Abstract:
An exemplary method of making a key is provided. A bitted surface is formed in a key blade of a key blank. A groove is formed in a first side of the key blade. At least one receptacle is formed in the groove. A notch is formed in the groove adjacent to the at least one receptacle for mating with a rib in a lock cylinder.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   The present application is a continuation of and claims benefit from U.S. application Ser. No. 10/408,955, filed Apr. 8, 2003, now U.S. Pat. No. 7,040,126 which claims the benefit of U.S. provisional application No. 60/371,262 filed on Apr. 9, 2002, and U.S. provisional application No. 60/399,231 filed on Jul. 29, 2002, all applications of which are hereby incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   The invention relates to improvements in pin tumbler combination locks. It is known in the prior art to provide a pin tumbler lock system such as disclosed in U.S. Pat. No. 3,742,744. This patent discloses a primary locking system comprising a plurality of pin tumblers and a secondary locking system comprising opposed sets of lateral blocking pins aligned at right angles to the pin tumblers and adapted to engage in grooves in the key. One major disadvantage to this lock system is that the lateral blocking pins must be positioned between the primary pin tumblers. Thus due to the positioning of the lateral blocking pins between the primary pin tumblers, the prior art locking system has a very limited number of combinations. Still further, another disadvantage to this system is that each of the lateral blocking pins and the bores they are received in have a narrow inner portion connected to a larger second portion in order to prevent the pins from fully extending into and blocking the keyway. Thus due to the different diameters and step of each pin and the corresponding bore, additional machining steps are required for the pins and the cylinder plug. Another disadvantage to this system is that due to the length of the pins, the pins have a tendency to tilt in its chamber. Because of this tendency, the key must have a bevel at its tip in order to overcome the additional resistance caused by the pin&#39;s tendency to tilt in its chamber. For the foregoing reasons, there is a need for an improved pin tumbler lock with multiple tumbler combinations which overcomes the aforementioned disadvantages. 
   SUMMARY OF THE INVENTION 
   The present invention provides in one aspect a lock comprising a shell having a bore formed therein with a plug rotatably mounted within the bore and having a first set of bores aligned with a second set of bores in the shell. A plurality of pin tumblers are slidably disposed in the first set and the second set of bores. A keyway extends in the plug for receiving a key. One or more chambers are formed in the cylinder plug and intersect a portion of the keyway. Two or more ball bearings are mounted within the chamber. The plug further comprises a rib for preventing the ball bearings from blocking the keyway. The key further comprises one or more laterally spaced receptacles positioned for engagement with the ball bearings. 
   The invention provides in another aspect a lock comprising a shell having a cylindrical bore formed therein. A cylinder plug is rotatably mounted within the cylindrical bore and has a first set of bores aligned with a second set of bores in the shell. A plurality of pin tumblers are slidably disposed in the first set and the second set of bores. A keyway axially extends in the cylinder plug for receiving a key. One or more chambers are formed in the plug and intersect a portion of the keyway. A locking member is mounted within the chamber. The cylinder plug further comprising a rib for preventing the locking member from blocking the keyway. The key further comprises one or more laterally spaced receptacles positioned for communication with the locking member. 
   These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following description, appended claims, and accompanying drawings wherein: 
       FIG. 1  illustrates a perspective exploded view of a pin tumbler lock and key of the present invention; 
       FIG. 1A  illustrates al alternate embodiment of a locking member. 
       FIGS. 2 and 2   a  illustrate a cross-sectional view of the pin tumbler cylinder lock of  FIG. 1  with a key with the correct pin tumbler bitting and a correct receptacle; 
       FIG. 2   b  is the same as  FIG. 2  except that a different key profile is shown; 
       FIG. 3  is the same as  FIG. 2  except that a key without the proper receptacle is inserted; 
       FIGS. 4 and 4   a  illustrate a cross-sectional view of the pin tumbler cylinder lock with the ball bearing chamber at a different orientation than  FIG. 2 , and shown with a key with the correct pin tumbler bitting and a correct receptacle; 
       FIG. 5  shows a key of the present invention having all the potential receptacles for mating with the ball bearing chamber orientation of  FIG. 2 ; 
       FIG. 6  shows a key having all the potential receptacles for mating with the ball bearing chamber orientation of  FIG. 4 ; and 
       FIGS. 7   a ,  7   b , and  7   c  show alternate embodiments of the shell cavity; 
       FIGS. 8 ,  9  and  10  are perspective views of alternate key embodiments of the present invention; and 
       FIG. 11  is an end view of the keys of  FIGS. 8-10 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   As shown in  FIG. 1 , a lock arrangement comprising a pin tumbler cylinder is shown generally at  10 . As described in more detail below, the pin tumbler cylinder plug  20  includes one or more axially spaced pin tumbler bores  22  for housing a plurality of pin tumblers  40 , 42 . The pin tumblers  40 , 42  are oriented to intersect a keyway  24  and to operatively engage the blade  25  of a key  26 , as described in more detail. The cylinder plug  20  further includes one or more chambers  28  which intersect the keyway. 
   As can be seen in  FIGS. 2A and 4A , when a proper key is inserted in the cylinder, the proper receptacle  52  or slots  72 , 73  in the key permit the locking member  50  to enter the key way. When locking member  50  enters the key way it contacts rib  60 . As can be seen by  FIGS. 2A and 4A , because the locking member is spherically shaped, the locking member  50  contacts the rib  60  at a center portion  80  of the locking member  50 . Thus, the locking member  50  is effectively divided by center portion  80 , when it is in contact with rib  60 , into two different edge portions  82  and  84  that both intersect the key way when a proper key is inserted in the cylinder. 
   The pin tumbler cylinder plug  20  is rotatably received in a cylindrical bore  29  of a shell  30  for rotation about an axis of the shell. The shell  30  comprises a first cylindrical portion  31  including the cylindrical bore  29  and a second portion  33  extending radially from said first cylindrical portion. The shell second portion  33  includes one or more shell bores  32  aligned with the one or more pin tumbler cylinder bores  22  of the pin tumbler cylinder  20  when the pin tumbler lock is in a first or locking position. As shown in  FIG. 1 , the shell bores  32  and pin tumbler bores  22  are spaced in parallel planes along the shell longitudinal axis. A plurality of pin tumblers  40 , 42  are received in respective portions of the bores  32 , 22 . Spring  44  biases the pin tumblers  40 , 42  inward for mating engagement with a key blade  25 . 
   The keyway  24  of the pin tumbler cylinder plug  20  extends radially inward from the outer surface of the pin tumbler cylinder plug and is aligned in the same plane as the pin tumbler cylinder bores  22 . The key blade  25  is received in the keyway  24  for axial movement toward and away from the fully inserted, locking position. The key  26  comprises an edge portion  27  having a bitted surface  27   a  which cooperate with the pin tumblers  40 , 42  in the conventional manner. Thus when the proper bitted key blade  25  is inserted into the keyway  24 , the pin tumblers held in the cylinder plug terminate at the interface  29  of the shell and cylinder plug creating a shear plane so that the pin tumblers do not block rotation of the cylinder plug. Grooves  46  extend over the key sidewalls over its entire inserted length, wherein the grooves conformingly engage aligned sidewalls  48  of the keyway  24  to guide entry of the key blade into the keyway. 
   The pin tumbler cylinder plug  20  further comprises one or more chambers  28  for housing a locking member  50 . Preferably, the locking member is a ball bearing. More preferably, the locking member includes at least two ball bearings. The locking member may also comprise a cylindrical shape preferably having opposed spherically shaped ends ( FIG. 1A ). The locking member may also comprise a pin having opposed spherically shaped ends. However, ball bearings have an advantage over other shaped locking members in that the ball bearings provide significantly less friction, wear and do not require a bevel at the tip of the key to overcome resistance. The chamber  28  is preferably sized to have a depth D equal to or greater than the combined length of the locking member. If ball bearings are utilized, then the chamber depth should preferably be about equal to or greater than the combined diameters of the ball bearings. 
   The chamber  28  is positioned to intersect a portion of the keyway  24  so that the locking member or ball bearings cammingly engage a receptacle  52  located in a sidewall of the key. The receptacles  52  of the key are preferably arcuately shaped, and thus have a radius of curvature which closely matches the ball bearing curvature. The chamber  28  is additionally aligned with a cavity  54  in the shell interior surface when the cylinder plug  20  is oriented in a locked position. Thus if a fully inserted key has a properly aligned receptacle  52  which aligns with the chamber  28 , the locking member will be forced into the key receptacle and chamber by rotational torque applied to the key. If the fully inserted key does not have a receptacle, the locking member will be forced into the cavity  54  and the cylinder plug will be prevented from turning by a portion of the locking member being trapped in the cavity. 
   The pin tumbler cylinder plug  20  preferably further includes a rib  60  which extends in a longitudinal direction and is positioned to prevent the locking member from entering and blocking the keyway. Preferably, the rib  60  is located adjacent the keyway and the chamber, and more preferably, is located between the keyway  24  and the chamber  28 . See  FIGS. 3 and 4  which show different positions of the rib  60 . The rib may comprise any desired cross-sectional shape such as a triangle, etc. The key includes a complementary shaped notch  62  which is in mating engagement with the rib  60 . Preferably, the notch  62  is a v shaped groove. The key cross-sectional shape is not limited to what is shown in  FIGS. 2 and 3 , as other shapes would also work for the invention as shown in  FIG. 2   b . However, the key must be shaped to engage the locking member and the rib. 
   It is preferred that the locking member have a width or diameter less than the diameter of the pin tumblers so that the pin tumblers cannot be trapped in the chamber upon rotation of the cylinder. Further, the chamber  28  need not be oriented perpendicular to the keyway as shown in  FIGS. 2 and 3 . For example, see  FIG. 4  in which the orientation of the chamber intersects a portion of the keyway in a non-orthogonal angle ø. It is preferred that the orientation of the chamber be angularly inclined an angle ø in the range of about 45 degrees to about 135 degrees with respect to the plane of the keyway. With this different orientation of the chamber as shown in  FIG. 4 , the key receptacles are located on the opposite side of the key on the upper key groove  46  as shown in  FIG. 6 . 
   A plurality of chambers  28  are preferably utilized in the cylinder plug  20  of the pin tumbler cylinder  10  and which are uniformly laterally spaced on intervals of the ball bearing radius or larger in the direction of the cylinder axis on either side of the keyway. The shell cavity  54  is preferably sized to have a diameter equal to or greater than the diameter of the ball bearings. The cavity may preferably be dish-shaped or arced as shown in  FIG. 2  in discrete locations or along the entire length of the shell. The cavity may also be a cast, broached, drilled or milled hole as shown in  FIGS. 7A-7C  and which is aligned with the bottom edge of the chamber when in the locked position. 
   The invention also provides an improved locking system comprising a plurality of locks. Each lock preferably has two chambers with a minimum of two ball bearings in each chamber. For each of the locks in the improved locking system, the chambers  28  are spaced on intervals along the plug cylindrical axis, preferably slightly larger than the radius of the ball bearings. The chambers may be located on one side of the keyway or on both sides of the keyway. The chambers may also be oriented at different angles. Each key in the locking system has a corresponding receptacle which is also spaced on the same intervals as the chambers. If the chambers are located on the same side of the keyway, then it is preferred that adjacent positions not be used because of the close proximity of the ball bearings to each other. 
   The improved locking system further provides for a service key  70  as shown in  FIGS. 9-11 . The service key  70  has the same characteristics as described above, except that it has one or more slots  72 , 73  instead of receptacles  52 . The slots  72 , 73  are positioned to cooperate with the locking member or ball bearings so that they may be partially received within the slot so that the pin tumbler cylinder plug  20  can rotate. The slots may be sized or arranged to service a plurality of lock cylinders which have different combinations or arrangements of the locking member and chambers  28 . The length of the slot  72 , 73  dictates the number of locks which may be serviced. 
   An example of the locking system of the present invention is as follows. A plurality of locks may be provided with each lock providing for five potential chamber positions located adjacent each other and labeled sequentially A, B, C, D, and E. Each lock would have two chambers. It is preferred that adjacent chamber positions on the same side of the lock not be used. Thus the A and B positions would not be used, however, it would be possible to use A and C on a first lock, chamber positions A and D on a second lock, positions A and E on a third lock. Thus as set forth in Table I below, having only five potential chamber/receptacle positions in a lock system will have the potential of producing six different unique combinations of receptacles on the key. 
   
     
       
             
           
             
             
             
           
         
             
               TABLE I 
             
           
           
             
                 
             
             
               Example of Chamber Positions Selected for Lock System 
             
           
        
         
             
                 
               Lock System 
               Chamber Positions 
             
             
                 
                 
             
             
                 
               Lock 1 
               A and C 
             
             
                 
               Lock 2 
               A and D 
             
             
                 
               Lock 3 
               A and E 
             
             
                 
               Lock 4 
               B and D 
             
             
                 
               Lock 5 
               B and E 
             
             
                 
               Lock 6 
               C and E 
             
             
                 
                 
             
           
        
       
     
   
   For example, in a lock having four standard pin tumblers that use 8 depths of cut there are 4,096 potential depth combinations. The lock system having five chamber locations as described above offers the ability to increase that number six-fold to a total potential of 24,576 unique combinations. Thus by increasing the number of available chamber positions in a lock system, it is possible to increase the potential for different combinations of non-adjacent receptacles. 
   For example, adding just one more chamber position to the five mentioned above will allow four additional position combinations of A-F, B-F, C-F, and D-F which would increase the number of positional combinations to ten and the overall potential combinations from 4,096 to 40,960 unique combinations. If the lock system having five chamber positions is used in conjunction with a six pin cylinder with the same bitting specifications, the number of unique combinations can be increased to 1,572,864 from 262,144 standard combinations. If six chamber positions are used, the number of possible combinations increases to 2,621,440 unique combinations. 
   It is also possible to use in combination a plurality of chambers having different orientations (i.e., different φ&#39;s). Each different orientation of the chamber would require a mating receptacle on the key. For example it is possible to intermix the chamber configurations as shown in  FIGS. 2 and 4 . As shown in  FIGS. 4 and 6 , if thirteen receptacle positions of a first type were utilized in conjunction with thirteen receptacle positions of a second type for the four pin tumbler described above, there would be a total of 301 additional unique arrangements which could be used. Combining the 301 additional arrangements with the 4096 standard combinations for a 4 pin tumbler results in a total of 1,232,896 combinations. If a six pin tumbler is used, a total of 78,905,344 unique combinations may be realized. 
   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.