Abstract:
A shock absorber for a bicycle comprises a base, a clutch assembly, a control assembly and a shock-absorbing spring. The shock-absorbing spring provides damper elastic force for the respective components of the shock absorber. The shock-absorbing function can be turned off when riding up slope, so it prevents the drag force from being increased by the up and down motion of the shock absorber. The shock-absorbing function can be turned off when riding on a horizontal road, and it can be turned off again when riding down a slope, thus preventing the increase of the front tilt angle of the bike and leading to turnover.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a shock absorber, and more particularly to a shock absorber that is used on the bike.  
         [0003]     2. Description of the Prior Art  
         [0004]     The conventional shock absorber used on the bike usually comprises inner spring, cylinder base and other components that cooperate with each to produce a shock-absorbing effect (whether the operation space for the inner spring is filled with hydraulic oil is not the essential condition of the present invention, further discussions on this matter will be omitted). A conventional shock absorber, used on the bike, includes base, axial shaft and shock-absorbing spring. The base is mounted to the fork of the bike, and the axial shaft is mounted on the frame of the bike. The shock-absorbing spring is biased between the base and the axial shaft. This kind of shock absorber has been used on different kinds of mechanisms and bikes, there are still some defects need to be improved as follows:  
         [0005]     First, the buffering function of the conventional shock absorber cannot be turned off. When riding up a slope, the up-and-down motion of the shock absorber will increase the drag force because the motion of the shock absorber counteracts the pedaling force applied by the user.  
         [0006]     Second, due to the buffering function of the conventional shock absorber cannot be turned off. When riding down a slope, the up-and-down motion of the shock absorber will change the front tilt angle of the bike, especially when the front shocker is moving downward, the front tilt angle of the bike will be increased substantially. Thereby, there is a danger of falling over.  
         [0007]     The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.  
       SUMMARY OF THE INVENTION  
       [0008]     The primary object of the present invention is to provide a shock absorber, wherein the shock-absorbing function the shock absorber can be turned on/off. The shock absorber comprises a base, a clutch assembly, a control assembly and a shock-absorbing spring. The shock-absorbing spring provides damper elastic force for the respective components of the shock absorber. The shock-absorbing function can be turned off when riding up a slope, so as to prevent the drag force being increased by the up and down motion of the shock absorber. The shock-absorbing function can be turned on when riding on a horizontal road, and it can be turned off again when riding down a slope, so as to prevent the increase of the front tilt angle of the bike and leading to turnover.  
         [0009]     The present invention will become more obvious from the following description when taken in connection with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiments in accordance with the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is an exploded view of a shock absorber in accordance with a preferred embodiment of the present invention;  
         [0011]      FIG. 2  is a cross sectional view of the shock absorber in accordance with the present invention;  
         [0012]      FIG. 3  is a cross sectional view in accordance with the present invention for showing the shock absorber in a state of being unlocked;  
         [0013]      FIG. 4  is a cross sectional view in accordance with the present invention for showing the shock absorber in a state of being locked. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0014]     Referring to  FIGS. 1-4 , a shock absorber for a bicycle in accordance with a preferred embodiment of the present invention is shown and generally comprises: a base  10 , a clutch assembly  20 , a control assembly  30  and a shock-absorbing spring  40 .  
         [0015]     The base  10  is formed at a lower end thereof with a gap  11  that is to be coupled to the front wheel axle of a bike. At the bottom of the inner space of the base  10  is fixed a baseboard  12  that is centrally formed with a threaded hole  121 . A mid sleeve  13  is disposed adjacent to the top end of the inner space of the base  10 , and in the mid sleeve  13  is received a receiving tube  14 . An upper end of the receiving tube  14  is fixed to the front fork of the bike, and at a lower end of the receiving tube  14  is provided a slide bush  15 . The mid sleeve  13  cooperates with the slide bush  15  to allow the receiving tube  14  to freely slide in the base  10 . The receiving tube  14  is provided at an end thereof with a bottom  141  that is located towards the baseboard  12 .  
         [0016]     The clutch assembly  20  includes a positioning member  21 , an axial tube  22 , a clutch member  23  and a control element  24 .  
         [0017]     At a first end of the positioning member  21  is provided with a plurality of threads  211  to be screwed in the threaded hole  121  of the baseboard  12  of the base  10 , and a second end of the positioning member  21  is formed with a plurality of locking grooves  212 . By using of several positioning retainers  213 , washers  214  and a buffer cushion  215 , the positioning member  21  is able to position the receiving tube  14 . In addition, the positioning member  21  is provided at the outer periphery thereof with plural positioning grooves  216 .  
         [0018]     The axial tube  22  is interiorly formed with a through hole  221  for slidably receiving the positioning member  21 . Plural positioning holes  222  are formed in the outer surface of the axial tube  22 . At a first end of the axial tube  22  are formed plural retaining grooves  223  to be fixed to the bottom  141  of the receiving tube  14  of base  10  by plural retaining rings  224  and washers  225 . A second end of the axial tube  22  facing the buffer cushion  215  is formed with a step periphery  226  and a retaining groove  227  respectively. A limit piece  229  is fixed in the retaining groove  227  by a retaining ring  228 . In the outer periphery of the limit piece  229  are provided a plurality of gaps  2240 .  
         [0019]     The clutch member  23  is slidably received in the positioning hole  222  of the axial tube  22 .  
         [0020]     The control element  24  is slidably mounted on the exterior periphery of the axial tube  22 , and in the control element  24  is formed an annular cone-shaped step portion  241  that divides the inner space of the control member  24  into a big diameter portion  242  and a small diameter portion  243 . The annular cone-shaped step portion  241  is located correspondingly to the positioning holes  222  of the axial tube  22 . At an end of the outer periphery of the control element  24  is formed a step periphery  244  that is located toward the bottom  141  of the receiving tube  14 .  
         [0021]     The control assembly  30  comprises a body  31 , a control shaft  32 , a rotary knob  33 , a back-moving spring  34 , an abutting member  35  and a control spring  36 .  
         [0022]     The body  31  is screwed to an upper end of the receiving tube  14  of the base  10  by means of a seal ring  311 . A first end of the body  31  is formed with an inner hole  312 , while a second end the body  31  is formed with a slot  313 , and a through hole  314  is located between the inner hole  312  and the slot  313 . Furthermore, plural holes  315  are formed adjacent to the through hole  314  for insertion of the spring.  
         [0023]     A first end of the control shaft  32  is inserted in the through hole  314  of the body  31  and is positioned therein by a seal ring  321 , approximately at the center of the control shaft  32  is formed a retaining groove  322  in which is disposed a retaining member  322 , so that the control shaft  32  is positioned in the base by the retaining member  322 . A second end of the control shaft  32  is formed with a plurality of driving threads  324 .  
         [0024]     The rotary knob  33  will rotate if the user pulls the steel cord A (the steel cord is controlled by user). The rotary knob  33  is fixed to the control shaft  32  by positioning screws  331 . A hole  333  is formed in a bottom of the outer periphery  332  at a first end of the rotary knob  33  for insertion of spring. The steel cord A is fixed to a second end of the rotary knob  33  by screws  334  and positioning cushions  335 . The rotary knob  33  is rotatable relative to the body  31 .  
         [0025]     The back-moving spring  34  is mounted on the outer periphery  332  of the rotary knob  33  and serves to produce a rotating elastic force in a predetermined direction. A first end of the back-moving spring  34  is inserted in the holes  315  of the body  31  (can be inserted in any of the holes  315  so as to produce different elastic forces). A second end of the back-moving spring  34  is inserted in the hole  333  of the rotary knob  33 .  
         [0026]     The abutting member  35 , at a first end of which is disposed an axial bush  351 , and inside the axial bush  351  are formed a plurality of driving threads  3511  for meshing with the driving threads  323  at the end of the control shaft. In this case, the first end of the abutting member  35  can be interactively connected to the control shaft  32  via the axial bush  35  (the abutting member  35  can transmit motion to the control shaft  32 , and vice versa). The second end of the abutting member  35  is inserted in the gaps  2240  of the limit piece  229  at an end of the axial tube  22  and abuts against the end surface of the control element  24  of the clutch assembly  20 .  
         [0027]     The control spring  36  is installed on the outer periphery of the axial tube  22  of the clutch assembly  20  and biased between the step periphery  244  of the control member  24  and the bottom  141  of the receiving tube  14  of the base  10 .  
         [0028]     The shock-absorbing spring  40  is biased between the baseboard  12  of the base  10  and the step periphery  151  of the slide bush  15  at the lower end of the receiving tube  14 .  
         [0029]     For a better understanding of the present invention, its operation and function, reference should be made then to  FIGS. 3 and 4 .  
         [0030]     As shown in  FIG. 3 , when wanting to turn on the shock absorbing function of the shock absorber, the user can pull a length of the steel cord A and fix it (the method of pulling and fixing the steel cord A belongs to conventional technology, so further remarks on this matter will be omitted), causing the rotary knob  33  and the control shaft  32  to rotate and making the back-moving spring  34  be compressed. Meanwhile, the driving threads  323  at the end of the control shaft  32  will move the abutting member  35  (since the driving threads  3511  of the axial bush  351  at the first end of the abutting member  14  is interactively connected to the driving threads  323  at the end of the control shaft, and the abutting member  35  is unrotatable due to its outer periphery is confined by the slot  313  at the end of the body  31 , furthermore, the second end of the abutting member  35  abuts against the end surface of the control element  24  after passing through the gap  2240  of the limit piece  229 ). At this moment, the abutting member  35  will move the control element  24  and synchronously compress the control spring  36 , enabling the clutch member  23  to slide from the small diameter portion  243  of the annular cone-shaped step portion  241  of the control element  24  into the big diameter portion  242 . Thus, the clutch member  23  will slide out of the positioning grooves  216  of the positioning member  21 . And as a result, the positioning member  21  and the axial tube  22  can move relative to each other. At this moment, the base  10 , the receiving tube  14  and the shock-absorbing spring  40  are able to produce a buffering effect.  
         [0031]     As shown in  FIG. 4 , when riding up or down a slop, and the shock absorbing function of the shock absorber should be turned off for safe purpose (to prevent the tilt angle being increased by the motion of the shock absorber and causing the bike fall over), the user can release a length of the steel cord A. The rotary knob  33  and the steel cord A will be pushed by the back-moving spring  34  to their original position. The control shaft  32  will be driven to rotate in opposite direction. The threads on the control shaft will drive the abutting member  35  to move, so as to form a space between the end of the abutting member  35  and the end surface of the control element  24 . Meanwhile, the control spring  36  will push the control element  24  to move. The small diameter portion  243  of the annular cone-shaped step portion  241  inside the control element  24  will push the clutch member  23  to move from the positioning hole  222  of the axial tube  22  and make it engage in one of the plural positioning grooves  216  of the positioning member  21 . At this moment, the positioning member  21  will be locked with the axial tube  22 , and the base  10  and the receiving tube  14  will not be moveable relative to each other. Thus, the shock absorbing function is turned off.  
         [0032]     The shock absorber still will move up and down if the positioning groove  216  of the positioning member  21  is not meshed with the clutch member  23 . During an instant period of motion of the shock absorber, when the clutch member  23  is in alignment with one of the positioning grooves  216 , the control spring  36  will instantly move the control element  24 , and the small diameter portion  243  of the annular cone-shaped step portion  241  of the control element A 10  pushes the clutch member  23  to move into the positioning groove  216  of the positioning member  21 . Since the positioning member  21  is provided with plural positioning grooves  216 , in real operation, the clutch member  23  can be pushed by the control spring  36  and engages into one of the positioning grooves  216  of the positioning member  21 . That is to say that the shock absorbing function of the shock absorber can be turned on/off according to needs.  
         [0033]     While we have shown and described various embodiments in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.