Patent Publication Number: US-2002011734-A1

Title: Single use lock

Description:
CROSS REFERENCED TO RELATED APPLICATION  
     [0001] This application is a completion application of a co-pending U.S. Provisional Patent Application Serial No. 60/198,543, filed Apr. 19, 2000, entitled “SINGLE USE LOCK”, the disclosure of which is hereby incorporated by reference. 
    
    
     
       BACKGROUND OF THE INVENTION  
       [0002] The present invention relates to padlocks and, more particularly, to single use locks for locking electric utility enclosures.  
       [0003] Generally, padlocks include a housing or body, a shackle and a locking mechanism contained within the housing. The shackle is inserted through the articles to be locked together, such as a latch or through the links of a chain, and is engaged by a locking mechanism to hold the shackle in the housing. Padlocks are usually removable, that is the locking mechanism can be locked and then unlocked utilizing a key or combination to release the shackle. After release of the shackle the lock can then be removed and used again by reactuating the locking mechanism.  
       [0004] In many circumstances, it is not necessary to frequently access a locked cabinet or enclosure. For example, an electric utility company may store electrical power distribution equipment located in cabinets or enclosures in remote locations. These enclosures are not frequently accessed but must be securely locked to prevent unwanted tampering and damage. In such circumstances, a single use lock may be utilized to prevent unwanted access to the cabinet or enclosure.  
       [0005] Once the single use lock is engaged, the enclosure can only be unlocked after a predetermined force is applied to the lock, thereby destroying the lock in the process.  
       SUMMARY OF THE INVENTION  
       [0006] The present invention concerns a single use locking apparatus that can be unlocked by applying a predetermined force to thereby destroy the locking apparatus. The locking apparatus includes: a lock ring having at least one straight portion terminating in a free end; at least one lock body having a lock ring aperture formed therethrough for receiving the lock ring straight portion, the lock ring aperture terminating at one end thereof and an enlarged retaining recess; and at least one snap ring being maintained in the retaining recess and having a central aperture defining an inner periphery.  
       [0007] When the straight portion is inserted through the lock ring aperture and through the central aperture, the inner periphery of the snap ring engages an outer surface of the straight portion requiring an application of force exceeding a predetermined amount to separate the lock ring from the lock body and the snap ring. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0008] The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of which a preferred embodiment when considered in the light of the accompanying drawings in which:  
     [0009]FIG. 1 is a front elevational view of a single use locking apparatus in accordance with the present invention;  
     [0010]FIG. 2 is an enlarged cross sectional view of one of the lock bodies shown in FIG. 1; and  
     [0011]FIG. 3 is an enlarged plan view of the lock ring shown in FIG. 2.  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0012] There is shown in FIG. 1 a single use locking apparatus ( 100 ) having a generally u-shaped lock ring ( 101 ) including a generally curved portion ( 102 ) connecting a pair of straight portions ( 103 ) extending generally parallel and terminating in free ends ( 104 ). A pair of lock bodies ( 105 ) is provided with each, and is attached to an associated one of the straight portions ( 103 ). Although the lock ring ( 101 ) depicted in FIG. 1 is generally u-shaped, the lock ring can be of any suitable shape, such as v-shaped or where the generally curved portion ( 102 ) defines in excess of one-half of a circle.  
     [0013] A cross sectional view of a lock body ( 105 ) of the present invention is depicted in FIG. 2. The body ( 105 ) may be of any suitable shape, such as a cylinder or cube, and has a lock ring aperture ( 106 ) formed therethrough for receiving the associated straight portion ( 103 ). The end portion of the aperture ( 106 ) is enlarged to form an annular retaining recess ( 107 ) in which a snap ring ( 108 ) is positioned.  
     [0014] As best depicted in FIG. 3, the snap ring ( 108 ) has a central aperture ( 109 ) with a plurality of cut-outs ( 110 ) extending from an inner periphery ( 111 ) at the central aperture toward an outer periphery ( 112 ) of the snap ring. The diameter of the central aperture ( 109 ) is slightly smaller than the outer diameter of the straight portion ( 103 ) and the interrupted inner periphery ( 112 ) forms a plurality of teeth that engage the surface of the straight portion.  
     [0015] The diameter of the snap ring ( 108 ) is slightly smaller than the diameter of the retaining recess ( 107 ) such that a portion of the lower end of the lock body is deformed inwardly at ( 113 ) to engage and maintain the snap ring ( 108 ) in the retaining recess ( 107 ). Typically, four of the inwardly deformed portions ( 113 ) are spaced equally about the retaining recess ( 107 ). Although four inwardly deformed portions ( 113 ) are typically utilized by the present invention, other numbers of inwardly deformed portions ( 113 ) such as 2,3,5 or 6 may be utilized by the present invention.  
     [0016] The snap ring ( 108 ) may be made of a hardened spring steel material while the lock ring ( 101 ) and the lock bodies ( 105 ) are preferably made of a softer aluminum material. This selection of materials allows for the plurality of teeth formed on the snap ring to engage the surface of the straight portion without failing as a force is applied. The use of a softer aluminum material in the lock body ( 105 ) also allows for easy formation of the inwardly deformed portions ( 113 ) of the lock body ( 105 ).  
     [0017] The lock body ( 105 ) and the snap ring ( 108 ) are preassembled by positioning the snap ring in the retaining recess ( 107 ) and forming the inwardly deformed portions ( 113 ). When it is desired to use the lock apparatus ( 100 ), the lock ring is passed through the openings of the structure to be locked, such as apertures or flanges that are attached to a pair of cabinet doors, and one of the preassembled lock body ( 105 ) and snap ring ( 108 ) assemblies is pushed onto each of the associated free ends ( 104 ) of the straight portions ( 103 ). As the lock body ( 105 ) is pushed onto the straight portion ( 103 ), the inner periphery ( 111 ), will deform downwardly. In use, one of the lock body ( 105 ) and snap ring ( 108 ) assemblies may be placed on the lock ring ( 101 ) before the lock ring is passed through an opening of the structure to be locked. Once the lock body ( 105 ) is positioned on the straight portion ( 103 ), if a subsequent force is applied to the lock body ( 105 ) toward the free end ( 104 ), the downwardly deformed inner periphery ( 111 ) will dig into the surface of the straight portion ( 103 ) thereby preventing removal of the lock body ( 105 ) until a predetermined force causing the above-relationship to fail is applied.  
     [0018] The present invention has been described in accordance with the relevant legal standards, thus the foregoing description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiment may become apparent to those skilled in the art. Accordingly, the scope of legal protection afforded this invention can only be determined by studying the following claims.