Abstract:
An improved lock for a trailer enables a latch bolt to be inserted conveniently, and allows locking and unlocking operations be done easily. The lock mainly consists of a latch bar and a lock member. The lock member includes a latch sleeve, a lock ring, a connection shaft and a lock core. The lock may be easily locked or unlocked by turning a key for 90°.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an improved lock for a trailer and particularly a trailer lock that is easy for a latch bolt to insert and to perform locking or unlocking operations. 
     2. Description of the Prior Art 
     Travel and recreational activities have become increasingly popular these days. They not only benefit people&#39;s physical and mental health, also are good to business and economic developments. During travels, many people use trailers to haul various outfits, foods, drinking water, etc. The trailer is usually fastened to the rear end of a car, and is anchored by a latch bolt. In order to guard the trailer against theft, a latch bolt doubles as a lock has been developed. FIGS. 9 through 11 show such a latch bolt. It mainly includes a lock member  60  with an insert hole  61  formed at one end for receiving a latch end  51  of a shank  50 . The lock member  60  has another end formed an opening  62  to engage sequentially a latch member  90  and a lock core  80 . The another end further has a groove  65  to engage with a cap  66 . The lock core  80  has a key way  81  formed at one end, a pin hole  82  formed on one side to match an aperture  66  formed on the lock member  60  to receive a pin  64  to anchor the lock core  80  in the lock member  60 , and a lock tongue  83  located at another end thereof to couple with a latch member  90 . The lock core  80  may be turned and controlled by a key  70 . The latch member  90  is integrally formed and includes a base plate  91  with a retain hole  911  formed thereon to match and couple with the lock tongue  83 , a connection section  92  extended on one side, and an upper plate  93  connected to the connection section  92 . The upper plate  93  has a latch frame  931  formed thereon. 
     When in use, the latch end  51  of the shank  50  is inserted into the latch member  90  through the insert hole  61  of the lock member  60 . Then the key  70  is turned to turn the lock core  80  which turns the lock tongue  83  and drives the latch member  90  to turn. As a result, the direction of the latch frame  931  on the upper plate  93  changes. Then the latch frame  931  may latch the latch end  51  of the shank  50  to prevent the shank  50  from being pulled out of the lock member  60 . This is a locked condition (as shown in FIGS.  12  and  13 ). On the other hand, the key  70  may be turned to drive the latch member  90  and change the direction of the latch frame  931  so that the shank  50  is not latched by latch frame  931 . Then the shank  50  may be removed from the lock member  60  to form an unlocking condition. Insertion of the latch end is done at the opposite directions 180° apart. Such a design has the following disadvantages: 
     1. As the latch end  51  and the insert hole  61  are aligned at positions of 180° apart, there are only two inserting locations for the latch end of the shank  50 . Operation is not convenient and is time-consuming. 
     2. The lock core has to be turned at a large angle of 180° when in use. It is against the prevailing trend of locking devices that mostly adopt the turning angle of 90°. Such a design has no competitiveness and incurs higher cost. 
     SUMMARY OF THE INVENTION 
     In view of aforesaid disadvantages, the primary object of the invention is to provide an improved lock for a trailer that is easy for the latch bolt to be inserted to perform locking or unlocking operations, and is turned at a smaller angle (about 90°) when in use. 
     To attain the foregoing object, the invention mainly includes a latch bar and a lock member. The latch bar includes a latch bolt to match the key way, lock ring, connection shaft and lock core of the lock. Locking operations can be done easily. Unlocking can be accomplished by turning the lock core for a small angle and can be done quickly and conveniently. 
    
    
     The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the invention. 
     FIG. 2 is an exploded view of the invention. 
     FIG. 3 is a sectional view of the invention, showing a locked condition 
     FIG. 4 is a cross section of a lock core taken along line A—A in FIG.  3 . 
     FIG. 5 is a cross section of a lock ring taken along line I—I in FIG.  3 . 
     FIG. 6 is a sectional view of the invention in use, for unlocking. 
     FIG. 7 is a cross section of a lock core taken along line C—C in FIG.  6 . 
     FIG. 8 is a cross section of a lock ring taken along line D—D in FIG.  6 . 
     FIG. 9 is an exploded view of a conventional lock for trailers. 
     FIG. 10 is a perspective view of a latch member and a lock core of a conventional lock for trailers. 
     FIG. 11 is a perspective view of a conventional lock for trailers. 
     FIG. 12 is a sectional view of a conventional lock for trailers. 
     FIG. 13 is a cross section of a conventional lock for trailers in use. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1 and 2, the invention mainly includes a latch bar  1  and a lock member  2 . 
     The latch bar  1  has a shank  10 , an anchor end  11  of a larger size located at one end of the shank  10 , and a latch bolt  12  located at another end of the shank  10 . The latch bolt  12  is coupled with a waterproof washer  13 . The latch bolt  12  has at least four symmetrical latch blocks  121  equally spaced from one another. Every two neighboring latch blocks  121  are divided by a longitudinal slot  122 . Each latch block  121  is cut through by an annular slot  123  in the middle portion to form a front latch block  1211  and a rear latch block  1212 . 
     The lock member  2  consists of: 
     a lock sleeve  21  which includes a hollow shell  20 , an insert hole  212  formed at one end for receiving the latch bolt  12 . The insert hole  212  has at least four symmetrical first notches  2122  formed on the peripheral rim equally spaced from one another. Every two neighboring first notches  2122  are bridged by a first lug  2121 . The insert hole  212  matches and is engageable with the latch bolt  12  of the latch bar  1 . The lock sleeve  21  has another end formed a round opening  213  and an annular groove  214  on the peripheral surface thereof. The round opening  213  may contain sequentially a lock ring  22 , a connection shaft  23  and a lock core  24 . The lock sleeve  21  further has an anchor hole  211  formed in the middle portion for receiving a pin  3  to anchor the lock core  24 ; 
     a lock ring  22  which has two wedge slots  221  formed at two ends and an inner hole  223  formed in the center matching the insert hole  212  of the lock sleeve  21 . The inner hole  223  has second notches  224  and second lugs  222  formed on the peripheral rim corresponding to the insert hole  212 ; 
     a connection shaft  23  which has a trough  231  formed at one end for housing the latch bolt  12 . The top rim of the trough  231  has two stubs  232  corresponding to the wedge slots  221  of the lock ring  22 . The connection shaft  23  has another end formed a wedge cavity  233  and an outer rim formed a retain groove  234 ; 
     a lock core  24  which is a standard element and has an aperture  241  located at a front section corresponding to the anchor hole  211  of the lock sleeve  21  to engage with the pin  3  to anchor the lock core  24  in the lock sleeve  21 . The lock core  24  has a lock tongue  242  located at one end to engage with the wedge cavity  233  of the connection shaft  23 , and a retain stub  243  located on the peripheral rim of one end. The retain stub  243  is movable within the retain groove  234  of the connection shaft  23 . The lock core  24  has a key way  244  formed at another end to receive a key  4  (as shown in FIG.  6 ); and 
     a dust guarding cap  25  which includes a coupling ring  251  for fastening to the annular groove  214  of the lock sleeve  21  and a movable lid  252  for covering the key way  244  to prevent rain water and dusts from entering into the key way  244 . 
     Referring to FIGS. 3,  4  and  5 , when in use for locking, the latch bolt  12  of the latch bar  1  is inserted into the insert hole  212  of the lock member  2 . As the second notches  224  are formed in a symmetrical fashion, the latch bolt  12  may be inserted into the insert hole  212  in a small angular range rapidly. Moreover, as the insert hole  212  has at least four aligned insert points on the peripheral rim, the key  4  may be turned for a small angle (about 90°) to make the lock tongue  242  of the lock core  24  to drive the connection shaft  23  and the lock ring  22 . And the lock ring  22  may be moved in the annular slot  123  of the latch bolt  12  such that the inner hole  223  is moved in a staggered manner against the insert hole  212  of the lock sleeve  21  (as shown in FIGS. 4 and 5) to accomplish the locking function. On the other hand, for unlocking, turn the key  4  to drive the lock core  24  to move the lock tongue  242 , consequently the connection shaft  23  and the lock ring  22  are turned to enable the inner hole  223  of the lock ring  22  and the insert hole  212  of the lock sleeve  21  to align with each other. Then the latch bar  1  may be removed freely from the lock member  2  to complete the unlocking operations (as shown in FIGS. 6,  7  and  8 ). 
     By means of the construction set forth above, the trailer lock of the invention enables the latch bolt to be inserted conveniently, and locking and unlocking operations can be done easily to effectively overcome the problems occurred to conventional trailer locks.