Patent Publication Number: US-2012034023-A1

Title: Telescopic Apparatus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a telescopic apparatus and, more particularly, to a control unit operable to allow and avoid changes in the effective length of the telescopic apparatus. 
     2. Description of the Prior Art 
     As disclosed in U.S. Pat. No. 6,247,882 issued to the present applicant, a conventional telescopic apparatus includes a rod  10  telescopically inserted in a tube  20 . The rod  10  includes depressions  12  defined therein. Changes in the effective length of the conventional telescopic apparatus are under the control of a control unit. The control unit includes a sleeve  30 , a lever  35 , a spring  39 , a blade  40  and a shaft  50 . The sleeve  30  is secured to the tube  20 . The sleeve  30  includes a pair of flaps  32  in parallel to each other. 
     The blade  40  includes two ears  41  each inserted through an aperture  36  defined in a related one of the flaps  32 . The blade  40  includes a projection  42  extending from a side thereof and a bulge  43  extending from an opposite side thereof for insertion in a selected one of the depressions  12 . 
     The shaft  50  is movably inserted through an aperture  37  defined in one of the flaps  32  and an aperture  38  defined in the other flap  32 . A nut  55  is engaged with the shaft  50 . The shaft  50  is in the form of a screw with sections of different diameters. The shaft  50  includes two grooves  54  defined in and around the periphery. A selected one of the grooves  54  receives the extension  42 . 
     The lever  35  includes a pawl  80  extending from an end for insertion in a selected one of the depressions  12  to retain a value of the effective length of the conventional telescopic apparatus. The lever  35  is pivotally connected to the flaps  32  by a pin  34 . 
     The spring  39  includes a helical section extending between two rectilinear sections. The helical section of the spring  39  is pivotally located around the pin  34 . One of the rectilinear sections of the spring  39  is located against the blade  40  while the other rectilinear section of the spring  39  is located against the lever  35 . 
     When a larger one of the sections of the shaft  50  is located against the lever  35 , the lever  35  cannot be pivoted and the pawl  80  cannot be removed from the selected depression  12 . Hence, the effective length of the conventional telescopic apparatus is retained. The projection  42  is located in one of the grooves  54 . When a smaller one of the sections of the shaft  50  is located below the lever  35 , the lever  35  can be pivoted and the pawl  80  can be removed from the selected depression  12 . Hence, the effective length of the conventional telescopic apparatus can be changed. The projection  42  is located in the other groove  54 . 
     There are however some problems with the conventional telescopic apparatus. At first, the gap between the lever  35  and the blade  40  is too small to encompass the spring  39  to facilitate the insertion of the pin  34  through the helical section of the spring  39 . Secondly, the insertion of the shaft  50  into the flaps  32  and the removal of the former from the latter are hindered by the insertion of the projection  42  in a selected one of the grooves  54 . Thirdly, it takes quite some time for a user to use a hand to hold the shaft  50  and the other hand to operate a tool to rotate the nut  55  to engage the nut  55  with the shaft  50 . 
     Therefore, the present invention is intended to obviate or at least alleviate the problems encountered in prior art. 
     SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide an telescopic apparatus that can be made and used easily. 
     To achieve the foregoing objective, the telescopic apparatus includes an internal tube telescopically inserted in an external tube. The internal tube includes depressions defined therein. A frame is secured to the external tube. The frame includes two walls in parallel to each other. A lever is pivotally connected to the walls. The lever includes a space transversely defined therein, a groove in communication with and in parallel to the space, and a pawl for insertion in a selected one of the depressions for locking the internal tube relative to the external tube. A spring is substantially located in the space. The spring includes a hook for hooking one of the walls and a bent section located in the groove. A short tube is located in the space and against the spring. A screw is inserted through the walls, the spring and the short tube. A security unit is movably connected to the walls between a locking position against the lever to avoid pivoting of the lever and a releasing position away from the lever to allow pivoting of the lever. 
     Other objectives, advantages and features of the present invention will be apparent from the following description referring to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The present invention will be described via detailed illustration of the preferred embodiment referring to the drawings wherein: 
         FIG. 1  is a perspective view of a telescopic apparatus in accordance with the preferred embodiment of the present invention; 
         FIG. 2  is a partial, cross-sectional view of the telescopic apparatus shown in  FIG. 1 ; 
         FIG. 3  is a partial, exploded view of the telescopic apparatus of  FIG. 1 ; 
         FIG. 4  is another partial, cross-sectional view of the telescopic apparatus shown in  FIG. 1 ; 
         FIG. 5  is another partial, cross-sectional view of the telescopic apparatus shown in  FIG. 1 ; and 
         FIG. 6  is another partial, cross-sectional view of the telescopic apparatus shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings and initially to  FIGS. 1 and 2 , a telescopic apparatus includes an internal tube  20  telescopically inserted in an external tube  30  in accordance with the preferred embodiment of the present invention. The internal tube  20  includes several depressions  24  defined in a flat side  22  formed thereon. 
     A contact unit  12  is pivotally connected to an end of each of the tubes  20  and  30 . To this end, a plug  21  is fit in the end of the internal tube  20 , and a plug  31  is fit in the end of the tube  30 . A screw  11  is driven in each of the plugs  21  and  31 . The contact unit  12  includes a plate  13  substantially covered by a protective layer  14 . The plate  13  is preferably made of metal while the protective layer  14  is preferably made of rubber or plastics. The plate  13  includes two ears  15  extending from a side. The ears  15  are not covered by the protective layer  14 . The ears  15  are pivotally connected to the screw  11  by a fastener  17  such as a screw and a rivet. A washer  16  may be provided on the fastener  17 . 
     Referring to  FIGS. 3 through 6 , changes in the effective length of the telescopic apparatus are under the control of a control unit  40 . The control unit  40  includes a frame  41 , a leaf  50 , a security unit, a lever  70  and a screw  80 . The frame  41  includes two walls  42  in parallel to each other. The frame  41  is formed with a brace  43  that includes two jaws  44 . The frame  41  is provided on the external tube  30 . The external tube  30  is located between the walls  42 . The external tube  30  is located between the jaws  44  of the brace  43 . A screw  32  is driven through the jaws  44  before it is engaged with a nut. Thus, the frame  41  is secured to the external tube  30 . A square aperture  45  is defined in one of the walls  42  while a circular aperture  46  is defined in the other wall  42 . A cutout  47  is defined in an edge of each of the walls  42 . An aperture  48  is defined in each of the walls  42 . An aperture  56  is defined in one of the walls  42  while an aperture  58  is defined in the other wall  42 . The size of the aperture  56  is smaller than that of the aperture  58 . 
     The leaf  50  is made with elasticity. The leaf  50  is preferably a leaf spring made of metal. The leaf  50  includes two pivots  51  laterally extending from an end, a first bulge  52  formed on a side, and a second bulge  53  formed on an opposite side. Each of the pivots  51  is inserted through the aperture  48  defined in a related one of the walls  42  for pivotally connecting the leaf  50  to the walls  42 . The first bulge  52  can be inserted in a selected one of the depressions  24 . The second bulge  53  is located closer to the pivots  51  than the first bulge  52  is. The leaf  50  is made with a bent configuration including two sections, with an angle  54  defined between the sections. 
     The lever  70  includes a pawl  71  extending from an end, a space  72  defined therein transversely, and a groove  73  defined therein transversely. The space  72  is in communication with the groove  73 . The axis of the space  72  is in parallel to the length of the groove  73 . 
     There are provided a spring  74  and a short tube  75 . The spring  74  is a torque spring with a helical section extending between a hook  76  and a bent section  77 . 
     The screw  80  includes a generally circular head  81 , a square block  82  and of course a thread. The square block  82  is located between the head  81  and the thread. The diameter of the circular head  81  is larger than the dimension of the sides of the square block  82 . 
     Both of the spring  74  and the short tube  75  are located in the space  72  before the lever  70  is located between the walls  42 . The helical section of the spring  74  is located in the space  72  while the bent section  77  is located in the groove  73 . The hook  76  is located in the cutout  47  defined in a selected one of the walls  42 . The threaded section of the screw  80  is inserted through the square apertures  45 , the helical section of the spring  74 , the short tube  75 , a washer  83  and the circular aperture  46 . The square block  82  is located in the square aperture  45 . Thus, the screw  80  cannot be rotated relative to the frame  41 . The screw  80  is engaged with a nut  84 . Thus, the lever  70  is pivotally connected to the frame  41 . The lever  70  is biased toward the internal tube  20  because of the spring  74 . The engagement of the screw  80  with the nut  84  is easy because the screw  80  cannot be rotated relative to the frame  41 . 
     The security unit includes a pin  60  engaged with a cap  62 . The pin  60  includes is formed with a head  61 . The cap  62  is formed with a head  63  identical to the head  61 . The pin  60  is movably located in the aperture  56  while the cap  62  is movably located in the aperture  58 . The pin  60  is fit in the cap  62 . To enhance the connection of the pin  60  to the cap  62 , an adhesive material may be provided between them. The connection of the pin  60  to the cap  62  is easy. The pin  60  can be replaced with a screw while the cap  62  can be replaced with a nut in another embodiment. 
     In use, the pawl  71  is located in a selected one of the depressions  24 . The cap  62  is located against the lever  70 . Thus, the lever  70  cannot be pivoted. The pawl  71  is retained in a selected one of the depressions  24  to lock the internal tube  20  relative to the external tube  30 , i.e., the effective length of the telescopic apparatus is retained. The first bulge  52  is located in a selected one of the depressions  24 . The pin  60  is located against the second bulge  53 . 
     To change the effective length of the telescopic apparatus, the security unit is operated so that the cap  62  is not located against the lever  70 . The lever  70  is pivoted, and the pawl  71  removed from the selected depression  24 . Hence, the internal tube  20  can be moved relative to the external tube  30 , i.e., the effective length of the telescopic apparatus can be changed. Because of the elasticity of the leaf  50 , the first bulge  52  can be removed from one of the depressions  24  and inserted in another one of the depressions  24 , and clicks are made. 
     The telescopic apparatus of the present invention exhibits several advantages over the one disclosed in U.S. Pat. No. 6,247,882. At first, it is easy to insert the screw  80  through the helical section of the spring  74  and the short tube  75 , which are located in the space  72 . Secondly, the insertion of the security unit through the walls  42  and the removal of the former from the latter are easy since the security unit consists of two elements that are made separately and later joined together. At last, the engagement of the nut  84  with the screw  80  is easy because the screw  80  cannot be rotated relative to the frame  41  when the square block  82  is located in the square aperture  45 . 
     The present invention has been described via the detailed illustration of the preferred embodiment. Those skilled in the art can derive variations from the preferred embodiment without departing from the scope of the present invention. Therefore, the preferred embodiment shall not limit the scope of the present invention defined in the claims.