature  20  without any rotation or arcuate movement of armature  20  around any axis. Such translational movement is also clear of any sliding contact with any valve part to ensure particle-free and reliable operation. This arrangement also brings puck  25  accurately back to the same engagement with valve seat  26  for each subsequent closed valve position so that puck  25  and seat  26  always engage in the same circular ring. This ensures that leakage does not develop between puck  25  and valve seat  26  from eccentric and overlapping successive engagements. 
   Another preferred valve embodiment  60  using a cylindrically shaped helical spring  50  to support a solenoid armature  40  is shown in  FIG. 4 . Except for armature  40 , spring  50 , and seal  45 , parts of solenoid  11 , including coil  12 , flux stop  13 , and abutment core  14  are all as previously described for the embodiment of  FIGS. 1 and 2 . 
   The main difference in the embodiment of  FIG. 4  is the use of a helical coil spring  50 , rather than a washer shaped spring such as shown in  FIGS. 1 and 2 . Helical coil spring  50  is preferably machined of a piece of spring steel and formed in a generally cylindrical shape with a moveable end flange  36  fitting armature  40  and a fixed end flange  36  fitting valve body  35 . Spring  50  can also have its fixed and moveable ends welded in place, but since it is being made of machined steel, it is efficient to form a fixed flange  36  fitted to valve body  35  and a movable end flange  37  fitted to and supporting armature  40 . Such flanges can be shaped in many different ways. 
   As explained for valve  10  of  FIGS. 1 and 2 , valve  60  of  FIG. 4  moves armature  40  axially to pull seal  45  away from valve seat  46 , against the bias of spring  50 , without armature  40  or seal  45  departing from a translational movement. Also, armature  40  contacts only spring  50  and abutment  14  and does not slide in contact with any fixed valve surface during opening and closing movement. Valve  60  thus accomplishes the same goals of particle-free and accurate operation as described for valve  10 . 
   Seal  45 , as shown in  FIGS. 4 and 5  is preferably based on U.S. Pat. No. 6,135,132, which shows how a seal of tetrafluoroethylene can be arranged to perform well in a poppet valve environment. Tests made according to this invention have determined that a washer shaped spring support  30 , as illustrated in  FIGS. 1 ,  2 , and  5  can perform accurately enough to accommodate the limitations of a tetrafluoroethylene seal  45 . The results of these tests show that armature  20  is accurately consistent in its translational movement so that seal  45  performs flawlessly. 
   Besides ensuring accurate axial translational movement of armature  20 , support spring  30  and solenoid  11  operate to ensure that armature  20  does not rotate. This occurs partially from the controlled support of spring  30  and partly from the fact that magnetic flux forces are applied only peripherally of armature  20  and only axially of armature  20  so that no force tends to rotate armature  20 . A washer shaped spring support  30 , because of its accurate control of armature movement, thus promises to accommodate any sort of puck or sealing material required for a poppet valve. 
     FIGS. 6 and 7  show valves  70 , which are similar to valves  10  of  FIGS. 1 and 2 , arranged in tandem, as is preferred for space vehicles. Allowing a discharge of propellant for maneuvering purposes requires that both valves  70  be open, and the tandem arrangement of valves  70  increases the chances that at least one of the valves  70  will close to prevent any unwanted waste of propellant. The valves of  FIGS. 6 and 7  each use a washer-shaped spring  30  such as described above and shown in  FIGS. 3A–C , to support and bias an armature  20  carrying a valve sealing puck  25 , as also explained above. 
   Differences between the valves of  FIGS. 6 and 7  primarily involve a one pound closing bias for springs  30  in valve  70  of  FIG. 6 , and a five pound closure bias of springs  30  of valves  70  of  FIG. 7 . Armatures  20  of valves  70  of  FIGS. 6 and 7  also move translationally without any sliding contact with other valve parts, as previously explained. 
   Valve  80  of  FIG. 8  uses a pair of valves that are each similar to the valve of  FIG. 5 , but are arranged in tandem as preferred. Armatures  20  are supported for translational movement by washer-type springs  30  which apply a five pound valve closure bias. Seal  45  is preferably a tetrafluoroethylene seal such as previously described for the valves of  FIGS. 4 and 5  as suitable for bi-propellants. Springs  30 , as previously explained, have been proven to control translational movement of armature  30  accurately enough for reliable operation of seals  45 . 
   Valves  90 , of  FIG. 9 , are shown arranged in tandem for bi-propellant control, and are otherwise similar to valves  60  shown in  FIG. 4 . Valves  90  use helical springs  50  supporting and controlling the translational movement of armatures  40 , which carry seals  45  of the type shown in  FIGS. 4 ,  5 , and  8  for bi-propellant control. Helical springs  50  are arranged to exert five pounds closure force on seals  45  of valves  90 , but different closure forces are also possible. 
   Many different arrangements of disk and helical springs can achieve the same advantages as explained for the illustrated valves. Also different materials and solenoids can be used to adapt the invention to different applications.