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CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This invention claims priority to U.S. Provisional Patent Application Serial No. 60/354,605, filed Feb. 5, 2002. 
     
    
     
       BACKGROUND  
         [0002]    The prior art locking cam, as shown in FIG. 7 of the drawings, includes a locking cam ( 20 ), a torsion spring ( 27 ), and a ring plate ( 28 ). The locking cam has crescent shaped cutouts ( 30 ) for mating engagement with a set of ball bearings, a spring retention slot ( 29 ), bearing surfaces ( 26 ) with a reduced diameter section ( 22 ), and driver surface ( 31 ). When assembled, a first end ( 32 ) of the torsion spring ( 27 ) is retained in the slot ( 29 ), the locating ring ( 28 ) is placed on the reduced diameter section ( 22 ) of the cam, and the second end ( 33 ) of the torsion spring ( 27 ) is wound to allow attachment to a projection ( 34 ) on the locator ring ( 28 ). When the locking cam ( 20 ) is inserted into a cavity in a lock body, the projection ( 34 ) on the locator ring ( 28 ) positions the locking cam ( 20 ) into the correct orientation in the lock body cavity by insertion into a retention cavity. A key cylinder then contacts the locking cam at the driver surface ( 31 ) such that when the key cylinder is rotated from locked to unlocked positions, the locking cam is rotated such as to align the cutouts ( 30 ) with the ball bearings. When the cutouts ( 30 ) and ball bearings are aligned, the ball bearings can move into the cutouts ( 30 ) thereby allowing the toe side of the_shackle to be removed from the lock body.  
           [0003]    In the prior art structure, the torsion spring is located on the outside of the cam and the ring plate is used to orient one end of the spring in the lock. In use, the prior art locking assembly has a tendency to tip off-axis since the outer diameter of the assembly is not constant and therefore does not match to the constant diameter bore in the lock body. In addition, as the cam of the lock rotates the spring will cock. The rotation of the spring causes the spring coil to elongate. The torsional force and elongation cause the spring to get off axis creating instability in the assembly.  
         SUMMARY OF THE INVENTION  
         [0004]    One embodiment of the invention is a locking device for padlocks with multi-functioning cams. The locking device contains a cam and a driver partially housed within the cam. The locking device also contains a torsion spring housed within the driver.  
           [0005]    A method of locking and unlocking the locking device by rotating a key cylinder in a clockwise direction in which an assembled driver, spring, and cam are connected to the key cylinder. The key cylinder causes the driver to rotate in a clockwise direction, in which the direction of rotation is defined by viewing towards the key insertion point of the key cylinder. The driver drives the cam by applying a torque to a drive surface of the cam. The torque rotates the cam in a clockwise direction. A spring end stops the rotation of the cam by butting against a stop surface of the cam.  
           [0006]    An option desired by customers is to be able to insert and have operate a variety of key cylinders and the invention accommodates this desire by implementing three different styles of drivers that can be used in the assembly. The type of cylinder used in a lock is also dependent upon the geometry of the lock body. The customers also have a requirement for two different modes of operation commonly known as Non Key Retaining (NKR) and Non Removable Key (NRK). In order to provide the NKR function, the invention must be capable of allowing the driver component to turn independently without affecting the orientation of the cam component. This motion without interaction is commonly called ‘lost motion.’ 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 shows a perspective view of one embodiment of the internal components of the locking device assembled.  
         [0008]    [0008]FIGS. 2A, 2B, and  2 C show perspective views of different embodiments of a driver of the present invention.  
         [0009]    [0009]FIGS. 3A and 3B show a perspective view of different embodiments of a spring of the present invention.  
         [0010]    [0010]FIGS. 4A and 4B show perspective views of different embodiments of a cam of the present invention.  
         [0011]    [0011]FIG. 5 shows a perspective view of one embodiment of a cam of the present invention.  
         [0012]    [0012]FIG. 6 shows an exploded view of one embodiment of the present invention.  
         [0013]    [0013]FIG. 7 shows an exploded view of the prior art. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]    The invention will be described in reference to the drawings. FIG. 1 shows the internal mechanisms of a padlock body  100  a driver  3 , a torsion spring  6 , and a cam  1 . The driver  3  is housed partially in the cam  1 . Located within the driver  3  and in contact with the cam  1  is the torsion spring  6 .  
         [0015]    As shown in FIG. 5, the cam  1  is generally cylindrical with two crescent shaped recesses  11  cut from an external wall  80  of the cam  1 . In addition, the cam  1  has a cavity  36  formed by the internal wall of the cam and extending approximately half-way down cam  1 . The external wall of cam  1  extends to a variety of heights, thereby forming two stop surfaces  7  and  9 . Two ledges  8  and  10  connect the two stop surfaces  7  and  9  and are at two different heights. Ledges  8  and  10  meet at rest surface  40 . Thus, aperture  10   a  is formed by stop surface  9 , rest surface  40  and ledge  10 .  
         [0016]    The crescent shaped recesses  11  and the first cavity  36  of the cam  1  intersect and form two windows  22 . In addition to the first cavity  36 , there is a second cavity  37  within the first cavity  36  that extends deeper inside the cam  1 . Bearing surfaces  75  and  76  are formed by the internal walls inside the two cavities  36  and  37 .  
         [0017]    The driver may be a number of different embodiments, as shown in FIGS. 2A, 2B, and  2 C, each having a pivot rod  21 , a trepanned collar  41  with an aperture  13   a  formed by wall surfaces  13  and  14 , and two drive surfaces  15  and  16 .  
         [0018]    Shown in FIG. 3A, the torsion spring  6  is a coiled spring with two radially protruding ends identified as a long end  19  and a short end  20 .  
         [0019]    When assembled, the torsion spring  6  fits inside the trepanned collar  41  of the driver  3  so that the long spring end  19  projects through the aperture  13   a  of the driver and the short spring end  20  extends beyond the trepanned collar  41  and engages cam  1  or  2  at one of the two windows  22 , but does not extend beyond the external wall  80  of cam  1  or  2 . The aperture  13   a  prevents relative motion between the long spring end  19  and the locking mechanisms in at least one direction. The driver pivot rod  21  fits in the second cavity  37  of the cam  1  and the short spring end  20  is engaged through the window  22  of the cam  1  directly under the additional ledge  10 . The driver rests on and is supported by ledge  8 . The bearing surfaces  75  and  76  within the first and second cavities  36  and  37  stabilize the driver  3  within the cam  1  to eliminate tilt. During assembly, a preload is applied to the torsion spring  6  via the driver  3  to cause the long spring end  19  to project through the cam aperture  10   a.    
         [0020]    The driver is engaged with the end of a key cylinder  44  called a cylinder plug  45 . Three different embodiments of the driver  3 ,  4  and  5  are shown in FIGS. 2A, 2B, and  2 C illustrating a different engaging structure with the key cylinder  44 . FIG. 2A shows a first embodiment for the driver  3  which is designed to engage a tenon on the end of a key cylinder with the drive surface  15  on the end of the driver  3 . FIG. 2B shows a second embodiment for the driver  4  which is designed to engage the cylinder plug  45  of various door hardware type key cylinders via a tenon  17 . FIG. 2C shows a third embodiment for the driver  5  which is designed to engage a small format interchangeable core via throw member studs  18 .  
         [0021]    The key cylinder  44  applies clockwise torque to the drive surface  15  of the driver  3 , the tenon  17  of the driver  4 , or the throw member studs  18  of the driver  5 , depending upon which driver is used in the assembly. The torque is transferred to drive surface  16  of the driver which in turn transfers the torque to stop surface  7  of the cam  1  or  2 . The long spring end  19  has been at rest against rest surface  39  or  40  of the cam  1  or  2  and held captive within a cavity in cam  1  or  2 . Cam  1  or  2  turns clockwise as a result of the torque and can continue to rotate until the stop surface  9  of cam  1  or  2  makes contact with the long spring end  19  and the rotation of cam  1  or  2  is stopped. At some point in the rotation, the recesses  11  in cam  1  or  2  become aligned to allow the ball bearings  43  to move toward the center of cam  1  or  2  to a point where the ball bearings  43  no longer engage the crescent shaped cutouts  42  in the shackle  50 . Shackle  50  may be pulled outward from the padlock body  100  until the toe end  46  is clear and in the unlocked position while the heel end  47  of shackle  50  is retained in the padlock body  100 .  
         [0022]    When shackle  50  is in the unlocked position the heel end ball bearing  43  is trapped between shackle  50  and cam  1  or  2  to prevent withdrawal of the heel end  47  from the padlock body  100 . Cam  1  or  2  is under spring pressure from the winding of the torsion spring  6 . After the toe end  46  of shackle  50  is returned to the closed position this spring pressure rotates the cam counter-clockwise and the cam pushes outward on the ball bearings  43  and forces the ball bearings  43  out of recesses  11  in the cam into the crescent shaped cutouts  42  in shackle  50  locking the padlock body  100 .  
         [0023]    In operation of the NKR (Non Key Retaining) version of the invention shown in FIGS. 4A and 5, stop surface  12  is eliminated thereby allowing counter-clockwise rotation of the driver  4  even though the cam  1  is held in position via the relationship of the ball bearings  43  and the unlocked shackle  50 . Torque may be applied to the key in the counter-clockwise direction to allow the key cylinder to be rotated to the key pull position, thus allowing withdrawal of the key from the key cylinder  44 . The torsion spring  6  is now under full load and applying torque to the cam  1  in a counter-clockwise direction. When the shackle  50  is pushed back into the locked position within the padlock body  100  the torque on the cam  1  forces the ball bearings  43  away from the center of the cam  1  and out of the recesses  11  and into the crescent shaped cutouts  42  in the shackle  50 , locking the shackle  50  into place. When the ball bearings  43  are no longer engaging the recesses  11 , the cam  1  is rotated in a counter-clockwise direction until surface  39  makes contact with the long spring end  19 .  
         [0024]    In operation of the NRK (Non Removable Key) version of the invention shown in FIG. 4B, the added surface  12  on the NRK cam  2  is in direct contact with surface  15  of the driver  5  and the driver  5  cannot turn in a counter-clockwise direction unless the cam  2  does. The torsion spring  6  is now under full load and applying torque to the cam  2  in a counter-clockwise direction. When the shackle  50  is pushed back into the locked position within the padlock body  100  the torque on the cam  2  forces the ball bearings  43  away from the center of the cam  2  and out of the recesses  11  and into the crescent shaped cutouts  42  in the shackle  50 , locking the shackle  50  in place. When the ball bearings  43  are no longer engaging the recesses  11 , the cam  2  is rotated in a counter-clockwise direction until surface  40  makes contact with the long spring end  19 .  
         [0025]    [0025]FIG. 3B illustrates the same component relationships using a different torsion spring  24 . The spring end  25  corresponds to the short spring end  20  on torsion spring  6  for location and function and a longitudinal spring end  23  is designed to enter a third cavity  38  in the cam. This third cavity  38  prevents rotation of the longitudinal spring end  23  relative to the cam. With longitudinal spring end  23  in a third cavity  38 , shown in FIG. 5, and spring end  25  against driver surface  13 , the driver is rotated until surface  16  of the driver rests against surface  7  of the cam. In this orientation spring end  25  continues to rest against surface  13  of the driver which is coplanar with surface  39  of the cam. This rotation of the driver provides the preload needed for correct operation of the invention.  
         [0026]    Although the present invention has been described in detail with reference to certain preferred embodiments thereof, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred embodiment contained herein.

Summary:
A locking device for locking systems that use different key cylinder types. The locking device is capable of allowing a key to be removed when a lock is in an unlocked position or retaining the key within the padlock body in an unlocked position. The device prevents fatigue of an internal torsion spring and creates more stability for all the internal mechanisms inside the padlock body.