Abstract:
A lock for securing a trailer hitch includes a latching member, a position-limiting assembly, and a housing. The position-limiting assembly includes first and second position-limiting members, a magnetic member, and a securing pin. The first position-limiting member is configured for detachable engagement with the latching member. The second position-limiting member is mounted in the housing, receives the magnetic member, and is slidably connected to the first position-limiting member via the securing pin in order to be moved to an engaged position and a disengaged position. When at the engaged position, the second position-limiting member is mounted to the latching member due to the magnetic member and thereby fixes the first position-limiting member in position. When at the disengaged position, the second position-limiting member is separate from an end portion of the latching member to allow detachment of the first position-limiting member from the latching member.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation in part of U.S. application Ser. No. 14/548,763 filed on Nov. 20, 2014, currently pending. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to a lock for securing a trailer hitch and more particularly to a lock whose components can be easily disassembled (disengaged from one another) and reassembled (reengaged with one another). 
     2. Description of Related Art 
     It is now common practice to attach a trailer to the rear of a vehicle via a coupler and a securing assembly so that there is more space for carrying people and/or goods. Such securing assemblies are well known in the art. For example, US Patent Application Publication No. 20120212000 “Trailer lock”, U.S. Pat. No. 6,364,339 “Trailer hitch and lock assembly”, and U.S. Pat. No. 6,402,181 “Trailer hitch and lock assembly” disclose, in essence, a latching member and a lock. The latching member is configured to be passed through a trailer coupler. More specifically, the latching member has an end portion passing through the trailer coupler and provided with an engaging portion. The lock has a mounting hole, an engaging member, and a keyhole. The end portion of the latching member is enclosed in the mounting hole. A key can be inserted into the keyhole and turned to drive the engaging member into engagement with the engaging portion, thereby locking the latching member. 
     The prior art cited above, however, leaves room for improvement. First and foremost, the lock must be locked and unlocked with a key, which leads to complexity in operation and hence inconvenience. Second, the numerous components and complicated structure of the lock hinder manufacture and assemble, making it difficult to lower production cost, let alone product price. 
     There are also securing structures without a lock core. For example, Taiwan Patent No. M274264 “Lock for a vehicle towing hitch” essentially discloses a latching member with an engaging bar and a spring. The spring can push a locking block into engagement with the engaging bar such that the locking block and the latching member are fixed in position. Since this latching member is no ordinary latching member and must be equipped with the engaging bar and the spring, the cost of the end product would be high. 
     BRIEF SUMMARY OF THE INVENTION 
     In order to provide a trailer hitch securing assembly which is not only structurally simple but also applicable to standard latching members for use with trailer hitches, the inventor of the present invention conducted extensive research and experiment and finally succeeded in developing a lock for securing a trailer hitch as disclosed herein. The lock includes a latching member, a position-limiting assembly, and a housing. The latching member is configured to extend through the trailer hitch and has an end portion and a fitting groove in the end portion. The position-limiting assembly includes a first position-limiting member, a second position-limiting member, a magnetic member, and a securing pin. The first position-limiting member is configured to prevent the latching member from separating from the trailer hitch and has a fitting portion and an extension portion. The fitting portion defines a fitting space and an opening in communication with the fitting space so that the fitting groove of the latching member can be placed into the fitting space of the first position-limiting member through the opening, thereby bringing the latching member and the first position-limiting member into detachable engagement. The extension portion has a slide groove. The second position-limiting member has one end defining an accommodating space. The accommodating space corresponds to the end portion of the latching member. The opposite end of the second position-limiting member defines a receiving groove, in which the magnetic member is mounted. The second position-limiting member is slidably connected to the slide groove of the first position-limiting member by the securing pin in order to be moved to an engaged position and a disengaged position. When at the engaged position, the second position-limiting member is secured to the latching member by the magnetic member; as a result, the first position-limiting member is fixed in position, and the end portion of the latching member is enclosed in the accommodating space of the second position-limiting member. When the second position-limiting member is at the disengaged position, the end portion of the latching member is separate from the accommodating space of the second position-limiting member, allowing the first position-limiting member to be detached from the latching member. The housing defines a receiving space for receiving the second position-limiting member, is connected to the second position-limiting member by the securing pin, and has a projecting portion. The projecting portion is located in the receiving space and is configured to be pressed against the magnetic member. 
     The lock described above for securing the trailer hitch may further include a pressing assembly which is mounted in the receiving space of the housing and includes an elastic member and an engaging member. The elastic member is compressed between the housing and the engaging member. While the second position-limiting member is moved to the engaged position, the elastic member applies an elastic force to the engaging member. The elastic force causes the engaging member to engage with the first position-limiting member, thereby securing the second position-limiting member at the engaged position. Once the engaging member overcomes the elastic force and separates from the first position-limiting member, the second position-limiting member is allowed to move from the engaged position to the disengaged position. 
     Preferably, the extension portion has a stop edge adjacent to the slide groove, and the engaging member includes an engaging portion. The engaging portion has a guide surface and a stop surface. The guide surface corresponds to an end surface of the extension portion of the first position-limiting member while the stop surface faces away from the guide surface. After the guide surface of the engaging member moves past the end surface of the extension portion, the stop surface of the engaging member enters the slide groove and consequently faces the stop edge. 
     Preferably, the housing has a through hole in communication with the receiving space, and the engaging member includes a pushing portion jutting out of the through hole of the housing. The pushing portion has a first extension length less than or equal to the diameter of the through hole. The engaging member has a second extension length greater than the diameter of the through hole. 
     Preferably, the elastic member is a spring, the engaging member has a groove, and the spring has one end mounted in the groove. 
     The foregoing technical features have the following advantages: 
     1. The movably connected first and second position-limiting members of the position-limiting assembly only have to be secured sequentially to the latching member to enter the engaged state, and locking and unlocking can be done without a lock core and a matching key. The lock of the present invention is therefore more convenient, structurally simpler, and less costly than its conventional counterparts. 
     2. As the position-limiting assembly can be used with standard latching members, the present invention has wide applicability. 
     3. Since the position-limiting assembly is secured in place by magnetic attraction, the securing effect is less susceptible to dust or dirt in the environment than in the prior art. 
     4. The engaging member can be movably pressed against the first position-limiting member to better secure the second position-limiting member at the engaged position and prevent the second position-limiting member from moving to the disengaged position directly. Thus, the danger associated with inadvertent unlocking is avoided. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is an assembled perspective view of a first embodiment of the present invention; 
         FIG. 2  is an exploded perspective view of the first embodiment of the present invention; 
         FIG. 3  is a sectional view showing a state of use of the first embodiment of the present invention; 
         FIG. 4  is a sectional view showing another state of use of the first embodiment of the present invention; 
         FIG. 5  is a sectional view showing yet another state of use of the first embodiment of the present invention; 
         FIG. 6  is a perspective view of the first embodiment of the present invention, showing the position-limiting assembly in the engaged state; 
         FIG. 7  is an exploded perspective view of the second embodiment of the present invention; 
         FIG. 8  is a sectional view showing a state of use of the second embodiment of the present invention; 
         FIG. 9  is a sectional view showing another state of use of the second embodiment of the present invention; 
         FIG. 10  is a sectional view showing yet another state of use of the second embodiment of the present invention; and 
         FIG. 11  is a sectional view showing still another state of use of the second embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention incorporates the foregoing technical features into a lock for securing a trailer hitch, and the major effects of the lock are detailed below with reference to some illustrative embodiments. 
     Referring to  FIG. 1 , the lock for securing a trailer hitch according to the first embodiment of the present invention includes a latching member  1 , a position-limiting assembly  2 , and a housing  3 . The latching member  1  is configured to be passed through a trailer hitch A 2 , or more specifically to be passed through a receiver tube A 1  at the rear of a vehicle as well as the trailer hitch A 2 . The latching member  1  is made of iron or an iron alloy, for example. The latching member  1  has a stop portion  11 , an end portion  12 , and a body portion  13  connecting the stop portion  11  and the end portion  12 . The latching member  1  further has a fitting groove  121  in the end portion  12 . 
     Referring to  FIG. 2  and  FIG. 3 , the position-limiting assembly  2  includes a first position-limiting member  21 , a second position-limiting member  22 , a magnetic member  23 , and a securing pin  24 . The first position-limiting member  21  has a fitting portion  211  and an extension portion  212  connected to the fitting portion  211 . The fitting portion  211  defines a fitting space  213  and an opening  214  in communication with the fitting space  213  so that the fitting groove  121  of the latching member  1  can be placed into the fitting space  213  of the first position-limiting member  21  through the opening  214 , thereby mounting the first position-limiting member  21  to the latching member  1 . The extension portion  212  has a slide groove  215 . 
     With continued reference to  FIG. 2  and  FIG. 3 , the second position-limiting member  22  has one end defining an accommodating space  221 . The accommodating space  221  corresponds to the end portion  12  of the latching member  1 . The other end of the second position-limiting member  22  defines a receiving groove  222 , and the magnetic member  23  is mounted in the receiving groove  222 . The second position-limiting member  22  is slidably connected to the slide groove  215  of the first position-limiting member  21  via the securing pin  24 . 
     With continued reference to  FIG. 2  and  FIG. 3 , the housing  3  defines a receiving space  31  for receiving the second position-limiting member  22 . The housing  3  is connected to the second position-limiting member  22  by the securing pin  24  and has a projecting portion  32 . The projecting portion  32  is located in the receiving space  31  and is configured to be pressed against the magnetic member  23  so that the magnetic member  23  is securely positioned in the receiving groove  222  of the second position-limiting member  22 . 
     To secure the latching member  1  to the receiver tube A 1  and the trailer hitch A 2 , referring to  FIG. 3  and  FIG. 4 , the body portion  13  of the latching member  1  is passed through the receiver tube A 1  and the trailer hitch A 2  until the end portion  12  of the latching member  1  juts out of the receiver tube A 1  and the trailer hitch A 2 . Then, the fitting portion  211  of the first position-limiting member  21  is fitted into the fitting groove  121  in the end portion  12 . After that, referring to  FIG. 4  and  FIG. 5 , the second position-limiting member  22  is manually displaced toward the end portion  12  of the latching member  1  (in the meantime, the second position-limiting member  22  is displaced also by magnetic attraction of the magnetic member  23 ). With the assistance of the magnetic attraction of the magnetic member  23 , the accommodating space  221  of the second position-limiting member  22  encloses the end portion  12  of the latching member  1  and is thus fixed at an engaged position. As the second position-limiting member  22  is connected to the first position-limiting member  21 , the first position-limiting member  21  is also fixed in position once the second position-limiting member  22  is in place. The first position-limiting member  21  and the stop portion  11  provided respectively at the two ends of the latching member  1  jointly prevent the latching member  1  from separating from the receiver tube A 1  and the trailer hitch A 2  (see  FIG. 6 ). 
     For disengagement, referring back to  FIG. 4 , the second position-limiting member  22  is pushed in the opposite direction. Once the pushing force overcomes the magnetic attraction of the magnetic member  23 , the second position-limiting member  22  can be displaced to a disengaged position, where the second position-limiting member  22  is separate from the end portion  12  of the latching member  1 . As the first position-limiting member  21  is fixed in position only when the second position-limiting member  22  is secured to the latching member  1 , disengagement of the second position-limiting member  22  from the end portion  12  of the latching member  1  makes it possible to detach the first position-limiting member  21  from the latching member  1 . 
       FIG. 7  shows the second embodiment of the present invention, which is similar to the first embodiment in that it also includes a latching member  1 A, a position-limiting assembly  2 A, and a housing  3 A, and that the position-limiting assembly  2 A also includes a first position-limiting member  21 A, a second position-limiting member  22 A, a magnetic member  23 A, and a securing pin  24 A. The second embodiment is different from the first embodiment mainly in that the housing  3 A further has a through hole  33 A on one side, that the through hole  33 A is in communication with the receiving space  31 A of the housing  3 A, and that the lock further includes a pressing assembly  4 A. 
     Referring to  FIG. 7  and  FIG. 8 , the pressing assembly  4 A is mounted in the receiving space  31 A of the housing  3 A and includes an elastic member  41 A and an engaging member  42 A. The elastic member  41 A is compressed between the housing  3 A and the engaging member  42 A. The engaging member  42 A includes an engaging portion  421 A and a pushing portion  422 A opposite the engaging portion  421 A. The engaging portion  421 A has a guide surface  423 A and a stop surface  424 A. The guide surface  423 A corresponds to an end surface  2121 A of an extension portion  212 A of the first position-limiting member  21 A. The stop surface  424 A faces away from the guide surface  423 A. The pushing portion  422 A extends out of the through hole  33 A of the housing  3 A. 
     More specifically, referring to  FIG. 9 , the pushing portion  422 A has a first extension length L 1 , which is less than or equal to the diameter of the through hole  33 A, and the engaging portion  421 A has a second extension length L 2 , which is greater than the diameter of the through hole  33 A to prevent the engaging member  42 A from falling out of the housing  3 A. Preferably, the elastic member  41 A is a spring, the engaging member  42 A has a groove  425 A, and the spring has one end fitted in the groove  425 A to ensure that the elastic member  41 A is securely positioned. 
     The lock in the second embodiment is used in generally the same way as its counterpart in the first embodiment, one major difference being that, referring to  FIG. 9  and  FIG. 10 , when the second position-limiting member  22 A is displaced toward an end portion  12 A of the latching member  1 A and thus presses the guide surface  423 A of the engaging member  42 A against the end surface  2121 A of the extension portion  212 A of the first position-limiting member  21 A, the engaging portion  421 A of the engaging member  42 A is pushed by the end surface  2121 A of the extension portion  212 A and in turn compresses the elastic member  41 A. After the guide surface  423 A of the engaging member  42 A moves past the end surface  2121 A of the extension portion  212 A, referring to  FIG. 11 , the stop surface  424 A enters a slide groove  215 A of the extension portion  212 A and ends up facing a stop edge  2151 A adjacent to the slide groove  215 A. Thus, the second position-limiting member  22 A is fixed at an engaged position not only because of the magnetic member  23 A, which secures the second position-limiting member  22 A to the end portion  12 A of the latching member  1 A by magnetic attraction, but also because of the engaging member  42 A engaged in the slide groove  215 A of the first position-limiting member  21 A. 
     To disengage, referring again to  FIG. 11 , the pushing portion  422 A of the engaging member  42 A is pushed until the engaging portion  421 A of the engaging member  42 A is moved away from the slide groove  215 A of the first position-limiting member  21 A. Then, the second position-limiting member  22 A is pushed in the opposite direction. Once the pushing force overcomes the magnetic attraction of the magnetic member  23 A, the second position-limiting member  22 A can be displaced to a disengaged position, where the second position-limiting member  22 A is separate from the end portion  12 A of the latching member  1 A. Since the first position-limiting member  21 A is fixed in position only when the second position-limiting member  22 A is secured to the latching member  1 A, disengagement of the second position-limiting member  22 A from the end portion  12 A of the latching member  1 A makes it possible to detach the first position-limiting member  21 A from the latching member  1 A. 
     The foregoing description of the two embodiments should be able to enable a person of ordinary skill in the art to fully understand the operation, use, and effects of the present invention. However, the embodiments described above are only some preferred ones of the invention and should not be construed as limiting the scope of the invention. All simple equivalent changes and modification based on the appended claims and the disclosure of the specification should fall within the scope of the present invention.