Abstract:
An anti-lock brake system for a bicycle having sliding assembly (having a brake shoe therein) and a plurality of springs defined in a brake shoe holder in turn, a bottom of the brake shoe holder and a connecting side of the sliding assembly are correspondingly in gradient formed and both of them to be abutted against each other and they are slanted formed outwardly in accordance with the direction of the rotation of the tire of the bicycle. The sliding assembly further includes a plurality of recesses formed therein for receiving sliding members, an abrasion-resistant member disposed at the bottom of the recess of the brake shoe holder.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a brake device, and more particularly to an anti-lock brake system for a bicycle. 
     2. Description of the Prior Arts 
     A conventional brake device for a bicycle generally includes a pair of brake shoes and a brake arm, the brake shoes are coupled to both legs of the brake arm and then the brake arm is mounted to the rear and/or front fork of a bicycle with the brake shoes standing oppositely at both sides of the wheel rim of the bicycle. The brake shoes are employed to press against the wheel rim from both sides by virtue of the brake arm and a friction to be generated to stop the rotation of the tires. This kind of brake device has been commonly used in nowadays, however, there are still some shortcomings need to be improved: 
     In event of an emergency brake, the braking force is greater than the friction force of the tires due to a great force applied by the rider to press on the hand brake in order to stop the rotation of the tires, which will generate a dead lock of the tire in a sudden and result in a skidding and overturning of the bicycle and hurt of the rider. 
     A buffering device targeting at the solution of the above problem is shown in FIG. 1 including: a brake shoe holder  10 , the brake shoe holder  10  to be mounted to a brake arm by virtue of a connecting rod  11  coupled at a side opposite to the wheel rim of the tire and has a pair of protruding edges opposite to each other defining a space for accommodating a sliding piece  17  therein, furthermore, the brake shoe holder  10  defining a threaded hole  12  at a first end for engaging a bolt  13  and a recess  14  at a second end for accommodating an elastic member  15 , a brake shoe  16  to be engaged in the sliding piece  17  and the sliding piece  17  has a first end connected to the elastic member  15  and a slot  18  defined at a second end engaging with the bolt  13  for preventing the sliding piece  17  from sliding out from the brake shoe holder  10 , in such a manner, taking use of the slide of the sliding piece  17  in the space of the brake shoe holder  10  and the elastic member  15  to buffer a friction of the brake shoe  16  while it pressing against the wheel rim the tire. Although this braking device has been commonly used, there are also some shortcomings need to be improved: 
     First, this braking device is too complicated that the brake shoe holder  10  not only needs a pair of protruding opposite edges to define a space for the receiving and slide of the brake shoe  16  therein but also the brake shoe  16  should be engaged in the a sliding piece  17  having a slot  18  for engaging a bolt  13 , in this case, it&#39;s not only complicated in assembling process but the production cost is increased as well. 
     Second, there is only a very short distance (about a 1 mm in distance) for the slide of the brake shoe  16  in the brake shoe holder  10  according to this device, which is not long enough for buffering the friction generated from the braking motion and accordingly a rider is not able to control the bicycle effectively. 
     Third, in accordance with the brake device for a bicycle, the brake shoe only has a very short contracting distance while a braking motion being operated and it will be contracted to an end thereof and will not return to the original position till the rider release the handle brake, thereby, there will be a great friction caused from a part of the tire and the ground and do a great harm to the tire. 
     Fourth, in accordance with this conventional brake device for a bicycle, the brake shoe holder  10 , the recess  14 , the brake shoe  16  and the sliding piece  17  all move in a straight line, however, the tires of the bicycle do rotational movement, in such a manner, a stress of the tire is generated from the friction of the brake shoe  16  while a braking motion being operated which can&#39;t be transmitted completely to the elastic member  15  and a part of it can&#39;t be counteracted (which is perpendicular to a direction of the movement of the brake shoe  16 ), as a result, the brake shoes  16  is not allowed to move smoothly and freely in the space of the brake shoe holder  10  and great frictions and collisions will be caused in the related parts. 
     The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional anti-lock brake system for a bicycle. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention, there is provided an anti-lock brake system for a bicycle having sliding assembly (having a brake shoe therein) and a plurality of springs defined in a brake shoe holder in turn, an acting direction and location of the springs are corresponding to that stress direction of the brake shoe, the brake shoe is partially engaged in the brake shoe holder, a bottom of the brake shoe holder and a connecting side of the sliding assembly is correspondingly in gradient formed and both of them to be abutted against each other and slantingly formed outwardly in accordance with the direction of the rotation of the tires of the bicycle. (For an alternative that a plurality of sliding members also can be defined between the bottom of the brake shoe holder and the sliding assembly and in addition, an abrasion-resistant member can be defined at the bottom of the recess of the brake shoe holder). In such a manner, which not only can buffer a braking friction generated from an emergency brake but also prevent a great friction from being caused in the related parts of the braking device. 
     The primary objective of the present invention is to provide an improved anti-lock brake system for a bicycle, which is not only capable of buffering a braking friction from being generated from an emergency brake but also preventing a great friction caused in the related parts of the braking device. 
     Another objective of the present invention is to provide a simple anti-lock brake system for a bicycle, which is not only reduce the production cost to the least but also simplify the assembling process. 
     A further objective of the prevent invention is to provide an improved anti-lock brake system for a bicycle allowing a free and smooth slide of the sliding assembly in the brake shoe holder and the quick return of the brake shoe to the original position so as to provide a smooth braking operation. 
     The present invention will become more obvious from the following description when taken in connection with the accompanying drawings, which shows, for purpose of illustrations only, the preferred embodiments in accordance with the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross sectional view of a conventional brake device for a bicycle; 
     FIG. 2 is an exploded view of an anti-lock brake system for a bicycle in accordance with a first embodiment of the present invention; 
     FIG. 3 is an elevational view of an anti-lock brake system for a bicycle in accordance with the first embodiment of the present invention; 
     FIG. 4 is a schematic illustration view in accordance with the first embodiment of the present invention showing an anti-lock brake system mounted to a brake arm of a bicycle; 
     FIG. 5 is a cross sectional view in accordance with the first embodiment of the present invention of showing the status of an anti-lock brake system for a bicycle before a braking action being operated; 
     FIG. 6 is a cross sectional view in accordance with the first embodiment of the present invention of showing the very beginning status of an anti-lock brake system for a bicycle while a braking action being operated; 
     FIG. 7 a cross sectional view in accordance with the first embodiment of the present invention of showing a continuous braking action of an anti-lock brake system for a bicycle is being operated; 
     FIG. 8 is a cross sectional view in accordance with the first embodiment of the present invention of showing a second circle of braking operation of an anti-lock brake system for a bicycle; 
     FIG. 9 is an exploded view of an anti-lock brake system for a bicycle in accordance with a second embodiment of the present invention; 
     FIG. 10 is a longitudinal sectional view of anti-lock brake system for a bicycle in accordance with the second embodiment of the present invention; 
     FIG. 11 is a cross sectional view in accordance with the second embodiment of the present invention of showing the status of an anti-lock brake system for a bicycle before a braking action being operated. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the FIGS. 2-4, in which, an anti-lock brake system in accordance with one aspect of the present invention comprises a brake shoe holder  20 , a sliding assembly  30 , a brake shoe  40  and two springs  50 . The brake shoe holder  20  has a shape of curved recess  21  and an opening  24  defined at a side facing to a wheel rim  60  and has bolt  22  located at a bottom thereof which is respectively to be coupled to both ends of a brake arm  61  by virtue of the bolt  22  and screw nuts  23 . 
     Both sides of the opening  24  are curvely formed with edges  25 , a slope  26  is formed at the bottom of the recess  21  in a manner that the slope  26  slants outward in a forward rotating direction of the tire, two protrusions  27  are formed at a side corresponding to the slope  26 . The brake shoe holder  20  is curvely formed in an arc A corresponding to a rotary angel of the wheel rim  60 . 
     The sliding assembly  30  is received in the recess  21  of the brake shoe holder  20  and confined in the opening  24  by the curved edge  25 . The brake shoe  40  is partially accommodated in sliding assembly  30  and partially protruding the opening  24  of the brake shoe holder  20  therefrom (corresponding to the both sides of the wheel rim  60  of the bicycle). A pair of protrusions  31  are formed at a side of the sliding assembly  30  corresponding to that protrusions  27  of the brake shoe holder  20 . The sliding assembly  30  also has a slope  32  formed at the bottom of the sliding assembly in a manner that the slope  32  slants outward in the forward rotating direction of the tire corresponding to the slope  26  of the brake shoe holder  20 . The spring  50  is accommodated in the recess  21  of the brake shoe holder  20  having a first end engaged with the protrusions  27  and a second end engaged with the protrusions  31  of the sliding assembly  30 . 
     Referring further to the FIGS. 5-8, which shows the first embodiment of the present invention. In the FIG. 5 shows the status of the anti-lock brake system of the present invention before a braking action being operated, in which, the brake shoe holders  20  at both ends of the brake arm  61  are apart from the wheel rim  60  of the bicycle by virtue of the brake arm  61 , the sliding members  30  are pushed to one end of the recesses  21  of the brake shoe holders  20  by the springs  50  and further by the cooperation of the slope  32  of the sliding assembly  30  and the slope  26  of the brake shoe holder  20  abutting against each other, thereby the wheel rim  60  of the bicycle is not in the braking status (is not being pressed by the brake shoes  40 ). 
     Referring the FIG. 6, which shows the very beginning status of a braking action just be operated, when a rider press the hand brake, the brake arm  61  will enforce the two brake shoe holders  20  to press against the wheel rim  60  of the bicycle and the part of the brake shoe  40  protruding from the opening  24  of the brake shoe holder  20  begin to rub the wheel rim  60  of the bicycle, right this moment, a great inertial stress will be transmitted to the brake shoes  40  from the wheel rim  60  of the bicycle, accordingly it will be further transmitted to the slopes  32  and the springs  50  by the brake shoes  40  and the sliding assembly  30 , due to the inertial force of the bicycle is minor than the elastic force of the springs  50 , the sliding assembly  30  stay motionlessly in the brake shoe holders  20 , and thereby the bicycle in a low speed can be stopped. 
     Referring to the FIG. 7, which shows a continuous braking action (an emergency brake) of an anti-lock brake system for a bicycle is being operated, in this status, both a force the rider pressed on the hand brake and the inertial force of the bicycle are very great, and the inertial force of the bicycle is greater than the elastic force of the springs  50 , so the sliding assembly  30  begin to push and compress the springs  50 , accordingly the sliding assembly  30  slide relatively in the recess  21  of the brake shoe holder  20  and slide slantingly outward by a cooperation of the slope  32  of the sliding assembly  30  and the slope  26  of the brake shoe holder  20  abutting against each other and the brake shoes  40  slide slantingly outward too, in such a manner, a stress generated form the braking action can be absorbed by the slope  26  and the springs  50  without difficulties by virtue of the arc A of the brake shoe holders  20 , the sliding members  30  and the brake shoes  40 , thereby the friction force of the brake shoes will be reduced and the braking force will not be greater than the friction of the tire of the bicycle (no dead lock of tire&#39;s rotation happened), furthermore, the wheel rim  60  can be a bit rotate forward and no overly great friction force between the tires and the ground caused and the rider will not lose steering. 
     Referring the FIG. 8, which shows a secondary circle of the braking action, due to the slant slide of the brake shoes  40 , the friction force is reduced, the springs  50  begin to release the restoring force pushing the sliding assembly  30  to return slantingly inward by the cooperation of the slope  26 , 32 , which increase the friction force of the brake shoes  40  acting on the wheel rim  60 , such an action of the sliding members  30  will be repeatedly so as to achieve an effect of an anti-lock brake system and an emergency brake of he bicycle can be smoothly eased off by the release and compress of the brake alternatively happened in a twinkling, in this manner the rider will not lose steering control of the bicycle and no overly friction caused in the related parts. 
     Furthermore, the braking distance of the tire is based on the elastic force of the springs, the inclination of the slope and the inertia force, so which can be adjusted by the manufacturers as deferent requirements of the riders. 
     It is to be noted that the brake shoe holders  20  are permitted to be whole-set replaced, which is easy for assembling and dismantling and the structure is simple (reduce the production cost). 
     Referring again to the FIG. 2, a plurality of draining holes  70  can be defined in a side of the brake shoe holder  20  which allowing for the drainage of the mud or greasy dirt therefrom and allow the rider inject grease or clean the inside therethrough. 
     An anti-lock brake system for a bicycle in accordance with the first embodiment of the present invention is described as above. 
     In accordance with a second embodiment of the present invention there is provided another anti-lock brake system for a bicycle as shown in FIGS. 9-11 which structural arrangement is basically identical with that of the first embodiment, the only difference is: a plurality of sliding members  80  and an abrasion-resistant member  90  are added, furthermore, the sliding assembly  30  is provided with a plurality of cavities  33 . 
     The sliding members  80  may be metal balls, rollers, needle rollers or the like, slidably received in the respective cavities  33  of the sliding assembly  30 , which will be rolling in the event that the sliding assembly  30  is sliding so as to provide a smooth slide of the sliding assembly  30  in the recess  21  of the brake shoe holder  20 . 
     The abrasion-resistant member  90 , corresponding to the slope  26  at the bottom of the recess  21  of the brake shoe holder  20 , is made from abrasion-resistant material, which correspondingly providing a rolling friction to the sliding members  80 . 
     Due to the working principles of the two anti-brake lock systems in according with the first and second embodiment of the present invention are identical, further remarks on this matter will seem superfluous. 
     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 embodiment may be made without departing from the scope of the present invention.