Abstract:
A fastening device for a wheel is disclosed. A hub nut which has been fastened to a hub bolt cannot be loosened owing to a decoupling prevention unit of the hub nut and a rotation prevention protuberance of the hub bolt, as long as an assembling tool is not used. Consequently, the fastening device improves the steering stability of an automobile and prevents separation of the wheels from the axles while the vehicle is in motion.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a fastening device for a wheel, and more particularly, to a fastening device for a wheel in which the coupling forces between the hub bolts and the hub nuts are improved, thereby preventing separation of the wheel from the vehicular axle while the vehicle is in motion.  
         BACKGROUND OF THE INVENTION  
         [0002]    A conventional automobile wheel consists of a disc wheel and a tire fitted to the disc wheel so as to be rotated with the disc wheel. The wheel is fastened to a wheel hub by using hub bolts and hub nuts. The hub is coupled to the vehicular axle. The hub bolts pass through the disc wheel. The hub nuts are fastened to the ends of the hub bolts, thereby coupling the wheel to the wheel hub. If the hub bolts and the hub nuts are to be fastened together or unfastened from each other, an assembling tool such as a wrench is used.  
           [0003]    However, conventional hub bolts and hub nuts are coupled together only by the threads. Accordingly, if the hub bolts and hub nuts are not fastened properly, the coupling force between the wheel and the wheel hub becomes loose, and steering stability is degraded while the vehicle is in motion, or the wheel may be separated from the wheel hub, potentially causing injury to occupants and damage to the vehicle.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention provides a fastening device for a wheel that prevents deterioration of the steering stability and separation of the wheel from the vehicular axle, even if the hub bolts and the hub nuts are loosely fastened, thereby preventing injury to occupants and damage to the vehicle.  
           [0005]    In accordance with an embodiment of the present invention, a hub bolt passes through a wheel hub and a disc wheel to couple with the hub nut. A rotation prevention protuberance is formed integrally on the leading end of the hub bolt with a predetermined length. A decoupling prevention means is elastically and pivotally installed in the hub nut so as to selectively interact with the rotation prevention protuberance and prevent any unintended decoupling of the hub bolt and the hub nut.  
           [0006]    In an alternative preferred embodiment, a bolt has a protuberance extending from one end and a nut is configured to be threaded over said bolt. The nut includes a bracket configured and dimensioned to be received over said protuberance and lock thereon. Preferably, an elastic member acts on the bracket to bias it over the protuberance when the nut is threaded on the bolt such that the nut is locked on the bolt by the bracket. Further preferably, the bracket is pivotably mounted within the nut such that one end extends beyond a peripheral surface of the nut when biased over the protuberance. The bracket is further configured to be pivoted by placement of a tool over the nut such that the bracket is disengaged from the protuberance, whereby the nut is unlocked from the bolt. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    For fuller understanding of the nature and objects of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings in which:  
         [0008]    [0008]FIG. 1 is a side view of a hub bolt and nut according to an embodiment of the invention;  
         [0009]    [0009]FIG. 2 is a perspective view of a hub nut according to the invention;  
         [0010]    [0010]FIG. 3. is a side view of a decoupling prevention means installed on a hub nut of the present invention;  
         [0011]    [0011]FIG. 4 is a schematic view with an enlarged view portion illustrating use of a tool on the hub nut of the invention; and  
         [0012]    [0012]FIG. 5 is a view similar to FIG. 4 without the tool. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0013]    The present invention will be described in detail referring to the attached drawings.  
         [0014]    As shown in FIG. 1, a rotation prevention protuberance  21  a with a predetermined length is formed on the leading end of the hub bolt  21 . Hub nut  22  is provided with a decoupling prevention means  30 , which selectively interacts with the rotation prevention protuberance  21  a so as to make it impossible to rotate the hub nut  22  without using an appropriate assembling tool T. The protuberance  21  a is preferably formed in the shape of an angular pole such as a tetragonal pole or a hexagonal pole. The reason for the angular shape is so that when the hub bolt  21  and the hub nut  22  are fastened together, the decoupling prevention means  30  will cause an interference and effectively prevent any unintended rotation of the hub nut  22 .  
         [0015]    As shown in FIGS. 2 and 3, the decoupling prevention means  30  includes a rotation shaft  31  with its both ends secured in the hub nut  22  in a direction crossing the axis of the hub bolt  21 . A pivotal bracket  33  is pivotally installed on the rotation shaft  31 , with one end of the pivotal bracket  33  projecting out of the hub nut and the other end of the pivotal bracket  33  extending inwardly beyond the inner circumference of the hub nut. When the assembling tool T is fitted onto the hub nut  22  (see, e.g., FIG. 4), the pivotal bracket  33  is rotated in one direction (counter clockwise direction) so that its two ends are rotated toward the body of the hub nut  22 . An elastic member  35  is installed between the rotation shaft  31  and the pivotal bracket  33 , for elastically forcing the other end of the pivotal bracket  33  inwardly. When the assembling tool T is not fitted to the hub nut  22 , one end of the pivotal bracket  33  projects out of the hub nut  22 , while the other end is buried inwardly beyond the inner circumference of the hub nut  22 .  
         [0016]    When the assembling tool T is fitted to the hub nut  22  by overcoming the elastic force of the elastic member  35 , then the other end of the pivotal bracket  33  withdraws outwardly, and therefore, the rotation prevention protuberance  21   a  of the hub bolt  21  can be freely rotated within the hub nut  22 . When the assembling tool T is removed, the other end of the pivotal bracket  33  is pivoted inwardly (beyond the inner circumference of the hub nut  22 ) owing to the elastic force of the elastic member  35 . Pivotal bracket  33  comes to interact with the rotation prevention protuberance  21  a of the hub bolt  21 . The elastic member  35  may consist of a torsion spring.  
         [0017]    In a state where the hub bolt  21  is inserted into the wheel (which has been closely attached to the wheel hub  51 ), if an assembling tool T is used to fasten the hub nut  22  with the hub bolt  21 , then the pivotal bracket  33  of the decoupling prevention means  30  is pivoted in counter clockwise direction by the assembling tool T as shown in FIG. 4. Thus, the other end of the pivotal bracket  33 , which projects inwardly toward the inner circumference of the hub nut  22 , is rotated toward the outer circumference of the hub nut  22  and does not interact with the rotation prevention protuberance  21   a  of the hub bolt  21 . Under this condition, the assembling tool T can be rotated in one direction to fasten the hub nut  22  to the hub bolt  21 .  
         [0018]    After completion of the fastening of the hub nut  22  to the hub bolt  21 , the assembling tool T is removed from the hub nut  22 . The pivotal bracket  33  of the decoupling prevention means  30  is restored to its original position due to the elastic force of the elastic member  35  as shown in FIG. 5. As a result, the other end of the pivotal bracket  33  protrudes inwardly beyond the inner circumference of the hub nut  22  to interact with the rotation prevention protuberance  21  a of the hub bolt  21 , so that the hub nut  22  can be prevented from being separated from the hub bolt  21 .  
         [0019]    Hub nut  22  is not loosened from the hub bolt  21  by itself, but if the assembling tool T is used, the pivotal bracket  33  is pivoted to release the interaction between the pivotal bracket  33  and the rotation prevention protuberance  21   a . Hence, the hub nut  22  can easily be unfastened like a conventional hub nut.  
         [0020]    According to the present invention as described above, as long as the assembling tool is not used, the hub nuts should not loosen from the hub bolts, owing to the rotation prevention protuberance of the hub bolt and the decoupling prevention means of the hub nut. Therefore, separation of the wheels from the wheel hubs while the vehicle is in motion may be reduced or avoided, lessening the possibility of injury to occupants and damage to the vehicle.