Patent Publication Number: US-11391060-B2

Title: Weather resistant lock

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This is a Continuation-in-Part of U.S. patent application Ser. No. 15/050,709 filed Feb. 23, 2016, and which claims priority from Canadian Patent Application No. 2,920,469, dated Feb. 9, 2016. The contents of these applications are hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to keyed tumbler locks including pin tumbler locks, wafer tumbler locks, disc tumbler locks and other cylinder lock designs and to a method of providing weather resistant features which are desirable for outdoor use. 
     BACKGROUND 
     As an example, known pin tumbler locks are prone to weather related failure, corrosion, water penetration and other weather related problems. U.S. patent application Ser. No. 12/004,856 filed on Dec. 21, 2007 and published under publication number 2008/0276666 and issued to patent under U.S. Pat. No. 9,273,487 is an example of one such available pin tumbler lock. 
     See  FIGS. 1-3 and 7  of the present application which illustrate the features of one example of a prior art pin tumbler lock used in mailboxes including outdoor mailbox applications.  FIG. 7  illustrates a rear view of a simplified profile  200  of a prior art pin tumbler lock, viewed from the distal end of the prior art pin tumbler lock assembly  100 . When this lock design is installed in locations which are exposed to outdoor weather conditions, there are a number of potential weather related issues. 
     By way of example, when installed in outdoor locations, such locks are prone to freezing particularly during weather conditions including temperature changes from rain to freezing rain or snow. With regard to the prior art drawings,  FIGS. 1-3  and particularly  FIG. 1 , water ingress is often a problem from:
         The front of the prior art pin lock between keyhole  125  and dust cover  119  and between cylinder  101  and plug cap  123  in prior art pin tumbler lock assembly  100 ; and   The top of the prior art pin lock at the interface between the spring retainer  117  and the surrounding edge of the prior art cylinder  101 . Furthermore, the shape of the top rear of cylinder  101  allows water dripping down from the mail compartment door to be biased towards spring retainer  117 . The spring retainer  117  is made from flat bar material. Spring retainer  117  is held in place by crimping the surrounding edge of the cylinder  101  to form an overlapping lip from the cast metal used to make the cylinder  101 . Often, tolerances are such that water can easily pass around and under the lip and around the edges of spring retainer  117 , into the pin chambers below.       

     The rear of the prior art pin lock may also experience water ingress between cylinder  101  and plug  103 . The dust cover  119  frequently does not fully close when dust, dirt or ice is present. The upper and lower pivot points of dust cover  119  are square and do not promote easy or smooth pivoting of the door. Water may pool at the lower pivot point which in turn may freeze and hinder movement of the dust cover. 
     Under these circumstances, water may freeze and render the lock inoperable. By way of further example:
         Pins  113 , retainer  126  and springs  115  may freeze in the pin chambers thus preventing the key from turning;   Ice may build up in cylinder  101  to prevent plug  103  from rotating. With regard to  FIG. 2 , stop  601  may prevent cylinder  101  from rotating if ice builds-up in stop chamber  602  which is positioned at the bottom of cylinder  101  where water and ice may accumulate;   Ice may build up in keyway  127  so that the key cannot be fully inserted; and   Ice may build up at the bottom of dust cover  119  and so that the dust cover will not open.       

     In some cases, customers may bend the dust cover  119  when ice builds up at the bottom of dust cover  119  and the cover won&#39;t open when force is applied with a key. A customer faced with ice build-up may firmly push on key  111  with sufficient force to bend the door near the lower pivot point. Deformation of the dust cover may prevent the dust cover from subsequently operating correctly and it may become necessary to replace the prior art pin lock. 
     Prior art locks may also be prone to corrosion or other water/ice related damage because of water penetration and accumulation within those locks. 
     There is a need for a suitable lock design with weather resistant features for use in outdoor applications. 
     Introduction to the Invention 
     The invention includes an improved, weather resistant, keyed cylindrical lock design which may be applied to pin tumbler locks, wafer tumbler locks, disc tumbler locks and other keyed lock designs. Various embodiments and aspects of the invention will be apparent to persons skilled in the art, upon reading the entirety of this specification, including the description, drawings and claims appended hereto. The following introduction is meant to provide an overview of the invention, without limiting the invention to the specific aspects and features which are described in general terms for illustration of some examples of the invention. 
     In one embodiment, a keyed cylindrical tumbler activated lock extends along a longitudinal axis from an outer face at a proximate end to a distal end. The cylindrical lock includes a shell extending between the proximate and distal ends. The shell houses a rotatable cylindrical core. The core rotates within an interior chamber defined by the shell. In some embodiments, such as a pin tumbler lock, the shell defines an elevated pinway extending along the longitudinal axis. The elevated pinway extends upwardly to a top wall from an intermediate edge defined by the shell. The elevated pinway is bounded by first and second opposed vertical side walls and a vertical end wall extending between the first and second opposed side walls. The end wall is adjacent the distal end of the pin lock. The rotatable core defines a first linear plurality of pin slots communicating with the keyway when an operating key is inserted into the keyway. The elevated pinway defines a second linear plurality of pin slots in opposing relation to the first plurality of pin slots defined by the rotatable core. A first set of pins is held in the first linear plurality of pin slots abutting in coplanar interfacial alignment with a second set of pins in the second linear plurality of pin slots. When the key is inserted and the lock is in the first position, the core is allowed to rotate, about the axis, within the shell. 
     In this example, a hood is secured above the elevated pinway. The hood, which may take the form of a top cap, defines a rigid water barrier enclosing the second set of pins in the second linear array of pin slots. The hood extends downwardly from the top wall to the intermediate edge, and about the vertical side walls and the end wall. Preferably, the hood is secured to the elevated pinway along a band adjacent the intermediate edge. 
     In some aspects of the invention, a band defined by an interior surface of the hood projects inwardly to secure the hood to the elevated pinway. The band may be formed by crimping a lower edge of the hood for secure engagement along the intermediate edge of the elevated pinway. The hood may also be crimped to form the band at the intermediate edge of the elevated pinway. 
     In some embodiments, the intermediate edge is adjacent to a bottom edge of the elevated pinway, extending along a shoulder defined by a bottom portion of the shell. 
     Some aspects of the invention may feature an interior drainway which extends downwardly and outwardly from within the tumbler lock, for example, a pin tumbler lock. The drainway may extend below an access door to the keyway which is pivotably mounted between the outer face and the keyway. Preferably, a drainway is provided to promote the flow of water outwardly and downwardly via a sloped channel and connected drain opening. The drainway may define a pathway for water to flow outwardly from the shell, the rotatable core, the access door, and an (optional) outer face ring which covers the face of the shell (if a face cover is provided) while surrounding the keyway. The access door may be pivotably mounted on a post extending between a top recess in a frame and a bottom recess in the frame. The bottom of the access door may define an elevated bottom edge which travels above an adjacent surface defined by the frame or a bottom edge of a recess within the face of the rotatable core. The elevated edge may define a clearance gap above the adjacent surface when the access door pivots within the frame. The post may be rotatable relative to the frame and the access door. 
     A detent may be featured adjacent the intermediate edge, between the interior surface of the hood and an adjacent surface of the elevated pinway to more securely fasten the hood to the elevated pinway. The hood may be crimped, press-fit, snap-fit, slide-fit or the band may be formed in another manner to provide secure engagement with the detent. 
     By way of further example, the detent may be an elevated ridge or a recess adjacent the intermediate edge. 
     In another aspect, the pin tumbler lock comprises an outer face ring at a proximate end. The pin lock includes a shell defining an elongated body extending along a longitudinal axis between the proximate end and the distal end. The shell houses a rotatable core adapted for connection to a driver, cam or other component of a lock mechanism. The shell defines an elevated pinway extending along the longitudinal axis. The elevated pinway extends upwardly to a top wall from an intermediate edge extending from a pair of opposed shoulders defined by the shell. The elevated pinway comprises: a first vertical side wall, a second vertical side wall opposite to the first vertical side wall, and a vertical end wall extending between the first and second side walls, the end wall being adjacent the distal end. The elevated pinway defines a first set of pins in a first linear plurality of pin slots through the top wall and vertically opposed to a second set of pins in a second linear plurality of pin slots defined by the rotatable core, the first and second linear plurality of pin slots being vertically aligned and communicating with a keyway in the rotatable core when an operating key is inserted into the keyway when the lock is in a first position. An interior drainway extends downwardly and outwardly from within the pin lock. The drainway comprises a channel along the bottom interior of the shell, and a dripway from the keyway in communication with the channel. The dripway extends along an access door to the keyway and along a proximate lower edge of the shell, for water to flow outwardly via a drain opening. The access door rotates about a post pivotably mounted within a frame between the outer face and the keyway when the access door is pushed away from the keyway upon entry of the operating key into the keyway. The access door may be elevated to define a gap upon rotation above a bottom ledge of the frame. A hood defines a rigid water barrier closing the first linear array of pin slots in the top wall. Preferably, the first set of pins are biased inwardly from a top interior surface of the hood toward the rotatable core. The hood may extend downwardly from the top wall to the intermediate edge, and about the first and second vertical side walls and the end wall, and when the hood is engaged with the elevated pinway, a band defined by an interior surface of the hood projects inwardly to secure the hood to the elevated pinway. 
     In some aspects, the band may project between the hood and the elevated pinway to secure the hood to the pinway. The hood may be glued or otherwise affixed with adhesive, crimped, press-fit, snap-fit, slide fit or assembled in some other manner, into secure engagement between the band and the elevated pinway. The band may be formed by crimping the hood into secure engagement with a detent defined by the elevated pinway. 
     In some other aspects, the drainway may define a pathway for water to flow outwardly from the interior of the shell, the interior of the rotatable core, the access door, and an outer face ring surrounding the keyway. In some aspects, a water resistant seal is provided at the proximate end between the outer face ring and the shell or at the distal end to inhibit water ingress between the rotatable core and the shell. Preferably, the pin lock includes water resistant seals at the proximate end and the distal end to minimize water ingress. 
     In other preferred aspects of the invention, the drainway includes a drainway opening, for example, a channel within the head of the core and extending downwardly, in communication with an exterior elongated channel opening. The exterior elongated channel opening extends partially along the bottom of the shell (and optional face covering if provided), beginning inwardly of the face and ending offset outwardly from the vertical outer face of a storage structure in which the lock is secured. In the preferred embodiment, the exterior elongated channel is configured as a slot extending toward the outer face of the storage structure but sufficiently offset from the face of the storage structure to inhibit water from dripping or running along the face of the storage structure. When the rotatable cylindrical core is in its locked position, the drainway is oriented at the bottom of the shell, in alignment so that the drainway opening aligns within the exterior elongated channel opening (for example a slot), to enhance outward and downward flow of water away from the interior of the lock via the drainway. Where the drainway includes an elongated drainage outlet opening, the lower outer edge of the outlet may define a drip edge to further enhance downward flow of water, away from the interior of the lock. 
     The head of the rotatable core preferably includes an arcuate recess extending within the lower right quadrant (between the 3 o&#39;clock and 6 o&#39;clock position, for example, in cylindrical locks unlocked by rotating clockwise 90 degrees) or the lower left quadrant (between the 6 o&#39;clock and 9 o&#39;clock position, for example, in cylindrical locks unlocked by rotating counterclockwise 90 degrees). The arcuate recess provides a gap between the rotatable core and the stationary shell to take up accumulated water, ice formed from undrained water, and pieces of ice or other debris when the cylindrical core is rotated in cold weather or other adverse conditions. When the core is rotated, the frozen undrained residue, ice particles or other debris may reside within the arcuate head space, to reduce the torque needed to operate the rotatable core. Preferably, the arcuate head space is configured to define a downwardly and outwardly sloped drainway segment when the cylindrical core is in the locked position. 
     In another preferred embodiment, a tumbler lock is provided in which the shell has an asymmetrical profile extending across the longitudinal axis. The tumbler lock may be used as a retrofit replacement (or as an OEM part) for another shell having a corresponding asymmetrical profile when viewed across the longitudinal axis extending along the length of the tumbler lock. The tumbler lock of the present invention may be used to replace another lock having a shell comprising a top surface with an opening sealed with a cap (see for example, the pin lock illustrated in U.S. Pat. No. 9,273,487 shown with a flat pin retainer atop an elevated pinway). In this example, the substitute lock of the present invention may be used to provide improved resistance to water ingress into a locking system including the substitute lock. The substitute lock comprises a shell defining a solid waterproof outer perimeter surface extending about and along the longitudinal axis. The outer perimeter surface comprises a solid waterproof top surface extending along the longitudinal axis. The top surface may be provided on an elevated rail defining a portion of the solid waterproof outer perimeter wall extending around the longitudinal axis. 
     In this aspect of the substitute lock, the shell defines an asymmetrical profile extending across a mid portion of the longitudinal axis. The shell includes a solid waterproof outer perimeter wall extending about and along the longitudinal axis. The outer perimeter wall comprises an upwardly projecting rail comprising a solid waterproof top surface. The rail extends downwardly to a base. The base extends outwardly from the rail along opposed shoulders. Each shoulder extends downwardly along a corresponding side wall of the waterproof outer perimeter to a rounded bottom, outer shell wall. 
     In the substitute lock, the rotatable core and the interior chamber of the shell may be configured to provide a different array of tumblers, for example, wafer locks in place of pin tumblers. In one of the preferred aspects, the substitute lock may comprise an upper course of tumblers engaging an upper channel in the shell when the core is in the locked position. An opposite lower course of tumblers may be provided to engage a portion of the drainway extending along a lower interior surface of the shell. The tumblers may be configured as wafers biased for outward projection from the rotatable core when the core is in the locked position. 
     In one aspect, the substitute lock comprises a shell which is configured for interchangeable use in place of another lock having a shell with a corresponding asymmetrical perimeter profile. Although the substitute lock may have a corresponding asymmetrical profile for interchangeabligity with the other lock, the substitute lock may be configured with a different core chamber within the shell for housing a different rotatable core having a different array of tumblers, different tumbler configurations, and other different internal features. For example, a user may wish to substitute a wafer lock for a pin lock in an existing locking system, Such interchangeability may be particularly beneficial in retrofit applications where a user wishes to substitute a new tumbler lock design for a worn or broken locking core and shell but to preserve and continue to use an existing locking system. This aspect may also be beneficial in certain OEM applications. 
     In a preferred embodiment, the lock comprises a stainless steel MIM core rotating within a shell, typically cast from zinc or other corrosion inhibiting alloys. 
     The invention also comprises storage structures which have been provided with a tumbler lock having one or more of these features. 
     The invention also includes a method of inhibiting water accumulation within a tumbler lock in a locking system. In one aspect, the method comprises identifying a substitute tumbler lock with a solid water impermeable outer wall for replacing another lock having a corresponding outer perimeter profile and a water permeable closed opening on its top surface. The substitute tumbler lock with its solid water impermeable outer wall replaces the other tumbler lock with the corresponding outer perimeter profile for operative engagement with a locking system in a storage structure. 
     In another aspect, the invention includes providing a drainway to channel water outwardly from the tumbler lock. 
     In another aspect, the method may include providing a first rotatable core in the substitute tumbler lock with a tumbler configuration which is different from the tumbler configuration of the lock being replaced. 
     Other aspects of the invention will become apparent upon a review of the appended drawings and the following detailed description of preferred embodiments of the invention. 
     Preferred embodiments of the invention will be described in detail having regard to the appended drawings. However, it will be understood that these examples illustrate certain embodiments of the invention and that the illustrated examples are not to be interpreted as limiting the scope of the invention. Persons skilled in the art will understand that the invention may be implemented for use in other forms, systems, and methods and that many other variations, modifications and embodiments fall within the scope of the invention. 
    
    
     
       THE DRAWINGS 
         FIG. 1  is a drawing of an exploded view, in perspective, of the components in a prior art pin lock; 
         FIG. 2  is a drawing in perspective, showing a core and a shell of the prior art pin lock shown in  FIG. 1 ; 
         FIG. 3  is a drawing of a perspective view of an enlarged retainer clip  505  provided with the prior art pin lock shown in  FIG. 1 ; 
         FIG. 4  is a drawing of an exploded view, in perspective, of the components of an embodiment of the present invention, namely, a pin lock; 
         FIG. 5A  is a side view of the rotatable core of the embodiment of the invention shown in  FIG. 4 ; 
         FIG. 5B  is a frontal view of the rotatable core of the embodiment of the invention shown in  FIG. 4 ; 
         FIG. 5C  is a side view in perspective from the distal end of the rotatable core of the embodiment of the invention shown in  FIG. 4 ; 
         FIG. 6A  is a frontal view, in perspective, of the proximate end of the shell housing of the embodiment of the invention shown in  FIG. 4  configured for clockwise (CW) rotation of the rotatable core; 
         FIG. 6B  is a frontal view of the shell housing of the embodiment of the invention shown in  FIG. 4  configured for clockwise (CW) rotation of the rotatable core; 
         FIG. 6C  is a perspective view, from the distal end, of the shell housing of the embodiment of the invention shown in  FIG. 4 ; 
         FIG. 6D  is a frontal view, in perspective, of the proximate end of the shell housing of the embodiment of the invention shown in  FIG. 4  configured for counter clockwise (CCW) rotation of the rotatable core; 
         FIG. 6E  is a frontal view of the shell housing of the embodiment of the invention shown in  FIG. 6D  configured for counter clockwise (CCW) rotation of the rotatable core; 
         FIG. 6F  is a perspective view, from the distal end, of the shell housing of the embodiment of the invention shown in  FIG. 6D ; 
         FIG. 7  is a profile view of the distal end of the prior art shell shown in  FIGS. 1 and 2 ; 
         FIG. 8  is a frontal view of the core head of another embodiment of the invention, viewed from the proximate end of the core; 
         FIG. 9  is a frontal view, in perspective, of the bottom of the core shown in  FIG. 8 , viewed from the proximate end of the core; 
         FIG. 10  is a frontal view of the core shown in  FIGS. 8 and 9 , inserted into the shell of this embodiment, viewed from the proximate end of the combined core and shell; 
         FIG. 11  is a frontal view, in perspective, of the bottom of the combined core and shell of  FIG. 10 , viewed from the proximate end; 
         FIG. 12  is a rear view, in perspective, of the bottom of the combined core and shell of  FIGS. 10 and 11 , viewed from the distal end; and 
         FIG. 13  is a second rear view, in perspective, of the bottom of the combined core and shell of  FIGS. 10-12 , viewed from the distal end, 
         FIG. 14  is a drawing of an exploded view, in perspective, of the components of another embodiment of the present invention, namely, a wafer lock; 
         FIG. 15A  is a frontal view in perspective of a shell component in the embodiment of  FIG. 14 ; 
         FIG. 15B  is a frontal view in perspective of a rotatable core component in the embodiment of  FIG. 14 ; 
         FIG. 16  is a partial sectional side view in perspective of a rotatable core and shell combination in the embodiment of  FIG. 14 ; 
         FIG. 17  is another partial sectional side view in perspective of a key inserted into the rotatable core and shell combination in the embodiment of  FIG. 14 ; 
         FIG. 18A  is a rear view of the rotatable core and shell combination in the embodiment of  FIG. 14 ; 
         FIG. 18B  is a cross sectional side view along the longitudinal axis of the rotatable core and shell combination at section A-A in  FIG. 18A ; 
         FIG. 19A  is a side view of the rotatable core and shell combination in the embodiment of  FIG. 14 ; 
         FIG. 19B  is a cross sectional view across the longitudinal axis of the rotatable core and shell combination at section B-B in  FIG. 19A ; 
     
    
    
     in which the embodiments and certain features are described in more detail below. 
     DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS OF THE INVENTION 
     A preferred embodiment of the invention is described below having regard to the example of a tumbler lock as illustrated in  FIGS. 4, 5A-5C, and 6A-6C . For applications in which a pin lock of the present invention will be used in retrofit installations, the shell assembly will be configured to match the existing furniture cut-out representing the available space for installation of the replacement lock. In this example, the profile of cylinder  101  is shown as  200  in  FIG. 7 . It is preferred that the shape of cylinder  208  of the present invention is designed to match the existing profile in the furniture so that the lock can be retrofitted into existing furniture, for example, a storage structure having at least one locking compartment. 
     With reference to  FIGS. 4 and 6C , a preferred pin lock of the present invention includes a shell configured as a generally U-shaped cylinder  208  which defines a chamber housing rotatable core  207 , preferably made from stainless steel. The shell head  401  of the shell  208  is configured to securely accommodate protective shell scalp  201 . The shell  208  is provided with shoulders  410 ,  411  extending to intermediate edge  412  which defines the transition between the shoulders  410 ,  411  and vertical sidewalls  407 ,  407 A and vertical end wall  408  joining the sidewalls  407  and  407 A. In this embodiment, the elevated pinway is illustrated as a modified pin chamber area  404  configured to accept snug fitting top cap  209 . The top edges of sidewalls  407 ,  407 A and end wall  408  are preferably beveled to permit a hood, for example, the top cap  209 , to be more easily placed and properly aligned with the elevated pinway during assembly of the preferred pin lock. 
     Preferably, the top cap  209  is crimped such that a band of the top cap  209  is formed to engage with groove  405  to securely hold the top cap  209  in place, closing the second linear array of pin slots  450 , after the crimping operation. The top cap  209  functions as a pin slot closure and a water resistant hood which inhibits water from entering the pin slots  450  and  250  and freezing the pins  217 , retaining pin  218 , springs  216 . The top cap  209  may be made from a suitable material, preferably a metal suitable for the manufacturing process, such as crimping, in the preferred embodiment, and to meet other product specifications. 
     In other embodiments, the top cap  209  may be configured so that the top cap is fastened to an elevated pinway using another manufacturing technique. For example, the top cap may be press-fit, snap-fit, or slide-fit into place so that a preformed band on the top cap engages a detent on the elevated pinway. By way of further example, the detent may be a ridge or a depression formed on the elevated pinway, preferably adjacent the intermediate edge  412 . Upon reading this specification, it will be apparent to persons skilled in the art that other techniques and features may be used to secure a hood to an elevated pinway of the present invention. 
     In the preferred embodiment of an assembled pin lock, a drainway is provided to channel water outwardly from the interior of the lock so that the water is removed to avoid, for example, freezing which may damage or render the lock inoperable. In the preferred embodiment as illustrated in  FIGS. 5B and 6A-6C , the drainway comprises a drainage channel  212  at the bottom of the shell interior which extends from its distal end  212 B, toward the proximate end of the shell  208 , over drip edge  222 . Drainage channel  212  is configured so that water drains from the distal end  212 B forward to drain through drainage holes  403 ,  203 A and  201 A. 
     As shown in  FIG. 5B , a lower cavity  302  is also provided in the proximate face of the rotatable core  207  so that water may vacate more easily away from the keyway, and thus preventing ice build-up behind an access door such as the illustrated dust shutter door  204 . Preferably, the lower cavity  302  is positioned so that, when the lock is in the locked position, the lower cavity  302  is positioned above drainage hole  403  and shell drainage hole  201 A. The funnel-like shape (with inwardly sloped side walls) and position of the lower cavity  302  below the dust shutter door  204  also creates a gap below the lower edge of the shutter door  204  to permit less restrictive rotational movement of the dust shutter door  204  when it is pushed open with a customer&#39;s key  219 . 
     The proximate face of the rotatable core  207  is configured to mount and receive the components of the dust shutter assembly  206 . The recesses are adequately shaped and dimensioned to allow the opposite ends of dust shutter pin  202  to engage pin pockets  301 A,  301 B while supporting dust shutter door  204  and torsional spring  205  within the bracket arms of shutter face plate  203 . 
     The torsional spring  205  is preferably configured as a dual arm spring urging the dust shutter door  204  toward its closed position, to block debris from entering the opening to the keyway when the lock is not being operated with a key  219 . The dust shutter pin  202  is preferably round to support the preferred, stronger dual arm torsion spring  205  to improve the closing operation of the dust shutter door  204  particularly when the dust shutter door is impeded by dirt, dust, water or ice. The rounded pin  202  should also rotate more easily even when the dust shutter door or the rounded pin is impeded by dirt or ice. 
     It is also preferable to avoid accumulation of any water near the rotational range interface defined by, for example, stop  215  which travels within a rotational track defined by cavity  402  as illustrated in  FIGS. 5A and 6B . 
     In the prior art pin lock as shown in  FIG. 2 , stop  601  rotates clockwise from the 3-to-6 o&#39;clock position in stop cavity  602 . The stop cavity is near the bottom of cylinder  101 . Because of its orientation when the prior art lock is in the locked position, this cavity configuration is prone to buildup of ice adjacent the top of the shell. 
     In a lock of the present invention designed for clockwise (CW) rotation of the core from a locked to an unlocked position, as illustrated in  FIGS. 6A, 6B and 6C , the preferred solution is to move the stop  215  to the 12 o&#39;clock position shown in  FIGS. 5A, 5C . In the preferred embodiment of the present invention, the stop  215  rotates clockwise (CW) from a position starting at 12 o&#39;clock and rotating to 3 o&#39;clock. Stop cavity  402  is correspondingly placed at the top of the interior of shell  208  so that ice cannot build up along the interior ceiling of shell  208 . In another variant of the invention illustrated in  FIGS. 6D, 6E and 6F  in which the lock is designed for counter clockwise (CCW) rotation of the core from a locked to an unlocked position, the preferred solution is to provide a configuration in which the stop  215  rotates counter clockwise (CCW) from a position starting at 12 o&#39;clock and rotating to 9 o&#39;clock. 
     In addition to the preferred drainway which may be provided to drain any penetrating water from within the pin lock, it is also preferable to provide water resistant seals to inhibit the inward flow of rain or other water surrounding the pin lock. 
     For example, the rotatable core may be lengthened to provide additional mounting space shown as O-ring groove  214  to hold a rubber O-ring  211  as a barrier to inhibit water ingress from the distal end between rotatable core  207  and shell  208 . For example, the rubber O-ring  211  may be mounted within O-ring groove  214  prior to assembly. 
     A shell scalp  201  is shown as a rigid protective shroud to be fastened over the proximate face of the shell  208 . The shell scalp is configured to hold the dust shutter assembly  206  in place and to inhibit water ingress from the proximate end, which is often exposed to the elements when the lock is used in outdoor installations. A front gasket  210  may also be added adjacent the proximate end of the pin lock, between the pin lock shell and a surrounding wall of a storage structure such as a lock box. The gasket material is preferably selected to satisfy a product specification for outdoor use. These are only two examples of the various kinds or seals which may be provided to inhibit water ingress. 
       FIGS. 8-13  illustrate a preferred embodiment of the invention comprising a preferred wafer tumbler lock having a modified stainless steel MIM core  207 ′ which nests, rotatably, within modified shell  208 ′. The fully assembled wafer tumbler lock preferably has a stainless steel shell scalp  201 ′ which is held in place over the proximate end (face) of the shell  208 ′ by shell scalp retainers  531 ,  532 . The shell scalp  201 ′ may be secured about the shell head by press fit, snap fit, crimping or another suitable method understood by persons skilled in the art. 
     With regard to  FIGS. 8 and 9 , the core head  277  of core  207 ′ is provided with a dust shutter cavity  301 ′, and pin pockets  301 A′,  301 B′ to receive the components of a dust shutter assembly which may be similar to the examples ( 202 - 206 ) shown in  FIG. 4 . In this embodiment, the core  207 ′ is provided with a plurality of wafer tumbler slots  528  (to receive spring loaded reciprocating wafers which wafers are not shown) and a security retainer wafer (or pin) slot  529  to further inhibit unauthorized tampering, or operation or removal of the core  207 ′. (However, a security wafer or pin is not shown.) 
     In this embodiment, the core head  277  is provided with a core head drain hole  302 ′ which is illustrated as being in fluid communication with shell drainage channel  403 ′ which in turn communicates with drainage channel  201 A′ defined by an opening in the stainless steel shell scalp  201 ′, to provide a drainage outlet to the exterior of the tumbler lock. Preferably, the core head drain hole  302 ′ is positioned to communicate water flow from behind the dust shutter assembly and from other communicating portions of the core, including the opening to keyway  527 . 
     The drainage channel  201 A′ may include a drip edge  709  such as, but not limited to, an extended lip or protrusion configured to enhance water movement downwardly and outwardly from the interior of the tumbler lock. Preferably, the drip edge  809  is configured to direct water away from the lock and away from any outdoor storage structure in which the lock may be installed. 
     In some embodiments, the drip edge may also include supplementary ridges or other drip enhancing features provided on shell scalp retainers  531 ,  532  which have been suitably positioned and configured to promote outward flow of water from within the interior of the tumbler lock, via other portions of the drainway. 
     In this embodiment, the core head  277  defines a recess  460  extending between recess walls  462 ,  463  which project outwardly from opposite ends of core head surface  464 . When the stainless steel core  207 ′ is inserted within the shell  208 ′, the core head surface  464 , recess walls  462 ,  463  and a concave interior wall of the shell  208 ′ opposing surface  464 , define a chamber  465  which includes the space within recess  460 . When the tumbler lock is installed and operated by rotational movement of an operating key inserted into keyway  527 , the chamber  465  travels along the concave interior wall of the shell  208 ′, taking with it, any debris, including any water or ice which may have accumulated or formed within the chamber  465 , for example, when the tumbler lock was in a locked position. Recess shoulders  462 ′,  463 ′ are preferably smoothed, rounded, beveled or otherwise shaped to reduce friction when the core is rotated within the shell  208 ′. In a preferred embodiment, the chamber  465  will also be in fluid communication with other portions of the drainway, to promote outward flow of water from within the tumbler lock assembly, including when the tumbler lock is in the locked position. 
     The core head  277  may also include a cavity  525 , often, to save MIM material and reduce component weight. Preferably, any cavities within the core  207 ′ or shell  208 ′ will be in fluid communication with other portions of the drainway within the tumbler lock, which may be similar to drainage channel  212 , although persons skilled in the art will appreciate, after reading this specification, that other variations and combinations of drainage features may be provided. 
     In this invention, the drainway may comprise a single fluid pathway or a plurality of fluid pathways to channel fluid flow outwardly and downwardly from the tumbler lock, when the tumbler lock is installed. Where a plurality of fluid pathways are provided, the fluid pathways are preferably interconnected for outward fluid communication between the interior of the tumbler lock and the exterior of the tumbler lock via the drain outlet. The drainway may include a plurality of features (for example, those illustrated and described in  FIGS. 4 to 6 , and  FIGS. 8 to 13  and the related description) to provide a fluid pathway such as but not limited to one or more of the following features to channel outward fluid flow: a conduit, recess, gap, trough, dripway, drip edge, bore, slot, drain opening, drain outlet, and other fluid communication features. 
     In some embodiments, the drain opening may comprise the drain outlet, a drip edge, dripway or other features to provide or promote fluid egress from the interior of the tumbler lock. 
     Preferably, the drainway comprises an arcuate recess between the outer surface of the core head and an opposing interior surface of the shell for fluid communication with a drainage opening adjacent the bottom of the proximate end of the shell. 
     Another embodiment of the invention includes a method of inhibiting water accumulation in a locking system designed for use in a storage structure. The method includes a step of identifying a first shell for use as a substitute tumbler lock having an asymmetrical profile across a longitudinal axis. The first shell comprises a solid waterproof circumferential outer wall extending around the longitudinal axis of the first shell. The first shell is configured for housing a first rotatable locking core. The method includes verifying that the asymmetrical configuration of the first shell corresponds to an asymmetrical profile of a second shell having a top opening in a top surface. The top opening in the second shell is closed with a cap. The first shell and the second shell are suitable for use in the same locking system for the storage structure. 
     The second shell is configured for housing a second rotatable locking core. The method includes replacing the second shell with the first shell, for aligning engagement with a correspondingly configured mounting recess defined by the storage structure. The first shell and the first rotatable core of the tumbler lock operatively communicate with the locking system. 
     In another embodiment, the method includes replacing the second shell with the first shell wherein the first shell defines a first chamber with a first cylindrical core profile and the second shell defines a second chamber with a second cylindrical core profile. The first cylindrical core profile may be different from the second cylindrical core profile. For example, the first core profile may include tumblers configured as spring biased wafers which project outwardly from the first rotatable core when the first rotatable core is in its locked position. By way of further example, the different second core profile may include tumblers configured as pins for locking engagement with the second shell having a different internal configuration to accommodate the second core profile. 
     In another embodiment, the method includes selecting a first shell defining a first chamber for housing the first rotatable locking core. The first rotatable locking core has a first core profile defining a first array of tumblers for engaging an upper recess defined by an upper interior surface of the first chamber. The first rotatable core also defines a second array of tumblers for engaging a lower recess defined by a lower interior surface of the first chamber, opposite the upper recess. The first and second array of tumblers in the first rotatable locking core may be configured as wafers biased for outward projection from the first rotatable locking core when the first rotatable core is in the locked position. The second shell being replaced, may define a second chamber for housing the second rotatable locking core having a different core profile with a third array of tumblers configured as pins biased upwardly and outwardly toward the top opening in the second shell when the second rotatable locking core is in its locked position. 
     In another embodiment, the method includes providing a drainway comprising a channel in a lower interior wall of the first shell to channel water flow downwardly and outwardly from within the first shell. Preferably, the channel is in fluid communication with a keyway in the first rotatable locking core. 
       FIGS. 14-19  illustrate another preferred embodiment of the invention.  FIG. 14  shows an exploded view of a tumbler lock comprising a shell  608  housing a rotatable core  607  in which the tumblers are configured as lower wafers  618  and upper wafers  718 . The upper springs  717  act on their corresponding wafer shoulders  718   a  to urge the upper wafers  718  outwardly from the upper array  750  of wafer slots in the rotatable core toward, and into, the upper channel  712  when the rotatable core  607  is in the locked position. Similarly, the lower springs  617  act on their corresponding wafer shoulders  618   a  to urge the lower wafers  618  downwardly and outwardly from the lower wafer slots  650  in the rotatable core  607  toward, and into, the shell drainage channel  612  when the rotatable core  607  is in the locked position. 
     At the proximate end P of the tumbler lock, a dust shutter assembly  606  includes a protective SS shell scalp  701  provided as a protective outer cover of the face of the tumbler lock. A SS dust shutter face plate  603  is mounted inwardly of the scalp  701 , as a frame to support a SS dust shutter door  604  which pivots on a freely rotatable SS dust shutter pin  702 . A dual arm torsional spring  605  urges the dust shutter door  604  toward its closed position, against the inner surface of the dust shutter face plat  603 , to inhibit ingress of debris and moisture into the tumbler lock. 
     Positioned adjacent and inwardly of the distal end D the tumbler lock, an O ring  611  is seated in O-ring groove  614  to inhibit ingress of debris and other contaminants into the interior of the tumbler lock, 
     When the key  619  is inserted into the keyway  627  the upper wafers  718  and the lower wafers  618  are withdrawn from the upper channel  712  and shell drain channel  612 , into their respective arrays of wafer slots  750  and  650  to permit rotation of the rotatable core  607  within the defined rotational range. 
     The shell  608  is configured with an example of an asymmetrical profile defined by the outer shell perimeter  815  as illustrated in  FIGS. 14, 18A and 19B  extending across the longitudinal axis. In this example, vertical sidewalls  807 ,  807 A extend downwardly in parallel from the top surface  715  of solid rail  713 . Vertical end wall  808  extends downwardly from the top surface  715  at the distal end D of the tumbler lock. Exterior shell shoulders  810 ,  811  extend outwardly from the solid rail  713  as part of the shell perimeter. Shell side walls  813 ,  813 A extend downwardly from their corresponding shell shoulders  810 ,  811  to join with curved lower shell wall  814 , to form a generally “spade-shaped” asymmetrical profile. 
     The shell  608  defines an interior chamber  865  to house rotatable core  607  for rotation within a defined range, in part determined by stop  615  on the core head  777 , the stop  615  moving within a track defined within the interior of the shell  608  (not shown). The core head  777  defines a recess  660  in communication with the drainway and extending between recess side walls  662 ,  663 . Recess shoulders  664 ,  665  may be beveled or polished, to reduce the risk of binding with the interior chamber wall and to enhance smooth rotational movement of the rotatable core  607 . In this embodiment, the recess  660  is also defined by the interior chamber wall  866  and opposing recess surface  661  on core head  777 . 
     In this embodiment, the drainway includes the recess  660  configured on the core head  777 , and the shell channel  612  extending toward the proximate end P of the tumbler lock from the distal end  612 D of the shell drainage channel  612 . At the proximate end P of the keyway  627 , the core head  777  defines a core drainage hole  802  which drains into drainage slot  803  defined at the proximate end of the bottom of the shell  608 . A drip edge  809  is provided along opposing sides of the shell drainage slot  803 . 
     The tumbler lock may be used as a retrofit replacement (or as an OEM part) for another tumbler lock having a corresponding asymmetrical profile, such as the “spade shaped” profile illustrated in this example. This embodiment which may be used to replace a different lock, for example, the pin lock illustrated in U.S. Pat. No. 9,273,487, having a flat bar crimped into place to seal its opening atop an elevated pinway. In this embodiment of the present invention, the substitute lock may be used to provide improved resistance to water ingress in part due to the waterproof barrier provided at the top of the solid rail  713 . The substitute lock is provided with a solid waterproof outer shell perimeter surface  815  extending about and along the longitudinal axis. 
     In this aspect of the substitute lock, the shell  608  and rotatable core  607  may be configured to provide a different array of tumblers, for example, wafer locks in place of pin tumblers. In one of the preferred aspects, the substitute lock is shown having an upper course of tumblers engaging an upper channel in the shell when the core is in the locked position. This example also shows an opposite lower course of tumblers provided to engage a portion of the drainway extending along a lower interior surface of the shell. In other embodiments, it may be useful to provide yet another, different array of tumblers, and a different channel arrangement for engaging the tumblers with the interior of the shell. 
     Persons skilled in the art will also appreciate that one or more of the features described in association with one embodiment may be selected for use in other embodiments of the invention, including those other embodiments described herein. 
     Preferred Materials Choices 
     While it will be understood that persons skilled in the art will have reasons to select from a wide variety of construction materials, the following materials are preferred for the present invention. 
       201  Scalp—preferably stainless steel; 
       206  Dust Shutter Assembly ( 202 - 205 )—preferably stainless steel; 
       207  Core—preferably stainless steel, preferably MIM (Metal Injection Molded) hardened to appropriate manufacturing specifications selected for the product installation(s); 
       208  Shell—preferably cast from zinc; 
     Hex Nut  105 , Retaining Clip  505  are preferably plated in Zinc Nickel Alloy (automotive grade plating) to reduce rusting; and 
     Pins  113  and Retaining Pin  126 , or other tumbler configurations and retainers are preferably made of stainless steel. 
     Preferably, the tumbler lock is treated with lubrication during assembly. 
     Persons skilled in the art will appreciate that the foregoing description was directed to specific embodiments of the invention. However, many other variations and modifications of the invention are also possible. Preferred embodiments of the invention have been described with regard to the appended drawings. It will be apparent to those skilled in the art that additional embodiments are possible and that such embodiments will also fall within the scope of the appended claims. 
     Various materials may be used to manufacture the components of the tumbler lock, storage compartments, storage structures and other embodiments of the present invention, as would be evident to a skilled person. 
     Also, it should be understood that the above-described embodiments of the present invention, particularly, any “preferred” embodiments, are only examples of implementations, which are merely set forth to better understand the principles of the invention. Many variations and modifications may be made to the above-described embodiment(s) of the invention as will be evident to those skilled in the art. Additional embodiments and variations are possible and such embodiments and variations will fall within the scope of the appended claims. 
     In this document where a list of one or more items is prefaced by the expression “such as” or “including”, or is followed by the abbreviation “etc.”, or is prefaced or followed by the expression “for example”, or “e.g.”, this is done to expressly convey and emphasize that the list is not exhaustive, irrespective of the length of the list. The absence of such an expression, or another similar expression, is in no way intended to imply that a list is exhaustive. Unless otherwise expressly stated or clearly implied, such lists shall be read to include all comparable or equivalent variations of the listed item(s), and alternatives to the item(s), in the list that a skilled person would understand would be suitable for the purpose that the one or more items are listed. 
     The words “having”, “comprises” and “comprising”, when used in this specification and the claims, are used to specify the presence of stated features, elements, integers, steps or components, and do not preclude, nor imply the necessity for, the presence or addition of one or more other features, elements, integers, steps, components or groups thereof. 
     Nothing in this specification or the claims that follow is to be construed as a promise. 
     The scope of the claims that follow is not limited by the embodiments set forth in the description. The claims should be given the broadest purposive construction consistent with the description as a whole. 
     PARTS LIST (OF THE EMBODIMENTS DESCRIBED HEREIN) 
     In which “SS” indicates stainless steel. 
     
       FIGS. 4, 5A-5C, 6A-6F 
     
     
         
           201 —SS Shell Scalp 
           201 A—Shell Drainage Hole 
           202 —SS Dust Shutter Pin 
           203 —SS Dust Shutter Face Plate 
           203 A—Dust Shutter Drainage Hole 
           204 —SS Dust Shutter Door 
           205 —Dual Arm Torsion Spring 
           206 —Dust Shutter Assembly (Shown as  202 - 205 ) 
           207 —SS MIM Core 
           208 —Shell 
           209 —Top Cap 
           210 —Front Gasket 
           211 —Rear O-Ring 
           212 —Shell Drainage Channel 
           212 B—distal end of shell drainage channel 
           213 —Hex Nut 
           214 —O-Ring Groove 
           215 —stop 
           222 —drip edge 
           250 —first linear array of pin slots 
           301 —dust shutter cavity 
           301 A—pin pocket 
           301 B—pin pocket 
           302 —lower cavity 
           401 —shell head 
           402 —stop cavity 
           403 —drainage hole 
           404 —pin chamber area 
           405 —groove 
           407 ,  407 A—vertical sidewalls 
           408 —vertical end wall 
           410 , 411 —shoulders 
           412 —intermediate edge 
           415 —elevated pinway 
           450 —second linear array of pin slots 
           601 —stop 
           602 —stop cavity
 
 FIGS. 8-13 
 
           201 ′ SS shell scalp 
           201 A′ shell drainage channel 
           207 ′ SS MIM core 
           208 ′ Shell 
           277  core head 
           301 ′ dust shutter cavity 
           301 A′ pin pocket 
           301 B′ pin pocket 
           302 ′ core head drain hole 
           403 ′ shell drainage channel 
           460  recess 
           462 ,  463  recess walls  462 ′,  463 ′ recess shoulders 
           464  core head surface 
           465  chamber 
           525  cavity 
           527  keyway 
           528  wafer tumbler slots 
           529  security retainer slot 
           531 ,  532  scalp retainers 
           509  drip edge
 
 FIGS. 14-19 
 
         P proximate end 
         D distal end 
           603  SS Dust shutter face plate 
           604  SS dust shutter door 
           605  dual arm torsion spring 
           606  dust shutter assembly ( 603 - 5 ,  702 ) 
           607  SS MIM core 
           608  shell 
           611  rear O-ring 
           612  shell drainage channel 
           612 B distal end of shell drainage channel 
           614  O-ring groove 
           615  stop 
           617  lower spring 
           618  lower wafer 
           618   a  lower wafer shoulder 
           619  key 
           650  lower array of wafer slots 
           660  recess 
           661  recess surface 
           662 ,  663  recess walls 
           664 ,  665  recess shoulders 
           701  SS shell scalp 
           702  SS dust shutter pin 
           712  upper channel 
           713  solid rail 
           715  rail top surface 
           717  upper spring 
           718  upper wafer 
           718   a  upper wafer shoulder 
           750  upper array of wafer slots 
           777  core head 
           802  core head drainage hole 
           803  shell drainage slot 
           807 ,  807 A vertical side walls 
           808  vertical end wall 
           809  drip edge 
           810 ,  811  shoulders 
           813 ,  813 A shell side walls 
           814  shell bottom wall 
           815  shell perimeter surface