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RELATED APPLICATIONS 
     Not applicable. 
     BACKGROUND 
     The invention relates generally to a magnetic lock and key assembly. More particularly, the invention relates to a magnetic lock assembly configured to operate in cooperation with a corresponding magnetic key assembly. 
     Many conventional locks include internal lock components that are mechanically engaged by a key inserted into an opening in the lock. This general lock configuration incorporates a number of precision elements that must work in concert to ensure proper operation of the lock. In addition, the opening in the lock hampers the operational life and ultimate security afforded by the lock. For instance, debris, such as dust, water, and other contaminants can enter the lock through the opening and foul the internal lock components. Furthermore, nefarious characters exploit the key opening in efforts to tamper with and defeat the security aspects of the lock. 
     Magnetic lock and key assemblies are generally described in U.S. application Ser. No. 13/561,785 filed on Jul. 30, 2012, U.S. application Ser. No. 13/400,428 filed on Feb. 20, 2012, and U.S. application Ser. No. 13/034,499 filed on Feb. 24, 2011. The entire disclosures of the above-listed applications are hereby incorporated by reference as if fully set forth herein. 
     In light of at least the above considerations, a need exists for a lock assembly having improved construction and operation. 
     BRIEF SUMMARY OF THE INVENTION 
     In one aspect, the present invention provides a magnetic lock and key system including a magnetic lock that includes: a body, a lock element arranged at least partially within the body and moveable between a locked position and an unlocked position, a cap coupled to the body and defining a dome, and an arc magnet arranged within the body between the cap and the lock element, the arc magnet defining a chamfered edge and moveable between a first position corresponding with the locked position of the lock element and a second position corresponding to the unlocked position of the lock element; and a magnetic key arranged to engage the cap of the magnetic lock and including a key magnet moveable between a first position spaced apart from the dome of the cap, and a second position adjacent the dome of the cap, the key magnet defining a countersink corresponding to the chamfered edge. 
     In another aspect, the invention provides a magnetic lock for use with a magnetic key, the magnetic lock including a body, a lock element arranged at least partially within the body and moveable between a locked position and an unlocked position, a cap coupled to the body and defining a dome, and an arc magnet arranged within the body between the cap and the lock element, the arc magnet defining a chamfered edge and moveable between a first position corresponding with the locked position of the lock element and a second position corresponding to the unlocked position of the lock element. 
     In another aspect, the invention provides a magnetic key for use with a magnetic lock, the magnetic key including a handle, a trigger coupled to the handle and rotatable relative thereto between a first position and a second position, a collet coupled to the handle, configured to engage the magnetic lock, and defining a magnet aperture, and a key magnet received in the magnet aperture and defining a countersink, the key magnet is free to rotate within the collet and is actuatable by the trigger between an on position and an off position. 
     The foregoing and other aspects and advantages of the invention will appear from the following description. In the description, reference is made to the accompanying drawings that form a part hereof, and in which there is shown by way of illustration a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention, however, and reference is made therefore to the claims and herein for interpreting the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The invention will be better understood and features, aspects, and advantages other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such detailed description makes reference to the following drawings. 
         FIG. 1  is a sectional view of a magnetic lock. 
         FIG. 2  is a sectional view of a magnetic key. 
         FIG. 3  is a sectional view of the magnetic lock of  FIG. 1  and the magnetic key of  FIG. 2  coupled together in a first position. 
         FIG. 4  is a sectional view of the magnetic lock of  FIG. 1  and the magnetic key of  FIG. 2  coupled together in a second position. 
         FIG. 5  is a sectional view of the magnetic lock of  FIG. 1  and the magnetic key of  FIG. 2  coupled together in a third position. 
         FIG. 6  is a sectional view of the magnetic lock of  FIG. 1  and the magnetic key of  FIG. 2  decoupled from one another. 
         FIG. 7  is an exploded pictorial view of an arc magnet. 
         FIG. 8  is a pictorial view of the arc magnet of  FIG. 7  and a key magnet. 
         FIG. 9  is a plan view of the arc magnet of  FIG. 7  and the key magnet of  FIG. 8  arranged in two different positions. 
         FIG. 10  is a sectional view of a magnetic key engaging a magnetic lock according to one embodiment of the invention. 
         FIG. 11  is a pictorial view of a key magnet according to one embodiment of the invention. 
         FIG. 12  is a plan view of the key magnet of  FIG. 11 . 
         FIG. 13  is a sectional plan view of the key magnet of  FIG. 11  taken along line  13 - 13  of  FIG. 12 . 
         FIG. 14  is a pictorial view of an arc magnet according to one embodiment of the invention. 
         FIG. 15  is a plan view of the arc magnet of  FIG. 14 . 
         FIG. 16  is a pictorial view of a key magnet according to one embodiment of the invention. 
         FIG. 17  is a plan view of the key magnet of  FIG. 16 . 
         FIG. 18  is a sectional plan view of the key magnet of  FIG. 16  taken along line  18 - 18  of  FIG. 17 . 
         FIG. 19  is a sectional view of a magnetic lock similar to  FIG. 1  and a magnetic key similar to  FIG. 2  compared to the magnetic lock and magnetic key of  FIG. 10 . 
         FIG. 20  is a sectional view of a magnetic lock similar to  FIG. 1  compared to the magnetic lock of  FIG. 10 , each receiving a generic magnet. 
         FIG. 21  is a sectional view of a magnetic lock similar to  FIG. 1  compared to the magnetic lock of  FIG. 10 , each receiving another generic magnet. 
         FIG. 22  is a sectional view of a magnetic lock similar to  FIG. 1  compared to the magnetic lock of  FIG. 10 , each receiving a further generic magnet. 
         FIG. 23  is a sectional view of a magnetic lock similar to  FIG. 1  compared to the magnetic lock of  FIG. 10 , each receiving yet another generic magnet. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Before any 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 components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
     The following discussion is presented to enable a person skilled in the art to make and use embodiments of the invention. Various modifications to the illustrated embodiments will be readily apparent to those skilled in the art, and the principles herein can be applied to other embodiments and applications without departing from embodiments of the invention. Thus, embodiments of the invention are not intended to be limited to embodiments shown, but are to be accorded the widest scope consistent with the principles and features disclosed herein. The following detailed description is to be read with reference to the figures, in which like elements in different figures have like reference numerals. The figures, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of embodiments of the invention. Skilled artisans will recognize the examples provided herein have many useful alternatives and fall within the scope of embodiments of the invention. 
       FIG. 1  shows a magnetic lock  10  that includes a lock element in the form of two steel balls  14  received in a lock body  18 , a plunger  22  received in the lock body  18 , a compression spring  26 , a keyed cap  30 , and an arc magnet  34 . The lock body  18  defines a plunger aperture  38  extending along a longitudinal axis of the lock body  18  and sized to receive the plunger  22 , and locking apertures  42  formed in the lock body  18  transverse to the plunger aperture  38  and sized to receive the steel balls  14 . In other embodiments, the locking element may be a lever, or a different locking mechanism, as desired. Additionally, any suitable material may be used for the locking element. 
     The plunger  22  defines a countersink  46  arranged to receive (e.g., rotatably, fixably, or otherwise) the arc magnet  34 , a spring aperture  50  recessed into the countersink  46  and sized to receive the compression spring  26 , an unlocking diameter  54 , and a locking diameter  58 . 
     The keyed cap  30  is rigidly coupled to the lock body  18  to capture the plunger  22 , the compression spring  26 , and the arc magnet  34  therebetween. The plunger  22  and/or the arc magnet  34  may be rotatable within the lock body  18 . The keyed cap  30  defines a key receiving feature  62 . 
     The arc magnet  34  will be described with respect to  FIG. 7 . The arc magnet  34  includes a first magnet half  66  and a second magnet half  70  coupled together. In one embodiment, the first half  66  is bonded to the second half  70  with adhesive. The first half  66  and the second half  70  are each axially magnetized permanent magnets and define a central aperture such that when the arc magnet  34  is assembled a central aperture sized to receive the compression spring  26  is formed. The first half  66  and the second half  70  are arranged so that the arc magnet  34  has a north pole on one of the first half  66  and the second half  70  (e.g., a top surface of the first half  66  as shown in  FIG. 7 ) and a south pole on the other half (e.g., a top surface of the second half  70  as shown in  FIG. 7 ). 
     Turning back to  FIG. 1 , the magnetic lock  10  is assembled by, in one example, bonding the arc magnet  34  into the countersink  46  of the plunger  22 . The two steel balls  14  are installed in the locking apertures  42  of the lock body  18 , and the plunger is inserted into the plunger aperture  38  of the lock body  18 . The compression spring  26  is then placed in the spring aperture  50 , and the keyed cap  30  is coupled to the lock body  18 . 
     In operation, the magnetic lock  10  is movable between a first or locked position (shown in  FIG. 1 ) and a second or unlocked position (see  FIG. 4 ). The illustrated magnetic lock  10  is normally arranged in the locked position with the compression spring  26  biasing the plunger  22  toward and into a locked position with the steel balls  14  forced outward by the locking diameter  58  of the plunger  22 . When a suitable magnetic field is enacted on the arc magnet  34 , the magnetic attraction draws the arc magnet  34  toward an unlocked position against the bias of the compression spring  26 . As shown in  FIG. 4 , when the arc magnet  34  is drawn to the unlocked position toward the keyed cap  30 , the two balls  14  move inward with respect to the lock body  18  and into contact with the unlocking diameter  54  of the plunger  22 . 
       FIG. 2  shows a magnetic key  74  that includes a collet  78 , a magnet cup  82 , a key magnet  86 , a pusher rod  90 , a return spring  94 , an end cap  98 , a handle  102 , and a trigger  106 . The collet  78  includes fingers  110  arranged to engage the key receiving feature  62  of the magnetic lock  10 . A magnet aperture  114  is defined in an end of the collet  78  adjacent the fingers  110  and is sized to receive the magnet cup  82 . A coupling feature in the form of threads  118  couple the collet  78  to the handle  102 . 
     The magnet cup  82  defines an open end  122  arranged to receive the key magnet  86  and a closed lock engaging end  126  that is produced with features corresponding to the features of the key receiving feature  62  of the magnetic lock  10 . The magnet cup  82  is sized to be slidingly received in the magnet aperture  114  of the collet  78 . 
     The key magnet  86  will be described with respect to  FIG. 8 . The key magnet  86  includes a first magnet half  130  and a second magnet half  134  coupled together. In one embodiment, the first half  130  is bonded to the second half  134  with adhesive. The first half  130  and the second half  134  are each axially magnetized permanent magnets and define a central aperture such that when the key magnet  86  is assembled a central aperture is formed. The first half  130  and the second half  134  are arranged so that the key magnet  86  has a north pole on one of the first half  130  and the second half  134  (e.g., a top surface of the first half  130  as shown in  FIG. 8 ) and a south pole on the other half (e.g., a top surface of the second half  134  as shown in  FIG. 8 ). 
     Turning back to  FIG. 2 , the pusher rod  90  includes a head  138  sized to be press fit into the open end  122  of the magnet cup  82 , a shaft  142  extending from the head  138 , and a coupling portion  146  located opposite the head  138  and arranged to engage the end cap  98 . 
     The handle  102  defines a key mechanism aperture  150  and a collet engaging portion  154  arranged to engage the threads  118  of the collet  78 . The trigger  106  includes a pivot point  158  and a lever  162 . 
     The magnetic key  74  is assembled by inserting the key magnet  86  into the magnet cup  82 , and then press fitting the head  138  of the pusher rod  90 . The spring  94  is then installed over the shaft  142  of the pusher rod  90  as it extends through the collet  78 , and the end cap  98  is coupled to the coupling portion  146  of the pusher rod  90 . The collet  78  is then threadingly coupled to the handle  102  with the end cap  98 , the spring  94 , and a portion of the pusher rod  90  received within the key mechanism aperture  150 . The trigger  106  is coupled to the handle  102  via the pivot point  158  with the lever  162  arranged to engage the end cap  98  as shown in  FIG. 2 . 
     In operation, the magnetic key  74  is actuatable between an off position (shown in  FIG. 2 ) and an on position (generally shown in  FIG. 3 ), via manipulation of the trigger  106 . The return spring  94  biases the magnetic key  74  toward the off position by biasing the end cap  98  away from the collet  78 . To force the magnetic key  74  toward the on position, the trigger  106  is pulled such that the lever  162  urges the end cap  98  toward the collet  78  against the bias of the return spring  94 . In turn, the pusher rod  90  moves and forces the magnet cup  82  toward the fingers  110  of the collet  78 . The key magnet  86  is trapped by the magnet cup  82  and is moved therewith. Upon releasing the trigger  106 , the return spring  94  returns the magnetic key  74  to the off position. Additionally, the key magnet  86  is arranged and received within the magnet cup  82  such that the key magnet  86  can, in some embodiments, rotate freely. 
     Coordinated operation of the magnetic lock  10  and the magnetic key  74  will be discussed below with respect to  FIGS. 3-6 .  FIG. 3  shows the magnetic lock  10  arranged in the locked position, the magnetic key  74  engaged with the magnetic lock  10  such that the fingers  110  of the collet  78  are engaged with the key receiving feature  62  of the keyed cap  30 , and the magnetic key  74  in the on position. The fingers  110  may be tapered radially inward or otherwise configured such that the fingers  110  flex radially outward due to interaction with the magnet cup  82  and/or the key magnet  86  when the magnetic key  74  is in the on position.  FIG. 3  shows the initial condition when the magnetic key  74  is inserted into the magnetic lock  10  and the trigger  106  is pulled. As shown, the key magnet  86  is not necessarily initially magnetically aligned with the arc magnet  34 . With the key magnet  86  in sufficiently close proximity to the arc magnet  34 , the key magnet  86  rotates within the magnet cup  82  to align with the poles of the arc magnet  34 . Alternatively, the arc magnet  34  may be rotatable alone or in addition to the key magnet  86 . 
     Turning to  FIG. 4 , once the key magnet  86  and the arc magnet  34  are sufficiently aligned, the attractive force between the key magnet  86  and the arc magnet  34  will overcome the bias of the compression spring  26  and the plunger  22  will be pulled toward the keyed cap  30  and the magnetic lock  10  is moved to the unlocked position. 
     After the magnetic lock  10  is unlocked, the trigger  106  is released and the magnetic key  74  moves back to the off position (as shown in  FIG. 5 ). With the key magnet  86  moved away from the arc magnet  34 , the compression spring  26  forces the plunger  22  away from the keyed cap  30  and the magnetic lock  10  returns to the locked position. 
       FIG. 6  shows how the magnetic key  74  is removed from the magnetic lock  10  by pulling and rotating the magnetic key  74  relative to the magnetic lock  10  such that the fingers  110  flex and disengage from the key receiving feature  62  of the keyed cap  30 . 
     A more detailed discussion of the interaction between the arc magnet  34  and the key magnet  86  will be discussed with respect to  FIGS. 8 and 9 . As discussed above, the key magnet  86  is free to rotate (and/or the arc magnet  34  may also be free to rotate in some embodiments). As shown in  FIG. 8 , the key magnet  86  will tend to rotate into magnetic alignment with the arc magnet  34  when the key magnet  86  is within sufficient proximity to the arc magnet  34 . In other words, when the magnets  34 ,  86  are placed within proximity to one another, the magnetic fields exert a rotational force between the magnets  34 ,  86  that tends to align the magnets  34 ,  86  so that the north pole at the top of the arc magnet  34  aligns with the south pole at the bottom of the key magnet  86  and vice versa. As long as one or both magnets  34 ,  86  are allowed to rotate freely, the magnets  34 ,  86  will always assume this orientation because this is the lowest energy state for the system. 
     When the magnets  34 ,  86  are aligned as above there is an attractive force parallel to the center axis that acts to pull the magnets  34 ,  86  closer together. The magnitude of this force is generally inversely proportional to the square of the distance or air gap between the magnets  34 ,  86 . Therefore, doubling the air gap will decrease the attractive force between the magnet assemblies by a factor of four. In other words, the arrangement shown at the left in  FIG. 9  experiences an attractive force four times larger than the arrangement shown at the right. 
     Turning to  FIG. 10 , a new magnetic lock  510  and a new magnetic key  574  arrangement will be discussed. Many portions of the magnetic lock  510  and the magnetic key  574  are similar to the magnetic lock  10  and the magnetic key  74  discussed above and are numbered similarly in the  500  and  600  series accordingly. 
     An arc magnet  700  is received in the countersink  546  of the plunger  522  similar to how the arc magnet  34  is received in the countersink  46  of the plunger  22  discussed with respect to  FIG. 1 . The arc magnet  700  defines a chamfered top edge  704  that is chamfered at an angle A of about thirty degrees (30°) with respect to horizontal (as shown in  FIG. 15 ). The angle A may be different according to the desired characteristics of the magnetic lock  510 . In other embodiments, the chamfered edge may be a curved surface, spherically shaped, arranged at different angles, or include another profile shape, as desired. 
     The arc magnet  700  includes a first magnet half  708  (see  FIG. 14 ) and a second magnet half  712  (see  FIG. 15 ) coupled together. In one embodiment, the first half  708  is bonded to the second half  712  with adhesive. The first half  708  and the second half  712  are each axially magnetized permanent magnets and define a central aperture such that when the arc magnet  700  is assembled a central aperture is formed. The first half  708  and the second half  712  are arranged so that the arc magnet  700  has a north pole on one of the first half  708  and the second half  712  (e.g., the chamfered surface  704  of the first half  708  as shown in  FIG. 14 ) and a south pole on the other half (e.g., the chamfered surface  704  of the second half  712  as shown in  FIG. 15 ). 
     A keyed cap  716  includes a body engaging portion  720  arranged to rigidly couple with the lock body  518 , an interior cavity  724  sized to receive the plunger  522 , the arc magnet  700 , and the compression spring  526 , an annular shoulder  728 , and a dome  732 . The dome  732  defines an annular and angled side wall  736  arranged at about the same angle as the angle A of the chamfered surface  704  on the arc magnet  700 . In the illustrated embodiment, the angled side wall  736  is arranged at about thirty degrees (30°) with respect to horizontal (as shown in  FIG. 10 ). A flat top surface  740  is defined at the top of the angled side wall  736 . 
     The magnetic key  574  includes a magnet cup  744  that defines a closed lock engaging end  748  shaped to correspond to the shape and profile of the dome  732 . That is to say, the closed lock engaging end  748  defines an inverted dome shape that is arranged to substantially mate with or receive the dome  732  of the keyed cap  716 . 
     A key magnet  752  is received within the magnet cup  744  and shaped to match the profile of the dome  732 . In other words, the key magnet  752  defines a countersunk angled wall  756  shaped or angled to match the chamfered top edge  704  of the arc magnet  700 . That is to say that in the illustrated embodiment, the angle of the countersink  756  is about thirty degrees (30°), but may be a different angle or a different shape, as desired. The key magnet  752  includes a central aperture  762  that extends along a longitudinal axis of the key magnet  752  (see  FIGS. 16-18 ).  FIGS. 11-13  show an alternative key magnet  764  that does not include a central aperture. 
       FIG. 19  shows a comparison of the general magnetic lock  10  (without a central protrusion extending from the keyed cap  30 ) and the general magnetic key  74  (without a mating recess in the magnet cup  82 ) to the magnetic lock  510  and the magnetic key  574 . As is shown, the effective gap between the magnets remains significantly consistent between the two designs. This allows both designs to function effectively using the principals outlined above. In the illustrated embodiment, the air gap is about 0.160 inches. In other embodiments, the size of the locks and the air gaps may be different, as desired. 
       FIG. 20  shows a similar comparison of the general magnetic lock  10  and the magnetic lock  510  when a non-key magnet  800  is inserted into the magnetic locks  10 ,  510 . The magnetic lock  10  allows the non-key magnet  800  to achieve a proximity to the arc magnet  34  that is sufficient to actuate the magnetic lock  10  to the unlocked position. The dome  732  of the magnetic lock  510  inhibits the non-key magnet  800  from achieving a sufficient proximity. In other words, the non-key lock  800  cannot achieve a large enough attractive force with the arc magnet  700  to actuate the magnetic lock  510  to the unlocked position. 
     Similarly,  FIGS. 21-23  show examples of non-key magnets  801 ,  802 ,  803  engaged with the general magnetic lock  10  and the magnetic lock  510 . In each scenario, the dome  732  is effective in increasing the proximity achieved by the non-key magnet  801 ,  802 ,  803  to the arc magnet  700 . As discussed above, the attractive force is generally affected by the square of the distance between the magnets. In turn, the dome  732  is effective for greatly reducing the ability of non-key magnets to actuate the magnetic lock  510 . 
     It will be appreciated by those skilled in the art that while the invention has been described above in connection with particular embodiments and examples, the invention is not necessarily so limited, and that numerous other embodiments, examples, uses, modifications and departures from the embodiments, examples and uses are intended to be encompassed by the claims attached hereto. The entire disclosure of each patent and publication cited herein is incorporated by reference, as if each such patent or publication were individually incorporated by reference herein.

Summary:
A magnetic lock and key system including a magnetic lock that includes: a body, a lock element arranged at least partially within the body and moveable between a locked position and an unlocked position, a cap coupled to the body and defining a dome, and an arc magnet arranged within the body between the cap and the lock element, the arc magnet defining a chamfered edge and moveable between a first position corresponding with the locked position of the lock element and a second position corresponding to the unlocked position of the lock element; and a magnetic key arranged to engage the cap of the magnetic lock and including a key magnet moveable between a first position spaced apart from the dome of the cap, and a second position adjacent the dome of the cap, the key magnet defining a countersink corresponding to chamfered edge.