Abstract:
An adjustable eccentric wheel hub assembly includes a wheel hub having an eccentric through hole, a core member mounted in the wheel hub, an axle mounted in an eccentric through hole of the core member, and an adjustment wheel mounted on the axle tube and controlled to lock/unlock the core member, enabling the axle to be set in the center of the wheel hub for enabling the bicycle in which the adjustable eccentric wheel hub assembly is installed to be moved horizontally forwards, or in an eccentric position relative to the wheel hub for enabling the bicycle to be moved alternatively up and down when running.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an adjustable eccentric wheel hub assembly and, more particularly, to such an adjustable eccentric wheel hub assembly, which is used in a bicycle and adjusted to let the wheel of the bicycle be rotated eccentrically. 
     The wheels of a bicycle are constantly turned about a fixed center. U.S. Pat. No. 6,024,367, equivalent to Taiwan Patent #143641, issued to the present inventor, discloses a stepless bicycle eccentric arrangement, which enables the bicycle to oscillate alternatively up and down when running. This design is functional, however it is complicated. Because this design is comprised of a big number of parts, its manufacturing cost is high. 
     SUMMARY OF THE INVENTION 
     The invention has been accomplished under the circumstances in view. It is one object of the present invention to provide an adjustable eccentric wheel hub assembly, which enables the bicycle to alternatively oscillate up and down when running. It is another object of the present invention to provide an adjustable eccentric wheel hub assembly, which has a simple structure practical for mass production. The adjustable eccentric wheel hub assembly of the present invention comprises a wheel hub having an eccentric through hole, a core member mounted in the wheel hub, an axle mounted in an eccentric through hole of the core member, and an adjustment wheel mounted on the axle tube and controlled to lock/unlock the core member, enabling the axle to be set in the center of the wheel hub for enabling the bicycle in which the adjustable eccentric wheel hub assembly is installed to be moved horizontally forwards, or in an eccentric position relative to the wheel hub for enabling the bicycle to be moved alternatively up and down when running. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded view of an adjustable eccentric wheel hub assembly according to the present invention. 
     FIG. 2 is an elevational view of the adjustable eccentric wheel hub assembly according to the present invention. 
     FIGS. 3A,  3 B and  3 C illustrate the outer appearance of the adjustable eccentric wheel hub assembly according to the present invention when viewed from different sides. 
     FIG. 4 is a longitudinal sectional view of the adjustable eccentric wheel hub assembly according to the present invention. 
     FIG. 5 is a cross sectional view of the adjustable eccentric wheel hub assembly according to the present invention. 
     FIGS.  6 A˜ 6 D illustrate the adjustment of the eccentric distance according to the present invention. 
     FIGS. 7A and 7B illustrate the extent of the adjustment of the eccentric distance according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. from  1  through  4 , an adjustable eccentric vehicle hub assembly is generally comprised of a wheel hub  10 , a core member  20 , a stop ring  21 , a stop block  22 , a spring plate  23 , a right dust cover  30 , an axle tube  60 , a key  61 , an adjustment wheel  40 , a first axle bush  50 , an axle  70 , a core cap  90 , a left dust cover  31 , and a second axle bush  80 . 
     The wheel hub  10  holds the core member  20 , the stop ring  21 , the stop block  22 , the spring plate  23 , the core cap  90 , the axle tube  60  and the key  61  on the inside, comprising two outward mounting flanges  101  raised around the periphery thereof at two sides and adapted for fastening to a vehicle wheel, an eccentrically axially extended, stepped through hole  102 , the stepped through hole  102  defining a first step and a second step, six mounting holes  104  equiangularly spaced on the first step of the stepped through hole  102 , and two annular grooves  103  respectively disposed at front and rear sides thereof around the through hole  102 . The core member  20  is a cylindrical member matching the stepped through hole  102  of the wheel hub  10 , comprising a through hole  204  axially eccentrically extended through the two opposite end walls thereof, a locating groove  206  axially extended through the two opposite end walls and disposed in communication with the through hole  204 , an outward flange  203  raised around the periphery near one end thereof, which is stopped at the second step in the stepped through hole  102  of the wheel hub  10  after insertion of the core member  20  in the stepped through hole  102 , a first slot  201  and a second slot  202  respectively formed on one end wall, and a plurality of mounting holes  205  axially extended through the two opposite end walls. The first slot  201  cuts perpendicularly through the second slot  202 . The second slot  202  extends radially from the through hole  204 . The stop block  22  is slidably mounted in the second slot  202  of the core member  20 , having a projecting rod  221  perpendicularly extended from one end thereof. The spring plate  23  is a U-shaped metal spring mounted in the first slot  201  of the core member  20 . The stop ring  21  is supported on the outward flange  203  of the core member  20 , comprising four recessed portions  213  equiangularly spaced around the inner diameter thereof, four axial grooves  211  respectively disposed in the recessed portions  213 , and six axially extended mounting holes  212  respectively fastened to the mounting holes  104  of the wheel hub  10  by screws. The right dust cover  30  is press-fitted into one annular groove  103  of the wheel hub  10  to hold down the stop ring  21  on the core member  20 , comprising an eccentric hole  303  aimed at the through hole  204  of the core member  20 , a slot  302  extended from the eccentric hole  303  and aimed at the second slot  202  of the core member  20 , and a plurality of mounting holes  301  respectively fastened to the mounting holes  205  of the core member  20  by screws. The axle tube  60  is inserted through the eccentric hole  303  of the right dust cover  30  and the through hole  204  of the core member  20 , comprising two outer threads  63  at two distal ends thereof, and a longitudinal key slot  62 . The key  61  is mounted in the longitudinal key slot  62  to secure the axle sleeve  60  in place. The adjustment wheel  40  is mounted around the axle tube  60  and supported on the right dust cover  30 , comprising a guide block  41  on the inside. The periphery of the adjustment wheel  40  is toothed. The first axle bush  50  is threaded onto one outer thread  63  of the axle tube  60  and partially engaged into the inner diameter of the adjustment wheel  40 , comprising six equiangularly spaced mounting holes  501  adapted for fastening to the disk brake of the bicycle in which the adjustable eccentric wheel hub assembly is installed, and an axle bearing chamber  502  at one end adapted to hold a ball bearing. The axle  70  is inserted through the axle tube  60 . The core cap  90  is mounted around the axle tube  60  and covered on one end of the core member  20 , comprising a plurality of mounting holes  901  respectively fastened to the mounting holes  205  of the core member  20 . The left dust cover  31  is mounted around the axle sleeve  60  and press-fitted into one annular groove  103  of the wheel hub  10 , and then fixedly fastened to the mounting holes  205  of the core member  20 . The second axle bush  80  comprises an inner thread  801  threaded onto one outer thread  63  of the axle tube  60 . Further, two axle bearings  72  are respectively mounted in the axle bearing chamber  501  of the first axle bush  50  and the axle bearing chamber (not shown) of the second axle bush  80 , and then two washers  73  are respectively mounted on the axle  70  and attached to the axle bearings  72 , and then two nuts  71  are respectively threaded onto the threaded opposite ends of the axle  70  to secure the aforesaid parts of the adjustable eccentric wheel hub assembly together. 
     During operation, the adjustable eccentric wheel hub assembly can be alternatively set between the centered normal mode, and the three-step eccentric mode. When at the centered normal mode, as shown in FIG. 5, the wheel hub  10 , the axle tube  60 , the axle  70 , and the core member  20  have a common center, the stop block  22  is inserted into the second slot  202  of the core member  20  and forced by the spring plate  23  into engagement with one groove  211  of the stop ring  21  to hold down the core member  20 , keeping the axial center of the wheel hub  10  in coincidence with the axial center of the core member  20 , and therefore the adjustment wheel  40  and the core member  20  are rotated with the wheel of the bicycle synchronously. The pawl A is turned and disengaged from the adjustment wheel  40 , and the wheel of the bicycle is smoothly horizontally rotated forwards. When changing to the eccentric mode during, riding, the pawl A is released and forced into engagement with the adjustment wheel  40  (see FIG. 6A) to stop the adjustment wheel  40  from rotary motion with the wheel of the bicycle and the wheel hub  10 . At this time, the wheel hub  10  is continuously rotated with the wheel of the bicycle, the guide block  41  of the adjustment wheel  40  imparts a pressure to the projecting rod  221  of the stop block  22 , causing the stop block  22  to be moved away from the corresponding groove  211  of the stop ring  21  (see FIG.  6 B). After the stop block  22  had been disengaged from the grooves  211  of the stop ring  21 , the second axle bush  80  is driven by an external force (for example, the sprocket wheel of the bicycle) to rotate the axle tube  60  and the core member  20 , causing the core member  20  to be released from synchronous rotation with the wheel hub  10 . When the wheel hub  10  is continuously rotated, the spring plate  23  forces the stop block  22  outwards (see FIG.  6 C), and therefore the stop block  22  is moved along one recessed portion  213  to a next groove  211  (see FIG.  6 D), causing the core member  20  to be synchronously rotated with the wheel hub  10  again, and therefore the wheel of the bicycle is rotated in an eccentric manner. Thereafter, the pawl A is lifted a way from the adjustment wheel  40 , and the rider can thus enjoy up and down riding of the bicycle. If desired, the eccentric mode can be adjusted further to the second stage shown in FIG. 7A, or the third stage shown in FIG.  7 B. When adjusted to the third stage eccentric mode, the extent of eccentric condition reaches the maximum status, and the stroke of the up and down movement of the bicycle reaches the maximum range. 
     It is to be understood that the drawings are designed for purposes of illustration only, and are not intended for use as a definition of the limits and scope of the invention disclosed.