Patent Abstract:
A magnetic lid closure sensor uses a magnet sensor element mounted within the washing machine housing below the closed lid. Flux directors conduct flux from a magnet in the lid to the magnet sensor. A lock mechanism employs a hook engaging an aperture in the lid so that opening of the lid does not impart a torque to the hook such as would disengage it, allowing the hook to be activated and deactivated with a simple bi-directional solenoid.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is divisional application of Ser. No. 10/609,252 filed Jun. 27, 2003 which is a continuation-in-part of U.S. application Ser. No. 10/342,452 filed Jan. 14, 2003 now abandoned. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     BACKGROUND OF THE INVENTION 
     The present invention relates to clothes washing machines and the like, and specifically, to a lid locking mechanism that may optionally include a magnetic lid sensor. 
     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. Desirably, the locking mechanism minimizes projecting parts on the washing machine lid which might snag clothing or reduce access to the spin basket, and is simply integrated into the washing machine housing. 
     A signal indicating the state of the washing machine lid as opened or closed may be used to “wake” circuitry from a power saving mode, or to coordinate operation of the lid lock by ensuring the lid is closed before the lock in engaged. Such a signal may be provided by a switch communicating with the washing machine lid. Ideally such a switch could not be easily defeated, would operate reliably when used with other washing machine components with normal manufacturing tolerances, and would be resistant to contamination by water and dirt. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a magnetic lid sensor for a washing machine lid supporting a magnet where the sensor includes a sensor housing mountable on the washing machine and a magnet sensor element held within the sensor housing displaced from a point of rest of the magnet when the washing machine lid is closed. At least one ferromagnetic flux director is held by the sensor housing having a first end near the point of rest of the magnet and having a second end near the magnet sensor to conduct flux there between. 
     Thus it is one object of the invention to provide a practical magnetic lid sensor for a washing machine. Magnetic flux directors allow the magnet sensor to be positioned in a protected position within the housing and still receive sufficient variation in magnetic flux to switch reliably and predictably with lid opening. 
     The magnet sensor may be a reed switch, the sensor housing may be non-magnetic and two ferromagnetic flux directors may be used to conduct the magnet flux in a loop between the magnet sensor and the magnet. 
     Thus it is another object of the invention to conduct sufficient magnetic flux to reliably activate a low cost magnet sensor. 
     The invention also provides a lid lock assembly which includes a cap sized to cover a mounting hole in the housing of a washing machine near a point of rest of the washing machine lid when the washing machine lid is closed. The cap may include at least one downwardly extending threaded hole. A housing of the lid lock may be located below the hole in the housing of the washing machine and may have a hole receiving an upwardly extending screw. The screw engages the downwardly extending threaded hole of the cap to hold the washing machine housing between an upper surface of the lock housing and a lower surface of the cap. The mounting hole is near the pivot point of a hook that may be used to lock the lid in the closed position. 
     Thus it is another object of the invention to provide a simple mounting system for a lid lock. Thus, it is another object of the invention to provide a simple mechanism for supporting a movable bolt that is robust against the force of a person attempting to open the lid. 
     The cap may include only a single downwardly extending threaded hole and the lock housing may include only a single mounting hole for attaching the lock housing to the washing machine. 
     It is thus another object of the invention to provide a lid lock that may be attached to the housing with a single screw. The positioning of the pivot of the hook to minimize torsion on the housing and to transfer forces on the lid to additional compression of the lock housing against the washing machine increases the robustness of this single screw mounting. 
     The downwardly extending hole in the cap may be blind to present a continuous upper cap surface. 
     Thus it is another object of the invention to minimize any holes that might accumulate or conduct water and dirt. 
     The cap may be an elastomeric plastic molded over a non-elastomeric plastic forming the threaded hole. 
     It is another object of the invention to provide both cushioning bumper and support for the lock housing in one structure. It is another object of the invention to provide a bumper that passes magnetic flux and that covers a hole in the washing machine housing sufficient in size to freely pass magnetic flux. 
     The present invention also provides generally a lid lock for a washing machine using a hook pivoting about an axis so as to move between a first locked position in which the opening of the closed lid is prevented by interference between the hook and an engagement surface on the lid and a second position in which the closed lid is free to open. An actuator may move the hook between the first position and the second position. A contact interface between the hook and the engagement surface is selected to prevent the force of opening the closed lid from moving the hook to the second position. 
     Thus it is another object of the invention to provide a locking mechanism with low friction that remains stably in the locked position without the application of a locking force. 
     The actuator may operate to alternatively move the hook toward and away from the locked position and may, for example, be a bi-directional solenoid. 
     Thus, it is another object of the invention to provide a lock that may be quickly locked and unlocked through electrical signals and yet does not require continuous consumption of electrical power or manual setting or resetting. 
     The engagement surface may move along a tangent line with first movement of the closed lid to open and the pivot axis of the hook may lie along a tangent line opposite the direction of movement of the engagement surface. 
     Thus it is another object of the invention to provide that opening force on the lid result in an upward force to the locking mechanism such as is absorbed against the housing of the washing machine. 
     The engagement surface in the lid may be an aperture and the hook may engage the aperture. 
     Thus it is another object of the invention to provide an extremely simple lid locking mechanism that does not require projections that might snag clothing or interfere with access to the spin basket. 
     The hook may include a central tooth engaging the aperture and flanking shoulders resting against sides of the aperture when the tooth is so engaged. 
     Thus it is another object of the invention to provide a simple structure for limiting the depth of engagement of the hook with the lid when the lid is in place. 
     The lock mechanism may include a spring communicating with the hook for urging the hook toward the first position when the hook is proximate to the first position and urging the hook toward the second position when the hook is proximate to the second position. A contact set may communicate with the hook to provide a switch output indicating when the hook is at the first position as distinguished from when the hook is at the second position. 
     Thus it is another object of the invention to create a bi-stable positioning of the hook such as simplifies determination of the hook state using a contact set and which prevents inadvertent movement of the hook under vibration and the like. 
     The contact set may provide a closed circuit between a first and second terminal when the hook is in the first position in an open circuit between the first and second terminals when the hook is in the second position. 
     It is thus another object of the invention to provide certainty in any signal indicating the lid is locked in the presence of possible wiring failure. 
     The contact set may include a sliding contact moving laterally over a stationary contact and the stationary contact may be positioned next to a cam surface engaging the sliding contact with over travel of the sliding contact to lift the sliding contact transversely away from the stationary contact. 
     Thus it is another object of the invention to provide a contact set capable of detecting small motions while using large area contacts. 
     These particular objects and advantages may apply to only some embodiments falling within the claims and thus do not define the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a top loading washing machine suitable for use with the present invention showing a strike formed from a side of an opened lid of the washing machine and a bolt for engaging the same when the lid is closed; 
         FIG. 2  is a fragmentary cutaway of the portion of the lid and washing machine near the bolt of  FIG. 1  showing support of a locking mechanism beneath a lid well; 
         FIG. 3  is a simplified top plan view of the bolt of  FIG. 2  extending through a wall of the lid well to engage a strike of the lid and illustrating a retraction position, engagement position, and extension position of the bolt and further showing corresponding states of an electrical switch connected to the bolt to provide an indication of bolt position; 
         FIG. 4  is a top plan view of the locking mechanism of  FIG. 2  in partial cutaway to show a rotating shaft connecting the bolt of  FIG. 3  to a contact assembly and a bi-directional actuator; 
         FIG. 5  is a perspective view of the contact assembly of  FIG. 4  such as implements the switch of  FIG. 3  and showing an overcenter spring that causes the bolt to be bi-stable in the extension and retraction position when the lid is open, and the engagement and retraction position when the lid is closed; 
         FIG. 6  is a perspective, exploded, fragmentary view of a portion of the housing of  FIGS. 2 and 4  showing mounting of the locking mechanism to the washing machine; 
         FIG. 7  is a cross-sectional view taken along line  7 - 7  of  FIG. 6  showing flux directors for conducting magnetic flux from a magnet mounted in the lid of the washing machine into the washing machine housing to a magnet sensor; 
         FIG. 8  is a cross-sectional view taken along line  8 - 8  of  FIG. 7  showing the interface between the hook and lid and the location of the pivot point of the hook such as prevents movement of the hook by forces generated by attempted opening of the lid; and 
         FIGS. 9 through 11  are side elevational views of one contact of the switch of  FIG. 5  showing the use of a cam surface for lifting the contact upon overtravel. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     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. 
     Referring now to  FIG. 2 , when the lid  12  is in the closed position, it sits within a lid well  18  having vertical walls  32  surrounding vertical walls  22  of the lid  12  and having a horizontal ledge  19  on which the lower surface of the lid  12  may rest. A vertical wall  22  of the lid  12  near a front edge  16  of the lid  12  provides a strike plate  24  having a bolt hole  26 . 
     Referring also to  FIG. 3 , the bolt hole  26  is sized to receive a tooth portion  28  of a lateral extension  40  of a hook  30  passing horizontally through a vertical wall  32  of the lid well  18  opposite the strike plate  24  when the lid  12  is closed. When the tooth portion  28  is engaged in the bolt hole  26 , the lid  12  may not be raised vertically as indicated by arrow  36  as a result of the lower edge of the bolt hole  26  interfering with a lower edge of the tooth portion  28 . 
     The tooth portion  28  extends from shoulders  34  which flank the tooth portion  28  and are sized to be larger than the bolt hole  26  so that the shoulders  34  may not pass through the bolt hole  26 . When the lid  12  is closed, the shoulders  34  limit the amount that the hook  30  may extend through the bolt hole  26  and thus limit the length of extension of the hook  30  from the vertical wall  32  of the lid well  18 . When the lid  12  is open, however, the shoulders  34  may move further in extension as will be described. 
     Referring also to  FIG. 4 , the lateral extension  40  of the hook  30  is connected to a radial portion  42  to form a hook pivoting, as indicated by arrow  45 , about a rotation axis  44  where the hook is attached to an axle  46 . The axle  46  is supported for rotation within a housing  48  of a locking mechanism positioned beneath the lid well  18 . 
     Referring now to  FIG. 3 , as will be discussed in detail below, the hook  30  communicates via the axle  46  (shown schematically in  FIG. 3 ) with a contact set  52 . The contact set  52  provides a three position switch in which two poles  54   a  and  54   b  connecting to respective terminals  56   a  and  56   b  in a center position (B) and disconnect from terminals  56   b  in left and right positions (C) and (A), respectively. Where the poles  54   a  and  54   b  are joined to each other so that in position (B), a closed circuit is presented across terminals  56   a  and  56   b  and in positions (A) and (C), an open circuit is presented across terminals  56   a  and  56   b.    
     These three switch positions (A), (B), and (C) correspond to three positions (A′), (B′), and (C′) of the hook  30 . The first hook position (A′) is where the forward tooth portion  28  of the hook  30  remains retracted behind the vertical wall  32  of the lid well  18 . The hook  30  may be in this position prior to the hook  30  being actuated or if the hook has been actuated, but was obstructed or jammed, or if the actuator fails. In this position, an open circuit is presented across terminals  56   a  and  56   b.    
     The second hook position (B′) is where tooth portion  28  of the hook  30  extends through the bolt hole  26  and the shoulders  34  of the hook abut strike plate  24 . The hook  30  will be in this position if the lid  12  is closed and the hook  30  is actuated. In this position, the lid  12  is locked and a closed circuit is presented across terminals  56   a  and  56   b.    
     The third hook position (C′) is where tooth portion  28  and the shoulders  34  of the hook  30  extends past the position normally occupied by the strike plate  24  as may occur if the lid  12  is open at the time of actuation of the hook  30 . In this position, an open circuit is presented across terminals  56   a  and  56   b.    
     Thus, it will be understood that a proper locking of the lid by the hook  30  is indicated by a closed circuit across terminals  56   a  and  56   b , whereas an open circuit across these terminals  56   a  and  56   b , indicates either an obstruction of the hook  30  at the aperture in the vertical wall  32  or failure of the actuator or over-extension indicating that the lid  12  was not closed at the time of locking or an electrical break in the wiring communicating with the terminals  56   a  and  56   b . Any of these latter open circuit conditions suggest that access may be had to the opening  20  leading to the spin basket of the washing machine and may be used to override the spin cycle, stopping it or preventing it from starting. 
     Referring now to  FIGS. 4 and 5 , motion of the hook  30  along the lateral axis  60  causes rotation of the axle  46  within the housing  48 . The axle  46  includes two downward extending forks  62   a  and  62   b  that engage tabs  64  on a carriage  66 . In this way, rotation of the axle  46  with motion of the hook  30  along the lateral axis causes motion of the carriage  66  on a carriage track  65  along lateral axis  68  parallel to lateral axis  60 . 
     The carriage  66  supports a horseshoe conductor  70  fitted to the top of the carriage  66  having laterally extending arms that form throws  54   a  and  54   b . The arm forming throw  54   a  of the horseshoe conductor  70  extends along the lateral axis  68  over throw pads  72   a . The arm forming throw  54   b  of the horseshoe conductor  70  extends along the lateral axis  68  over throw pads  72   b - 72   d.    
     Throw pad  72   a  is a conductive metallic plate connected to terminal  56   a  and extending a distance along the lateral axis  68  sufficient so that it maintains contact with pole  54   a  for the entire range of motion of the carriage  66 . Throw pad  72   c  is a conductive metallic plate connected to terminal  56   b  and contacting pole  54   b  only when the hook  30  is in the second hook position (B). Throw pads  72   b  and  72   d  are insulators that support the pole  54   b  when the hook  30  is in the hook positions (A) and (C), respectively, providing no electrical connection to terminal  56   b.    
     A helical compression spring  80  is girdled at a midpoint along its length by tabs  82  on the under side of the carriage  66 . The ends of the helical compression spring  80  are held by retaining posts  83  on opposed inside walls of carriage track  65 . The helical compression spring  80  in a relaxed state is longer than the separation of the retaining posts on the inside walls of the carriage track  65  so as to make the carriage  66  bi-stable in positions (A′) and (C′) corresponding to hook positions (A) and (C). Bi-stability means that the carriage  66  tends to move toward position (A′) when the carriage is near position (A′), and that the carriage  66  tends to move toward position (C′) when the carriage is near position (C′). When the carriage is in position (B′), it is also urged toward position (C′). 
     Accordingly, referring again to  FIG. 3 , the hook  30  is stable in positions (A) and (C) when the lid  12  is open and is stable in positions (A) and (B) when the lid  12  is closed, the stability at position (B) being provided by the blocking action of the strike plate  24 . 
     The carriage  66  is attached to an arm  86  extending from a metal slug  88  held within solenoids  90   a  and  90   b . The solenoids  90   a  and  90   b  may be alternatively energized through terminals  92  so that when solenoid  90   b  is energized, the carriage  66  is pushed toward position (A′), and when solenoid  90   a  is energized, the solenoid is pushed toward position (C′) and hence also (B′). 
     In this way, the lid  12  may be alternately locked or unlocked by electrical signals through terminals  92 . Upon ceasing of the signals through terminals  92 , the hook  30  is held in its current state by the bi-stable mechanism of spring  80 . 
     Referring now to  FIG. 6 , the housing  48  of the lid lock, near the axle  46 , has an upper surface  100  having a through-hole  108  passing vertically through the housing  48 , two blind registration holes  110  flanking the through hole  108 , and two upwardly extending posts  106  displaced to one side of the line defined by the through-hole  108  and registration holes  110 , the posts  106  being separated by approximately the spacing to the registration holes  110 . The posts  106  include vertically extending metal slugs (not shown in  FIG. 6 ) providing flux directors as will be described. 
     The upper surface  100  of the housing  48  fits against a lower surface  102  of the horizontal ledge  19  of the lid well  18 . A hole  104  may be cut in the horizontal ledge  19  to expose on the upper surface  100  the upwardly extending posts  106 , the through-hole  108 , and the two registration holes  110 . 
     A cap  112  placed on the hole  104  extends partially therethrough to receive the posts  106  within a cavity of the cap  112 . Registration pins  116  and a boss  118  extend downwardly from the lower surface of the cap  112  to be received within the registration holes  110  and the through-hole  108  respectively. 
     The boss  118  has a downwardly open threaded hole  120 . A machine screw  122  may be inserted upwardly through the through hole  108  from the bottom of the housing  48  to be received by the threaded hole  120 . Tightening of the threaded fastener  122  draws the housing  48  and cap  112  together sandwiching the horizontal ledge  19  there between and fixing the housing  48  to the washing machine  10 . Referring also to  FIG. 7 , the cap  112  may include a core  128  of rigid thermoplastic over-molded with a soft elastomer  130  to provide an outward cushioning for the lid  12  and yet a firm purchase for the threaded fastener  122 . 
     The lid  12  of the washing machine  10  may be constructed of a shell of enameled steel having a concave lower surface receiving a plastic liner  124  providing a lower wall to the lid  12 . The liner  124  holds a bar magnet  126  on its inner surface where the bar magnet  126  may be shielded from exposure to water and the like. The bar magnet  126  is positioned so that when the lid  12  is closed against the horizontal ledge  19 , the bar magnet  126  rests above the cap  112 . 
     Referring to  FIGS. 6 and 7 , the hole  104  in the horizontal ledge  19  of the washing machine  10  is sized to remove steel from a path between the magnet  126  and a reed switch  131  held in the housing  48  of the lid lock. The separation of the posts  106  extending up through the hole  104  (and thus the separation of the contained flux directors  109 ) is set to be substantially the same as the length of the bar magnet  126  extending between and above them and comparable to a length of the magnetic reed switch  131  positioned at the lower ends of the flux directors  109 . 
     When the lid  12  is closed, magnetic flux  132  is directed by the flux directors  109  to the reed switch  131  forming a complete magnetic circuit therewith. When the lid  12  is opened, the magnetic flux circuit is broken. The flux directors  109  allow displacement of the reed switch  131  deeper into the housing of the washing machine while still allowing the reed switch  131  to be activated with a magnet of modest size. The flux directors  109  also may serve to concentrate the magnetic flux  132  producing a better defined switching point as the lid is opened. 
     The reed switch  131  may communicate with conductors  134  that connect with pins added to pins  56  and  92  as have been described to provide a lid closed signal for activation of other circuitry associated with the washing machine. 
     Referring now to  FIG. 8 , the rotation axis  44  of axle  46  may be located directly below a point of engagement (contact interface) of the hook  30  and the lid  12 . As so located, upward motion of the lid  12  initially along tangent  140  produces an upward vector  142  on axle  46  creating minimal torque on the housing  48  and mostly upward force against the lower surface of the ledge  19  augmenting that provided by screw  122  (shown in  FIG. 6 ). 
     In addition, the contact interface (occurring between a lower surface of the tooth  28  of the hook  30  and the lower surface of the bolt hole  26 ) is such as to impart no torque or a slight engaging torque (counterclockwise in  FIG. 8 ) to the hook  30  about axis  44  with upward motion of the lid  12 . This is accomplished simply by ensuring that the slope at the contact interface is zero or slightly canted inward (toward the lid  12 ) with respect to upward vector  142 . This design greatly simplifies construction of the lock mechanism and is particularly well suited for the bi-directional solenoid  90  described above because it allows the lock to function without continued activation of the solenoids  90   a  or  90   b . The slight bi-stability added by the spring  80  described with respect to the contact set of  FIG. 5  ensures that unintended movement with vibration and the like does not occur. 
     Referring now to  FIG. 9 , sliding contact  54 , described above with respect to  FIG. 5 , may include a downwardly sloping spring portion  150  terminating in a substantially horizontal contact surface  152  followed by an upwardly sloping ramp portion  154 . As shown in  FIG. 2 , when the switch is in position (A), the horizontal contact surface  152  will be suspended in air or contacting an insulator. 
     As shown in  FIG. 2 , when the switch is in position (B), the horizontal contact surface  152  will abut a corresponding horizontal contact surface  156  of stationary contact  72 . The area of the contact surfaces  152  and  156  may be large enough to provide desirable low contact resistance and suitable current carrying capability. 
     Normally separation of the contact surfaces  152  and  156  with over travel would require over travel equal to the length of combined lateral extent of contact surfaces  156  and  152  would be required for full disengagement of the contacts  54  and  72 . In order to provide greater precision in detect angular changes in the hook  30  (tied to the contacts  54 ) a cam surface  160  is located immediately following stationary contact  72  and formed of the material of the housing  48  also supporting stationary contact  72 . The cam surface  160  interacts with the ramp portion  154  of the sliding contact  54  moving the contacts  54  and  72  in separation in a transverse direction  162  perpendicular to the lateral sliding direction  159 . Thus a slight additional over travel motion completely separates the contacts without the need for them to slide laterally entirely out of engagement. 
     It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.

Technology Classification (CPC): 3