Abstract:
A latch system provides a latch striker including a flexible arm that can navigate a hook on the latch striker through an aperture in a corresponding latch mechanism. The aperture provides a tortuous passageway through which a hook on the latch striker must pass to activate an internal switch allowing operation of the appliance.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a National Phase of International Application No. PCT/US2014/063619, filed Nov. 3, 2014, and claims the benefit of U.S. provisional application 61/899,462 filed Nov. 4, 2013, and hereby incorporated in its entirety by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to home appliances such as clothes washing machines and the like and, in particular, to a lid locking mechanism that is highly resistant to tampering. 
       BACKGROUND OF THE INVENTION 
       [0003]    The spin cycle of a washing machine removes water centrifugally from wet clothes by spinning the clothes at high speed in a spin basket. In order to reduce the possibility of injury to the user during the spin cycle, it is known to use an electronically actuated lock for holding the washing machine lid in the closed position. U.S. Pat. Nos. 6,363,755; 5,823,017; and 5,520,424, assigned to the present assignee and hereby incorporated by reference, describe several locking mechanisms. 
         [0004]    In order to prevent tampering with the lock mechanism, for example, by holding the lid open when the lock is actuated, it is known to provide for lid closure sensing to ensure that the lid is in a proper position before the lock mechanism is engaged. Conventional mechanical lid closure switches can often be defeated by wedging the switch open, for example, with the end of a pencil or the like. U.S. Pat. No 7,251,961, assigned to the assignee of the present invention and hereby incorporated by reference, describes a lid sensor using a magnet and electrical reed switch to detect lid closure. The use of a magnetic actuator reduces the possibility of casual tampering. 
         [0005]    US patent application 2012/0312594, assigned to the assignee of the present invention and hereby incorporated by reference, describes a lock mechanism in which the magnet is incorporated into a hook or striker that engages the latch. The magnet activates an anti-tamper feature which indicates that the striker and not a foreign object is engaging the latch. In this design, the striker is spring mounted to follow a serpentine path as it engages the latch. This path further defeats simple tampering by requiring that the striker and engagement of the latch have a particular dimension and are able to navigate flexibly along that path. A similar design that does not require the magnet feature is disclosed in U.S. provisional patent application 61/911,659 also incorporated by reference. Each of the above listed patents and applications is hereby incorporated by reference. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention provides a simplified striker for use with anti-tamper or other latches of a type that require the striker to resist tensile, upward forces caused by attempts to open the door of the appliance when it is latched, but that provides the necessary flexibility to navigate a serpentine engagement path. The latch incorporates a single piece design where resilient elements of a molded element provide the necessary flexure and spring biasing. Proper configuration of the hinge may limit the flexibility to a single pivot axis resisting sideward force and limiting pivot angle to protect the striker from over-flexure. A floating mounting may be provided to automatically align the striker with the latch rather than bend the latch. 
         [0007]    Specifically, in one embodiment the invention provides a latch system having a latch striker with a base providing a mounting surface for abutment against a surface of an appliance lid to stably support the base against the appliance lid. Attached to the base is an arm extending outward from the base along an arm axis and terminating in a hook. The hook extends from an end of the arm removed from the base in a hook direction along a hook axis substantially perpendicular to the arm axis. A resilient connection joins the base and arm and allows flexure along the hook axis from an initial position under force along the hook axis to change an angle of the latch hook axis with respect to the base and returns to the initial position after removal of the force and further resists flexure of the arm perpendicular to both the hook axis and the arm axis under the force. 
         [0008]    In use the latch striker is received by a latch having a housing providing a mounting surface for stably supporting the housing against an appliance lid-receiving portion of the appliance. The latch includes an electrical switch contained in the housing for actuation by the latch hook and an aperture for receiving the arm and hook therethrough, the aperture requiring a flexure of the resilient connection along the hook axis, as the hook moves through the aperture, to actuate electrical switch. 
         [0009]    It is thus a feature of at least one embodiment of the invention to provide a lower cost striker for use in a sophisticated appliance latch that requires complex movement of the latch striker within the latch. 
         [0010]    The base may include at least two holes adapted to receive mounting screws passing in part through the surface of the appliance lid and received within the two holes. 
         [0011]    It is thus a feature of at least one embodiment of the invention to provide a robust method of attaching the striker to a variety of appliance lids. 
         [0012]    The two holes may include two collars extending from corresponding shoulders around the holes so that the collars may fit through a slot in the appliance housing with the shoulders abutting a face of the slot to allow adjustment of the base by sliding the collars in the slot. 
         [0013]    It is thus a feature of at least one embodiment of the invention to permit lateral adjustment using the same elements used to attach the latch striker to the appliance for additional cost savings. 
         [0014]    The hook may include lateral surfaces perpendicular to the hook axis sloping outward along the arm axis toward the base and the aperture may provide funneling surfaces receiving the lateral surfaces of the hook to center the hook within the aperture in a direction perpendicular to the hook axis. 
         [0015]    It is thus a feature of at least one embodiment of the invention to provide a self-aligning striker that accommodates minor tolerance variations in the location of the appliance lid. 
         [0016]    The collars may be sized to extend through and beyond a material of the slot to prevent a machine screw installed in the holes from tightening against a material of the slot. 
         [0017]    It is thus a feature of at least one embodiment of the invention to retain the base against the appliance while allowing lateral sliding of the base to accommodate a self-aligning feature. 
         [0018]    The collars may extend away from the base along the arm axis toward the hook. 
         [0019]    It is thus a feature of at least one embodiment of the invention to permit the base to be installed under a rolled lip of a sheet steel appliance lid for reduced height. 
         [0020]    The resilient connection may be a torsion bar extending from a proximal end of the arm perpendicular to the hook axis and the arm axis. 
         [0021]    It is thus a feature of at least one embodiment of the invention to provide a high torsion spring that can be fabricated of injection molded thermoplastic material and that provides for differentiated resilience allowing lower flexure forces along the hook axis and higher flexure forces perpendicular to the hook axis and the arm axis. 
         [0022]    The torsion bar may extend respectively in opposite directions from the proximal end of the arm toward separate portions of the base each including one of the two holes. 
         [0023]    It is thus a feature of at least one embodiment of the invention to provide balanced restoring forces that resist twisting along the arm axis. 
         [0024]    The resilient connection may be narrowing that reduces a thickness of the arm near the base as measured parallel to the hook axis. 
         [0025]    It is thus a feature of at least one embodiment of the invention to provide a living hinge design that may be readily fabricated using injection molding processes. 
         [0026]    The base may further include stop elements extending on either side of the arm to positively stop flexure of the arm beyond a predetermined range. 
         [0027]    It is thus a feature of at least one embodiment of the invention to allow relatively easy flexure of the arm without the risk of over flexure that might weaken or break the arm at the resilient connection. 
         [0028]    The stop elements may comprise interengaging fingers and shoulders, the fingers extending along the arm axis and shoulders abutting axial ends of the fingers, the fingers and shoulders on opposite ones of the base and arm. 
         [0029]    It is thus a feature of at least one embodiment of the invention to provide a stop that can be fabricated of relatively thin thermoplastic elements by providing an abutment between the stop and the fingers that puts the thermoplastic material in compression. 
         [0030]    The base, arm, hook, and resilient connection may be integrally formed of a thermoplastic material and the resilient connection provides a living hinge. 
         [0031]    It is thus a feature of at least one embodiment of the invention to provide a latch striker that can be molded entirely of thermoplastic material for low cost and corrosion resistance. 
         [0032]    Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings in which like numerals are used to designate like features. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0033]      FIG. 1  is a perspective view and inset detail of a top loading washing machine suitable for use with the present invention showing a strike aperture positioned near the front of an upwardly opening lid and showing a downwardly extending striker for engaging the strike aperture and a latch when the lid is closed; 
           [0034]      FIG. 2  is a fragmentary cross-section along line  2 - 2  of  FIG. 1  showing a floating mounting of the striker allowing close tolerance interaction between the striker and a latch to move a trap element within the latch to a retaining and locking position; 
           [0035]      FIG. 3  is a perspective view of the first embodiment of a one-piece molded striker providing the necessary floating mounting through a torsion bar; 
           [0036]      FIG. 4  is a fragmentary detail of the mounting element of the striker of  FIG. 3  showing its engagement with a slot in the lid for sideward adjustability; 
           [0037]      FIG. 5  is an alternative embodiment of the striker of  FIG. 3  providing the necessary floating mounting through a living hinge; 
           [0038]      FIGS. 6 a  and 6 b    are cross-sections along lines  6 - 6  of  FIG. 5  showing the living hinge in an unselect and flexed state where the striker abuts a travel stop; 
           [0039]      FIG. 7  is a detailed fragmentary view of  FIG. 6 b    showing the conversion of bending forces into compression and tension forces accommodated by the striker; 
           [0040]      FIG. 8  is a side cross-sectional view of the embodiment of  FIG. 3  showing support of the striker on the inside of a lower lip of an appliance lid to reduce striker height while providing flexibility; 
           [0041]      FIG. 9  is a front view of the striker of  FIG. 8  showing a beveling of the lateral surfaces of the hook to interact with funnel surfaces of the latch aperture to align the hook within the aperture; and 
           [0042]      FIG. 10  is a figure similar to  FIG. 3  but viewed from the opposite direction and of an alternative embodiment including additional stabilizing features. 
       
    
    
       [0043]    Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0044]    Referring now to  FIG. 1 , a top loading washing machine  10  suitable for use with the present invention includes a lid  12  opening upward about a horizontal lid hinge axis  14 . The lid hinge axis  14  is positioned near the top rear edge of the washing machine  10  so that a front edge  16  of the lid  12  may raise and lower to expose and cover an opening  20  through which clothing may be inserted into the spin basket. A front-loading washing machine (not shown) is also suitable for use with the present invention as will be apparent to those of ordinary skill in the art from the following description with an appropriate adjustment of the orientation. 
         [0045]    A horizontal surface of the top  22  of the washing machine  10 , at the periphery of the opening  20 , may support a strike aperture  24  formed in a housing  21  of a latch  25  fastened to the underside of the top  22 . The strike aperture  24  opens upward to receive a downwardly extending striker  26  attached to an underside of the lid  12 . Both the strike aperture  24  and the striker  26  may be offset parallel to the axis  14  and offset from a center of the front edge  16  so as to minimize interference with loading and unloading the washing machine  10 . 
         [0046]    Referring now to  FIG. 2 , the striker  26  may include a downwardly extending arm  28  along arm axis  27  terminating in a hook  30  extending leftward from the arm  28 , as shown in  FIG. 2 , generally toward a user of the washing machine  10  along a hook axis  35 . The upper end of the arm  28  may be mounted to the lid  12  via a base  33  for longitudinal pivoting  32  (left and right as indicated by arrows in  FIG. 2 ) generally along the hook axis  35  with respect to the lid  12  under restoring spring forces indicated schematically by springs  34 . In this way, the left and right surfaces of the hook  30  may translate longitudinally as may be necessary to accommodate positional tolerances in the manufacture of the washing machine  10  and wear of the washing machine  10  and importantly to provide movement of a trap to be described. 
         [0047]    As the lid is closed, the hook  30  moves toward the strike aperture  24  and is guided rightward by a right facing first sloping edge  36  of an aperture bezel  38  defining the strike aperture  24 . The aperture bezel moves the hook  30  to position  29   b  with a left edge of the striker  26  aligned at first position  31  with the right edge of an un-retracted trap  40  (shown in a retracted position in  FIG. 2 ). The striker  26  is then urged left by a left facing second sloping edge  42  so as to push the trap  40  leftward against a restoring spring (not shown in  FIG. 2 ) so that a left edge of an opening in the trap  40  is moved to position  31 ′ as hook  30  passes to position  29   c.    
         [0048]    A following surface  44  of the trap  40 , when the trap is retracted with the striker  26  in position  29   c,  prevents rightward movement of the hook  30  trapping it beneath a ledge on the underside of the sloping edge  36 . This serpentine path defined by sloping edges  36  and  42  ensures that the left edge of the striker  26  abuts the left edge  41  of the trap  40  in close proximity despite tolerance variations between the lid  12  and the top  22  and allows the striker  26  to move the trap  40  to the retracted position needed for locking as will be described. It will be understood that the dimensions of the hook  30  are important in ensuring movement of the trap  40  thus reducing the risk of tampering by insertion of an element, for example, like a rod of uniform cross-section. 
         [0049]    Referring now to  FIG. 3 , the striker  26  may be formed of a single injection molded thermoplastic element in which the arm  28  extends upward from the hook  30  to attach to a torsion bar  50  communicating with a sockets  56  forming the base  33 . The upper end of the arm  28  may include an offset portion  23  extending longitudinally from the upper end of the arm  28  to the torsion bar  50  whose purpose will be described below. The torsion bar  50  extends transversely along a pivot axis  52  from the left and right sides of the top of the arm  28 . As such, the torsion bars  50  provide a resilient connection between the arm  28  and the base  33  that implements the springs  34  to allow longitudinal pivoting  32  of the hook  30  as discussed above through elastic twisting of the torsion bar  50  under force on the hook  30  along the hook axis  35 . This twisting is sufficient to provide at least three degrees of deflection of the arm  28  from a normal position where the torsion bars  50  are relaxed and the arm  28  extends downward substantially perpendicular to a plane of the appliance lid  12  (shown in  FIG. 1 ). The torsion bars  50  operate within their elastic limit to return the hook  30  to a normal position when that force is removed. 
         [0050]    The pivot axis  52  is generally transverse and perpendicular to the arm axis  27  and the hook axis  35 . Any transverse forces  54  acting on the hook  30  are nevertheless resisted by the torsion bars  50  and instead provide a net left or right transverse force on the striker  26  along the pivot axis  52  that may be used for self-alignment as will be discussed. 
         [0051]    Opposite ends of the torsion bar  50  extending from the upper end of the arm  28  attached to mounting sockets  56 , described above, each provide vertically extending through-bores  58  through which machine screws  60  may be inserted upward along insertion 
         [0052]    Substitute Specification-Clean Copy axis  63  to attach the sockets  56  to a lip of the lid  12  extending along the underside of the lid  12 . 
         [0053]    Referring now to  FIGS. 3, 4 and 5 , a lower surface of the mounting sockets  56  may provide shoulders that abut an upper surface of a folded over sheet metal lip  62  forming a front edge  16  of the lid  12  (also shown in  FIG. 2 ). A collar  70  extending downward from each socket  56  coaxially about the bore  58  may fit within a corresponding slot  61  in that lip  62  to slide transversely therein. A machine screw  60 , providing a threaded shank  64 , may be threadably received within the bore  58  to attach to the sockets  56  so that the head  68  of the machine screw  60  is spaced away from the sheet metal lip  62  by a gap  73  (shown in  FIG. 8 ) so that it slides longitudinally along extending side portions of the slot  61  over the lower surface of the sheet metal lip  62  to retain the sockets  56  against the lip  62  while allowing this transverse motion  66  over a full range of the slot  61 . The offset portion  23  of the arm  28  allows the arm  28  to extend downward past the edge of the metal lip  62 . 
         [0054]    Referring to  FIGS. 1 and 9 , this transverse motion  66  permits alignment of the striker  26  with the strike aperture  24  in a lateral direction in the face of minor tolerance buildups in the assembly of the appliance. The aperture bezel  38  (for example, shown in  FIGS. 2 and 9 ) may provide for a transverse funneled opening  39  to receive the downwardly extending striker  26  and to center the hook  30  of the striker  26  by guidance of the former within the bezel  38  by sloping inner walls  45  of the bezel  38  which produce these transverse forces  54 . The selective resistance of the torsion bars  50  to transverse forces  54 , while complying with forces that would produce longitudinal pivoting  32 , allows this adjustment to occur by the sliding left or right of the striker  26  without the transverse forces  54  being absorbed by flexure of the striker  26 . 
         [0055]    Referring now to  FIG. 5 , in an alternative embodiment, the torsion bars  50  may be replaced with a relatively stiff and torsionally unyielding support frame  72  extending between the mounting sockets  56 . The arm  28  of the striker  26  may attach to the underside of the support frame  72  to extend downward therefrom by means of narrowing that forms a living hinge  76 , the latter allowing for longitudinal pivoting  32  of the arm  28  by flexure of the living hinge  76  while resisting other bending moments because of a lack of narrowing in the transverse direction. Transverse motion  66  can be provided by the same slot and screw mechanism discussed above with respect to  FIGS. 3 and 4 . 
         [0056]    Referring now also to  FIGS. 6 a , 6 b    and  7 , the living hinge  76  may be longitudinally flanked by travel stops  78  providing fingers extending downward from the underside of the support frame  72 . Flexure of the living hinge  76  in either longitudinal direction beyond an angular range whose magnitude is shown in  FIG. 6 b    provides an abutment between an upper longitudinal shoulder  81  of arm  28  below the living hinge  76  and a lower edge of the travel stops  78 , this abutment preventing over-flexure of the living hinge  76  such as might damage the living hinge  76 . The abutment of the upper edge of the arm  28  and the lower edge of the travel stop  78  converts the force of longitudinal flexure into a tensile force  79  on the living hinge  76  more readily resisted by the living hinge  76  and compression forces on the fingers of the travel stops  78  and the shoulder  81 , also easily accommodated by a thermoplastic material. 
         [0057]    Each of the hook  30 , arm  28 , torsion bars  50  or support frame  72 , and sockets  56  may be formed as a single, integrated injection molded component requiring no post-molding assembly. Suitable thermoplastic materials include nylon, polyethylene, and polypropylene, the latter two of which have excellent fatigue resistance. 
         [0058]    Referring now to  FIG. 10 , additional stabilization of the torsion bars  50  may be provided by curving tabs  82  upward from the sheet metal of the lip  62  of the lid  12  to curve around the torsion bars  50  between the sockets  56  and the offset portion  23  to provide a surrounding bearing surface. These tabs  82  may be formed when the striker  26  is in place. In addition, the point of attachment of the offset portion  23  to the torsion bars  50  is rounded so that it may provide a bearing surface against the upper surface of the lip  62  during movement. A lower face of the offset portion  23  may provide a downwardly extending tooth  84  passing into a corresponding slot  86  in the sheet metal of the lip  62  to transfer force into the sheet metal when the lid  12  is pulled open while locked. A rear surface of the arm  28  near the lip  62  extends in a hook  88  that may engage the lower surface of the sheet metal  62  to protect the torsion bars  50  if the lid  12  is slammed during closure. Finally a stabilizer bar  90  may extend between the sockets alongside of the torsion bar  50  to provide additional strength to the base  33 . 
         [0059]    Certain terminology is used herein for purposes of reference only, and thus is not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, and “below” refer to directions in the drawings to which reference is made. Terms such as “left”, “right”, “front”, “back”, “rear”, “bottom” and “side”, describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms “first”, “second” and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context. 
         [0060]    When introducing elements or features of the present disclosure and the exemplary embodiments, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of such elements or features. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements or features other than those specifically noted. It is further to be understood that the method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
         [0061]    Various features of the invention are set forth in the following claims. It should be understood that the invention is not limited in its application to the details of construction and arrangements of the components set forth herein. The invention is capable of other embodiments and of being practiced or carried out in various ways. Variations and modifications of the foregoing are within the scope of the present invention. It also being understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention.