Abstract:
An attachment structure for a caliper of a disc brake assembly consisting of a caliper and a rotor. The caliper is attached to a wheel supporting portion of a cycle frame which supports a wheel with the rotor fixedly attached to the wheel and the rotor lying in a fixed plane relative to the supporting portion of the frame. The supporting portion of the frame has a pair of attachment bores oriented to attach the caliper with the rotor received between a pair of brake pads advanced into and out of contact with the rotor by the caliper along a select axis. The attachment structure allows for infinite variation of the angle of incidence between the select axis and the plane of the rotor within a defined range. Attachment bolts secure the caliper to the frame with a select angle of incidence between the select axis and the plane of the rotor.

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 09/383,121, filed Aug. 25, 1999, now U.S. Pat. No. 6,230,849 entitled, “Structure for Adjustably Attaching a Bicycle Disc Brake Caliper to a Bicycle Frame,” which claims priority from U.S. Provisional Patent Application Ser. No. 60/142,559, filed Jul. 7, 1999, entitled “Structure for Adjustably Attaching a Disc Brake Caliper to a Bicycle Frame.” 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention is directed toward bicycle brakes, and more particularly toward a structure for adjustably attaching a disc brake caliper to a bicycle frame. 
     2. Background Art 
     Disc brakes for bicycles are growing in popularity as consumers demand and bicycle manufacturers strive to provide ever advancing technology on bicycles. Disc brake systems generally consist of a rotor which is fixedly attached to the hub of a bicycle wheel and a caliper which is fixedly attached to a wheel supporting portion of the bicycle frame and which receives the rotor between a pair of bike pads which are advanced into and out of contact with the rotor along a select axis. The wheel supporting portion of the frame has some structure for attaching the caliper to the chain or seat stay in the rear or fork in the front of the frame. This structure typically consists of a boss or a pair of bosses which extend from the frame substantially parallel to the plane of the rotor and which have internally threaded bores in their distal ends which are intended to lie in a plane normal to the plane of the rotor. The caliper, in turn, has a mounting foot which extends from the caliper body and includes a pair of holes corresponding to the bores in the ends of the attachment bosses. The caliper is then bolted to the frame by bolts axially received the holes in the mounting foot. When properly aligned, the rotor will be received between the brake pads of the caliper so that the brake pads of the caliper are advanced into and out of contact with the rotor along an axis that is normal to the plane of the rotor. 
     Assuming that the attachment bosses extend parallel to the plane of the rotor and that the ends of the attachment bosses lie in a plane perpendicular to the plane of the rotor, prior art calipers would be properly aligned with the brake pads being advanced along an axis normal to the rotor. In practice, however, the normal range of manufacturing tolerances in the bicycle and caliper makes it unlikely that the caliper will be properly aligned with respect to the rotor. When the caliper is not properly aligned, the brake pads will not strike the rotor flush which can degrade brake performance. It can even lead to the brake pads rubbing against the rotor and deteriorating bicycle performance. 
     One structure known in the prior art for addressing this improper alignment is providing elongate slots on the mounting foot of the caliper corresponding to the bores in the mounting bosses which extend substantially parallel to the select axis of advancement of the pads. These slots allow translational movement of the caliper toward and away from the rotor to precisely position the rotor intermediate the pads of the caliper. In addition, these slots enable the caliper to be canted about an axis parallel to an axis of the mounting boss bores to compensate for some misalignment between the rotor and the caliper. However, because these slots only allow for translational movement and some range of canting, they do not enable proper alignment with the rotor if the tolerances cause misalignment outside of these limited directions of travel. 
     The present invention is directed toward overcoming one or more of the problems discussed above. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is an attachment structure for a caliper of a disc brake assembly consisting of a caliper and a rotor. The caliper is attached to a wheel supporting portion of a cycle frame which supports a wheel with the rotor fixedly attached to the wheel and the rotor lying in a fixed plane relative to the supporting portion of the frame. The supporting portion of the frame has a pair of attachment bores oriented to attach the caliper with the rotor received between a pair of brake pads advanced into and out of contact with the rotor by the caliper along a select axis. The attachment structure allows for infinite variation of the angle of incidence between the select axis and the plane of the rotor within a defined range. Attachment bolts secure the caliper to the frame with a select angle of incidence between the select axis and the plane of the rotor. 
     Another aspect of the present invention is a disc brake assembly attachable to a wheel supporting portion of a frame of a cycle. The disc brake assembly includes a rotor fixedly attached to a wheel mounted to the wheel supporting portion of the frame, with the rotor residing in a plane of fixed orientation relative to the wheel supporting portion of the frame. A caliper receives the rotor between a pair of brake pads with the caliper advancing the brake pads into and out of contact with the rotor along a select axis. An attachment structure attaches the caliper to the wheel supporting portion of the frame with the angle of incidence between the select axis and the plane of rotor being infinitely variable within a defined range. In this manner, the caliper can be aligned with the select axis normal to the rotor. At least one bolt is operatively associated with the attaching structure to secure the caliper to the frame with the select axis aligned normal to the rotor. The attaching structure preferably includes slots on the caliper substantially parallel to the select axis for enabling translational movement of the caliper toward and away from the rotor. 
     The attaching structure may include a pair of spaced bores on the wheel supporting portion of the frame defining a line substantially parallel to the plane of the rotor, the bores having openings which lie in a plane substantially normal to the plane of the rotor. A convex surface is associated with the mouth of each bore. A mating concave surface is associated with a bottom of a mounting foot of the caliper. Aligned holes extend through each of the concave and convex surfaces and correspond to the bores in the wheel supporting portion of the frame. A pair of slots in the mounting foot of the caliper also corresponds to the bores. These slots are substantially parallel to the select axis. A bolt having a head and a shaft is axially received in each slot, aligned hole and corresponding bore with the head protruding therefrom. The bolt is threadably engaged with the bores to maintain the caliper with the select axis aligned normal to the rotor. The attaching structure preferably further includes a pair of washers having mating concave and convex surfaces and opposite flat surfaces receiving the bolt with one of the flat surfaces abutting a top of the mounting foot of the caliper and the other of the flat surfaces abutting the head of the bolt. 
     In one embodiment, the mating concave and convex surfaces associated with the mouth of each bore and the underside of the mounting foot of the caliper comprise a pair of washers having mating concave and convex surfaces and opposite flat surfaces, with the washer pairs residing with one of the flat surfaces abutting the bottom of the caliper mounting foot and the other of the flat surfaces abutting the wheel supporting portion of the frame. 
     In another embodiment, the mating concave and convex surfaces associated with the mouth of each bore and the bottom of the mounting foot consists of a pair of plates having the mating concave and convex surfaces and opposite flat surfaces, the pair of plates further including the aligned holes, the plates residing with one flat surface abutting the bottom of the mounting foot and the other flat surface abutting the wheel supporting portion of the frame. Preferably, the aligned holes are elongate and correspond to the slots in the caliper mounting foot. 
     Yet another aspect of the present invention is a structure for attaching a caliper of a disc brake system to a cycle frame with a pair of brake pads advanced by the caliper in operative engagement with a rotor of the disc brake system, the frame having a pair of threaded caliper mounting bores and the caliper having a mounting foot. The attachment structure consists of mating concave and convex surfaces between the frame and a bottom of the caliper mounting foot to pivot the caliper about a pivoting axis. A pair of holes corresponding to the caliper mounting bores extend through the concave and convex mounting surfaces. A pair of spaced slots on the caliper mounting foot extend transverse the pivoting axis and are aligned with the holes and the mounting bores. A pair of bolts are axially received in the aligned slots, holes and the threaded mounting bores with the bolts engaging the threaded mounting bores to maintain the pads of the caliper in a select orientation relative to the rotor. The mating concave and convex surfaces may be a pair of washers residing between the bottom of the caliper mounting foot and the frame corresponding to each of the caliper mounting bores. Alternatively, the mating concave and convex surfaces residing between the bottom of the caliper mounting foot and the frame may be formed on a pair of elongate plates. Alternatively, one of the concave and convex surfaces may be on the bottom of the caliper mounting foot and the other may be on an elongate plate residing between the bottom of the caliper mounting foot and the frame. In this embodiment, the pair of holes in the elongate plate are preferably elongate to correspond to the slots in the caliper mounting foot. Preferably, mating concave and convex surfaces are further provided between the head of the bolt and the top of the caliper mounting foot. The mating concave and convex surfaces are preferably on a pair of washers corresponding to each of the bolt heads residing between the bolt heads and the top of the caliper mounting foot. 
     The structure for adjustably attaching a disc brake caliper to a bicycle frame of the present invention allows for infinite variation of the angle of incidence between an axis of movement of caliper brake pads and the plane of a rotor within a defined range. Thus, the caliper can be adjusted so that the select axis in is the desired orientation of normal to the plane of the rotor notwithstanding manufacturing tolerances and manufacturing defects that would cause the axis of pad travel of prior art calipers not to be normal to the plane of the rotor. In addition, the attachment structure allows translation of the caliper toward and away from the rotor to compensate for variations in the spacing between the attachment studs and the disc brake rotor amongst the bicycles of various manufacturers. The structure for adjustably attaching the disc brake is virtually self-adjusting within its defined range. The caliper can be readily self-aligned simply by loosening the attachment bolts, actuating the brake pads into abutment with the rotor and then tightening the attachment bolts. Thus, the many advantages of having the select axis of movement of the brake pads normal to the rotor can be achieved with minimal effort on the part of the user. Moreover, the structure providing these many advantages is inexpensive to manufacture and can be made from off the shelf parts making it an inexpensive solution to an otherwise vexing problem. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a caliper mounted to the front fork of a bicycle in operative association with a rotor using a structure for adjustably attaching a disc brake to a bicycle frame of the present invention; 
     FIG. 2 is an exploded view of the structure for adjustably attaching a disc brake caliper to a front fork of a bicycle frame of FIG. 1; 
     FIG. 3 is a perspective view of a caliper mounted to a chain stay of a bicycle frame in operative engagement with a rotor using a second embodiment of a structure for adjustably attaching a disc brake to a bicycle frame of the present invention; 
     FIG. 4 is an exploded view the structure for adjustably attaching a disc brake caliper to bicycle frame of FIG. 3; 
     FIG. 5 is a rear view of the caliper of FIG. 1 showing the translational movement of the caliper relative to the rotor afforded by the present invention; 
     FIG. 6 is a rear view of the caliper of FIG. 1 showing the canting movement afforded by the caliper relative to a rotor of the present invention; 
     FIG. 7 is a bottom view of the caliper of FIG. 1 showing the hinged movement of the caliper relative to the rotor afforded by the present invention; and 
     FIG. 8 is a perspective view of a third embodiment of an attachment structure of the present invention providing the translational movement of FIG. 5, the canting movement of FIG. 6, the hinged movement of FIG. 7 as well as axial movement along a rod. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A disc brake system  10  consisting of a caliper  12  and a rotor  14  is illustrated in FIG. 1 with the caliper attached to a front fork  16  of a bicycle frame. Although omitted for the sake of clarity, the rotor  14  is fixedly attached to a hub of a wheel for rotation with the wheel with the wheel hub being attached to the bracket  18  of the front fork. Thus, the front fork  16  acts as a wheel support portion of the bicycle frame. The rotor  14  is maintained in a fixed plane relative to the wheel and the front fork. 
     The rotor  14  is received between a pair of brake pads  20 ,  22  attached to the caliper  12  which are best viewed in FIG.  7 . The brake pads are advanced into and out of contact with the rotor along a select axis  24  which is intended to be normal to the plane  26  of the rotor  14 . 
     A pair of attachment bosses  30  extend from the fork  16  preferably parallel to the plane of the rotor  14 . Referring to FIG. 2, the distal ends  32  of the attachment bosses have an internally threaded bore  34  which is also preferably parallel to the plane of the rotor  14 . The distal ends of the attachment bosses  30  preferably each lie in a common plane which is normal to the plane of the rotor  14 . However, due to manufacturing tolerances and in some cases manufacturing defects, often one of the axes of the threaded bores  34 , the distal ends  32  of the attachment bosses  30  or the plane of the rotor  14  are not precisely in the desired alignment. A structure for adjustably attaching the caliper to a bicycle frame  28  is intended to allow for necessary realignment. 
     The structure for adjustably attaching the caliper to a bicycle frame  28  consists of first and second pairs of washers  36 ,  38 . A first washer  40  of the washer pair  36  has a concave semispherical surface  42  and a flat surface  44  with a hole  45  extending there between. The second washer  46  of the washer pair  36  has a convex semispherical surface  48  which mates with the concave surface  42 . Opposite the convex surface  48  is a flat surface  50 . A hole  51  extends between the surfaces. The second washer pair  38  is identical to the first washer pair  36 . The first and second washer pairs  36 ,  38  reside between the distal ends  32  of the attachment bosses  30  and the bottom  52  of a mounting foot  54  of the caliper  12 . Third and fourth identical washer pairs  56 ,  58  reside between a top surface  60  of the mounting foot  54  and the head  62  of bolt  64 . The mounting foot  54  has a pair of elongate slots  66  which extend lengthwise parallel to the select axis  24 . The shaft  68  of the bolt  64  is axially received through the holes in the third washer pair and the elongate slot  66  and the holes in the first washer pair  36  and the shaft  68  is threadably engaged with the bore  34  of the attachment boss  30 . A conventional washer  70  may be further provided adjacent the head  62  of the attachment bolt  64 . 
     In use, with the caliper attached as described above, the caliper is moveable in several directions which enable the angle of incidence of the select axis  24  to vary infinitely within a select range so that the select axis  24  can be aligned normal to the plane of the rotor  14 . Referring to FIG. 1, arrow  72  illustrates how the caliper can be moved by translation toward and away from the rotor  14 . This movement is also illustrated by the arrows  72  in FIG.  5 . This movement is possible by virtue of the elongate slots  66 . The elongate slots  66  also enable canting of the caliper  12  relative to the rotor  14  as illustrated by arcuate arrow  74  in FIG.  1  and also in FIG.  6 . Finally, the caliper can be pivoted about a virtual axis  76  such that the caliper is in essence hinged about the engaging concave and convex surfaces of the first and second washer pairs  36 ,  38 . This movement is illustrated by the arrow  78  in FIGS. 1 and 7. 
     By virtue of the canting movement allowed by the elongate slots  66  and the hinged movement allowed by the engaging concave and convex surface of the first and second washer pairs  36 ,  38 , the select axis  24  can be moved relative to the plane of the rotor  14  to have an angle of incidence which is infinitely variable in three dimensions within a select range of movement. Thus, the caliper  12  can be aligned so that the select axis  24  is normal to the plane of the rotor  14 . Furthermore, the elongate slot  66  enables translational movement of the caliper relative to the rotor  14  to allow the rotor  14  to be placed in a desired position between the brake pads  22 . 
     FIG.  3 . illustrates a second embodiment of the structure for adjustably attaching the caliper to a bicycle frame  28 A. As best seen in FIG. 4, this embodiment, a mounting bracket  86  is fixedly attached to a chain stay  88  which would be at the rear of the bicycle frame. A bracket  90  is at the intersection of the chain stay  88  and the seat stay  92  to which a wheel, which has been omitted for clarity, can be attached to the rear of the bicycle frame. The rotor  14 A is fixedly attached to a hub of the wheel. As with rotor  14  of FIG. 1, rotor  14 A is maintained in a fixed plane relative to the wheel and the chain stay  88 . The mounting bracket  86  has a pair of internally threaded bores  93  the openings of which lie in a plane defined by the surface  94  which is intended to be substantially perpendicular to the plane of the caliper  14 A. 
     The second embodiment of the attachment structure for adjustably attaching a caliper to a bicycle frame  28 A consists of an elongate plate  94  having a pair of transverse elongate slots  96  extending between a concave surface  98  and a flat surface  100 . The caliper  12 A has a mounting foot  50 A having an elongate convex bottom surface  102  which mates with the concave surface  98  of the elongate plate  94 . A pair of elongate slots  104  corresponding with and aligning with the elongate slots  96  in the elongate plate  94  extend parallel to the select axis  24  between the top  106  and the convex bottom  102  of the foot  50 A. First and second washer pairs  108 ,  110  which are identical to the washer pair  36  discussed above with regard to FIG. 2, reside between the head  62 A of the attachment bolt  64 A and the top  106  of the mounting foot  50 A. The shafts  68 A are axially received by an optional conventional washer  111  and the washer pairs  108 , 110 , the elongate slots  104 , in the mounting foot  50 A, and the elongate slots  96  in the elongate plate  94  and threadably engaged in the threaded bores  93  to maintain the caliper in a select position. 
     As with the first embodiment discussed with referenced FIGS. 1,  2 ,  5 ,  6  and  7 , the elongate slots  96 ,  104  allow translational movement in the direction of the arrow  72  and canting movement in the direction of the arcuate arrow  74 . The mating concave and convex surfaces allow for hinged movement as illustrated by arrow  78 . In this manner, the second embodiment  28 A allows for the same movement and adjustable attachment as the first embodiment  28 . 
     It should be noted that the first and second washer pairs  36 ,  38  could be substituted for the plate  94  and the convex surface  102  of the foot  50 A. However, the second embodiment provides a greater surface area to resist slipping. 
     FIG. 8 illustrates a third embodiment in the present invention that allows for a fourth direction of movement of the caliper  12 . In this embodiment, a caliper attachment bracket  120  consists of a rod  122  attached to footing plates  124  at each end. The footing plates  124  include elongate slots  126 . The footing plates  124  are attachable to the distal ends of the attachment bosses  30  discussed with reference to FIGS. 1 and 2. A plate  128  having a transverse chanel  130  therein for receiving the bar  122  has a number of holes  132  to allow for fixed attachment of the plate  128  to the bottom of the caliper  12  with a number of screws or bolts, not shown. Once attached, the caliper can be moved translationally as indicated by the arrow  72  canted relative to a rotor illustrated by the arcuate arrows  74  in a hinged manner as illustrated by the arcuate arrow  78  and axially of the bar  122  as illustrated by the arrow  134 . Thus, the third embodiment illustrated in FIG. 8 allows for an additional direction of travel over the first and second embodiments  28 ,  28 A. 
     The caliper attachment structure of the present invention allows for a great range of movement of the caliper so that the caliper pads can travel along a select axis normal to the plane of the operatively associated rotor regardless of manufacturing tolerances and minor defects. In this manner, braking efficiency can be maximized by assuring that the brake pads are brought into full-flush contact with the rotor. In addition, undesired rubbing between the caliper pads and rotor by misalignment can be minimized. The caliper attachment structure also provides for virtually instantaneous self-alignment. The user need only loosen the attachment bolts, actuate the caliper to advance the brake pads into engagement with the rotor and then tighten the attachment bolts. The attachment structure therefore compensates for manufacturing tolerances and manufacturing defects which can result in misalignment between caliper pads and a rotor of a disc brake system. As can be readily appreciated, these many advantages are provided by a structure which is capable of being fabricated from off the shelf parts and is easily assembled and, perhaps most importantly, is extremely easy for a user to employ.