Patent Publication Number: US-7713177-B2

Title: Buffering apparatus

Description:
BACKGROUND OF INVENTION 
   1. Field of Invention 
   The present invention relates to a treadmill and, more particularly, to a buffering apparatus for use in a treadmill. 
   2. Related Prior Art 
   Many people live a busy and stressed life. Exercise of an adequate quantity and an appropriate intensity is good for the physical and mental health of these people and even for their efficiencies while working. 
   Treadmills are popular in gyms and homes because they are easily operable and help people of almost all ages enjoy exercise. As treadmills are getting popular, people are paying more attention to their safety on treadmills. That is, people are paying more attention to the strength and reliability of treadmills. To this end, people tend to make bigger treadmills. However, bigger treadmills are heavier and occupy more space. Moreover, bigger treadmills cost more since materials are more and more expensive. 
   The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art. 
   SUMMARY OF INVENTION 
   It is the primary objective of the present invention to provide a buffering apparatus for a treadmill with excellent buffering effects. 
   According to the present invention, a treadmill includes an external frame, an internal frame connected to the external frame, a belt in the form of a loop supported on the internal frame and a buffering apparatus for buffering the internal frame. The buffering apparatus includes a crossbar and two buffer sets. The crossbar is rotationally provided on the external frame between various positions. Each of the buffer sets includes a plurality of buffering blocks made with different elastic coefficients so that a selected one of the buffering blocks is brought into contact with the internal frame when the crossbar is in a related one of the positions. 
   Other objectives, advantages and features of the present invention will become apparent from the following description referring to the attached drawings. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
     The present invention will be described via the detailed illustration of the preferred embodiment referring to the drawings. 
       FIG. 1  is a perspective view of a treadmill equipped with a buffering apparatus according to the preferred embodiment of the present invention. 
       FIG. 2  is a perspective view of the buffering apparatus of  FIG. 1 . 
       FIG. 3  is a rear view of the buffering apparatus shown in  FIG. 2 . 
       FIG. 4  is a rear view of the buffering apparatus in another position than shown in  FIG. 3 . 
       FIG. 5  is an exploded view of the buffering apparatus shown in  FIG. 2 . 
       FIG. 6  is an enlarged partial view of the buffering apparatus shown in  FIG. 4 . 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
   Referring to  FIG. 1 , a treadmill includes a platform  10 , a belt  12 , a handle unit  20  and a buffering apparatus  30  according to the preferred embodiment of the present invention. The platform  10  includes an external frame  11 , an internal frame  13  and joints  15  for connecting the external frame  11  to the internal frame  13 . Two apertures  16  are defined in a middle portion of the external frame  11 . 
   The belt  12  is in the form of a loop movably provided around the internal frame  13 . The belt  12  slides on the internal frame  13  when a person runs on the belt  12 . 
   Casters  14  are attached to the external frame  11  so that the treadmill is movable. 
   The handle unit  20  includes two lower bars  21  and two upper bars  22  connected to the lower bars  21 . Although not shown, a handlebar is provided between the upper bars  22 , and an instrument is often provided on the handle bar. 
   Referring to  FIGS. 2 and 5 , the buffering apparatus  30  includes a crossbar  31 , two buffer sets  32  provided near two ends of the crossbar  31 , a helical spring  39 , two sleeves  35  and  36 , two bushings  33  and  34 , a ring  37  and a knob  38 . The crossbar  31  includes two reduced ends  311  and  312  which are square in a cross-sectional view. 
   Each of the buffer sets  32  includes four buffering blocks  321 ,  322 ,  323  and  324  secured to the crossbar  31 . The buffering blocks  321 ,  322 ,  323  and  324  are made of different elastic coefficients. In a first position of the crossbar  31  on the external frame  11 , the buffering blocks  321  are in contact with the internal frame  13 . In a second position, the buffering blocks  322  are in contact with the internal frame  13 . In a third position, the buffering blocks  323  are in contact with the internal frame  13 . In a fourth position, the buffering blocks  324  are in contact with the internal frame  13 . 
   The sleeve  36  includes an aperture  362 . The reduced end  312  of the crossbar  31  is inserted in the aperture  362  so that the former cannot rotate but slide within the latter. 
   The bushing  34  is fit in one of the apertures  16 . The sleeve  36  is rotationally inserted in the bushing  34 . 
   The helical spring  39  is provided around the reduced end  311  of the crossbar  31 . 
   The sleeve  35  includes an aperture  352 . The reduced end  311  of the crossbar  31  is inserted in the aperture  352  so that the former cannot rotate but slide in the latter. The helical spring  39  is compressed between the crossbar  31  and the sleeve  35 . 
   The bushing  33  is fit in the other aperture  16 . The sleeve  35  is rotationally inserted in the bushing  33 . 
   The ring  37  is secured to the external frame  11 . That is, the ring  37  cannot be rotated on the external frame  11 . The ring  37  includes an aperture  372  that is non-circular and preferably square. The reduced end  311  of the crossbar  31  can be rotated in the aperture  372  of the ring  37 . 
   The knob  38  includes a block  382  secured to the square reduced end  311  of the crossbar  31  with a threaded bolt  381 . The block  382  is non-circular and preferably square. The block  382  cannot be rotated in the aperture  372 . 
   Referring to  FIGS. 3 and 4 , due to the helical spring  39  compressed between the external frame  11  and the sleeve  35 , the block  382  is retained in the aperture  372  so that the knob  38  cannot be rotated relative to the ring  37 . Accordingly, the crossbar  31  is retained in the first position for example. Hence, the buffering blocks  321  contact the belts  12 . 
   Referring to  FIG. 6 , the knob  38  is pulled so that the block  382  is moved out of the aperture  372  while the reduced end  311  is inserted in the aperture  372 . As mentioned, the reduced end  311  can be rotated in the aperture  372 . Accordingly, the crossbar  31  can be rotated to another position from the first position so that the internal frame  13  contacts other buffering blocks than the buffering blocks  321 . 
   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.