Patent Publication Number: US-9422744-B2

Title: Burglarproof primary-secondary row sheet lock

Description:
(a) TECHNICAL FIELD OF THE INVENTION 
     The present invention relates generally to the technical field locks, and more particularly to an improved design of a burglarproof primary-secondary row sheet lock. 
     (b) DESCRIPTION OF THE PRIOR ART 
     A lock is a device that provides a function of closure and generally comprises a lock and a key, wherein the key can be operated to unlock the lock so as to achieve an effect of management and control. In the modern technology, locks are classified as drawer locks, pin tumbler locks, mortise locks, cylindrical locks, and electronic locks. With the continuous upgrading of living standard of people, the consciousness of security is being intensified so that the demand for high-end security-purpose locks is continuously increased. However, the known locks cannot satisfy the needs of consumers. 
     In view of this, the present inventor develops a primary-secondary row sheet lock that offers an improved effect of burglary resistance and, as such, the present invention is provided. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a burglarproof primary-secondary row sheet lock, which greatly enhances security of locks. 
     To achieve the above object, the present invention provides the following technical solution: 
     A burglarproof primary-secondary row sheet lock comprises a lock body and a key. The lock body comprises an outer cylinder, a plug, closure plates, secondary row sheets, primary row sheets, sheet return springs, a latch and, latch return springs. The outer cylinder comprises a cylindrical chamber formed therein. The cylindrical chamber has an inside surface having a latch trough formed therein. The plug is in the form of a cylinder and is received in the cylindrical chamber of the outer cylinder. The plug comprises row sheet receiving slots formed therein and also comprises a latch opening formed therein at one side of the row sheet receiving slots to correspond to the latch trough of the outer cylinder and extending to and in communication with the row sheet receiving slots. The plug has a front end in which a key way is formed and extending across and through the row sheet receiving slots. The plug has a rear end on which a lock bolt is formed and located outside the outer cylinder. The secondary row sheets each have a side edge in which a first latch notch is formed. The primary row sheets each comprise a secondary row sheet channel formed therein to extend completely therethrough in an up-down direction. The primary row sheets each have a side edge in which a second latch notch is formed to extend through the secondary row sheet channel. The primary row sheets are respectively set in the row sheet receiving slots. The secondary row sheets are respectively received in the secondary row sheet channels. The closure plates are set on and cover end openings of the row sheet receiving slots. Each of the sheet return springs is arranged between the closure plates and each of the secondary row sheets and the primary row sheets. The latch is received in the latch opening. The latch return springs are arranged between the latch and the plug. The key comprises a key blade insertable into the key way. The key blade comprises side cuts and central cuts formed therein to respectively lift up the secondary row sheets and the primary row sheets so as to have the first latch notches and the second latch notches aligned with the latch opening. 
     The secondary row sheets each comprise a first fake notch formed therein. 
     The primary row sheets each comprise a second fake notch formed therein. 
     The secondary row sheets and the primary row sheets each comprise a push tab formed thereon. The plug comprises spring recesses formed therein. The sheet return springs are respectively set in the spring recesses with an end of each of the sheet return springs supported on the closure plates and an opposite end abutting the push tab. 
     The plug is provided with an insertion opening formed in a circumference of a front end portion thereof and a drilling resistant plate is received in the insertion opening. 
     The latch trough is in the form of an arc groove and the latch has an outside surface that is in the form of an arc surface. 
     The key blade of the key has a front end that forms a guide-in surface. 
     Based on the above technical solution, without insertion of a matched key, the first latch notches of the secondary row sheets and the second latch notches of the primary row sheets are not in alignment with the latch opening so that the latch is prevented from sliding into the first latch notches and the second latch notches and is kept in the latch trough so as to hinder relative rotation of the plug with respect to the outer cylinder, whereby unlocking is not possible. With a matched key inserted, the first latch notches of the secondary row sheets and the second latch notches of the primary row sheets are all caused to be in alignment with the latch opening, allowing the latch to first slide into the second latch notches and then sliding into the first latch notches so as to get out of the latch trough and thus releasing the locking condition, whereby the plug is allowed to rotate relative to the outer cylinder and unlocking is now possible. 
     The number of combinations of key cuts that is available with the present invention is M to the Nth power, where M is the number of types of secondary row sheets and primary row sheets (different stages) and N is the total number of the secondary row sheets and the primary row sheets. Compared to a prior art lock, the number of combinations of the cuts of the present invention can be as high as tens of millions and this greatly improves lock security performance. 
     The foregoing objectives and summary provide only a brief introduction to the present invention. To fully appreciate these and other objects of the present invention as well as the invention itself, all of which will become apparent to those skilled in the art, the following detailed description of the invention and the claims should be read in conjunction with the accompanying drawings. Throughout the specification and drawings identical reference numerals refer to identical or similar parts. 
     Many other advantages and features of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view of the present invention (with an outer cylinder omitted). 
         FIG. 2  is a schematic view illustrating spatial relationship of the combination of a secondary row sheets and a primary row sheet of the present invention. 
         FIG. 3  is a perspective view showing the outer cylinder of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following descriptions are exemplary embodiments only, and are not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Various changes to the described embodiments may be made in the function and arrangement of the elements described without departing from the scope of the invention as set forth in the appended claims. 
     As shown in  FIGS. 1-3 , the present invention provides a burglarproof primary-secondary row sheet lock, which comprises a lock body  10  and a key  20 . 
     The lock body  10  comprises an outer cylinder  1 , a plug  2 , closure plates  3 , secondary row sheets  4 , primary row sheets  5 , sheet return springs  6 , a latch  7 , and latch return springs  8 . 
     The outer cylinder  1  comprises a cylindrical chamber  11  formed therein. The cylindrical chamber  11  has an inside surface having a latch trough  12  formed therein. 
     The plug  2  is in the form of a cylinder. The plug  2  is inserted in the cylindrical chamber  11  of the outer cylinder  1 . The plug  2  comprises row sheet receiving slots  21  formed therein and is formed, at one side of the row sheet receiving slots  21 , with a latch opening  22  corresponding to the latch trough  12  of the outer cylinder  1  and extending to and in communication with the row sheet receiving slots  21 . The plug  2  has a front end in which a key way  23  is formed and extending across and through the row sheet receiving slots  21 . The plug  2  has a rear end on which a lock bolt  24  is formed in such a way that the lock bolt  24  is located outside the outer cylinder  1 . 
     The closure plates  3  are set on and cover end openings of the row sheet receiving slots  21 . 
     The secondary row sheets  4  each have a side edge in which a first latch notch  41  is formed. 
     The primary row sheets  5  each comprise a secondary row sheet channel  51  formed therein to extend completely therethrough in an up-down direction. The primary row sheets  5  each have a side edge in which a second latch notch  52  is formed to extend through the secondary row sheet channel  51 . A number of the primary row sheets  5  is provided and respectively set in the row sheet receiving slots  21 . The secondary row sheets  4  are respectively inserted into the secondary row sheet channels  51 . The number of the secondary row sheets  4  and the primary row sheets  5  may be determined according to design requirements and is not limited to the illustration of the text and drawings presented herein. 
     The sheet return springs  6  are arranged between the closure plates  3  and the secondary row sheets  4  and the primary row sheets  5 . For easy installation and replacement, in the instant embodiment, each of the secondary row sheets  4  and each of the primary row sheets  5  are respectively formed with a push tab  43  and  56 , while the plug  2  is formed with spring recesses  25  that are located in the row sheet receiving slots  21  of the plug  2 , so that the sheet return springs  6  are respectively set in the spring recesses  25  and thus located in the row sheet receiving slots  21  with an end of each of the sheet return springs  6  supported on the closure plates  3  and an opposite end abutting the push tab  43  or  56 . 
     The latch  7  is received in the latch opening  22 . For easy and smooth movement of the latch  7  in an unlocking operation, in the instant embodiment, the latch  7  has an outside surface that is made in the form of an arc surface, while the latch trough  12  is in the form of an arc groove. 
     The latch return springs  8  are arranged between the latch  7  and the plug  2 . 
     The key  20  comprises a key blade  201 . The key blade  201  is insertable into the key way  23 . The key blade  201  comprises side cuts  202  and central cuts  203  formed therein. The side cuts  202  are arranged to lift up the secondary row sheets  4 , while the central cuts  203  lifts up the primary row sheets  5 , so that the first latch notches  41  and the second latch notches  52  are set in alignment with the latch opening  22  to allow for rotation of the plug  2  in conducting an unlocking operation. To ease the insertion of the key blade  201  to mate the secondary row sheets  4  and the primary row sheets  5 , in the instant embodiment, the key blade  201  has a front end that forms a guide-in surface  204 . 
     To further improve the security property of the lock and to prevent undesired unlocking through burglar skills, in the instant embodiment, the secondary row sheets  4  each comprise a first fake notch  42  formed therein and the primary row sheets  5  each comprise a second fake notch  55  formed therein. 
     To improve the resistance of the plug  2  against drilling, in the instant embodiment, the plug  2  is provided with an insertion opening  26  formed in a circumference of a front end portion thereof and a drilling resistant plate  27  is received in the insertion opening  26 . 
     After installation of the lock body  10  according to the present invention, the secondary row sheets  4  and the primary row sheets  5  are acted upon by the sheet return springs  6  to be received down into the row sheet receiving slots  21  with the first latch notches  41  of the secondary row sheets  4  and the second latch notches  52  of the primary row sheets  5  being not in alignment with the latch opening  22 . The latch  7  is thus kept in the latch trough  12  as being blocked by the secondary row sheets  4  and the primary row sheets  5  so that the plug  2  is prevented from rotating relative to the outer cylinder  1 . This provides an effect of locking. 
     When a non-matched key is inserted, the cuts of the key cannot lift the secondary row sheets  4  and the primary row sheets  5  up to such a position where the first latch notches  41  of the secondary row sheets  4  and the second latch notches  52  of the primary row sheets  5  are all in alignment with the latch opening  22  (wherein at least some of the first latch notch  41  and the second latch notch  52  are not in alignment with the latch opening  22  or all the first latch notches  41  and the second latch notches  52  are not in alignment with the latch opening  22 ) and thus, the latch  7  is still kept in the latch trough  12  and the rotation of the plug  2  relative to the outer cylinder  1  is still prevented, whereby the key cannot be operated to unlock and the effect of locking is maintained. 
     When the key blade  201  of a matched key  20  is inserted into the key way  23 , the side cuts  202  lift up the secondary row sheets  4  and the central cuts  203  lift up the primary row sheets  5  so that the first latch notches  41  and the second latch notches  52  are all in alignment with the latch opening  22 , whereby the key  20  is allowed to operate to rotate the plug  2  and the latch  7  is forced by the inside surface of the outer cylinder  1  to first slide into the second latch notches  52  and then further slide into the first latch notches  41  to eventually get out of the latch trough  12  completely and thus releasing the locking condition. Subsequent operation of the key  20  to rotate the plug  2  would cause the plug  2  to rotate relative to the outer cylinder  1  to drive the lock bolt  24  to get out of a locking hole (which is formed in a doorjamb or a device to be locked). This provides an effect of unlocking. 
     According to the present invention, the maximum number of combinations of key cuts available is M to the Nth power, where M is the number of types of secondary row sheets and primary row sheets (different stages) and N in the total number of the secondary row sheets and the primary row sheets. In the instant embodiment, N is 16, and M can be determined according to design requirement. The number of the combinations of the cuts can be as high as tens of millions and this greatly improves lock security performance. 
     It will be understood that each of the elements described above, or two or more together may also find a useful application in other types of methods differing from the type described above. 
     While certain novel features of this invention have been shown and described and are pointed out in the annexed claim, it is not intended to be limited to the details above, since it will be understood that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation can be made by those skilled in the art without departing in any way from the claims of the present invention.