Abstract:
A motorcycle including a front wheel, a rear wheel, a frame, a seat and handlebars is disclosed. The motorcycle includes a linkage connecting a brake pedal with a caliper. The caliper is located within a body perimeter of the motorcycle. The caliper is adapted to engage a disk and the caliper can have a line of action. The direction of the line of action of the caliper can be different than the axis of rotation of the rear wheel. The linkage can also convert vertical motion into horizontal motion.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention is directed to motorcycles, and in particular, to a linkage for a motorcycle braking system. 
   2. Background of the Invention 
   Conventional motorcycles include front and rear brakes. Often, these brakes are in the form of disk brakes mounted to the respective front and rear axles. Specifically, rear brake assemblies generally include a rear disk mounted to a rear axle. The rear disk rotates with the rear wheel. Calipers or other devices apply a braking force to the rear disk brake, which in turn, provides a braking force to the rear wheel. 
   Most of the braking on a motorcycle is done by the front disk brake. It has been estimated that from 60% to 80% of the braking is done by the front wheel. Also, it is typical for the front disk brake to be applied using a hand lever disposed on a handle bar and operated by a rider&#39;s hand. In contrast, the rear disk brake is typically applied by using a brake pedal operated by one of the rider&#39;s feet. 
   This braking arrangement can make proper braking of the rear wheel difficult. Because the majority of the braking is done by the front wheel, very little force is required to brake the rear wheel. Because of this, the rear wheel can be locked up easily during braking. This lock up problem is compounded by the fact that the rider must brake the rear wheel with the rider&#39;s foot as opposed to the rider&#39;s hand. Riders generally find their feet less sensitive and more difficult to precisely control than their hands. A braking system that provides better brake feel and more precise control is needed. 
   On conventional motorcycles, rear brakes are disposed coaxially with the rear wheel. In other words, the rear brake, be it a disk or drum, shares the same axis of rotation as the rear wheel. In this conventional design, the rear brake assembly moves with the rear wheel. All of the bumps and all of the vibrations experienced by the rear wheel is also experienced by the rear brake assembly. Because of this, braking on bumpy or uneven surfaces can be difficult because the vibration of the rear brake assembly can interfere with brake feel and make it difficult to properly modulate the braking force on the rear wheel. 
   Also, because conventional rear brake assemblies are mounted coaxially with the rear wheel, the weight or mass of the rear brake assembly is unsprung weight. Any increase in unsprung weight is not desirable and is detrimental to a vehicle&#39;s dynamics, balance and handling characteristics. 
   SUMMARY 
   A motorcycle with a linkage is disclosed. In one aspect, the motorcycle includes a braking system comprising a brake pedal connected to a first end of brake arm, the brake arm rotating about a brake arm fulcrum in a first plane. The second end of the brake arm is connected to a rocker arm and the rocker arm rotates in a second plane, where the second plane being different than the first plane. A follower assembly is connected to the rocker arm and is adapted to move across the width of the motorcycle. 
   In another aspect, a downward motion of the brake pedal causes the second end of the brake arm to move upwards. 
   In another aspect, an upward motion of the second end of the brake arm causes the rocker arm to rotate counter-clockwise. 
   In another aspect, the counter-clockwise rotation of the rocker arm causes the follower assembly to move in a generally horizontal direction. 
   In another aspect, a distal end of the follower assembly is mechanically associated with a caliper and motion of the distal end of the follower assembly actuates the caliper and the caliper squeezes at least one brake pad against a disk. 
   In another aspect, the invention provides a motorcycle comprising a front wheel, a rear wheel, a frame, a seat and handlebars. The motorcycle also has a body perimeter and a mechanical linkage connecting a brake pedal with a caliper. The caliper is located within the body perimeter of the motorcycle. 
   In another aspect, the brake pedal is on one side of the motorcycle and the caliper is on the other side of the motorcycle. 
   In another aspect, the mechanical linkage includes a follower assembly that extends from one side of the motorcycle to the other side of the motorcycle. 
   In another aspect, the mechanical linkage converts vertical motion into horizontal motion. 
   In another aspect, the brake pedal pivots about a brake arm fulcrum and includes a forward brake arm and a rear brake arm, and wherein the forward brake arm is adapted to receive a rider&#39;s foot, and wherein the rear brake arm is connected to an actuator that can be driven upwards. 
   In another aspect, the actuator is connected to a first end of a rocker arm and upwards motion of the actuator rotates the rocker arm, and wherein a follower assembly is connected to a second end of the rocker arm, whereby rotation of the rocker arm moves the follower assembly in a generally horizontal direction. 
   In another aspect, the mechanical linkage includes a rocker arm that converts generally vertical motion into generally horizontal motion. 
   In another aspect, the invention provides a motorcycle comprising a front wheel, a rear wheel having an axis of rotation, a frame, a seat and handlebars. The motorcycle also includes a braking system including a linkage that associates a brake pedal with a caliper. The caliper has a line of action and is adapted to engage a disk. The line of action of the caliper has a direction that is different than the axis of rotation of the rear wheel. 
   In another aspect, the caliper includes a first disk pad and a second disk pad, and the second disk pad is disposed forward of the first disk pad. 
   In another aspect, the first and second disk pads are disposed laterally with respect to the motorcycle. 
   In another aspect, the linkage includes a rocker arm that converts generally vertical motion into generally horizontal motion. 
   In another aspect, the linkage includes a follower assembly that extends from one side of the motorcycle to the other side. 
   In another aspect, the follower assembly moves in a generally horizontal direction and wherein the horizontal motion of the follower assembly actuates the caliper. 
   In another aspect, the line of action of the caliper is in a direction substantially similar to a longitudinal axis of the motorcycle. 
   In another aspect, the caliper engages a disk adapted to brake a rear wheel and having an axis of rotation different than the axis of rotation of a rear wheel. 
   Other configurations, features and advantages of the invention will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the following claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views. In the drawings: 
       FIG. 1  is a perspective view of a preferred embodiment of a motorcycle in accordance with the present invention; 
       FIG. 2  is an elevation view of the motorcycle shown in  FIG. 1 ; 
       FIG. 3  is an enlarged perspective view of the right side of motorcycle shown in  FIG. 1 ; 
       FIG. 4  is an enlarged view of a preferred embodiment of a brake pedal and associated components in accordance with the present invention; 
       FIG. 5  is a perspective view of the left side of the motorcycle shown in  FIG. 1 ; and 
       FIG. 6  is an enlarged perspective view of a preferred embodiment of a caliper in accordance with the present invention. 
   

   DETAILED DESCRIPTION 
     FIG. 1  is a perspective view of a preferred embodiment of a motorcycle  100  in accordance with the present invention. Motorcycle  100  includes a first side  102  and a second side  104 . In the embodiment shown in  FIG. 1 , first side  102  is the right side, from the perspective of the rider, and second side  104  is the left side from the perspective of the rider. 
   Motorcycle  100  also includes a longitudinal axis  120  and a lateral axis  122 . Longitudinal axis  120  extends along the length of motorcycle  100 . One direction of longitudinal axis  120  is a forward direction  124  and another direction of longitudinal axis  120  is a rearward direction  126 . Lateral axis  122  extends generally from one side to the other. In the embodiment shown in  FIG. 1 , lateral axis  122  extends in a left direction  130  and a right direction  128 . Lateral axis  122  generally extends in a direction different than longitudinal axis  120 . In some embodiments, lateral axis  122  is generally perpendicular to longitudinal axis  120 . 
   Motorcycle  100  includes a handlebar  106 , which is designed to be grasped by a rider and used by the rider to control motorcycle  100 . Handlebar  106  includes a right portion and a left portion. Right portion of handlebar  106  includes a lever  108  that controls front brake  140  (see  FIG. 2 ) and the left portion of handlebar  106  includes a clutch lever  110  that controls the clutch, as conventionally known. 
   Motorcycle  100  also includes additional controls in the form of pedals designed to be operated by the feet of the rider. Left pedal  114  (see  FIGS. 2 and 5 ) includes a shifter and right pedal  112  is used to brake rear wheel  116 . Right pedal  112  can also be referred to as a brake pedal. 
     FIG. 2  is an elevational view of motorcycle  100 .  FIG. 2  shows the left side  104  of motorcycle  100 . The front portion of motorcycle  100  includes front brake  140 , which comprises front caliper  142  and front disk  144 . Front disk  144  rotates about front axle  146 . Front wheel  148  also rotates about front axle  146 . Front wheel  148  and front disk  144  are rigidly related, so that a braking force imposed on front disk  144  is transferred to front wheel  148 . Front axle  146  is associated with front fork  154 . Preferably, front fork  154  includes one or more shock absorbers that provide a front suspension system to motorcycle  100 . 
   Preferably, motorcycle  100  includes a rear suspension. In some embodiments, motorcycle  100  includes a rear suspension that includes a swing arm assembly  156 . Swing arm assembly  156  is attached to frame  204  by a rear pivot  150 . The rear suspension can also include a shock absorber  152 . The preferred embodiment of shock absorber  152  is disclosed in U.S. patent application Ser. No. 10/730,282 filed on Dec. 9, 2003, which is assigned to the same assignee as the present application, the entirety of which is incorporated by reference herein. 
   Motorcycle  100  also includes a body perimeter  160 . Body perimeter  160  is defined as an imaginary boundary around frame  204  and all of the components connected to it except for those items that are designed to move freely relative to frame  204 . In the embodiment shown in  FIG. 2 , handlebar  106  and swing arm assembly  156  would be excluded from body perimeter  160  because those items are designed to move freely with respect to frame  204 . 
   As known in the vehicle arts, the “sprung weight” of a vehicle refers to the weight of all the components that are supported by the suspension system. In contrast, “unsprung weight” refers to all of the components that are not supported by the suspension system. Unsprung weight includes those components that are mounted outboard of the suspension systems and typically include items such as wheels and tires, brake assemblies, and front and rear axles. Regarding suspension components such as swing arms, forks and shock absorbers it is common practice to divide the mass or weight of these components between sprung weight and unsprung weight. So, for example, front fork might be assigned a sprung weight percentage of N % and an unsprung weight percentage of (100-N)%. Sprung weight is also sometimes referred to as “sprung mass.” 
     FIG. 3  is an enlarged view of the right side  102  of motorcycle  100 . Referring to  FIG. 3 , peg  202  is mounted to frame  204 . Preferably, peg  202  can be pivoted or folded to a non-use position if desired. Brake pedal  112  is mounted to brake arm  205  that includes a forward brake arm portion  206  and a rear brake arm portion  208 . Disposed between forward brake arm  206  and rear brake arm  208  is brake arm fulcrum  210 . Preferably, brake arm  205  rotates about brake arm fulcrum  210 , which is rotationally associated with frame  204 . In other words, brake arm  205  is attached to frame  204  at brake arm fulcrum  210  in a manner that permits brake arm  205  to rotate relative to frame  204 . The rotation of brake arm  205  occurs in a first plane. In the embodiment shown in the Figures, this first plane extends in a generally longitudinal direction. 
   Referring to  FIG. 4 , which is an enlarged view of brake pedal  112  and other associated components, the operation of brake pedal  112  and its associated linkage can be observed. As brake pedal  112  is pressed downwards  302 , brake arm  205  rotates clockwise about brake arm fulcrum  210 . This clockwise motion  302  tends to move rear brake arm  208  upwards  304 . Rear brake arm  208  is connected to an actuator  306 , which is also driven upwards  304  by the motion of rear brake arm  208 . 
   Actuator  306  is connected to a first arm  307  of rocker arm  308 . This in turn, induces rocker arm  308  to rotate  312  about rocker arm fulcrum  310  in a counter clockwise direction  312 . The rotation  312  of rocker arm  308  occurs in a second plane. This second plane is different than the first plane, in which brake arm  205  rotates. In the embodiment shown in the Figures, this second plane extends in a generally lateral direction. Rocker arm  308  includes a second arm  309 . Second arm  309  is connected to follower assembly  314  and spring  316 . Rocker arm  308  pivots or rotates about rocker arm fulcrum  310  against the bias of spring  316 , which is designed to bias rocker arm  308  in a clockwise direction. This bias also helps to raise brake pedal  112  to a rest position, as shown in  FIG. 4 . 
   The counter clockwise motion  312  of rocker arm  308  causes follower assembly  314  to move in an inward direction, towards the inner portion of motorcycle  100  (see  FIG. 1 ) and towards the other side of the motorcycle. In some cases, follower assembly  314  can move in a generally horizontal direction. 
   The motion of follower assembly  314  on the left side  104  of motorcycle  100 , as well as components on the left side  104  of motorcycle  100 , can be observed with reference to  FIGS. 2 ,  5  and  6 . 
     FIG. 5  shows a perspective view, looking forward, of the left side  104  of motorcycle  100 . Referring to  FIGS. 2 and 5 , motorcycle  100  includes a left peg  402  and a shifter  114 . Shifter  114  is mechanically linked to gearbox  404  and gearbox  404  is mechanically coupled to engine  430 , as is conventionally known. 
   The output shaft of gearbox  404  is attached to rear disk brake assembly  406 . Rear disk brake assembly  406  includes disk  408 , caliper  410  and fender  412 . Fender  412  is designed to keep the rider, passenger or articles of clothing from being caught in disk  408 . In the embodiment shown in the Figures, the output shaft is connected to first side  440  (see  FIG. 6 ) of disk  408 . A universal joint  420  is attached to the rear, or second side  442  of disk  408  and a drive shaft  422  is attached to universal joint  420 . Disk  408  includes an axis of rotation centrally located on disk  408 . Disk  408  rotates about this axis of rotation. Axis of rotation of disk  408  can be similar to the axis of rotation of the output shaft of gearbox  404 . The axis of rotation of disk  408  can also be similar to the axis of rotation of the portion of universal joint  420  attached to disk  408 . In some embodiments, universal joint  420  is replaced by a constant velocity (CV) joint. CV joints can be used when a more consistent angular velocity output is desired. Drive shaft  422  drives rear wheel  116  through a typical shaft drive arrangement. 
   Preferably, as shown in  FIG. 2 , disk  408  is disposed within body perimeter  160  of motorcycle  100 . As noted above, body perimeter  160  of motorcycle  100  is an imaginary boundary that encompasses those components that are attached to frame  204 . So this imaginary boundary extends to the periphery of all of the components attached to frame  204 . As shown in  FIG. 2 , disk  408  is mounted within body perimeter  160 . In some embodiments, rear disk brake assembly  406 , in addition to disk  408 , is located within body perimeter  160 . 
   Preferably, rear brake assembly  406  is also located on motorcycle  100  as sprung weight. Recall that sprung weight or sprung mass means that a component is supported by the vehicle&#39;s suspension system. Thus, it is preferred that rear brake assembly  406  be supported by the suspension of motorcycle  100 . 
   In the embodiment shown in the Figures, sprung weight would include all of the components mounted inboard or inward of front fork  154 —in those embodiments where front fork  154  includes front suspension components and provides the front suspension for motorcycle  100 —and forward, or inward of rear suspension  152 . In contrast to sprung weight, in the embodiment shown in the Figures, unsprung weight would include those components mounted outboard, or beyond front fork  154 , such as front wheel  148 , front axle  146  and front brake assembly  140 . Unsprung weight would also include those components mounted outboard, or beyond rear suspension  152 . In the embodiment shown in the Figures, that would include rear wheel  116  and rear drive assembly  118 . 
   Applying these definitions to the embodiment shown in the Figures, disk  408  clearly qualifies as sprung weight as opposed to unsprung weight. As shown in the Figures, disk  408  is mounted so that its weight is supported by the front suspension and the rear suspension. Front fork  154  provides the front suspension and rear suspension  152  is shown in  FIG. 2 . In the embodiment shown in the Figures, disk  408  qualifies as sprung weight because its weight is supported by front fork  154  and rear suspension  152 . 
   It can also be observed that disk  408  is spaced from rear wheel  116  and disposed inboard of rear wheel  116 . In this arrangement, braking force is applied to disk  408 , which is attached to drive shaft  422 , as opposed to braking force being directly applied to rear wheel  116 . Because disk  408  is rotationally mounted to the output shaft of gearbox  404  as opposed to a moving wheel, this inboard arrangement provides better brake feel and modulation, especially on bumpy surfaces. Also, because disk  408 , caliper  410 , fender  412  and other components that comprise disk brake assembly  406  are mounted in a manner that qualifies brake assembly  406  as sprung weight, this arrangement reduces overall unsprung weight of motorcycle  100 . This enhances the ability of the rear suspension to control rear wheel motion. This also improves the dynamics and balance of motorcycle  100  and also improves handling. This arrangement also makes braking easier and requires less foot pressure from the rider than a typical braking system. 
   As shown in  FIGS. 2 ,  4  and  6 , disk  408  of rear brake assembly  406  is disposed proximate gearbox  404  and receives the output shaft of gearbox  404 . Preferably, the output shaft of gearbox  404  is coupled directly to disk  408  so that disk  408  shares a similar axis of rotation as the output shaft. In some embodiments, disk  408  and the output shaft share the same axis of rotation. Because of this arrangement, the axis of rotation of disk  408  is more closely aligned with the longitudinal axis  120  (see  FIG. 1 ) of motorcycle  100  than the lateral axis  122  (see  FIG. 1 ) of motorcycle  100 . In some embodiments, the axis of rotation of disk  408  is nearly parallel to longitudinal axis  120 . 
   It can also be observed that the axis of rotation of disk  408  has a different direction than lateral axis  122  and also extends in a direction different the axis of rotation of rear wheel  116 . It can also be observed that the axis of rotation of disk  408  is spaced from the axis of rotation of rear wheel  116 . 
   Returning to the motion of follower assembly  314 ,  FIG. 6  is an enlarged perspective view of caliper  410 . Follower assembly  314  is attached to a bottom portion of caliper  410 . Recall from above that follower assembly  314  is being pushed from the right side  102  of motorcycle  100  to the left side  104  of the motorcycle  100 . As shown in  FIG. 6 , distal end  502  of follower assembly  314  tends to move away from motorcycle  100  in direction  504 . This motion squeezes caliper  410  so that first brake pad  506  and second brake pad  508  engage disk  408 . 
   First brake pad  506  is disposed rearward of second brake pad  508 . These disk pads move towards each other when caliper  410  is activated. The disk pads  506  and  508  have a line of action  510  that is in a direction generally different than lateral axis  122  (see  FIG. 1 ). In the embodiment shown in the figures, rear wheel has an axis of rotation that is generally similar to lateral axis  122 . It can be observed that the line of action of disk pads  506  and  508  is generally different than the axis of rotation of rear wheel  116 . In some embodiments, line of action  510  is in a direction that is similar to longitudinal axis  120  (see  FIG. 1 ). 
   While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that may more embodiments and implementations are possible that are within the scope of the invention.