Abstract:
A solenoid actuated valve includes a plastic nylon bobbin which has a relatively rigid portion which supports the electrical actuation coil and a separate, relatively resilient portion, which is integrally formed with the rigid portion of the bobbin for the mounting thereof. An armature is positioned for reciprocating displacement within a central passageway of the bobbin in response to selective energization of the coil. A spool valve is operatively connected for movement with the armature. A frame assembly supports the solenoid valve and continuously compressively loads the resilient portion of the bobbin within a non-plastic range of deformation.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates generally to solenoids, and particularly to solenoid valves. 
       BACKGROUND OF THE INVENTION 
       [0002]    Solenoids are used in a myriad of applications in the automotive industry. For example, solenoids may be used for high power switches with a lower power control signal. Solenoids are also used in automated or remote valves, such as a canister vent solenoid associated with evaporative emission control systems. Such solenoid valves may be used to control the flow of a variety of fluids or gasses. For example, in the context of a canister vent solenoid, the solenoid valve may be used to control the flow of fuel vapors into a charcoal canister. Solenoid valves may be similarly used to control the flow of liquids and vapors for other vehicle systems. 
       SUMMARY OF THE INVENTION 
       [0003]    These and other features and advantages of this invention will become apparent upon reading the following specification, which, along with the drawings, describes preferred and alternative embodiments of the invention in detail. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
           [0005]      FIG. 1 , is a broken, perspective cross-sectional view of the actuator portion of an automotive oil control valve assembly embodying the present invention; 
           [0006]      FIG. 2 , is a rotated, front plan view of an electromagnetic coil, secondary magnetic flux plates and supporting bobbin from the actuator of  FIG. 1 ; 
           [0007]      FIG. 3 , is a side plan view of the bobbin from the actuator of  FIG. 1  on a substantially enlarged scale with a mesh superimposed thereon for FEA analysis of the hinge-like feature at the base of the bobbin; 
           [0008]      FIG. 4 , is a rotated, front plan view of the bobbin similar to that of  FIG. 2 , but with the electromagnetic coil and secondary magnetic flux plates removed, to illustrate structural detail of the bobbin itself; 
           [0009]      FIG. 5 , is a broken, side plan view of the bobbin of  FIG. 4  on an enlarged scale illustrating the (relatively rigid) portion of the bobbin for supporting the electromagnetic coil and (relatively resilient) base portion for flexing in response to varying axial loads; 
           [0010]      FIG. 6 , is a broken, side plan view of an bobbin similar to that of  FIG. 5  embodying an alternative embodiment of the invention; 
           [0011]      FIG. 7 , is a broken, side plan view of a bobbin similar to that of  FIG. 5  embodying a second alternative embodiment of the invention; 
           [0012]      FIGS. 8-16 , each depict a common side plan view of a model bobbin similar to that of  FIG. 2  illustrating a Normal stress map calculated for an axially applied pressure varying incrementally from 0 MPa ( FIG. 8 ) to 200 MPA ( FIG. 16 ); 
           [0013]      FIGS. 8A-16A , correspond with  FIGS. 8-16 , respectively, but with the Normal stress maps illustrated in color; 
           [0014]      FIG. 17 , is a broken, cross-sectional view of the base portion of the bobbin of  FIGS. 1-5  in an axially unloaded or relaxed condition; 
           [0015]      FIG. 18 , is a broken, cross-sectional view of the base portion of the bobbin if  FIGS. 1-5  in an axially loaded condition; and 
           [0016]      FIG. 19 , is a cross-sectional view of the bobbin of  FIG. 4 . 
       
    
    
       [0017]    Although the drawings represent embodiments of the present invention, the drawings are not necessarily to scale and certain features may be exaggerated in order to illustrate and explain the present invention. The exemplification set forth herein illustrates an embodiment of the invention, in one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
       DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0018]    Although suitable for many automotive and non-automotive applications, the present invention is particularly well adapted for use in an automotive oil control valve, and will be described in that context. 
         [0019]    In previous automotive oil control valve designs, it was noted that the bobbin can become loose after durability tests and engine tests. It is surmised that the bobbins can become loose due to the difference in thermal expansion coefficients between steel and plastic, that creates a creeping effect or deformation in the plastic. This can result in objectionable rattling, fluid leaks of malfunction of the device. Benchmarking demonstrated that existing competitive designs have similar design issues which were addressed by varying solutions such as press fits, separate spring washers and crimping steel-to-steel surfaces. Although partially effective solutions, these approaches prove to be expensive and can introduce new failure modes. An additional solution is the use of a crush rib which can only retard or lessen (but not fully resolve) the effect. 
         [0020]    The present invention provides a cheap (negligible additional cost) and permanent solution. 
         [0021]    The present invention proposes a hinge-like feature at the base of the bobbin that will damp the effect of the force exerted during the crimping operation (of the frame) during assembly. Over time, as the plastic yields beneath the steel frame, the hinge will spring-back (because it will not reach its yield strength) and retain rigidity of the assembly. 
         [0022]    Referring to  FIG. 1 , a solenoid actuator assembly  10  for use with an automotive oil control valve  12  (shown partially) is illustrated. The actuator assembly  10  includes a subassembly including a bobbin  14  formed in one piece of injection molded plastic such as nylon. The bobbin has a main or base portion  16  which carries an electromagnetic coil  18  on the outer surface thereof. One end of the bobbin  14  is closed to define an electrical connector terminal interface as well as mounting features for a secondary magnetic flux plate  20  (steel). The bobbin  14  is overmolded with non-conductive plastic-like material  22 . 
         [0023]    The subassembly, including the bobbin  14  and the overmolding material  22  is disposed within a generally cylindrical steel can or magnetic frame  24 , the inner diameter surface of which is in close proximity with the secondary plate  20 . The open end of the bobbin  14  defines a skirt-shaped portion  26  which extends axially from the base portion  16 . The base portion  16  and skirt portion  26  are integrally formed of nylon or other suitable material. The base portion  16  of the bobbin  14  is dimensioned and configured to be relatively rigid while the skirt portion  26  is dimensioned to be relatively resilient, particularly in the axial direction (A-A). 
         [0024]    A primary magnetic flux plate  28  (steel) is press fit within the frame  24  and includes an annular opening concentric with the central opening of the bobbin  14  for receiving a generally cylindrical/tubular cup guide  30 . Cup guide  30  has a flange  32  extending radially from the lower portion thereof which is clamped in position by a steel washer  34 . An inner primary magnetic flux plate  36  (steel) is disposed within the cup guide  30 . 
         [0025]    A steel housing  38  extends axially from the frame  24  to become the oil control valve  12 . An armature/plunger  40  is slidably disposed within the guide cup  30  and defines an axially extending damping passageway  42  therethrough. A steel spool valve  44  extends through housing  38  into valve  12 . 
         [0026]    The axial ends of the frame  24  are crimped radially inwardly to abut abut a radial step  46  formed in overmolding material  22  and a radial step  48  formed in housing  38  to apply an axial compressive load to the bobbin  14 , inter alia. 
         [0027]    The skirt portion  26  of the bobbin is formed as upper and lower axially spaced rings  50  and  52 , respectively, and an axially intermediate thin-walled section or web  54  integrally formed therewith. As best viewed in  FIGS. 17 and 18 , the upper portion of the web  54  transitions into upper ring  50  to define a downwardly (axially) facing abutment surface  56 . Likewise, the lower portion of the web  54  transitions into the lower ring  52  to define an upwardly (axially) facing abutment surface  58 . Abutment surfaces  56  and  28  are thus axially spaced when the bobbin is in the relaxed position as depicted in  FIG. 17 . The point of transition of the main portion  16  of the bobbin  14  into the skirt portion  26  also defines opposed, axially spaced abutment surfaces  60  and  62 , respectively, intersaced by a web  63 . 
         [0028]    When the frame  24  is crimped as part of the final assembly of the actuator assembly  10 , axially compressive loading is imposed upon the bobbin as depicted by arrows  64  and  66  in  FIG. 18 . Depending upon the axial force applied and other factors, such as ambient temperature, opposed abutment surfaces  56  and  58  as well as opposed abutment surfaces  60  and  62  will (axially) approach one another as their respective webs  54  and  63  are compressed and deformed. Under maximum design loading (as depicted in  FIG. 18 ), the abutment pairs  56 / 58  and  60 / 62  can approach or even contact one another. Further axial force levels beyond design limits will result in potentially destructive loading/deformation of the entire bobbin. 
         [0029]    The rings  50  and  52  as well as the web  54  are configured to ensure that the localized material forming the skirt portion  26  never exceed its characteristic yield point and, as a result, will maintain the bobbin  14  under compressive loading during thermal transition induced shrinkage and long term load induced creeping of the bobbin material. 
         [0030]    It is to be understood that the invention has been described with reference to specific embodiments and variations to provide the features and advantages previously described and that the embodiments are susceptible of modification as will be apparent to those skilled in the art. 
         [0031]    Furthermore, it is contemplated that many alternative, common inexpensive materials can be employed to construct the basis constituent components. Accordingly, the forgoing is not to be construed in a limiting sense. 
         [0032]    The invention has been described in an illustrative manner, and it is to be understood that the terminology, which has been used is intended to be in the nature of words of description rather than of limitation. 
         [0033]    Obviously, many modifications and variations of the present invention are possible in light of the above teachings. For example, . . . It is, therefore, to be understood that within the scope of the appended claims, wherein reference numerals are merely for illustrative purposes and convenience and are not in any way limiting, the invention, which is defined by the following claims as interpreted according to the principles of patent law, including the Doctrine of Equivalents, may be practiced otherwise than is specifically described. 
         [0034]    The specification of the below listed U.S. Patents and applications are incorporated herein by reference: 
         [0035]    U.S. Pat. No. 6,065,495 to Fong et al. 
         [0036]    U.S. 2005/0012062 A1 to Hayashi 
         [0037]    U.S. 2006/0054851 A1 to Young et al. 
         [0038]    U.S. 2005/0199846 A1 to Kim et al. 
         [0039]    U.S. Pat. No. 6,119,725 to Shinobu et al. 
         [0040]    U.S. Pat. No. 5,588,414 to Hrytzak et al. 
         [0041]    U.S. Pat. No. 5,992,822 to Nakao et al. 
         [0042]    U.S. Pat. No. 6,371,164 to Sakata et al. 
         [0043]    U.S. 2005/0081810 A1 to Isobe et al. 
         [0044]    U.S. Pat. No. 5,146,196 to Frank 
         [0045]    U.S. Pat. No. 5,119,055 to Kidd et al. 
         [0046]    U.S. Pat. No. 5,148,136 to Kid 
         [0047]    U.S. Pat. No. 5,038,123 to Brandon