Abstract:
An electric actuated control valve, such as an EGR valve, has an actuator whose armature contains an electromagnet coil for operating the actuator. Current for the coil is conveyed through a flexible circuit between the armature and a housing of the actuator.

Description:
REFERENCE TO A RELATED APPLICATION AND PRIORITY CLAIM  
       [0001]    This application derives from the following commonly owned co-pending patent application, the priority benefit of which is expressly claimed: Provisional Application Ser. No. 60/354,006 filed on Jan. 31, 2002 in the names of Gagnon et al. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention relates generally to electric-actuated control valves, such as emission control valves that are associated with automotive vehicle engines. More particularly, the invention relates to a control valve where electric current needs to be delivered to the armature of the actuator that positions a valve element relative to a valve seat. Principles of the invention are disclosed in an exemplary exhaust gas recirculation (EGR) valve.  
         BACKGROUND OF THE INVENTION  
         [0003]    The actuator of certain control valves comprises a solenoid that has an electromagnet coil that is energized by electric current to operate the valve. The electric current positions an armature of the actuator, with the armature motion being transmitted to a valve element to position the latter relative to a valve seat, thereby setting the restriction that the valve imposes on fluid flow through a body of the valve.  
           [0004]    In some actuators, the electromagnet coil is disposed on a stator of a magnetic circuit having an air gap at which magnetic flux generated in the stator acts on the armature. The stator and coil are stationary on the actuator, and so electric current is delivered to the coil via terminals that are also stationary.  
           [0005]    It has been discovered that certain attributes desired in an emission control valve can be obtained by mounting the coil on the armature rather than on the stator. One such attribute is the development of larger forces for operating the valve. Because the coil therefore moves with the armature, the electric connection between the moving coil and terminals that are stationarily mounted on the actuator to provide for connection of the coil with a remote source of electric current must accommodate the range of relative motion that can occur between the stator and the armature. Rather stringent demands from various sources, such as customers and government regulators, are imposed on emission control valves, and so a valve having a moving coil in its actuator must provide reliability and durability in the electric circuit connection leading to the coil.  
         SUMMARY OF THE INVENTION  
         [0006]    It is toward providing a valve of the latter type that the present invention is directed.  
           [0007]    One general aspect of the invention relates to an electric-actuated automotive emission control valve comprising a valve body comprising a passageway having an inlet port for receiving fluid and an outlet port for delivering fluid. A valve element is selectively positioned to selectively restrict the passageway. A mechanism for selectively positioning the valve element comprises a solenoid actuator comprising a magnetic circuit that comprises a stator, an armature, and an electromagnet coil disposed on one of the stator and armature. The stator, the armature, and the coil are collectively arranged to cause the armature and the stator to be relatively positioned along an axis in correlation with electric current in the coil. Wiring conducts the electric current between a termination at the coil and a termination at the other of the stator and the armature. The distance between the terminations, as measured along the axis, changes in correlation with the electric current, and the wiring has an arcuate shape about the axis as viewed in the direction of the axis.  
           [0008]    Another aspect relates to the solenoid actuator itself.  
           [0009]    The accompanying drawings, which are incorporated herein and constitute part of this specification, include a presently preferred embodiment of the invention, and together with a general description given above and a detailed description given below, serve to disclose principles of the invention in accordance with a best mode contemplated for carrying out the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a cross section view, in elevation, of an exemplary embodiment of an actuator of a valve embodying principles of the present invention, with the valve element and valve seat being portrayed schematically.  
         [0011]    [0011]FIG. 2 is a horizontal view in the direction of arrows  2 - 2  in FIG. 1.  
         [0012]    [0012]FIG. 3 is an exploded perspective view of the actuator. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0013]    The drawings show an electric exhaust gas recirculation valve (EEGR valve)  10  intended for use with an internal combustion engine to control the flow of exhaust gas being recirculated from an exhaust system of the engine to an intake system of the engine.  
         [0014]    Valve  10  comprises a body  12  containing a flow passage  13  extending between a valve inlet port  14  adapted to be communicated to the engine exhaust system and a valve outlet port  16  adapted to be communicated to the engine intake system.  
         [0015]    Valve  10  further comprises an actuator  18 , which is under control of an engine control system to control the extent to which valve  12  allows exhaust gas to be recirculated through flow passage  13 . In the closed position of valve  12  that blocks exhaust gas recirculation, a valve element  20  of valve  12  is closing on a valve seat  22  in flow passage  13 , closing the flow passage to flow of exhaust gas between ports  14  and  16 .  
         [0016]    As the engine control system delivers increasing electric current to actuator  18 , a point is reached where the current is sufficiently large to create sufficient force for unseating valve element  20  from seat  22 , thereby opening the valve. Further increases in current increasingly open the valve.  
         [0017]    Actuator  18  comprises a multi-part housing  24  that includes a base  26 , a spacer  28  and a cap  30 . Base  26  is a generally cup-shaped part that has a flat bottom wall  32  and a circular cylindrical sidewall  34  that stands upright on bottom wall  32 . Spacer  28  is a circular cylindrical part that stands on cup sidewall  32 , and cap  30  forms a closure for the open upper end of spacer  28 .  
         [0018]    Actuator  18  and valve body  12  are assembled together and share a common imaginary centerline  36 . The assembled parts  26 ,  28 , and  30  enclose an interior space of actuator  18  housing an armature  38  that is movable along centerline  36 . Armature  38  itself comprises several parts including a bobbin  40 , an electromagnet coil  42 , and an armature shaft  44 . Bobbin  40  comprises a transverse wall  46  and a circular cylindrical sidewall  48  that depends from the outer margin of wall  46 . The outer face of sidewall  48  comprises a recess containing coil  42 . A material such as magnesium is suitable for bobbin  40 .  
         [0019]    Two additional parts  50  and  52  of actuator  18  cooperate with base  26  to form a stator of the actuator. Part  50  is a magnet that provides magnetic flux for the magnetic circuit formed by the stator. Parts  50  and  52  are stacked as shown on bottom wall  32  within the actuator interior space. The parts cooperatively define a circular cylindrical groove  54  concentric with centerline  36  within the actuator interior space. The three parts  32 ,  50 , and  52  also cooperatively define a through-hole  56  on centerline  36 . A bearing sleeve  58  is fit to through-hole  56  to provide guidance for the motion of armature shaft  44  along centerline  36 . Armature shaft  44  extends completely through bearing sleeve  58 , being suitably fastened or otherwise joined to valve element  20  at one end, and being fastened to the center of bobbin wall  46  at its other end. The latter fastening is accomplished by abutment of a shoulder on shaft  44  with one end of a hub  60  at the center of bobbin  40 , and a retaining ring  62  that is assembled to shaft  44  to bear against wall  46  at the opposite end of hub  60 , thereby capturing bobbin  40  on shaft  44 .  
         [0020]    Armature  38  is spring-biased upwardly along centerline  36  by a helical coil spring  64  within actuator  18 . A zone of bobbin wall  46  surrounding hub  60  is formed to provide a seat for one end of spring  64 , while a confronting face of part  52  provides a seat for the opposite end of the spring. Spring  64  is partially axially compressed to exert an upward force that is effective to bias valve element  20  closed on seat  22  when coil  42  is not being energized. This is the position shown in FIG. 1.  
         [0021]    The upward bias force being imparted to armature  38  by spring  64  also acts to position a plunger  66  of a position sensor  68  housed within cap  30 . When the energization of coil  42  acts to move armature  38  downward to unseat valve element  20  from seat  22  and thereby open the valve, as will be more fully explained hereinafter, an internal spring within sensor  68  keeps plunger  66  biased against the end of shaft  44  so that sensor  68  faithfully tracks the position of armature  38  along centerline  36  and hence the extent to which the valve is open.  
         [0022]    Cap  30  also comprises an electric connector  70  via which the engine control system delivers electric current to coil  42  and sensor  68  is read by the engine control system. Connector  70  contains two electric terminals  72 ,  74  for providing connection to opposite terminations of coil  42 , and three terminals (not shown) associated with sensor  68 . However, because armature  38  moves relative to cap  30  as coil  42  is energized, circuit continuity from the fixed terminals  72 ,  74  to the moving coil  42  must be provided, and it is such continuity that is provided by the present invention.  
         [0023]    That continuity is provided by a flexible circuit  76  in the form of a flat, two-conductor insulated strip that has a circular arcuate shape about centerline  36  as viewed in the direction of the centerline. The strip contains two conductors  78 ,  80 , each connecting a respective terminal  72 ,  74  and a respective termination of coil  42 . In the illustrated embodiment, the flat strip has a width that is radial to centerline  36 - and a length that is generally circumferential about centerline  36 . The greater the circumferential extent of the strip, the less the strip will have to flex, and so it may be considered desirable for the strip to extend circumferentially as much as possible about the centerline. For example, short axial travel of the armature may allow the strip to have a circumferential extent in a range from about 90° to about 180°. For longer axial travel of the armature, the strip may have a circumferential extent greater than 180°. The strip is fabricated by known flexible circuit techniques and has appropriate terminations at the ends of the conductors  78 ,  80  for making connections with the cap terminals and the coil.  
         [0024]    One end of circuit  76  is disposed on an overhang  82  on the upper rim of spacer  28 . There, each of the two conductors  78 ,  80  makes connection with a respective one of the cap-mounted terminals  72 ,  74 . The opposite end of circuit  76  is disposed on bobbin  40  where each of the two conductors  78 ,  80  makes connection with a respective termination of coil  42 .  
         [0025]    As the engine control system delivers increasing electric current to coil  42 , the magnetic field that the coil generates interacts with the magnetic flux in the stator circuit across groove  54  to cause increasing downward force to be developed on armature  38 , increasingly compressing spring  64  and increasingly opening the valve in the process. Flexible circuit  76  increasingly flexes in the process, but remains fully capable of carrying the electric current flow to the coil. An example of a suitable flexible conductor is a Novaclad brand of conductor.  
         [0026]    While the foregoing has described a preferred embodiment of the present invention, it is to be appreciated that the inventive principles may be practiced in any form that falls within the scope of the following claims.